Topiramate is an oral antiepileptic drug (AED) used for partial-onset, generalized primary tonic-clonic seizures, and as an adjunct therapy in Lennox-Gastaut syndrome. It is derived from the naturally occurring monosaccharide D-fructose and is structurally different from other AEDs. Unlike other AEDs, topiramate appears to block the spread of seizures rather than raise the seizure threshold. Topiramate possesses more than one mechanism of action, which may explain why it can be effective in patients with various seizures that are refractory to other agents. Topiramate continues to be studied as both add-on therapy and monotherapy in various refractory epilepsies in children and adults, including infantile spasms associated with West syndrome. It is also used for migraine prophylaxis in adult and pediatric patients. There is some evidence of a role for topiramate treatment 'off-label' for eating disorders such as binge-eating disorder, for tics due to Tourette's syndrome or other chronic tic disorders, or for substance abuse disorders such as alcohol or cocaine dependence.
General Administration Information
For storage information, see specific product information within the How Supplied section.
Hazardous Drugs Classification
-NIOSH 2016 List: Group 3
-NIOSH (Draft) 2020 List: Table 2
-Observe and exercise appropriate precautions for handling, preparation, administration, and disposal of hazardous drugs.
-Use gloves to handle. Cutting, crushing, or otherwise manipulating tablets/capsules will increase exposure and require additional protective equipment. Eye/face and respiratory protection may be needed during preparation and administration.
Route-Specific Administration
Oral Administration
-May administer without regard to meals.
Oral Solid Formulations
Tablets
-Do not break the tablets due to bitter taste.
Sprinkle capsules
-Swallow whole. Alternatively, sprinkle the contents of the capsule on a small amount of soft food (e.g., applesauce, custard, ice cream, oatmeal, pudding, yogurt). Prepare entire dose and swallow immediately after preparation. Do not chew. Drink fluids to ensure entire dose is swallowed. Do not store any drug/food mixture for use at a later time.
-Additionally, the capsule contents may be administered via nasogastric (NG) tube; use an adequate amount of fluid to wash the full dose down the tube.
Trokendi XR extended-release capsules
-Swallow whole and intact. Do not sprinkle on food, chew, or crush.
-Extended-release capsules are not recommended for children younger than 6 years, as they must be swallowed whole and intact.
Qudexy XR extended-release capsules
-Swallow whole or sprinkle contents of the capsule on a small amount (teaspoon) of soft food. Prepare entire dose and swallow immediately after preparation. Do not chew or crush. Do not store any drug/food mixture for use at a later time.
Oral Liquid Formulations
Oral solution (25 mg/mL)
-Administer using a calibrated measuring device.
-Storage: Discard unused medication 30 days after opening the bottle.
Extemporaneous Compounding-Oral
Topiramate 20 mg/mL Oral Suspension
NOTE: A 25 mg/mL oral solution is commercially available. ASHP recommends topiramate 20 mg/mL as the compounded oral liquid standard concentration; however, this recommendation was made prior to commercial availability of a 25 mg/mL oral solution.
-Measure out 2,000 mg of topiramate tablets or powder. If tablets are used, pulverize them to a fine powder.
-Mix the powder with about 10 mL of Ora-Plus to form a smooth, uniform paste.
-Geometrically incorporate 40 mL of Ora-Plus and mix well.
-Add Ora-Sweet in a sufficient quantity for a final volume of 100 mL and mix well.
-Shake well prior to administration.
-Storage: Store in a tight, light-resistant container at controlled room temperature or in the refrigerator for up to 90 days.
Eleven percent of patients receiving topiramate 200 to 400 mg/day as adjunctive epilepsy therapy discontinued the drug due to adverse events. Of the 1,715 adult epileptic patients treated with topiramate at doses of 200 to 1,600 mg/day, 28% discontinued treatment because of adverse reactions which included sleepiness (3.2%), feeling dizzy (2.6%), balance issues (2.2%), paresthesia (2%), and language problems (2%). Side effects in pediatric patients at age and weight-adjusted dosages are similar to those of adults. Common adverse reactions reported in the monotherapy trials were similar to those reported in the adjunctive trials. Approximately 21% of the 159 adult patients in the 400 mg/day group who received topiramate as monotherapy in the controlled clinical trial discontinued therapy due to adverse events.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, the following centrally-mediated effects were reported in patients receiving 50 mg per day vs. 400 mg per day, respectively: paresthesias (21% vs. 40%), dizziness (13% vs. 14%), hypoesthesia (4% vs. 5%), ataxia (3% vs. 4%), drowsiness (10% vs. 15%), and insomnia (8% vs. 9%). During monotherapy evaluation of epilepsy in pediatric patients 6 to 15 years of age, paresthesias (3% vs. 12%), involuntary movements/muscle contractions (0% vs. 3%), and vertigo (0% vs. 3%) occurred in patients receiving topiramate 50 mg per day and 400 mg per day, respectively. In monotherapy clinical trials of topiramate 50 to 200 mg/day for the prophylaxis of migraines, the following CNS effects occurred more frequently with topiramate than placebo: paresthesias (35% to 51% vs. 6%), dizziness (8% to 12% vs. 10%), hypoesthesia (6% to 8% vs. 2%), language problems (6% to 7% vs. 2%), involuntary movements/muscle contractions (2% to 4% vs. 1%), ataxia (1% to 2% vs. < 1%), speech disorders/related speech problems such as dysarthria (<= 2% vs. < 1%), drowsiness (8% to 10% vs. 5%), and insomnia (6% to 7% vs. 5%). Dizziness (<= 6% vs. 4%), headache (2% to 8% vs. 2%), language problems (<= 15% vs. 2%), involuntary muscle contractions (<= 8% vs. 0%), insomnia (<= 9% vs. 2%), drowsiness (2% to 15% vs. 2%), and paresthesias (19% to 38% vs. 7%) were also reported during adolescent trials. Paresthesias, dizziness, drowsiness, and hypoesthesia were considered dose-related CNS effects. Aphasia (2%) and irritability (2%) were reported during adult adjunct therapy epilepsy trials. Other CNS effects reported during epilepsy clinical trials (monotherapy or adjunct therapy) in 0.1% to 1% of patients included peripheral neuropathy, apraxia, hyperesthesia, dysphonia, scotomata, ptosis, and EEG changes. Rare effects (< 0.1%) included upper motor neuron lesion, acute cerebellar syndrome, and tongue paralysis. During clinical trial evaluation of topiramate for the prophylaxis of migraines, headache, vertigo, tremor, sensory disturbance, and aggravated migraine were reported in > 1% of patients. Hyperkinesis (5%), hyporeflexia (2%), and grand mal seizures (1%) were reported in add-on epilepsy trials in pediatric patients.
All patients beginning treatment with anticonvulsants or currently receiving such treatment should be closely monitored for emerging or worsening suicidal thoughts/behavior, depression, or other changes in mood/behavior. During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, the following psychiatric effects were reported in patients receiving 50 mg per day vs. 400 mg per day, respectively: difficulty with memory NOS (memory impairment) (6% vs. 11%), depression (7% vs. 9%), impaired concentration/attention (7% vs. 8%), anxiety (4% vs. 6%), psychomotor impairment (3% vs. 5%), emotional lability (2% vs. 5%), cognitive impairment (1% vs. 4%), and libido decrease (0% vs. 3%). During monotherapy evaluation of epilepsy in pediatric patients 6 to 16 years of age, the following psychiatric effects were reported in patients in the 50 mg per day group vs. the 400 mg per day group: emotional lability (1% vs. 8%), impaired concentration/attention (7% vs. 10%), memory impairment (1% vs. 3%), cognitive impairment (1% vs. 6%), confusion (0% vs. 3%), depression (0% vs. 3%), and behavior problems (0% vs. 3%). In monotherapy adult clinical trials of topiramate 50 to 200 mg per day for migraine prophylaxis, the following effects occurred more frequently in the active treatment groups than the placebo group: memory impairment (7% to 11% vs. 2%), impaired concentration/attention (3% to 10% vs. 2%), anxiety (4% to 6% vs. 3%), emotional lability (3% to 6% vs. 2%), depression (3% to 6% vs. 4%), nervousness (4% vs. 2%), confusion (2% to 4% vs. 2%), psychomotor impairment (2% to 4% vs. 1%), libido decrease (1% to 2% vs. 1%), worsening depression (1% to 2% vs. 1%), agitation (1% to 2% vs. 1%), and cognitive impairment (< = 2% vs. 1%). Anxiety (<= 8% vs. 0%), impaired concentration/attention (<= 15% vs. 0%), memory impairment (<= 8% vs. 2%), emotional lability (2% to 8% vs. 4%), and psychomotor impairment (<= 8% vs. 0%) were also prevalent in adolescent migraine trials; in addition, nervousness was reported in >= 2% of adolescents. Hallucinations, psychosis, and suicide attempt were reported in > 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy. Euphoria, paranoia, delusions, delirium, and abnormal dreaming were reported 0.1% to 1% of patients. Rare effects (< 0.1%) included libido increase and mania (manic reaction). Anticonvulsants, including topiramate, are thought to carry an increased risk of suicidal ideation and behavior. An analysis by the FDA of previously gathered drug data showed that patients receiving anticonvulsants had approximately twice the risk of suicidal behavior or ideation (0.43%) as patients receiving placebo (0.24%). The relative risk for suicidality was higher in patients with epilepsy compared to those with other conditions. Age was not a determining factor. The increased risk of suicidal ideation and behavior occurred between 1 and 24 weeks after therapy initiation. However, a longer duration of therapy should not preclude the possibility of an association to the drug since most studies included in the analysis did not continue beyond 24 weeks. Patients and caregivers should be informed of the increased risk of suicidal thoughts and behaviors and should be advised to immediately report the emergence or worsening of depression, the emergence of suicidal thoughts or behavior, thoughts of self-harm, or other unusual changes in mood or behavior.
Hyperammonemia with and without encephalopathy has been reported with topiramate use and may be dose-related. In adolescent migraine prophylaxis trials, the incidence of hyperammonemia was 9% for placebo, 14% for topiramate 50 mg/day, and 26% for 100 mg/day. The incidence of markedly increased hyperammonemia (i.e., ammonia values at least 50% higher than the upper limit of normal) was 3% for placebo, 0% for topiramate 50 mg/day, and 9% for 100 mg/day; markedly abnormal concentrations returned to normal in all but 1 patient during the trial, in whom concentrations decreased to high instead of markedly abnormal. Although hyperammonemia can occur with topiramate monotherapy, it appears to be more common with adjuvant valproate therapy. Concomitant administration of topiramate and valproate may exacerbate existing metabolic deficits or unmask deficiencies in susceptible persons, and has been associated with hyperammonemia in patients who have tolerated either drug alone. Monitor serum ammonia concentrations in patients who develop unexplained lethargy, vomiting, changes in mental status, or hypothermia (i.e., an unintentional drop in core body temperature to < 35 degrees C), as these may be symptoms of hyperammonemic encephalopathy. Hypothermia may also occur in the absence of hyperammonemia. Patients who develop unexplained symptoms of hyperammonemic encephalopathy or hypothermia while receiving antiepileptic therapy should discontinue the afflicting drug and receive prompt treatment for hyperammonemia, if present. In most cases, signs and symptoms abate with discontinuation of either topiramate or valproate.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, the following gastrointestinal (GI) effects were reported in patients receiving 50 mg per day vs. 400 mg per day, respectively: constipation (1% vs. 4%), gastritis (0% vs. 3%), xerostomia (1% vs. 3%), dysgeusia (3% vs. 5%), gastroesophageal reflux (1% vs. 2%), anorexia (4% vs. 14%), and weight loss (6% vs. 17%). During monotherapy evaluation of epilepsy in pediatric patients 6 to 15 years of age, the following GI effects were reported in the 50 mg per day group vs. the 400 mg per day group: diarrhea (8% vs. 9%) and weight loss (7% vs. 17%). In monotherapy clinical trials of topiramate 50 to 200 mg per day for migraine prophylaxis, the following GI effects occurred more frequently with topiramate than placebo: nausea (9% to 14% vs. 8%), diarrhea (9% to 11% vs. 4%), abdominal pain (6% to 7% vs. 5%), dyspepsia (3% to 5% vs. 3%), xerostomia (2% to 5% vs. 2%), vomiting (1% to 3% vs. 2%), dysgeusia (8% to 15% vs. 1%), taste loss (1% to 2% vs. < 1%), anorexia (9% to 15% vs. 6%), weight loss (6% to 11%), and gastroenteritis (2% to 3% vs. 1%). Dysgeusia (2% to 8% vs. 2%), abdominal pain (7% to 15% vs. 9%), diarrhea (2% to 8% vs. 0%), nausea (<= 8% vs. 4%), weight loss (4% to 31% vs. 2%), anorexia (9% to 15% vs. 4%), and pharyngeal edema (<= 8% vs. 0%) were reported in adolescent migraine trials; vomiting and gastroenteritis also occurred in >= 2% of patients. Gingivitis was observed in 1% of adult patients receiving topiramate during add-on epilepsy trials; in pediatric patients, hypersalivation (6%), fecal incontinence (1%), flatulence (1%), glossitis (1%), dysphagia (1%), weight gain (1%), appetite stimulation (1%), and gingival hyperplasia (1%) were observed. Other GI effects reported in 0.1% to 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy included hemorrhoids, stomatitis, melena, gastritis, esophagitis, taste loss, and gingival bleeding. Tongue edema was reported rarely (< 0.1%). During clinical trial evaluation of topiramate for migraine prophylaxis, constipation and gastroesophageal reflux were reported in > 1% of patients.
Topiramate is associated with an increased risk for bleeding. In a pooled analysis of placebo-controlled trials, bleeding was more frequently reported for topiramate (4.5% adults and 4.4% pediatrics) than for placebo (3% adults and 2.3% pediatrics); serious bleeding events occurred in 0.3% vs. 0.2% of adult patients and 0.4% vs. 0% of pediatric patients for those treated with topiramate and placebo, respectively. Adverse events reported ranged from mild epistaxis, ecchymosis, and increased menstrual bleeding to life-threatening hemorrhage. In those with serious events, risk factors for bleeding were often present, or patients were taking other drugs that cause thrombocytopenia or affect platelet function or coagulation. During clinical trial evaluation of topiramate for migraine prophylaxis, epistaxis was reported in > 1% of adult patients and 2% to 8% of adolescent patients. In pediatric monotherapy trials for epilepsy, epistaxis was reported in 0% of patients receiving topiramate 50 mg per day and 4% of patients receiving 400 mg per day. Intractable epistaxis was reported in a 61 year old woman with cardiovascular disease who was receiving topiramate 25 mg daily for lower extremity neuropathy. Epistaxis developed 7 days after treatment initiation and resolved within 1 week of discontinuation. A rechallenge with topiramate 3 months later again resulted in epistaxis requiring 2 units of packed blood cells. According to the Naranjo probability scale, topiramate was the probable cause of epistaxis. Topiramate may modulate voltage-gated L type calcium ion channels located on vascular smooth muscle and non-contractile tissues such as platelets. During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, anemia was reported in 1% of patients receiving 50 mg per day and 2% of patients receiving 400 mg per day. In pediatric trials, anemia was reported in 1% of patients receiving 50 mg per day and 3% of patients receiving 400 mg per day. Leukopenia was reported in 1% to 2% of patients during add-on epilepsy trials in adults; in pediatric patients, thrombocytopenia (1%), purpura (8%), and hematoma (1%) were also observed. Deep vein thrombosis and thrombocytosis was reported infrequently (0.1% to 1%). Other hematologic effects reported rarely (< 0.1%) during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy included bone marrow depression, lymphadenopathy, eosinophilia, lymphopenia, granulocytopenia, and pancytopenia. Lymphocytosis and polycythemia were reported rarely (< 0.1%).
A syndrome consisting of acute myopia associated with secondary angle closure glaucoma has been reported in patients receiving topiramate. Symptoms include acute onset of decreased visual acuity and/or ocular pain. Ophthalmologic findings can include myopia, mydriasis, anterior chamber shallowing, ocular hyperemia (redness), choroidal detachments, retinal pigment epithelial detachments, macular striae, and increased intraocular pressure (ocular hypertension). This syndrome may be associated with supraciliary effusion resulting in anterior displacement of the lens and iris, with secondary closed-angle glaucoma. Symptoms typically occur within 1 month of initiating topiramate therapy. In contrast to primary narrow-angle glaucoma, which is rare in persons younger than 40 years, secondary closed-angle glaucoma associated with topiramate has been reported in children as well as adults. The primary treatment to reverse symptoms is discontinuation of topiramate as rapidly as possible. Other measures in conjunction with discontinuation of topiramate may be helpful. Elevated intraocular pressure of any etiology, if left untreated, can lead to serious sequelae including permanent vision loss. Visual field defects that are independent of elevated intraocular pressure have also been reported with topiramate in postmarketing experience. In clinical trials, most of these events were reversible after topiramate discontinuation. Consider discontinuing topiramate if visual problems occur at any time during topiramate treatment. In monotherapy clinical trials of topiramate 50 to 200 mg/day for migraine prophylaxis, the following ophthalmic effects occurred more frequently with topiramate than placebo: visual impairment (1% to 3% vs. less than 1%), blurred vision (2% to 4% vs. 2%), and conjunctivitis (1% to 2% vs. 1%). Nystagmus and diplopia were reported in 10% of adults during add-on epilepsy trials; in pediatric patients, abnormal lacrimation (1%) was also reported. Conjunctivitis was reported in more than 1% of adults during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy; incidence rates were 7% or less in adolescent migraine trials. Abnormal accomodation, photophobia, xerophthalmia, and strabismus were reported in 0.1% to 1% of patients. Rare effects (less than 0.1%) included mydriasis and iritis. During clinical trial evaluation of topiramate for migraine prophylaxis, abnormal accomodation and ocular pain were reported in more than 1% of adults; visual impairment and ocular pain were noted in 2% or more of adolescents. Maculopathy has occurred during postmarketing use.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, the following respiratory effects, infections, or related symptoms were reported in patients receiving 50 mg per day vs. 400 mg per day, respectively: viral infection (6% vs. 8%), infection (unspecified) (2% vs. 3%), bronchitis (3% vs. 4%), rhinitis (2% vs. 4%), and dyspnea (1% vs. 2%). During monotherapy evaluation of epilepsy in pediatric patients 6 to 15 years of age, the following effects occurred in patients receiving topiramate 50 mg per day vs. 400 mg per day, respectively: fever (1% vs. 12%), viral infection (3% vs. 6%), infection (unspecified) (3% vs. 8%), upper respiratory tract infection (16% vs. 18%), rhinitis (5% vs. 6%), bronchitis (1% vs. 5%), and sinusitis (1% vs. 4%). In monotherapy clinical trials for migraine prophylaxis, the following effects occurred more frequently with topiramate 50 to 200 mg per day than placebo: fever (1% to 2% vs. 1%), influenza-like symptoms (< = 2% vs. < 1%), secondary malignancy (<= 2% vs. < 1%), viral infection (3% to 4% vs. 3%), upper respiratory tract infection (12% to 14% vs. 12%), sinusitis (6% to 10% vs. 6%), pharyngitis (2% to 6% vs. 4%), cough (2% to 4% vs. 2%), bronchitis (3% vs. 2%), dyspnea (1% to 3% vs. 2%), and rhinitis (1% to 2% vs. 1%). Adolescent migraine trials reported fever (<= 6% vs. 2%), viral infection (4% to 15% vs. 4%), otitis media (<= 8% vs. 0%), cough (<= 7% vs. 0%), laryngitis (<= 8% vs. 0%), rhinitis (6% to 8% vs. 2%), sinusitis (4% to 15% vs. 2%), and upper respiratory tract infection (23% to 26% vs. 11%); infection (unspecified), influenza-like symptoms, pharyngitis, bronchitis, and asthma occurred in >= 2% of adolescent migraine patients. Thrombocythemia and pulmonary embolism were reported in 0.1% to 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy. Polycythemia was reported rarely (< 0.1%). During clinical trial evaluation for migraine prophylaxis, infection, genital candidiasis, pneumonia, and asthma (bronchospasm) were reported in > 1% of patients. Pallor (1%) has been reported in pediatric patients.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy, the following genitourinary (GU) effects were reported in adult patients receiving 50 mg/day vs. 400 mg/day, respectively: cystitis (1% vs. 3%), renal calculus or kidney stones (0% vs. 3%), urinary tract infection (1% vs. 2%), and increased urinary frequency (0% vs. 2%). In pediatric trials, increased urinary frequency (0% vs. 3%) and urinary incontinence (1% vs. 3%) were reported in patients receiving 50 mg/day vs. 400 mg/day, respectively. Urinary incontinence (1% to 2%) and hematuria (2% or less) were reported in adult patients during add-on epilepsy trials; in pediatric patients, urinary incontinence (1% to 4%) and nocturia (1%) were reported. In monotherapy clinical trials of 50 to 200 mg/day for migraine prophylaxis, the following GU effects occurred more frequently with topiramate than placebo: urinary tract infection (2% to 4% vs. 2%) and renal calculus (0% to 2% vs. 0%); adolescent migraine prophylaxis trials reported renal calculus (less than 1%), urinary incontinence (2% or more), and urinary tract infection (2% or more). Other GU effects reported in 0.1% to 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy included urinary retention, renal pain, albuminuria, polyuria, and oliguria. Topiramate has weak carbonic anhydrase inhibitor activity; carbonic anhydrase inhibitors promote stone formation by reducing urinary citrate excretion and by increasing urinary pH. During clinical trials of topiramate as monotherapy epilepsy treatment, overall 1.3% of topiramate-treated adult patients developed nephrolithiasis; the incidence was slightly higher in adjunct therapy trials (1.5%). This incidence is about 2 to 4 times that expected in a similar, untreated population and was higher in men. In a long-term open-label epilepsy study in pediatric patients 1 to 24 months old, 7% developed kidney or bladder stones. An increase in urinary calcium and a marked decrease in urinary citrate was observed in topiramate-treated pediatric patients ages 6 to 15 years in a 12-month active-controlled study. This increased ratio of urinary calcium/citrate increases the risk of kidney stones and/or nephrocalcinosis. Topiramate-treated pediatric patients (n = 28) demonstrated an increased risk for developing an increased serum creatinine concentration above the normal reference range. The concomitant use of topiramate with other carbonic anhydrase inhibitors or in patients on a ketogenic diet may create a physiological environment that increases the risk of kidney stone formation and should therefore be avoided. Instruct patients who are receiving topiramate and who have a history of kidney stones to increase their fluid intake in order to reduce the formation of kidney stones. Evaluate evidence of hematuria, dysuria, or crystalluria by renal ultrasound. Nephrocalcinosis has been observed with topiramate use during postmarketing experience.
Serious skin reactions (Stevens-Johnson syndrome [SJS] and toxic epidermal necrolysis [TEN]) have been reported in patients receiving topiramate. Discontinue topiramate at the first sign of a rash, unless the rash is clearly not drug-related. If signs or symptoms suggest SJS/TEN, do not resume topiramate use and consider alternative therapy. In a monotherapy epilepsy clinical trial in adults (16 years and older), the following dermatologic effects were reported in patients receiving topiramate 50 mg/day vs. 400 mg/day, respectively: rash (1% vs. 4%), pruritus (1% vs. 4%), alopecia (3% vs. 4%), and acne vulgaris (2% vs. 3%). In pediatric patients (6 to 15 years), alopecia (1% vs. 4%) and rash (3% vs. 4%) were reported in the 50 mg/day and 400 mg/day groups, respectively. Unspecified skin disorder was reported in 3% of pediatric patients (2 to 15 years) receiving topiramate in a placebo-controlled (2%), adjunctive epilepsy trials. In placebo-controlled adjunctive epilepsy trials in adults receiving topiramate 200 to 1,000 mg/day, hot flashes (1% to 2%), drug-induced body odor (0% to 1%), skin disorder (1% to 2%), hyperhidrosis (1% or less), and erythematous rash (1% or less) were reported with equal or greater frequency than placebo. In an adjunctive epilepsy trial in pediatric patients (2 to 16 years), skin disorder (3%), alopecia (2%), dermatitis (2%), hypertrichosis (2%), erythematous rash (2%), eczema (1%), seborrhea (1%), and skin discoloration (1%) occurred more frequently in topiramate-treated patients compared to patients given placebo. Pruritus was reported in 4%, 2%, and 2% of patients (including adolescents) receiving topiramate 50 mg/day, 100 mg/day, and 200 mg/day, respectively, for migraines in placebo-controlled (2%) clinical trials. Erythematous rash was reported in 8% of adolescents receiving topiramate 200 mg/day in pooled, double-blind migraine prophylaxis studies; however, it was not reported in adolescents receiving topiramate 50 or 100 mg/day. Pemphigus and bullous skin reactions (bullous rash), including erythema multiforme, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN), have been reported during postmarketing experience with topiramate.
Oligohidrosis and hyperthermia have been reported in association with topiramate use; heat stroke may occur. Oligohidrosis and hyperthermia have occurred primarily in children who were exposed to elevated environmental temperatures or were performing vigorous activity. Infrequent hospitalizations have occurred. To help prevent these adverse reactions in patients treated with topiramate, proper hydration is suggested before and during strenuous activity or exposure to warm temperatures. Use caution when topiramate is prescribed with other drugs that predispose patients to heat-related disorders, such as drugs with anticholinergic activity, carbonic anhydrase inhibitors, and zonisamide. Since topiramate exhibits carbonic anhydrase inhibitor activity, use with other carbonic anhydrase inhibitors is not recommended.
Topiramate is a weak carbonic anhydrase inhibitor and may lead to renal bicarbonate loss in a dose-dependent fashion. Hyperchloremic, non-anion gap, metabolic acidosis (hyperchloremic acidosis) is associated with topiramate. Metabolic acidosis due to topiramate is often asymptomatic. Measurement of baseline and periodic serum bicarbonate is recommended during topiramate therapy and prior to surgery. If metabolic acidosis develops and persists, consider a dosage reduction or discontinuation (using dose tapering). If the decision is made to continue topiramate despite persistent acidosis, alkali treatment should be considered. Bicarbonate loss is typically mild to moderate (roughly 4 mEq/L at an adult dose of 400 mg/day or a pediatric dose of 6 mg/kg/day) and tends to occur early in therapy, although cases can occur at any time. Rarely, bicarbonate loss may approach 10 mEq/L. Metabolic acidosis has been observed with doses as low as 50 mg/day. At doses of 400 mg/day in adjunctive epilepsy therapy trials, persistent reductions in serum bicarbonate less than 20 mEq/L occurred at an incidence of roughly 32% vs. 1% placebo. Markedly abnormal serum bicarbonate (i.e., less than 17 mEq/L and greater than 5 mEq/L reduction from baseline) occurred in 3% of topiramate-treated patients vs. 0% for placebo. In the monotherapy trials, the incidence of persistent decreases in serum bicarbonate in adults was 14% at doses of 50 mg/day and 25% for 400 mg/day. Markedly abnormal serum bicarbonate was observed in 1% of the 50 mg/day and 6% for the 400 mg/day adult group. During clinical trials for adjunctive treatment of Lennox-Gastaut syndrome or refractory partial onset seizures in pediatric patients 2 to 16 years of age, persistent decreases in serum bicarbonate occurred in 67% of topiramate-treated patients and 10% of placebo-treated patients; 11% of topiramate-treated patients had markedly abnormal serum concentrations. The incidence of markedly abnormal changes in adults receiving topiramate for migraine prophylaxis was less than 1% for placebo, 11% for 200 mg/day, 9% for 100 mg/day, and 2% for 50 mg/day. This incidence was similar in adolescent migraine prophylaxis trials; 2% for placebo, 2% for 50 mg/day, and 6% for 100 mg/day (criterion not met by the low number of patients [n = 13] in the 200 mg/day group). Although not FDA-approved in this population, a controlled trial in infants and children younger than 2 years demonstrated that the degree of metabolic acidosis caused by topiramate was notably greater in this population than that observed in trials of older children and adults. The incidence of metabolic acidosis (serum bicarbonate less than 20 mEq/L) was 0% for placebo, 30% for 5 mg/kg/day topiramate, 50% for 15 mg/kg/day, and 45% for 25 mg/kg/day. The incidence of markedly abnormal changes was 0% for placebo, 4% for 5 mg/kg/day, 5% for 15 mg/kg/day, and 5% for 25 mg/kg/day. Manifestations of metabolic acidosis, if symptomatic, may include: anorexia, cardiac arrhythmias, lethargy, hyperventilation, hypohidrosis, and stupor. Chronic metabolic acidosis may result in nephrolithiasis (renal stones), growth inhibition, osteomalacia, osteoporosis, and/or fractures. Statistically significant decreases in lumbar spine bone mineral density (BMD) and total body less head BMD occurred in pediatric patients 6 to 15 years of age treated with topiramate monotherapy during a 1 year, active controlled study. BMD decrease at 12 months was correlated with decreased serum bicarbonate (reflective of metabolic acidosis), suggesting that metabolic acidosis is at least a partial factor contributing to decreased BMD. BMD reductions (Z score change from baseline of -0.5 or more) occurred in 21% of topiramate-treated pediatric patients (n =28) compared to 0 patients treated with levetiracetam (n = 35). Patients age 6 to 9 years were most commonly affected, although decreases in BMD occurred across all age groups. At 12 months, the treatment differences in least square means (95% CI) for annual change in BMD of lumbar spine (g/cm2) and annual change in BMD of total body less head (g/cm2) were -0.036 (-0.058, -0.014) and -0.026 (-0.039, -0.012), respectively. All patients experienced metabolic acidosis (serum bicarbonate less than 20 mEq/L) at some time during the study, and 76% more topiramate-treated patients experienced persistent metabolic acidosis (i.e., 2 consecutive visits with or final serum bicarbonate less than 20 mEq/L) compared to the control group. Marked reductions in serum bicarbonate (i.e., absolute value less than 17 mEq/L and 5 mEq/L or more decrease from pre-treatment) occurred in 35% more topiramate-treated patients compared to the control group. Significant decreases in serum parathyroid hormone and 25-hydroxyvitamin D, hormones involved in bone metabolism, were observed, along with an increased excretion of urinary calcium in topiramate-treated patients. The risk of increased fracture is unknown. In the same study, topiramate was associated with negative effects on growth across all age subgroups, with the topiramate group experiencing statistically significant reductions in mean annual change from baseline in body weight compared to the levetiracetam group. At 12 months, the treatment difference in least square means (95% CI) for annual change in body weight (kg) was -2.05 (-3.66, -0.45). Slowed height velocity and height change from baseline also occurred in topiramate patients compared to those who received levetiracetam. Monitor growth carefully in pediatric patients receiving prolonged treatment with topiramate. Some data in infants and toddlers with intractable partial seizures receiving topiramate showed reductions from baseline in z-scores for length, weight, and head circumference compared to age and sex-matched normative data; however, it should be noted that these patients with epilepsy are likely to have different growth rates than normal infants. Reductions in z-scores for length and weight were correlated to the degree of acidosis.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, vaginal bleeding (hemorrhage) was reported in 0% of patients receiving 50 mg per day and 3% of patients receiving 400 mg per day. In pediatric trials, intermenstrual bleeding was reported in 0% and 3% of pediatric patients receiving 50 mg per day and 400 mg per day, respectively. Amenorrhea (2%) and menorrhagia (1% to 2%) were reported during add-on epilepsy trials. In monotherapy clinical trials for migraine prophylaxis, the following reproductive effects occurred more frequently with topiramate 50 to 200 mg per day than placebo: menstrual irregularity (menstrual disorder 2% to 3% vs. 2%) and ejaculation dysfunction (premature ejaculation 0% to 3% vs. 0%). Impotence (erectile dysfunction) was reported in > 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy. Ejaculation disorder and breast discharge were reported in 0.1% to 1% of patients. During clinical trial evaluation for migraine prophylaxis, intermenstrual bleeding was reported in > 1% of patients. Leukorrhea (2%) has been reported in pediatric patients.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, chest pain (unspecified) was reported in 1% of patients receiving 50 mg/day and 2% of patients receiving 400 mg/day. Edema (1% to 2%) and hypertension (2%) have been reported during add-on epilepsy trials. Other cardiovascular effects reported during epilepsy clinical trials (monotherapy or adjunct therapy) in 0.1% to 1% of patients included peripheral vasodilation, hypotension, orthostatic hypotension, AV block, and angina. During clinical trial evaluation of topiramate for migraine prophylaxis, chest pain was reported in > 1% of patients. Bradycardia (1%) has been reported in pediatric patients. Though the clinical significance has not been clearly established, notable changes (increases and decreases) from baseline in blood pressure and pulse rate were observed more commonly in pediatric patients treated with topiramate compared to those treated with placebo during migraine prophylaxis trials; these changes were often dose-related. The most notable changes were systolic blood pressure (SBP) < 90 mmHg, diastolic blood pressure (DBP) < 50 mmHg, SBP or DBP variation >= 20 mmHg, and pulse rate variation >= 30 beats per minute.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, hypertonia was reported in 0% of patients receiving 50 mg/day and 3% of patients receiving 400 mg/day. Other extrapyramidal effects reported during clinical trials of topiramate as monotherapy or adjunct therapy of epilepsy in 0.1% to 1% of patients included dyskinesia and dystonic reaction.
During clinical trials of topiramate as migraine prophylaxis, polydipsia was reported in 1% to 2% of patients receiving 50 mg/day vs. less than 1% of patients receiving 400 mg/day. Hyperthyroidism was reported in 8% of adolescent patients receiving 200 mg/day during migraine prophylaxis trials. Other metabolic or nutritional effects reported in 0.1% to 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy included dehydration, hypocalcemia, hyperlipidemia, hyperglycemia, and diabetes mellitus. Rarely reported effects (less than 0.1%) included hypernatremia, hyponatremia, hypocholesterolemia, and increased creatinine. Hypoglycemia (1%) has been reported in pediatric patients. During a 12-month active control study, topiramate-treated pediatric patients ages 6 to 15 years (n = 28) demonstrated an increased risk for developing an increased serum glucose concentration above the normal reference range. The clinical significance of various laboratory abnormalities observed during topiramate clinical trials has not been clearly established. For example, markedly decreased serum phosphorus (hypophosphatemia) (6%), markedly increased serum alkaline phosphatase (3%), and decreased serum potassium (0.4%) have also been observed during adult epilepsy trials. Additionally, BUN, creatinine, alkaline phosphatase, uric acid, total protein, platelets, and eosinophils were abnormally elevated more frequently in patients receiving topiramate compared to those receiving placebo in pediatric migraine prophylaxis trials. Phosphorus, total white blood cell count, and neutrophils were abnormally decreased in some subjects. Changes in several laboratory values (i.e., increased creatinine, BUN, alkaline phosphatase, total protein, total eosinophil count, and decreased potassium) have been observed in children younger than 2 years treated with topiramate for partial onset seizures.
Vascular effects reported in 0.1% to 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy included flushing, deep vein thrombosis, and phlebitis. Vasospasm was reported rarely (< 0.1%). Flushing was also reported in 0% and 5% of patients receiving topiramate 50 mg per day and 400 mg per day, respectively, during pediatric monotherapy trials for epilepsy.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, leg pain was reported in 2% of patients receiving 50 mg/day and 3% of patients receiving 400 mg/day. In monotherapy clinical trials of topiramate 50 to 200 mg/day for migraine prophylaxis, arthralgia occurred more frequently with topiramate (1% to 7%) than placebo (2%). Musculoskeletal effects reported in at least 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy included arthralgia (1% to 7%), leg muscle cramps (2%), and back pain (3% to 5%). Arthrosis (arthropathy) was reported infrequently (0.1% to 1%). During clinical trial evaluation of topiramate for migraine prophylaxis, myalgia was reported in > 1% of adult patients; myalgia, back pain, and pain (unspecified) were reported in >= 2% of adolescent patients.
During a monotherapy clinical trial of topiramate in the treatment of epilepsy in adults, increased gamma-glutamyl transpeptidase (GGT) was reported in 1% of patients receiving 50 mg/day and 3% of patients receiving 400 mg/day. Hepatic effects reported in 0.1% to 1% of patients during clinical trials of topiramate as monotherapy or adjunct therapy for epilepsy included elevated hepatic enzymes (ALT, AST). During post-marketing use, hepatic failure (including fatalities), and hepatitis have occurred; however, causality to the drug has not been established.
During topiramate epilepsy monotherapy trials, for daily doses of 50 mg vs. 400 mg, asthenia was reported in both adults (4% vs. 6%) and pediatric patients (0% vs. 3%). During migraine prophylaxis monotherapy trials, comparing topiramate 50 to 200 mg per day vs. placebo, the following were reported: fatigue (14% to 19% vs. 11%), injury (6% to 9% vs. 7%), asthenia (<= 2% vs. 1%), and allergy (<= 2% vs. < 1%); adolescent migraine trials also reported fatigue (7% to 15% vs. 7%). Syncope was reported in at least 1% of patients during epilepsy monotherapy or adjunct therapy trials. Enlarged abdomen, parosmia, and face edema were reported infrequently (0.1% to 1%), and alcohol intolerance was reported rarely (< 0.1%). During clinical trial evaluation for migraine prophylaxis, unspecified allergic reaction and pain were reported in > 1% of patients; leg pain was reported in 2% to 8% of adolescent patients. Pancreatitis has occurred during post-marketing use; however, causality to the drug has not been established.
During migraine prophylaxis monotherapy trials, tinnitus (<= 2% vs. 1%) and otitis media (1% to 2% vs. < 1%) were reported with topiramate 50 to 200 mg per day compared to placebo. Hearing loss occurred in 1% to 2% of patients during add-on epilepsy trials.
Topiramate is contraindicated for use in any patient hypersensitive to the drug or any of the product components. Serious and potentially fatal exfoliative dermatologic reactions have been reported in post-marketing experience with topiramate. Cross-sensitivity between antibiotic sulfonamides and nonantibiotic sulfonamides, such as topiramate, is controversial. Antibiotic sulfonamides contain an amine linked to a benzene ring (arylamine moiety), attached directly to the sulfonamide structure; this arylamine attached to the sulfonamide structure is believed to be the central pathogenesis of hypersensitivity reactions. Although topiramate is a simple sulfonamide, the sulfonamide structure is not directly connected to a ring structure, and it lacks an arylamine moiety. Some experts believe apparent cross-reactivity represents multiple concurrent and unlinked drug hypersensitivities in predisposed patients. Although cross-reactivity with sulfonamide antibiotics appears unlikely, precaution or complete avoidance of nonantibiotic sulfonamides in individuals whose previous reaction was serious and/or life-threatening or in those with multiple drug hypersensitivities may be prudent.
Monitor all patients beginning treatment with antiepileptic drugs (AEDs) or currently receiving topiramate closely for emerging or worsening depression or suicidal ideation. Advise patients and caregivers of the increased risk of suicidal thoughts and behaviors and to immediately report the emergence of new or worsening of depression, suicidal thoughts or behavior, thoughts of self-harm, or other unusual changes in mood or behavior. AEDs should be prescribed in the smallest quantity consistent with good patient management in order to reduce the risk of overdose. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with an increased risk of suicidal thoughts and behavior. If suicidal thoughts and behavior emerge during treatment, consider whether the emergence of these symptoms in any patient may be related to the illness being treated. There is an increased risk of suicidal ideation and behavior in patients receiving AEDs to treat epilepsy, psychiatric disorders, or other conditions (e.g., migraine, neuropathic pain). The primary analysis consisted of 199 placebo-controlled clinical studies with a total of 27,863 patients in drug treatment groups and 16,029 patients in placebo groups (5 years of age and older). There were 4 completed suicides among patients in drug treatment groups versus none in the placebo groups. Patients receiving AEDs had approximately twice the risk of suicidal behavior or ideation as patients receiving placebo (0.43% vs. 0.24%, respectively; RR 1.8, 95% CI: 1.2 to 2.7). The relative risk for suicidality was higher in patients with epilepsy compared to those with other conditions; however, the absolute risk differences were similar in trials for epilepsy and psychiatric indications. Age was not a determining factor. The increased risk of suicidal ideation and behavior was observed between 1 and 24 weeks after therapy initiation. However, a longer duration of therapy should not preclude the possibility of an association to the drug since most studies included in the analysis did not continue beyond 24 weeks.
In patients with or without a history of seizures or epilepsy, withdraw topiramate gradually to minimize the potential for seizures or increased seizure frequency. In situations where abrupt discontinuation of topiramate is medically required, appropriate monitoring is recommended.
Extended-release topiramate is contraindicated in patients with metabolic acidosis who are taking concomitant metformin. Topiramate can cause hyperchloremic, non-anion gap metabolic acidosis. Conditions or therapies that predispose patients to acidosis, such as kidney disease, severe pulmonary disease, status epilepticus, diarrhea, ketogenic diet, or certain drugs, may be additive to the bicarbonate lowering effects of topiramate. Measurement of baseline and periodic serum bicarbonate during topiramate treatment is recommended. If metabolic acidosis develops and persists, consider reducing the dose or discontinuing topiramate (using dose tapering). If the decision is made to continue patients on topiramate in the face of persistent acidosis, consider alkali treatment. Also, the concomitant use of topiramate with any other drug producing metabolic acidosis, or potentially in patients on a ketogenic diet, may create a physiological environment that increases the risk of kidney stone formation, and should therefore be avoided.
Trokendi XR is contraindicated with recent ethanol ingestion or ethanol intoxication (i.e., within 6 hours before and 6 hours after use). In the presence of alcohol, the pattern of topiramate release from Trokendi XR is significantly altered. As a result, plasma concentrations of topiramate may be markedly higher soon after dosing and subtherapeutic later in the day.
Closely monitor patients (especially neonates, infants, and children) treated with topiramate for evidence of decreased sweating and increased body temperature, especially in hot weather. Use caution when topiramate is given with other drugs that predispose patients to heat-related disorders; these drugs include, but are not limited to, other carbonic anhydrase inhibitors and drugs with anticholinergic activity. Oligohidrosis, infrequently resulting in hospitalization, has been reported in association with topiramate use. Some of the cases were reported after exposure to an ambient temperature increase. The majority of these reports have been in pediatric patients. Monitor growth carefully in pediatric patients receiving prolonged treatment with topiramate. Topiramate is associated with negative effects on growth (weight, height, and height velocity) in pediatric patients 6 to 15 years. Significant decreases in bone mineral density (lumbar spine and total body less head) were also reported in this population. Decreases in bone mineral density correlated with decreased serum bicarbonate (reflective of metabolic acidosis), suggesting that metabolic acidosis is at least a partial factor contributing to decreased bone mineral density.
Hyperammonemia with and without encephalopathy has been observed in patients who were taking topiramate. Patients with inborn errors of metabolism or reduced hepatic mitochondrial activity (mitochondrial disease) may be at an increased risk for hyperammonemia with or without encephalopathy. Although not studied, topiramate treatment or an interaction of concomitant topiramate-based product and valproic acid treatment may exacerbate existing defects or unmask deficiencies in susceptible persons. In patients who develop unexplained lethargy, vomiting, or changes in mental status associated with any topiramate treatment, consider hyperammonemic encephalopathy and measure an ammonia concentration.
According to the Beers Criteria, anticonvulsants are considered potentially inappropriate medications (PIMs) in geriatric adults with a history of falls or fractures and should be avoided in these patient populations, except for treating seizure and mood disorders, since anticonvulsants can produce ataxia, impaired psychomotor function, syncope, and additional falls. If topiramate must be used, consider reducing the use of other CNS-active medications that increase the risk of falls and fractures and implement strategies to reduce fall risk.
Topiramate dosage adjustment is necessary for patients with renal impairment. Before dosing, obtain an estimated creatinine clearance in patients at high risk for renal disease (e.g., older patients, or those with diabetes mellitus, hypertension, or autoimmune disease). In patients with renal insufficiency, a reduction in the topiramate dose is needed. In patients with renal failure receiving dialysis, a supplemental topiramate dose may be required; topiramate is removed by hemodialysis at a rate greater than in patients with normal renal function. Also, conditions that predispose patients to acidosis, such as renal disease, may be additive to the bicarbonate lowering effects of topiramate. Measurement of baseline and periodic serum bicarbonate during topiramate treatment is recommended. If metabolic acidosis develops and persists, consider reducing the dose or discontinuing topiramate (using dose tapering). If the decision is made to continue patients on topiramate in the face of persistent acidosis, consider alkali treatment.
Serious rash (Stevens-Johnson syndrome [SJS] and toxic epidermal necrolysis [TEN]) has been reported in patients receiving topiramate. Discontinue topiramate at the first sign of a rash, unless the rash is clearly not drug-related. If signs or symptoms suggest SJS/TEN, do not resume topiramate use and consider alternative therapy. Inform patients about the signs of serious skin reactions.
Topiramate is associated with an increased risk of bleeding. In patients with serious bleeding events, conditions that increased the risk for bleeding were often present, or patients were often taking drugs that cause thrombocytopenia (other antiepileptic drugs) or affect platelet function or coagulation (e.g., aspirin, nonsteroidal anti-inflammatory drugs, selective serotonin reuptake inhibitors, or warfarin or other anticoagulant therapy).
Warn patients about the potential for somnolence, dizziness, confusion, difficulty concentrating, or visual effects, and advise patients against driving or operating machinery until they have gained sufficient experience on topiramate to gauge whether it adversely affects their mental performance, motor performance, and/or vision.
Topiramate can cause fetal harm when administered to a pregnant person. Consider the benefits and risks of topiramate in patients of childbearing potential, particularly when it is being considered for conditions not usually associated with permanent injury or death. Counsel patients of childbearing potential regarding the potential risk to the fetus from topiramate exposure, and consider alternative therapeutic options in patients who are planning a pregnancy. Data from pregnancy registries indicate infants exposed to topiramate during pregnancy have an increased risk for cleft lip and/or cleft palate. The prevalence of oral clefts among topiramate-exposed infants was 1.4% compared to 0.3% in infants exposed to another antiepileptic drug (AED), and 0.11% in infants of persons without epilepsy or AED exposure. The relative risk of oral clefts in topiramate-exposed pregnancies was 12.5 (95% CI 5.9 to 26.37) compared to untreated patients. Oral clefts develop in the first trimester before many patients know that they are pregnant. Data from pregnancy registries indicate infants exposed to topiramate during pregnancy have an increased risk for being small for gestational age (SGA), defined as a birth weight below the tenth percentile. SGA has been seen at all doses and appears to be dose-dependent. SGA occurs more frequently in infants of patients who received higher topiramate doses or continued topiramate use until later in pregnancy (i.e., third trimester). According to registry data, the prevalence of SGA was 19.7% to 25% in topiramate-exposed infants compared to 7.9% in infants exposed to a reference AED, and 5.4% to 9% in infants of persons without epilepsy or AED exposure. Excluding oral clefts, no other specific patterns of major congential malformations were observed based on data from pregnancy registries. The prevalence of major congenital malformations among topiramate-exposed infants was 4.1% compared to 1.8% in infants exposed to another AED, and 1.1% in infants of persons without epilepsy or AED exposure. Registry data and findings from other studies suggest that combination therapy with AEDs may increase the risk of teratogenic effects compared to monotherapy with an AED. Structural malformations such as craniofacial defects and reduced fetal weight occurred in the offspring of multiple animal species during studies of topiramate. Topiramate can cause metabolic acidosis which, when occurring during pregnancy, has been associated with decreased fetal growth, decreased fetal oxygenation, fetal death, and may impact the ability of the fetus to tolerate labor. Monitor patients taking topiramate during pregnancy for metabolic acidosis and treat as in the nonpregnant state. In utero exposure to topiramate-induced metabolic acidosis may also cause metabolic acidosis in the neonate. Monitor newborns of patients receiving topiramate carefully. Limited data indicate topiramate may be associated with pre-term labor and premature delivery. There is a pregnancy exposure registry that monitors outcomes in pregnant patients exposed to topiramate; information about the registry can be obtained at www.aedpregnancyregistry.org or by calling 1-888-233-2334.
Topiramate is excreted in human breast milk. Diarrhea and somnolence have been observed in breast-fed infants whose mothers received topiramate. The effects of topiramate on milk production are unknown. Consider the developmental and health benefits from breast-feeding along with the mother's clinical need for topiramate and any potential adverse effects on the breast-fed infant from topiramate or the underlying maternal condition. Data from 5 breast-feeding infants has shown topiramate plasma concentrations of 10% to 20% of the maternal plasma concentration. Based on breast milk concentrations from 3 women taking 150 to 200 mg topiramate daily, it was estimated that a breast-fed infant (assuming a milk intake of 150 mL/kg/day) would receive approximately 0.1 to 0.7 mg/kg/day or 3% to 23% of the maternal weight-adjusted dose.
Topiramate is associated with reproductive risk. Discuss contraception requirements with the patient. Women of childbearing age who are not planning a pregnancy should use effective contraception because of the fetal risks of oral clefts and being small for gestational age.
For the treatment of partial seizures as monotherapy or adjunctive therapy:
-for the treatment of partial seizures as monotherapy:
Oral dosage (immediate-release):
Adults: 25 mg PO twice daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then by 100 mg/day weekly for 2 weeks. Usual dose: 200 mg PO twice daily.
Children and Adolescents 10 to 17 years: 25 mg PO twice daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then by 100 mg/day weekly for 2 weeks. Usual dose: 200 mg PO twice daily.
Children 2 to 9 years weighing more than 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 125 to 200 mg PO twice daily.
Children 2 to 9 years weighing 32 to 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 125 to 175 mg PO twice daily.
Children 2 to 9 years weighing 23 to 31 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 100 to 175 mg PO twice daily.
Children 2 to 9 years weighing 12 to 22 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 100 to 150 mg PO twice daily.
Children 2 to 9 years weighing 11 kg or less: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 75 to 125 mg PO twice daily.
Oral dosage (extended-release, Trokendi XR):
Adults: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children and Adolescents 10 to 17 years: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children 6 to 9 years weighing more than 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 400 mg PO once daily.
Children 6 to 9 years weighing 32 to 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 350 mg PO once daily.
Children 6 to 9 years weighing 23 to 31 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 350 mg PO once daily.
Children 6 to 9 years weighing 12 to 22 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 300 mg PO once daily.
Children 6 to 9 years weighing 11 kg or less: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 150 to 250 mg PO once daily.
Oral dosage (extended-release, Qudexy XR):
Adults: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children and Adolescents 10 to 17 years: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children 2 to 9 years weighing more than 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 400 mg PO once daily.
Children 2 to 9 years weighing 32 to 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 350 mg PO once daily.
Children 2 to 9 years weighing 23 to 31 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 350 mg PO once daily.
Children 2 to 9 years weighing 12 to 22 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 300 mg PO once daily.
Children 2 to 9 years weighing 11 kg or less: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 150 to 250 mg PO once daily.
-for the treatment of partial seizures as adjunctive therapy:
Oral dosage (immediate-release):
Adults: 25 mg PO once or twice daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 100 to 200 mg PO twice daily. Doses above 400 mg/day have not been shown to improve response.
Adolescents 17 years: 25 mg PO once or twice daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 100 to 200 mg PO twice daily. Doses above 400 mg/day have not been shown to improve response.
Children and Adolescents 2 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Increase the dose by 1 to 3 mg/kg/day every 1 to 2 weeks in 2 divided doses. Usual dose: 5 to 9 mg/kg/day in 2 divided doses. Max: 400 mg/day.
Infants* and Children younger than 2 years*: Limited data available; further study needed. A target dose of 3 to 25 mg/kg/day PO divided twice daily has been safely used in infants and young children with refractory partial seizures; however, efficacy data is lacking. Case reports have described topiramate efficacy at a dose range of 2.5 to 6 mg/kg/day PO in infants with refractory partial seizures; the maximum dose used in these reports was 7.7 mg/kg/day. However, in a double-blind, placebo-controlled, parallel-group, multicenter study of infants and young children (n = 149; mean age: 12 months; range: 1 to 24 months) topiramate 3 to 25 mg/kg/day was not effective as adjuvant treatment for refractory partial seizures. At 25 mg/kg/day, there was no significant difference in median percentage reduction from baseline in daily seizure rate compared to placebo (20.4% topiramate vs. 13.1% placebo). In addition, the percentages of treatment responders in the topiramate groups (27% in the 5 mg/kg/day group, 38% in the 15 mg/kg/day group, and 44% in the 25 mg/kg/day group) were not significantly different from placebo (36%).
Neonates*: Limited data available. In a retrospective review, adjunctive topiramate at a dose of 3 to 10 mg/kg/day administered via nasogastric tube controlled or reduced seizure activity (including generalized tonic, partial tonic, and partial clonic) in 4 of 6 term neonates who were considered refractory to phenobarbital or phenobarbital and phenytoin therapy. Maintenance therapy was initiated at 10 mg/kg/day in 5 patients and 3 mg/kg/day in 1 patient. At follow-up 5 to 11.5 months later, 5 of 6 patients were seizure free.
Oral dosage (extended-release, Trokendi XR):
Adults: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 200 to 400 mg PO once daily. Doses above 400 mg/day have not been shown to improve response.
Adolescents 17 years: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 200 to 400 mg PO once daily. Doses above 400 mg/day have not been shown to improve response.
Children and Adolescents 6 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Increase the dose by 1 to 3 mg/kg/day every 1 to 2 weeks. Usual dose: 5 to 9 mg/kg/day. Max: 400 mg/day.
Oral dosage (extended-release, Qudexy XR):
Adults: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 200 to 400 mg PO once daily. Doses above 400 mg/day have not been shown to improve response.
Adolescents 17 years: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 200 to 400 mg PO once daily. Doses above 400 mg/day have not been shown to improve response.
Children and Adolescents 2 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Increase the dose by 1 to 3 mg/kg/day every 1 to 2 weeks. Usual dose: 5 to 9 mg/kg/day. Max: 400 mg/day.
For the treatment of primary generalized tonic-clonic seizures as monotherapy or adjunctive therapy:
-for the treatment of primary generalized tonic-clonic seizures as monotherapy:
Oral dosage (immediate-release):
Adults: 25 mg PO twice daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then by 100 mg/day weekly for 2 weeks. Usual dose: 200 mg PO twice daily.
Children and Adolescents 10 to 17 years: 25 mg PO twice daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then by 100 mg/day weekly for 2 weeks. Usual dose: 200 mg PO twice daily.
Children 2 to 9 years weighing more than 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 125 to 200 mg PO twice daily.
Children 2 to 9 years weighing 32 to 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 125 to 175 mg PO twice daily.
Children 2 to 9 years weighing 23 to 31 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 100 to 175 mg PO twice daily.
Children 2 to 9 years weighing 12 to 22 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 100 to 150 mg PO twice daily.
Children 2 to 9 years weighing 11 kg or less: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then by 25 to 50 mg/day weekly as tolerated. Usual dose: 75 to 125 mg PO twice daily.
Oral dosage (extended-release, Trokendi XR):
Adults: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children and Adolescents 10 to 17 years: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children 6 to 9 years weighing more than 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 400 mg PO once daily.
Children 6 to 9 years weighing 32 to 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 350 mg PO once daily.
Children 6 to 9 years weighing 23 to 31 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 350 mg PO once daily.
Children 6 to 9 years weighing 12 to 22 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 300 mg PO once daily.
Children 6 to 9 years weighing 11 kg or less: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 150 to 250 mg PO once daily.
Oral dosage (extended-release, Qudexy XR):
Adults: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children and Adolescents 10 to 17 years: 50 mg PO once daily for 1 week, initially. Increase the dose by 50 mg/day weekly for 3 weeks, then 100 mg/day weekly for 2 weeks. Usual dose: 400 mg PO once daily.
Children 2 to 9 years weighing more than 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 400 mg PO once daily.
Children 2 to 9 years weighing 32 to 38 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 250 to 350 mg PO once daily.
Children 2 to 9 years weighing 23 to 31 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 350 mg PO once daily.
Children 2 to 9 years weighing 12 to 22 kg: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 200 to 300 mg PO once daily.
Children 2 to 9 years weighing 11 kg or less: 25 mg PO once daily in the evening for 1 week, initially. Increase the dose by 25 mg/day weekly for 1 week, then 25 to 50 mg/day weekly as tolerated. Usual dose: 150 to 250 mg PO once daily.
-for the treatment of primary generalized tonic-clonic seizures as adjunctive therapy:
Oral dosage (immediate-release):
Adults: 25 mg PO once or twice daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 200 mg PO twice daily.
Adolescents 17 years: 25 mg PO once or twice daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 200 mg PO twice daily.
Children and Adolescents 2 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Increase the dose by 1 to 3 mg/kg/day every 1 to 2 weeks in 2 divided doses. Usual dose: 5 to 9 mg/kg/day in 2 divided doses. Max: 400 mg/day.
Infants* and Children* younger than 2 years: Limited data available, particularly for tonic-clonic seizures; further study needed. A target dose of 3 to 25 mg/kg/day PO divided twice daily has been safely used in infants and young children with refractory partial seizures; however, efficacy data is lacking. Case reports have described topiramate efficacy at a dose range of 2.5 to 6 mg/kg/day PO in infants with refractory partial seizures; the maximum dose used in these reports was 7.7 mg/kg/day. However, in a double-blind, placebo-controlled, parallel-group, multicenter study of infants and young children (n = 149; mean age: 12 months; range: 1 to 24 months) topiramate 3 to 25 mg/kg/day was not effective as adjuvant treatment for refractory partial seizures. At 25 mg/kg/day, there was no significant difference in median percentage reduction from baseline in daily seizure rate compared to placebo (20.4% topiramate vs. 13.1% placebo). In addition, the percentages of treatment responders in the topiramate groups (27% in the 5 mg/kg/day group, 38% in the 15 mg/kg/day group, and 44% in the 25 mg/kg/day group) were not significantly different from placebo (36%).
Neonates*: Limited data available. In a retrospective review, adjunctive topiramate at a dose of 3 to 10 mg/kg/day administered via nasogastric tube controlled or reduced seizure activity (including generalized tonic, partial tonic, and partial clonic) in 4 of 6 term neonates who were considered refractory to phenobarbital or phenobarbital and phenytoin therapy. Maintenance therapy was initiated at 10 mg/kg/day in 5 patients and 3 mg/kg/day in 1 patient. At follow-up 5 to 11.5 months later, 5 of 6 patients were seizure free.
Oral dosage (extended-release, Trokendi XR):
Adults: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 400 mg PO once daily.
Adolescents 17 years: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 400 mg PO once daily.
Children and Adolescents 6 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Increase the dose by 1 to 3 mg/kg/day every 1 to 2 weeks. Usual dose: 5 to 9 mg/kg/day. Max: 400 mg/day.
Oral dosage (extended-release, Qudexy XR):
Adults: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 400 mg PO once daily.
Adolescents 17 years: 25 to 50 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day weekly. Usual dose: 400 mg PO once daily.
Children and Adolescents 2 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Increase the dose by 1 to 3 mg/kg/day every 1 to 2 weeks. Usual dose: 5 to 9 mg/kg/day. Max: 400 mg/day.
For the adjunctive treatment of Lennox-Gastaut syndrome:
NOTE: Topiramate is designated an orphan drug by the FDA for Lennox-Gastaut.
Oral dosage (immediate-release):
Adults: 25 mg PO once or twice daily for 1 week, initially. Titrate dose by 25 to 50 mg/day weekly. Usual Dose: 100 to 200 mg PO twice daily.
Adolescents 17 years: 25 mg PO once or twice daily for 1 week, initially. Titrate dose by 25 to 50 mg/day weekly. Usual Dose: 100 to 200 mg PO twice daily.
Children and Adolescents 2 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Titrate dose by 1 to 3 mg/kg/day every 1 to 2 weeks in 2 divided doses. Usual Dose: 5 to 9 mg/kg/day. Max: 400 mg/day.
Oral dosage (extended-release, Trokendi XR):
Adults: 25 to 50 mg PO once daily for 1 week, initially. Titrate dose by 25 to 50 mg/day weekly. Usual Dose: 200 to 400 mg PO once daily.
Adolescents 17 years: 25 to 50 mg PO once daily for 1 week, initially. Titrate dose by 25 to 50 mg/day weekly. Usual Dose: 200 to 400 mg PO once daily.
Children and Adolescents 6 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Titrate dose by 1 to 3 mg/kg/day every 1 to 2 weeks. Usual Dose: 5 to 9 mg/kg/day. Max: 400 mg/day.
Oral dosage (extended-release, Qudexy XR):
Adults: 25 to 50 mg PO once daily for 1 week, initially. Titrate dose by 25 to 50 mg/day weekly. Usual Dose: 200 to 400 mg PO once daily.
Adolescents 17 years: 25 to 50 mg PO once daily for 1 week, initially. Titrate dose by 25 to 50 mg/day weekly. Usual Dose: 200 to 400 mg PO once daily.
Children and Adolescents 2 to 16 years: 1 to 3 mg/kg/day PO once daily (Max: 25 mg/day) in the evening, initially. Titrate dose by 1 to 3 mg/kg/day every 1 to 2 weeks. Usual Dose: 5 to 9 mg/kg/day. Max: 400 mg/day.
For the adjunctive treatment of refractory infantile spasms* associated with West syndrome:
Oral dosage (immediate-release):
Children: 25 mg PO once daily, initially. Titrate dose by 25 mg every 2 to 3 days until spasms are controlled or up to a maximum dose of 24 mg/kg/day in divided doses.
For migraine prophylaxis:
Oral dosage (immediate-release):
Adults: 25 mg PO every evening for 1 week, then 25 mg PO twice daily for 1 week, then 25 mg PO every morning and 50 mg PO every evening for 1 week, and then 50 mg PO twice daily. Adjust dose and titration according to clinical outcome; use longer intervals between dose adjustments if needed. Guidelines classify topiramate as having established efficacy for migraine prophylaxis.
Children and Adolescents 12 to 17 years: 25 mg PO every evening for 1 week, then 25 mg PO twice daily for 1 week, then 25 mg PO every morning and 50 mg PO every evening for 1 week, and then 50 mg PO twice daily. Adjust dose and titration according to clinical outcome; use longer intervals between dose adjustments if needed. Pediatric patients receiving topiramate for migraine prophylaxis are probably more likely than those receiving placebo to have a decrease in headache frequency.
Children 6 to 11 years*: 12.5 to 25 mg PO once daily in the evening, initially. Titrate dose gradually every 1 to 2 weeks. Usual dose: 2 to 3 mg/kg/day or 50 mg PO twice daily. Some patients respond to doses as low as 25 mg/day. Max: 200 mg/day. Pediatric patients receiving topiramate are probably more likely than those receiving placebo to have a decrease in headache frequency.
Oral dosage (extended-release):
Adults: 25 mg PO once daily for 1 week, then 50 mg PO once daily for 1 week, then 75 mg PO once daily for 1 week, and then 100 mg PO once daily. Adjust dose and titration according to clinical outcome; use longer intervals between dose adjustments if needed. Guidelines classify topiramate as having established efficacy for migraine prophylaxis.
Children and Adolescents 12 to 17 years: 25 mg PO once daily for 1 week, then 50 mg PO once daily for 1 week, then 75 mg PO once daily for 1 week, and then 100 mg PO once daily. Adjust dose and titration according to clinical outcome; use longer intervals between dose adjustments if needed. Pediatric patients receiving topiramate for migraine prophylaxis are probably more likely than those receiving placebo to have a decrease in headache frequency.
For the treatment of alcohol dependence*:
Oral dosage (immediate-release):
Adults: 25 mg PO once daily, initially. Titrate dose according to response and tolerability. Max: 300 mg/day in divided doses. Guidelines suggest topiramate for patients with moderate to severe alcohol use disorder who have a goal of reducing alcohol consumption or achieving abstinence, prefer topiramate or are intolerant to or have not responded to naltrexone and acamprosate, and have no contraindications to the use of topiramate.
For the adjunctive treatment of bulimia nervosa*:
Oral dosage (immediate-release):
Adults: 25 mg PO once daily, initially. Titrate dose gradually. Dose range: 25 to 400 mg/day in divided doses.
For the treatment of cocaine dependence*:
-for treatment as monotherapy*:
Oral dosage (immediate-release):
Adults: 25 mg PO once or twice daily for 1 week, initially. Titrate by 25 to 50 mg/day each week. Usual dose: 100 to 150 mg PO twice daily. One guideline recommends considering topiramate for reduction of cocaine use, particularly in individuals who are highly motivated to achieve abstinence and/or those with concomitant alcohol use disorder, as topiramate may help reduce consumption of both substances (low certainty, conditional recommendation).
-for treatment in combination with extended-release mixed amphetamine salts*:
Oral dosage (immediate-release):
Adults: 25 mg PO once or twice daily for 1 week, initially. Titrate by 25 to 50 mg/day each week. Usual dose: 100 to 150 mg PO twice daily. In studies, this combination has been shown to reduce cocaine use and cocaine cravings. One guideline suggests this combination treatment may be particularly helpful for individuals with concomitant ADHD or those with alcohol use disorder, as topiramate has demonstrated a role in reduction of alcohol consumption (moderate certainty, conditional recommendation).
For long-term prophylaxis of short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT)*:
Oral dosage (immediate-release):
Adults: 12.5 to 25 mg PO once daily, initially. Titrate dose to 25 to 75 mg PO twice daily as tolerated. Higher doses of 150 to 400 mg PO twice daily have also been efficacious.
For the treatment of binge-eating disorder*:
Oral dosage (immediate-release):
Adults: 25 mg PO once daily for 1 week, initially. Increase the dose by 25 to 50 mg/day at weekly intervals for 4 weeks, then by up to 100 mg/day at weekly intervals. Usual dose: 200 to 300 mg/day in 2 divided doses. Usual Max: 400 mg/day (up to 600 mg/day). Clinical guidelines indicate that topiramate, alone or in combination with cognitive behavioral therapy, is associated with reductions in binge-eating behaviors. However, in randomized controlled trials of topiramate compared to placebo, study drop-outs and reports of adverse effects were common and may limit use.
For the treatment of Tourette's syndrome* or chronic tic disorders*:
Oral dosage (immediate-release):
Adults: 25 mg PO once or twice daily, initially. Titrate dose according to response and tolerability. Usual dose: 50 to 200 mg/day in divided doses. Doses more than 200 mg/day are poorly tolerated. Topiramate is possibly more likely than placebo to reduce tic severity in patients with Tourette's syndrome or chronic tic disorders and may be useful in patients with mild but troublesome tics and inadequate response or intolerance to other treatments.
Children and Adolescents 7 to 17 years: 25 mg PO once daily, initially. Titrate dose according to response and tolerability. Usual dose: 25 to 200 mg/day in divided doses. Doses more than 200 mg/day are poorly tolerated. Topiramate is possibly more likely than placebo to reduce tic severity in patients with Tourette's syndrome or chronic tic disorders and may be useful in patients with mild but troublesome tics and inadequate response or intolerance to other treatments.
For neuroprotection in neonates with hypoxic-ischemic encephalopathy*:
Oral dosage (immediate-release):
Neonates: Limited data; optimal dose and efficacy have not been established. Topiramate 5 mg/kg via naso- or orogastric tube once, then 3 to 5 mg/kg/day for 2 to 5 days has been used in trials with mixed outcomes; a higher dosage of 10 mg/kg/day for 3 days has also been used in a small pilot study. Topiramate 5 mg/kg once, then 3 mg/kg/day for 5 days reduced seizure activity and mortality in a randomized, controlled, double-blind trial of neonates also receiving therapeutic hypothermia (n = 110); however, these results did not reach statistical significance when compared to placebo. Topiramate achieved therapeutic serum concentrations (5 to 20 mg/L) in 36.9% and 75.5% of patients at 24 and 48 hours, respectively. Topiramate 5 mg/kg on day 1 then either 3 mg/kg/day (n = 11) or 5 mg/kg/day (n = 16) on days 2 and 3 was used in a safety study in combination with hypothermia. There was no statistically significant difference in short-term outcomes, survival rate at discharge, or incidence of cerebral lesions on MRI. Long-term effects on cognitive function were not assessed. Additionally, no significant differences were seen in the combined frequency of mortality and severe neurological disability in a small pilot trial (n = 44) comparing topiramate 10 mg/kg/dose for 3 days plus moderate hypothermia vs. hypothermia alone. Average topiramate serum concentrations were 6.5 to 7 mg/L after the first dose and increased to 12 to 13 mg/L after the third dose.
For the treatment of amphetamine-type stimulant use disorder*:
Oral dosage:
Adults: 25 mg PO once or twice daily for 1 week, initially. Titrate by 25 to 50 mg/day per week. Usual dose studied: 100 PO twice daily. In randomized controlled trials, patients given topiramate had a reduction in methamphetamine use compared to placebo, as well as a reduction in substance use disorder severity overall. While another multi-site randomized controlled trial reported that topiramate did not increase abstinence for the overall treatment group, it did significantly reduce the amount of methamphetamine used and recurrence of use in a subset of individuals. One guideline includes topiramate as a potential consideration for treatment given that treatment options are limited, and it may be particularly helpful for individuals with concomitant alcohol use disorder, as topiramate may help reduce consumption of both substances (low certainty, conditional recommendation).
Maximum Dosage Limits:
-Adults
400 mg/day PO for epilepsy; 100 mg/day PO for migraine prophylaxis.
-Geriatric
400 mg/day PO for epilepsy; 100 mg/day PO for migraine prophylaxis.
-Adolescents
17 years: 400 mg/day PO for epilepsy; 100 mg/day PO for migraine prophylaxis.
13 to 16 years: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy; 100 mg/day PO for migraine prophylaxis.
-Children
12 years: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy; 100 mg/day PO for migraine prophylaxis.
10 to 11 years: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing more than 38 kg: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing 23 to 38 kg: 350 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing 12 to 22 kg: 300 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing 11 kg or less: 250 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
Younger than 2 years: Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Specific guidelines for dosage adjustments in hepatic impairment are not available; however, clearance may be reduced.
Patients with Renal Impairment Dosing
Patients with renal impairment may require a longer time than patients with normal renal function to reach steady-state with each topiramate dosage adjustment.
CrCl 70 mL/minute or more: No dosage adjustment needed.
CrCl less than 70 mL/minute: In adults, reduce the topiramate dose to one-half of the usual dose.
In pediatric patients, adjustment to the usual mg/kg dosage may be required, but should be individualized since clearance rates are higher in the pediatric population than in adults. Some experts recommend administering one-half of the usual dose for pediatric patients with a GFR 10 to 50 mL/minute/1.73 m2 and one-quarter of the usual dose for pediatric patients with a GFR less than 10 mL/minute/1.73 m2.
Intermittent hemodialysis
During the hemodialysis session, adult patients clear topiramate at a rate that is 4 to 6 times greater than an adult person with normal renal function. A supplemental dose of topiramate may be required during or post-hemodialysis in some patients. Dosage adjustments should be based on duration of dialysis period, clearance rate of the dialysis system being used, and the effective renal clearance of topiramate in the patient to be dialyzed.
*non-FDA-approved indication
Abacavir; Dolutegravir; Lamivudine: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme.
Acetaminophen; Aspirin; Diphenhydramine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Concomitant use of dihydrocodeine with topiramate can decrease dihydrocodeine levels, resulting in less metabolism by CYP2D6 and decreased dihydromorphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. If coadministration is necessary, monitor for reduced efficacy of dihydrocodeine and signs of opioid withdrawal; consider increasing the dose of dihydrocodeine as needed. If topiramate is discontinued, consider a dose reduction of dihydrocodeine and frequently monitor for signs or respiratory depression and sedation. Topiramate is a weak inducer of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with doxylamine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Acetaminophen; Diphenhydramine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Acetaminophen; Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Acetaminophen; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Acetazolamide: (Major) Avoid concurrent use of acetazolamide or methazolamide with topiramate. Topiramate is a weak carbonic anhydrase inhibitor. Concomitant use of topiramate with acetazolamide or methazolamide may create a physiological environment that increases the risk of renal stone formation associated with topiramate use. Additionally, through an additive effect, the use of topiramate with agents that may increase the risk for heat-related disorders (acetazolamide and methazolamide), may lead to oligohidrosis, hyperthermia and heat stroke.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Alogliptin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Alogliptin; Pioglitazone: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control.
Alprazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Amitriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation and for increased amitriptyline-related adverse events during concomitant topiramate use. Concomitant use resulted in an increase in amitriptyline exposure by 12% and may increase the risk for additive CNS depression.
Amlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Atorvastatin: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Benazepril: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Celecoxib: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Olmesartan: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Valsartan: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide. (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Amphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Amphetamine; Dextroamphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Amphetamines: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Anticholinergics: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Anxiolytics; Sedatives; and Hypnotics: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Apixaban: (Moderate) Concurrent use of topiramate and anticoagulants, such as apixaban, may increase the risk of bleeding. In a pooled analysis of placebo-controlled trials, bleeding was more frequently reported in patients receiving topiramate (4.5%) compared to placebo (2-3%). In those with severe bleeding events, patients were often taking drugs that cause thrombocytopenia or affect platelet function or coagulation.
Aprepitant, Fosaprepitant: (Moderate) Use caution if topiramate and aprepitant, fosaprepitant are used concurrently and monitor for a possible decrease in the efficacy of aprepitant for several days after administration of a multi-day aprepitant regimen. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer; aprepitant is a CYP3A4 substrate. When a single dose of aprepitant (375 mg, or 3 times the maximum recommended dose) was administered on day 9 of a 14-day rifampin regimen (a strong CYP3A4 inducer), the AUC of aprepitant decreased approximately 11-fold and the mean terminal half-life decreased by 3-fold. The manufacturer of aprepitant recommends avoidance of administration with strong CYP3A4 inducers, but does not provide guidance for weak-to-moderate inducers. After administration, fosaprepitant is rapidly converted to aprepitant and shares the same drug interactions.
Aripiprazole: (Moderate) Monitor for unusal drowsiness and excessive sedation during concomitant aripiprazole and topiramate use due to the risk for additive CNS depression.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Aspirin, ASA; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Atazanavir: (Moderate) Caution is warranted when atazanavir is administered with topiramate as there is a potential for decreased concentrations of atazanavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Atazanavir is a substrate of CYP3A4.
Atazanavir; Cobicistat: (Moderate) Caution is warranted when atazanavir is administered with topiramate as there is a potential for decreased concentrations of atazanavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Atazanavir is a substrate of CYP3A4. (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4.
Atogepant: (Major) Avoid use of atogepant and topiramate when atogepant is used for chronic migraine. Use an atogepant dose of 30 or 60 mg PO once daily for episodic migraine if coadministered with topiramate. Concurrent use may decrease atogepant exposure and reduce efficacy. Atogepant is a CYP3A substrate and topiramate is a weak CYP3A inducer. Coadministration resulted in a 25% reduction in atogepant overall exposure and a 24% reduction in atogepant peak concentration.
Atovaquone; Proguanil: (Minor) Proguanil is metabolized to cycloguanil by CYP2C19. Potential interactions between proguanil or cycloguanil and other drugs that are CYP2C19 inhibitors are unknown. Use caution when combining atovaquone; proguanil with CYP2C19 inhibitors, such as topiramate.
Atropine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Atropine; Difenoxin: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Barbiturates: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Belladonna; Opium: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Belzutifan: (Moderate) Monitor for anemia and hypoxia if concomitant use of topiramate with belzutifan is necessary due to increased plasma exposure of belzutifan which may increase the incidence and severity of adverse reactions. Reduce the dose of belzutifan as recommended if anemia or hypoxia occur. Belzutifan is a CYP2C19 substrate and topiramate is a CYP2C19 inhibitor.
Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Benzodiazepines: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Benzphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Benztropine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Brexpiprazole: (Moderate) Because brexpiprazole is partially metabolized by CYP3A4, concurrent use of CYP3A4 inducers such as topiramate may result in decreased plasma concentrations of brexpiprazole. If these agents are used in combination, the patient should be carefully monitored for a decrease in brexpiprazole efficacy. An increase in brexpiprazole dosage may be clinically warranted in some patients. Similar precautions apply to combination products containing topiramate such as phentermine; topiramate.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Bumetanide: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Bupivacaine; Lidocaine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Butalbital; Acetaminophen: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Butalbital; Acetaminophen; Caffeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Butalbital; Aspirin; Caffeine; Codeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Cabotegravir; Rilpivirine: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Canagliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Carbamazepine: (Moderate) A topiramate dosage adjustment may be needed during concomitant carbamazepine use. Concomitant administration of topiramate with carbamazepine resulted in a clinically significant decrease (40%) in plasma topiramate concentrations.
Carbonic anhydrase inhibitors: (Major) Avoid concurrent use of acetazolamide or methazolamide with topiramate. Topiramate is a weak carbonic anhydrase inhibitor. Concomitant use of topiramate with acetazolamide or methazolamide may create a physiological environment that increases the risk of renal stone formation associated with topiramate use. Additionally, through an additive effect, the use of topiramate with agents that may increase the risk for heat-related disorders (acetazolamide and methazolamide), may lead to oligohidrosis, hyperthermia and heat stroke.
Cariprazine: (Major) Cariprazine and its active metabolites are extensively metabolized by CYP3A4. Concurrent use of cariprazine with CYP3A4 inducers, such as topiramate, has not been evaluated and is not recommended because the net effect on active drug and metabolites is unclear.
Celecoxib; Tramadol: (Moderate) Reserve concomitant prescribing of opioids and other CNS depressants, such as topiramate, for use in patients in whom alternate treatment options are inadequate. Limit dosages and durations to the minimum required and monitor patients closely for respiratory depression and sedation. If concomitant use is necessary, consider prescribing naloxone for the emergency treatment of opioid overdose. Concomitant use can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Chlordiazepoxide: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Chlordiazepoxide; Amitriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation and for increased amitriptyline-related adverse events during concomitant topiramate use. Concomitant use resulted in an increase in amitriptyline exposure by 12% and may increase the risk for additive CNS depression. (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Chlordiazepoxide; Clidinium: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia. (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Chlorothiazide: (Moderate) Topiramate is a carbonic anhydrase inhibitor. Concurrent use of topiramate with non-potassium sparing diuretics (e.g., thiazide diuretics) may potentiate the potassium-wasting action of these diuretics. Monitor baseline and periodic potassium concentrations during coadministration.
Chlorpheniramine; Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Chlorpromazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Cilostazol: (Moderate) Concurrent use of topiramate and drugs that affect platelet function such as cilostazol may increase the risk of bleeding. In a pooled analysis of placebo-controlled trials, bleeding was more frequently reported in patients receiving topiramate (4.5%) compared to placebo (2-3%). In those with severe bleeding events, patients were often taking drugs that cause thrombocytopenia or affect platelet function or coagulation. In addition, cilostazol is metabolized by the cytochrome P450 CYP2C19 hepatic isoenzyme and may interact with medications that are inhibitors of CYP2C19, including topiramate.
Citalopram: (Moderate) Limit the dose of citalopram to 20 mg/day if coadministered with topiramate. Concurrent use may increase citalopram exposure increasing the risk of QT prolongation. Citalopram is a sensitive CYP2C19 substrate; topiramate is a weak inhibitor of CYP2C19.
Clomipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant clomipramine and topiramate use due to the risk for additive CNS depression.
Clonazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Clorazepate: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4.
Cobimetinib: (Moderate) If concurrent use of cobimetinib and topiramate is necessary, use caution and monitor for decreased efficacy of cobimetinib. Cobimetinib is a CYP3A substrate in vitro, and topiramate is a weak inducer of CYP3A. The manufacturer of cobimetinib recommends avoiding coadministration of cobimetinib with moderate or strong CYP3A inducers based on simulations demonstrating that cobimetinib exposure would decrease by 73% or 83% when coadministered with a moderate or strong CYP3A inducer, respectively. Guidance is not available regarding concomitant use of cobimetinib with weak CYP3A inducers.
Codeine; Phenylephrine; Promethazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Codeine; Promethazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Conjugated Estrogens: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day.
Conjugated Estrogens; Bazedoxifene: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day.
Conjugated Estrogens; Medroxyprogesterone: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Dapagliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Dapsone: (Minor) The metabolism of dapsone may be accelerated when administered concurrently with topiramate, a known inducer of CYP3A4. Coadministration is expected to decrease the plasma concentration of dapsone and increase the formation of dapsone hydroxylamine (a metabolite associated with hemolysis). If these drugs must be administered together, closely monitor for a reduction in dapsone efficacy and signs of hemolytic anemia.
Darunavir: (Moderate) Caution is warranted when darunavir is administered with topiramate as there is a potential for decreased concentrations of darunavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Darunavir is a substrate of CYP3A4.
Darunavir; Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when darunavir is administered with topiramate as there is a potential for decreased concentrations of darunavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Darunavir is a substrate of CYP3A4.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when darunavir is administered with topiramate as there is a potential for decreased concentrations of darunavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Darunavir is a substrate of CYP3A4.
Delavirdine: (Moderate) Delavirdine is a potent inhibitor of cytochrome P450 2C9 and might decrease topiramate metabolism leading to increased topiramate serum concentrations and a risk of adverse reactions.
Desipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant desipramine and topiramate use due to the risk for additive CNS depression.
Desogestrel; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Dextroamphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Dichlorphenamide: (Moderate) Use dichlorphenamide and topiramate, another carbonic anhydrase inhibitor, together with caution as both drugs can cause metabolic acidosis. Concurrent use may increase the severity of metabolic acidosis. Measure sodium bicarbonate concentrations at baseline and periodically during dichlorphenamide treatment. If metabolic acidosis occurs or persists, consider reducing the dose or discontinuing dichlorphenamide therapy.
Dicyclomine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Dienogest; Estradiol valerate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Digoxin: (Moderate) Serum digoxin AUC was decreased by 12% when coadministered with topiramate. Although the clinical relevance has not been determined, the clinician should be aware that serum digoxin concentrations may be affected when digoxin and topiramate are used concomitantly.
Diltiazem: (Moderate) Monitor for loss of diltiazem efficacy and an increase in topiramate-related adverse events during coadministration. Concomitant use of diltiazem (240 mg) with topiramate (150 mg/day) resulted in a 10% decrease in Cmax and a 25% decrease in diltiazem AUC, a 27% decrease in Cmax and an 18% decrease in desacetyl diltiazem AUC, and no effect on N-desmethyl diltiazem. Co-administration of topiramate with diltiazem resulted in a 16% increase in Cmax and a 19% increase in AUC of topiramate.
Diphenhydramine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenhydramine; Ibuprofen: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenhydramine; Naproxen: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenhydramine; Phenylephrine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenoxylate; Atropine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Dolutegravir: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme.
Dolutegravir; Lamivudine: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme.
Dolutegravir; Rilpivirine: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme. (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Doravirine: (Minor) Concurrent administration of doravirine and topiramate may result in decreased doravirine exposure, resulting in potential loss of virologic control. Doravirine is a CYP3A4 substrate; topiramate is a weak CYP3A4 inducer.
Doravirine; Lamivudine; Tenofovir disoproxil fumarate: (Minor) Concurrent administration of doravirine and topiramate may result in decreased doravirine exposure, resulting in potential loss of virologic control. Doravirine is a CYP3A4 substrate; topiramate is a weak CYP3A4 inducer.
Doxepin: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant doxepin and topiramate use due to the risk for additive CNS depression.
Doxorubicin Liposomal: (Major) Topiramate is a mild CYP3A4 inducer; doxorubicin is a major substrate of CYP3A4. Inducers of CYP3A4 may decrease the concentration of doxorubicin and compromise the efficacy of chemotherapy. Avoid coadministration of topiramate and doxorubicin if possible. If not possible, monitor doxorubicin closely for efficacy.
Doxorubicin: (Major) Topiramate is a mild CYP3A4 inducer; doxorubicin is a major substrate of CYP3A4. Inducers of CYP3A4 may decrease the concentration of doxorubicin and compromise the efficacy of chemotherapy. Avoid coadministration of topiramate and doxorubicin if possible. If not possible, monitor doxorubicin closely for efficacy.
Doxylamine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with doxylamine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Doxylamine; Pyridoxine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with doxylamine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Dronabinol: (Moderate) Use caution if coadministration of dronabinol with topiramate is necessary, and monitor for a decrease in the efficacy of dronabinol. Dronabinol is a CYP2C9 and 3A4 substrate; topiramate is a weak inducer of CYP3A4. Concomitant use may result in decreased plasma concentrations of dronabinol.
Dronedarone: (Major) The concomitant use of dronedarone and CYP3A4 inducers should be avoided. Dronedarone is metabolized by CYP3A. Topiramate induces CYP3A4. Coadministration of CYP3A4 inducers, such as topiramate, with dronedarone may result in reduced plasma concentration and subsequent reduced effectiveness of dronedarone therapy.
Droperidol: (Major) Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Drospirenone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Estetrol: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Elagolix; Estradiol; Norethindrone acetate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Elbasvir; Grazoprevir: (Moderate) Caution is advised when administering elbasvir with topiramate. Topiramate is a mild CYP3A inducer, while elbasvir is a substrate of CYP3A. Use of these drugs together may decrease the plasma concentrations of elbasvir and could result in decreased virologic response. (Moderate) Caution is advised when administering elbasvir; grazoprevir with topiramate. Topiramate is a mild CYP3A inducer, while grazoprevir is a substrate of CYP3A. Use of these drugs together may decrease the plasma concentrations of grazoprevir and could result in decreased virologic response.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with topiramate as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Elvitegravir is a CYP3A4 substrate.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with topiramate as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Elvitegravir is a CYP3A4 substrate.
Empagliflozin; Linagliptin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended.
Empagliflozin; Linagliptin; Metformin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended. (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Empagliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Emtricitabine; Rilpivirine; Tenofovir Disoproxil Fumarate: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Ertugliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Estazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Esterified Estrogens: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day.
Esterified Estrogens; Methyltestosterone: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day.
Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day.
Estradiol; Levonorgestrel: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estradiol; Norethindrone: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estradiol; Norgestimate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estradiol; Progesterone: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estrogens affected by CYP3A inducers: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day.
Estropipate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day.
Eszopiclone: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Ethacrynic Acid: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Ethanol: (Major) Advise patients to avoid alcohol consumption while taking topiramate. Topiramate is a CNS depressant. Concomitant administration of topiramate with alcohol can result in significant CNS depression. Trokendi XR is contraindicated with recent alcohol use (i.e., within 6 hours before and 6 hours after use). In the presence of alcohol, the pattern of topiramate release from Trokendi XR is significantly altered. As a result, plasma concentrations of topiramate may be markedly higher soon after dosing and subtherapeutic later in the day. (Major) Avoid alcohol with topiramate. Topiramate is a CNS depressant. Concomitant administration of topiramate with alcohol can result in significant CNS depression. Trokendi XR is contraindicated with recent alcohol use (i.e., within 6 hours before and 6 hours after use). In the presence of alcohol, the pattern of topiramate release from Trokendi XR is significantly altered. As a result, plasma concentrations of topiramate may be markedly higher soon after dosing and subtherapeutic later in the day.
Ethinyl Estradiol; Norelgestromin: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Ethinyl Estradiol; Norethindrone Acetate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Ethinyl Estradiol; Norgestrel: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Ethotoin: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Ethynodiol Diacetate; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Etonogestrel: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Etonogestrel; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Fentanyl: (Moderate) Consider an increased dose of fentanyl and monitor for evidence of opioid withdrawal if concurrent use of topiramate is necessary. If topiramate is discontinued, consider reducing the fentanyl dosage and monitor for evidence of respiratory depression. Coadministration of a CYP3A4 inducer like topiramate with fentanyl, a CYP3A4 substrate, may decrease exposure to fentanyl resulting in decreased efficacy or onset of withdrawal symptoms in a patient who has developed physical dependence to fentanyl. Fentanyl plasma concentrations will increase once the inducer is stopped, which may increase or prolong the therapeutic and adverse effects, including serious respiratory depression.
Flavoxate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Flibanserin: (Major) The concomitant use of flibanserin with CYP3A4 inducers significantly decreases flibanserin exposure compared to the use of flibanserin alone. Therefore, concurrent use of flibanserin and CYP3A4 inducers, such as topiramate is not recommended.
Fluphenazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Flurazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Fosphenytoin: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Furosemide: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Gefitinib: (Moderate) Monitor for clinical response of gefitinib if used concomitantly with topiramate. Gefitinib is metabolized significantly by CYP3A4 and topiramate is a weak CYP3A4 inducer; coadministration may increase gefitinib metabolism and decrease gefitinib concentrations. This also applies to combination products containing topiramate, such as phentermine; topiramate. While the manufacturer has provided no guidance regarding the use of gefitinib with mild or moderate CYP3A4 inducers, administration of a single 500 mg gefitinib dose with a concurrent strong CYP3A4 inducer (rifampin) resulted in reduced mean AUC of gefitinib by 83%.
Glipizide; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Glyburide: (Minor) Coadministration of glyburide with topiramate may decrease systemic exposure to glyburide. A pharmacokinetic drug interaction study evaluated the combination of topiramate and glyburide. Reductions in AUC and Cmax were noted for glyburide and the active metabolites.
Glyburide; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known. (Minor) Coadministration of glyburide with topiramate may decrease systemic exposure to glyburide. A pharmacokinetic drug interaction study evaluated the combination of topiramate and glyburide. Reductions in AUC and Cmax were noted for glyburide and the active metabolites.
Glycopyrrolate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Glycopyrrolate; Formoterol: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Homatropine; Hydrocodone: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia. (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Hydantoins: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Hydrocodone; Ibuprofen: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Hydroxychloroquine: (Moderate) Monitor persons with epilepsy for seizure activity during concomitant topiramate and hydroxychloroquine use. Hydroxychloroquine can lower the seizure threshold; therefore, the activity of antiepileptic drugs may be impaired with concomitant use.
Hydroxyzine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with hydroxyzine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Hyoscyamine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Ibuprofen; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Imatinib: (Moderate) Imatinib is a potent inhibitors of cytochrome P450 2C9 and might decrease topiramate metabolism leading to increased topiramate serum concentrations and a risk of adverse reactions.
Imipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant imipramine and topiramate use due to the risk for additive CNS depression.
Indacaterol; Glycopyrrolate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Isavuconazonium: (Moderate) Caution and close monitoring are warranted when isavuconazonium is administered with topiramate as there is a potential for decreased concentrations of isavuconazonium. Decreased isavuconazonium concentrations may lead to a reduction of antifungal efficacy and the potential for treatment failure. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Isavuconazole, the active moiety of isavuconazonium, is a sensitive substrate of this enzyme.
Lacosamide: (Moderate) Use lacosamide with caution in patients taking concomitant medications that affect cardiac conduction including those that prolong PR interval, such as sodium channel blocking anticonvulsants (e.g., topiramate), because of the risk of AV block, bradycardia, or ventricular tachyarrhythmia. If use together is necessary, obtain an ECG prior to lacosamide initiation and after treatment has been titrated to steady-state. In addition, monitor patients receiving lacosamide via the intravenous route closely.
Lamotrigine: (Moderate) Monitor for loss of topiramate efficacy and/or an increase in topiramate-related adverse events during coadministration. Coadministration has resulted in both a 13% decrease and 15% increase in topiramate concentrations.
Leuprolide; Norethindrone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levamlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Levonorgestrel: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levonorgestrel; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Lidocaine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Lidocaine; Epinephrine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Lidocaine; Prilocaine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Linagliptin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended.
Linagliptin; Metformin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended. (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Lisdexamfetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Lithium: (Moderate) Monitor serum lithium concentrations during concomitant high-dose topiramate use. Lithium concentrations were unaffected during treatment with topiramate 200 mg/day; however, there was an observed increase in systemic exposure of lithium (26%) after topiramate doses up to 600 mg/day.
Loop diuretics: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Lopinavir; Ritonavir: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Lorazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Lumateperone: (Major) Avoid coadministration of lumateperone and topiramate as concurrent use may decrease lumateperone exposure which may reduce efficacy. Lumateperone is a CYP3A4 substrate; topiramate is a weak CYP3A4 inducer.
Lurasidone: (Moderate) Because lurasidone is primarily metabolized by CYP3A4, decreased plasma concentrations of lurasidone may theoretically occur when the drug is co-administered with inducers of CYP3A4 such as topiramate.
Maprotiline: (Moderate) Maprotiline, when used concomitantly with anticonvulsants, can increase CNS depression and may also lower the seizure threshold, leading to pharmacodynamic interactions. Monitor patients on anticonvulsants carefully when maprotiline is used concurrently. Because of the lowering of seizure threshold, an alternative antidepressant may be a more optimal choice for patients taking drugs for epilepsy.
Maraviroc: (Minor) Use caution if coadministration of maraviroc with topiramate is necessary, due to a possible decrease in maraviroc exposure. Maraviroc is a CYP3A substrate and topiramate is a CYP3A4 inducer. Monitor for a decrease in maraviroc efficacy with concomitant use.
Medroxyprogesterone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Mefloquine: (Moderate) Topiramate induces CYP3A4 and may increase the metabolism of mefloquine if coadministered. Use may reduce the clinical efficacy of mefloquine, increasing the risk of Plasmodium falciparum resistance during treatment of malaria. Coadministration of mefloquine and anticonvulsants may also result in lower than expected anticonvulsant concentrations and loss of seizure control. Monitoring of drug concentrations (if therapeutic monitoring is advised for the anticonvulsant) is recommended. When topiramate is used for other conditions, monitor for clinical efficacy. Mefloquine may additionally cause CNS side effects that may cause seizures or alter moods or behaviors.
Meprobamate: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Metformin; Repaglinide: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Metformin; Saxagliptin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Metformin; Sitagliptin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Methamphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Methazolamide: (Major) Avoid concurrent use of acetazolamide or methazolamide with topiramate. Topiramate is a weak carbonic anhydrase inhibitor. Concomitant use of topiramate with acetazolamide or methazolamide may create a physiological environment that increases the risk of renal stone formation associated with topiramate use. Additionally, through an additive effect, the use of topiramate with agents that may increase the risk for heat-related disorders (acetazolamide and methazolamide), may lead to oligohidrosis, hyperthermia and heat stroke.
Methenamine: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Methenamine; Sodium Salicylate: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde.
Methohexital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Methscopolamine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Midazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Molindone: (Moderate) Consistent with the pharmacology of molindone, additive effects may occur with other CNS active drugs such as anticonvulsants. In addition, seizures have been reported during the use of molindone, which is of particular significance in patients with a seizure disorder receiving anticonvulsants. Adequate dosages of anticonvulsants should be continued when molindone is added; patients should be monitored for clinical evidence of loss of seizure control or the need for dosage adjustments of either molindone or the anticonvulsant.
Nanoparticle Albumin-Bound Sirolimus: (Moderate) Monitor for reduced sirolimus efficacy if sirolimus is coadministered with topiramate. Concomitant use may decrease sirolimus exposure. Sirolimus is a CYP3A substrate and topiramate is a weak CYP3A inducer.
Neostigmine; Glycopyrrolate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Nirmatrelvir; Ritonavir: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Nisoldipine: (Major) Avoid coadministration of nisoldipine with topiramate due to decreased plasma concentrations of nisoldipine. Alternative antihypertensive therapy should be considered. Nisoldipine is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Coadministration with a strong CYP3A4 inducer lowered nisoldipine plasma concentrations to undetectable levels.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norethindrone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norethindrone; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norgestimate; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norgestrel: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Nortriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant nortriptyline and topiramate use due to the risk for additive CNS depression.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide. (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Oxazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Oxybutynin: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Pazopanib: (Moderate) Coadministration of pazopanib and topiramate may cause a decrease in systemic concentrations of pazopanib. Use caution when administering these drugs concomitantly. Pazopanib is a substrate for CYP3A4. Topiramate in a weak CYP3A4 inducer.
Pentobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Perampanel: (Moderate) During clinical trials, co-administration of topiramate and perampanel to patients led to a 20% decrease in the AUC of perampanel compared to patients not taking enzyme-inducing antiepileptic drugs. Topiramate is an inducer of CYP3A4, while perampanel is a substrate of this enzyme. Patients taking topiramate who begin treatment with perampanel should be closely monitored for adverse effects and receive a higher initial dose of perampanel. Addition or withdrawal of enzyme-inducing antiepileptic drugs may require a perampanel dose adjustment.
Perindopril; Amlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Perphenazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Perphenazine; Amitriptyline: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression. (Moderate) Monitor for unusual drowsiness or excess sedation and for increased amitriptyline-related adverse events during concomitant topiramate use. Concomitant use resulted in an increase in amitriptyline exposure by 12% and may increase the risk for additive CNS depression.
Phenobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Phenothiazines: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Phenytoin: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Pioglitazone: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control.
Pioglitazone; Glimepiride: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control.
Pioglitazone; Metformin: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control. (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Pregabalin: (Moderate) Monitor for respiratory depression and sedation during concomitant topiramate and pregabalin use; consider starting pregabalin at a low dose. Concomitant use increases the risk for additive CNS depression.
Primidone: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Probenecid: (Minor) Probenecid may increase the renal clearance of topiramate resulting in lower topiramate concentrations. Although not evaluated in humans, animal studies using probenecid along with topiramate showed a significant increase in renal clearance of topiramate. This suggests that topiramate may undergo renal tubular reabsorption. Probenecid may block renal tubular reabsorption of topiramate, thus increasing the renal clearance of the drug.
Probenecid; Colchicine: (Minor) Probenecid may increase the renal clearance of topiramate resulting in lower topiramate concentrations. Although not evaluated in humans, animal studies using probenecid along with topiramate showed a significant increase in renal clearance of topiramate. This suggests that topiramate may undergo renal tubular reabsorption. Probenecid may block renal tubular reabsorption of topiramate, thus increasing the renal clearance of the drug.
Prochlorperazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Progesterone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Progestins: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Promethazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Promethazine; Dextromethorphan: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Promethazine; Phenylephrine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Propantheline: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Protriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant protriptyline and topiramate use due to the risk for additive CNS depression.
Quazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Ramelteon: (Major) Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Relugolix; Estradiol; Norethindrone acetate: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Remimazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Rilpivirine: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Ritonavir: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Romidepsin: (Moderate) Romidepsin is a substrate for CYP3A4. Coadministration of a CYP3A4 inducer, like topiramate, may decrease systemic concentrations of romidepsin. Use caution when concomitant administration of these agents is necessary.
Scopolamine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Secobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Segesterone Acetate; Ethinyl Estradiol: (Major) Advise patients taking estrogen hormones for contraception to consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for at least 1 month following discontinuation of topiramate especially when topiramate is used at a dosage of greater than 200 mg per day. Higher-dose hormonal regimens containing a minimum of 30 mcg of ethinyl estradiol or equivalent may also be considered. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Topiramate may decrease estrogen hormone concentrations which may decrease efficacy and increase the risk for breakthrough bleeding in patients taking estrogen hormones for contraception. Estrogens are CYP3A substrates and topiramate is a CYP3A inducer. Concomitant use has been observed to decrease ethinyl estradiol exposure by 18%, 21%, and 30% at topiramate daily doses of 200 mg, 400 mg, and 800 mg, respectively. No significant changes in ethinyl estradiol exposure have been observed at topiramate doses of 50 mg to 200 mg per day. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Sirolimus: (Moderate) Monitor sirolimus concentrations and adjust sirolimus dosage as appropriate during concomitant use of topiramate. Concomitant use may decrease sirolimus exposure and efficacy. Sirolimus is a CYP3A substrate and topiramate is a weak CYP3A inducer.
Sofosbuvir; Velpatasvir: (Major) Use caution when administering velpatasvir with topiramate. Taking these drugs together may decrease velpatasvir plasma concentrations, potentially resulting in loss of antiviral efficacy. Velpatasvir is a CYP3A4 substrate; topiramate is a weak inducer of CYP3A4.
Sofosbuvir; Velpatasvir; Voxilaprevir: (Major) Use caution when administering velpatasvir with topiramate. Taking these drugs together may decrease velpatasvir plasma concentrations, potentially resulting in loss of antiviral efficacy. Velpatasvir is a CYP3A4 substrate; topiramate is a weak inducer of CYP3A4.
Solifenacin: (Moderate) Through an additive effect, the use of topiramate with agents that may increase the risk for heat related disorders, such as solifenacin, may lead to oligohidrosis, hyperthermia, and/or heat stroke.
Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Sufentanil: (Moderate) Because the dose of the sufentanil sublingual tablets cannot be titrated, consider an alternate opiate if topiramate must be administered. Monitor for reduced efficacy of sufentanil injection and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of sufentanil injection as needed. If topiramate is discontinued, consider a dose reduction of sufentanil injection and frequently monitor for signs or respiratory depression and sedation. Sufentanil is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease sufentanil concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Telmisartan; Amlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Temazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Terbinafine: (Moderate) Caution is advised when administering terbinafine with topiramate. Although this interaction has not been studied by the manufacturer, and published literature suggests the potential for interactions to be low, taking these drugs together may alter the systemic exposure of terbinafine. Predictions about the interaction can be made based on the metabolic pathways of both drugs. Terbinafine is metabolized by at least 7 CYP isoenyzmes, with major contributions coming from CYP2C19 and CYP3A4; topiramate is an inducer of CYP3A4 and an inhibitor of CYP2C19. Monitor patients for adverse reactions and breakthrough fungal infections if these drugs are coadministered.
Thioridazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Tolterodine: (Moderate) Through an additive effect, the use of topiramate (a weak carbonic anhydrase inhibitor) with agents that may increase the risk for heat-related disorders, such as antimuscarinics, may lead to oligohidrosis, hyperthermia and/or heat stroke.
Torsemide: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Tramadol: (Moderate) Reserve concomitant prescribing of opioids and other CNS depressants, such as topiramate, for use in patients in whom alternate treatment options are inadequate. Limit dosages and durations to the minimum required and monitor patients closely for respiratory depression and sedation. If concomitant use is necessary, consider prescribing naloxone for the emergency treatment of opioid overdose. Concomitant use can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Tramadol; Acetaminophen: (Moderate) Reserve concomitant prescribing of opioids and other CNS depressants, such as topiramate, for use in patients in whom alternate treatment options are inadequate. Limit dosages and durations to the minimum required and monitor patients closely for respiratory depression and sedation. If concomitant use is necessary, consider prescribing naloxone for the emergency treatment of opioid overdose. Concomitant use can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Triazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Trifluoperazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Trihexyphenidyl: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Trimipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant trimipramine and topiramate use due to the risk for additive CNS depression.
Trospium: (Moderate) Oligohidrosis and hyperthermia have been reported in post-marketing experience with topiramate. Use caution when topiramate is prescribed with agents known to predispose patients to similar heat-related disorders such as trospium.
Ulipristal: (Major) Avoid administration of ulipristal with drugs that induce CYP3A4. Ulipristal is a substrate of CYP3A4 and topiramate is a mild CYP3A4 inducer. Concomitant use may decrease the plasma concentration and effectiveness of ulipristal.
Valproic Acid, Divalproex Sodium: (Moderate) Concomitant administration of topiramate and valproic acid has been associated with hyperammonemia with or without encephalopathy in patients who have tolerated either drug alone. In addition, concomitant administration of topiramate and valproic acid has been associated with hypothermia with or without hyperammonemia in patients who have tolerated either drug alone. Assessment of blood ammonia levels may be advisable in patients presenting with symptoms of hypothermia. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as valproic acid, may also increase the risk of bleeding; monitor patients appropriately. In several case reports, children with localized epilepsy have presented with somnolence, seizure exacerbation, behavioral alteration, decline in speech and cognitive abilities, and ataxia while being treated with a combination of valproate and topiramate. Previously, the children tolerated valproic acid with other antiepileptic drugs. Children presented with elevated serum ammonia, normal or elevated LFTs, and generalized slowing of EEG background activity during encephalopathy, which promptly reverted to normal along with clinical improvement following withdrawal of valproate. The possible mechanism is topiramate-induced aggravation of all the known complications of valproic acid monotherapy; it is not due to a pharmacokinetic interaction. This condition is reversible with cessation of either valproic acid or topiramate.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Vemurafenib: (Major) Concomitant use of vemurafenib and topiramate may result in decreased concentrations of vemurafenib. Vemurafenib is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Use caution and monitor patients for therapeutic effects.
Vorapaxar: (Moderate) Use caution during concurrent use of vorapaxar and topiramate. Decreased serum concentrations of vorapaxar and thus decreased efficacy are possible when vorapaxar, a CYP3A4 substrate, is coadministered with topiramate, a mild inducer of CYP3A4 in vitro. In addition, concurrent use of topiramate and drugs that affect platelet function such as platelet inhibitors may increase the risk of bleeding. In a pooled analysis of placebo-controlled trials, bleeding was more frequently reported in patients receiving topiramate (4.5%) compared to placebo (23%). In those with severe bleeding events, patients were often taking drugs that cause thrombocytopenia or affect platelet function or coagulation.
Warfarin: (Moderate) Closely monitor the INR if coadministration of warfarin with topiramate is necessary as concurrent use may decrease the exposure of warfarin leading to reduced efficacy; increased bleeding is also possible with the combination. Topiramate is a weak CYP3A4 inducer and the R-enantiomer of warfarin is a CYP3A4 substrate. The S-enantiomer of warfarin exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer, but the R-enantiomer generally has a slower clearance.
Zaleplon: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Zolpidem: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Zonisamide: (Moderate) Monitor for the appearance or worsening of metabolic acidosis if zonisamide is given concomitantly with topiramate. Concomitant use of zonisamide with another carbonic anhydrase inhibitor, like topiramate, may increase the severity of metabolic acidosis and may also increase the risks of hyperammonemia, encephalopathy, and kidney stone formation. Monitor serum ammonia concentrations if signs or symptoms of encephalopathy occur. Hyperammonemia resulting from zonisamide resolves when zonisamide is discontinued and may resolve or decrease in severity with a decrease of the daily dose.
The exact mechanism of topiramate's anticonvulsant and migraine prophylaxis effects is unknown. It appears that topiramate may block the spread of seizures rather than raise the seizure threshold like other antiepileptic drugs (AEDs). The drug appears to have several mechanisms of action. First, topiramate reduces the duration of abnormal discharges and the number of action potentials within each discharge. This is probably secondary to its ability to block voltage-sensitive sodium channels. Second, topiramate enhances the activity of the inhibitory neurotransmitter gamma-aminobutyrate (GABA) at GABA-A receptors by increasing the frequency at which GABA activates GABA-A receptors. Third, topiramate inhibits excitatory transmission by antagonizing some types of glutamate receptors. Specifically, topiramate antagonizes the ability of kainate to activate the kainate/AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid; non-NMDA) subtype of excitatory amino acid (glutamate) receptor. There is no apparent effect on the activity of N-methyl-D-aspartate (NMDA) at the NMDA receptor subtype. Topiramate is also a weak carbonic anhydrase inhibitor (isozymes II and IV); however, while this action can cause a risk for metabolic acidosis, this mechanism does not appear to be involved in the anticonvulsant action of the drug.
In addition to its efficacy in epilepsy and migraine prophylaxis, topiramate has also demonstrated neuroprotective effects against hypoxic-ischemic brain damage in both in vitro and animal models. The cerebral damage of hypoxic-ischemic encephalopathy occurs in part due to an increased release of excitatory neurotransmitters, including glutamate. Glutamate activates AMPA receptors, depolarizes the cell, and promotes the removal of the voltage-sensitive magnesium block on NMDA receptors. This, in turn, promotes the entry of calcium into the cell, stimulating a series of reactions that lead to cell necrosis and apoptosis. The neuroprotective properties of topiramate appear to be primarily related to its inhibition of the kainate/AMPA subtype of glutamate receptors. In addition, blockade of sodium channels, high-voltage calcium currents, carbonic anhydrase isoenzymes, and mitochondrial permeability transition pore (MPTP) may also contribute to its neuroprotective effects.
Topiramate is administered orally. Protein binding ranges from 15% to 41% over the concentration range of 0.5 to 250 mcg/mL. It is not metabolized to a great extent. Six metabolites have been identified and are formed via hydroxylation, hydrolysis, and glucuronidation. None of these metabolites constitutes more than 5% of an administered dose. About 70% of an administered dose is eliminated unchanged in the urine. Topiramate undergoes renal tubular reabsorption. Oral plasma clearance (CL/F) is approximately 20 to 30 mL/minute in adults after oral administration. In general, weight-adjusted clearance of topiramate is greater in children vs. adults and in infants and younger children vs. older children and adolescents. The mean plasma elimination half-life is 21 hours after single or multiple doses of immediate-release tablets or capsules. The mean effective half-life of extended-release capsules (Qudexy XR) is about 56 hours. The mean elimination half-life of topiramate was approximately 31 hours after repeat administration of extended-release capsules (Trokendi XR).
Affected cytochrome P450 isoenzymes and drug transporters: CYP2C19, CYP3A4
In vitro studies indicate that topiramate may induce CYP3A4 (weak inducer) and inhibit CYP2C19 (weak inhibitor). Topiramate does not inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, CYP3A4/5 isozymes. Some hepatic enzyme-inducing antiepileptic drugs (i.e., phenytoin, carbamazepine) have been shown to reduce topiramate serum concentrations by 40% to 48%.
-Route-Specific Pharmacokinetics
Oral Route
Topiramate has a high bioavailability (80% to 95%).
Oral solution
Cmax occurs at approximately 0.5 hour after administration of the oral solution in healthy male subjects under fasting conditions. Steady-state concentrations are reached in 4 days. Administration of the oral solution with a high fat and high calorie meal did not affect topiramate AUC0-t and AUC0-infinity, but lowered the Cmax by 28% and delayed the Tmax by 5 hours. Pharmacokinetics are linear over a dosage range of 200 to 800 mg/day. Overall, the impact of food intake on topiramate pharmacokinetics is not expected to be clinically significant.
Immediate-release formulations
Immediate-release topiramate is rapidly absorbed with peak plasma concentrations occurring approximately 2 hours (range: 1.6 to 4 hours) after administration in adult patients. Steady-state concentrations are reached in 4 days. Oral tablets are bioequivalent to the sprinkle formulation and the dosage forms may be used interchangeably. Pharmacokinetics are linear with dose proportional increases in plasma concentration over a dosage range of 3 to 25 mg/kg/day in infants and young children and over a range of 1 to 9 mg/kg/day in older children and adolescents. The bioavailability of topiramate is not affected by food. In pharmacokinetic studies of healthy adult males, the administration of topiramate with a high fat meal decreased Cmax by 10% to 13% and delayed Tmax approximately 2 hours, compared to a fasted state. Extent of absorption was not affected.
Extended-release formulations
Although both extended-release formulations (Qudexy XR and Trokendi XR), when administered once daily and at steady-state, are bioequivalent to the immediate-release tablet administered twice daily, the 2 extended-release formulations are not bioequivalent or interchangeable to each other. Trokendi XR contains 3 types of beads coated for triphasic release: an immediate-release bead, a coated bead for extended-release, and another coated bead for a longer duration of extended-release. The specific ratio of all 3 beads is necessary to achieve the exact pharmacokinetic profile of topiramate release over 24 hours. In addition, the technologies in the triphasic dispersion do not allow for the capsule to be sprinkled, chewed, or crushed; the capsule must remain intact upon administration. On the contrary, Qudexy XR was specifically designed to be opened and sprinkled on a small amount of soft food if needed. Qudexy XR contains a single type of bead; hence, it cannot be expected to produce identical triphasic drug release when compared to Trokendi XR.
Qudexy XR
After a single dose, peak plasma concentrations occur in approximately 20 hours. With repeated daily dosing, steady-state is obtained in approximately 5 days and the Tmax shortens to 6 hours. During pharmacokinetic studies, fluctuation of topiramate plasma concentrations was 40% in healthy subjects compared to 53% for immediate-release topiramate. Pharmacokinetics are linear over a dosage range of 50 to 1,400 mg/day in adult patients. At an adult dose of 25 mg/day, pharmacokinetics are nonlinear, perhaps due to topiramate binding to carbonic anhydrase in the red blood cells. Administration with a high fat meal does not affect bioavailability, but may delay Tmax by approximately 4 hours. Qudexy XR, when opened and sprinkled on a spoonful of soft food, is bioequivalent to the intact capsule.
Trokendi XR
After a single dose, peak plasma concentrations occur in approximately 24 hours. During pharmacokinetic studies, fluctuation of topiramate plasma concentrations was 26% and 42% in healthy and epileptic subjects, respectively, compared to 40% and 51%, respectively, for immediate-release topiramate. Pharmacokinetics are linear over a dosage range of 50 to 200 mg/day in adult patients. At an adult dose of 25 mg/day, pharmacokinetics are nonlinear, perhaps due to topiramate binding to carbonic anhydrase in the red blood cells. Administration with a high fat meal increases Cmax by 37% and shortens Tmax to approximately 8 hours after a single dose; there is no effect on the AUC. Pharmacokinetic modeling has shown the effect of food on Cmax is significantly reduced with repeated dosing.
-Special Populations
Hepatic Impairment
Plasma clearance of topiramate decreased a mean of 26% in patients with moderate to severe hepatic impairment.
Renal Impairment
The clearance of topiramate was reduced by 42% in patients with moderate renal impairment (i.e., CrCl 30 to 69 mL/minute/1.73 m2) and by 54% in those with severe renal impairment (CrCl less than 30 mL/minute/1.73 m2) compared to subjects with normal renal function (CrCl 70 mL/minute/1.73 m2 or more).
Hemodialysis
Topiramate is significantly cleared by hemodialysis. Drug dialysis clearance was 120 mL/minute using a high-efficiency, counterflow, single pass-dialysate hemodialysis procedure, with blood flow through the dialyzer at 400 mL/minute; this is approximately 4 to 6 times higher than the clearance reported in healthy adults (20 to 30 mL/minute). This high clearance will remove a clinically significant amount of topiramate from the patient over the hemodialysis treatment period.
Pediatrics
In general, weight-adjusted clearance of topiramate is greater in children vs. adults and in infants and younger children vs. older children and adolescents. With the same mg/kg dose, plasma concentrations may be lower in children vs. adults and also in younger children vs. older children and adolescents.
Children and Adolescents 4 to 17 years
In a pharmacokinetic study of pediatric patients with epilepsy (n = 18; age range: 4 to 17 years) receiving concomitant antiepileptics drugs (AEDs), topiramate was initiated at an initial dose of 1 mg/kg/day and increased at weekly intervals to 3, 6, and 9 mg/kg/day, divided into twice daily dosing. At steady-state, Cmax and AUC (1 mg/kg, 3 mg/kg, and 9 mg/kg doses, respectively) for age bands broken into children 4 to 7 years (Cmax = 2.32, 3.91, 10.55 mcg/mL; AUC = 23.5, 61.4, 157 mcg x hour/mL), 8 to 11 years (Cmax = 2.74, 4.29, 11.5 mcg/mL; AUC = 31.5, 81.4, 205.4 mcg x hour/mL), and 12 to 17 years (Cmax = 1.72, 5.26, 12.37 mcg/mL; AUC = 29.4, 96.3, 222.2 mcg x hour/mL) were linear. Clearance and half-life were independent of the dose. Half-life estimates were shorter in the younger age group (4 to 7 years; half-life = 8 hours) compared to the older patients (8 to 17 years; half life = 11 to 13 hours); estimates were also shorter in patients taking concomitant enzyme-inducing AEDs (7.5 hours vs. 15 to 16 hours). In the aforementioned study, weight-adjusted drug plasma clearance was approximately 50% higher in children than adults for both those receiving adjunctive non-enzyme inducing AEDs (0.47 mL/kg/minute vs. 0.32 mL/kg/minute) and enzyme-inducing AEDs (1 mL/kg/minute vs. 0.66 mL/kg/minute). This information suggests that steady-state plasma topiramate concentrations for the same mg/kg dose would be approximately 33% lower in this age group compared to adults; therefore, larger weight-based dose requirements may be necessary to obtain therapeutic efficacy.
Infants and Children 1 to 3 years
In a pharmacokinetic study of 35 infants and children (age range: 2 to 22 months) with refractory partial-onset seizures, mean clearance values were similar across all groups independent of age, weight, and topiramate dose. Patients were randomized to receive adjuvant topiramate liquid or sprinkle formulation 3, 5, 15, or 25 mg/kg/day in divided doses every 12 hours. At steady-state, Cmin was 1.9 +/- 1, 3.3 +/- 1.9, 9.7 +/- 4.8, and 13.6 +/- 5.2 mcg/mL and AUC was 29.1 +/- 12.4, 50 +/- 19.6, 143 +/- 53.8, and 211 +/- 58 mcg x hour/mL, respectively. Reported mean clearance values were similar to those reported in another study of 22 young children (mean age: 2.7 years; range: 0.8 to 3.9 years) receiving topiramate (mean dose: 7 mg/kg/day) plus adjuvant therapy with enzyme-inducing (1.41 vs. 1.42 mL/kg/minute), enzyme-inhibiting (0.71 vs. 0.82 mL/kg/minute), or neutral (0.66 vs. 0.77 mL/kg/minute) antiepileptic agents. In adult patients, topiramate is primarily eliminated via renal excretion (70% to 85%) with only a small fraction eliminated via hepatic metabolism; it is not known whether renal excretion or metabolism is the major route of drug elimination in young children. However, elimination via both routes is potentially increased in this age group and may result in larger dose requirements on mg/kg basis to achieve therapeutic efficacy.
Neonates
Limited data available. In a study of 13 full-term neonates with hypoxic ischemic encephalopathy receiving either deep hypothermia (DH) or mild hypothermia (MH), peak plasma concentrations were achieved 3.8 +/- 2.2 hours after oral administration and ranged from 15.4 to 19.9 mcg/mL (mean Cmax: 18 mcg/mL). Mean plasma clearance was 0.26 mL/kg/minute and mean elimination half-life was 35.6 +/- 19.3 hours. Patients received topiramate sprinkles (5 mg/kg/dose) mixed with water and administered via orogastric tube once daily for the first 3 days of life, starting at the initiation of hypothermia. It is important to note that this dose was arbitrarily chosen to rapidly achieve therapeutic plasma concentrations for a short period of time; investigators hypothesized hypothermia would result in higher drug plasma concentrations and a prolonged half-life. In the study, topiramate plasma concentrations were within the 5 to 20 mcg/mL reference range (extrapolated from adult data) in 11 of the 13 neonates who were cooled for 72 hours; 2 neonates in DH exceeded the upper limit. The pharmacokinetic parameters between neonates treated with DH or MH did not significantly differ, although lower AUC, lower average plasma concentration, and prolonged half-life were observed in the DH group (DH AUC = 318.1 +/- 101.6 mcg x hour/mL, Cavg = 13.3 +/- 4.2 mcg/mL, half-life = 48.8 +/- 4.6 hours vs. MH AUC = 366.2 +/- 48.1 mcg x hour/mL, Cavg = 15.26 +/- 2 mcg/mL, half-life = 29 +/- 23.8 hours). Neonates treated with DH had higher topiramate concentrations between 48 to 72 hours than those treated with MH, most likely due to more irregular absorption and elimination.
Geriatric
In a controlled clinical study, the older adult subject population (65 to 85 years, n = 16) had reduced renal function (creatinine clearance [-20%]) compared to young adults. After a single oral topiramate 100 mg dose, maximum plasma concentration for older adults and young adults was achieved at approximately 1 to 2 hours. Topiramate plasma and renal clearance were reduced 21% and 19%, respectively, in older adult subjects, compared to young adults. Similarly, topiramate half-life was longer (13%) in older adults. Reduced topiramate clearance resulted in slightly higher maximum plasma concentration (23%) and AUC (25%) in older adult subjects than observed in young adults. Topiramate clearance is decreased in older adults only to the extent that renal function is reduced.
Gender Differences
Topiramate clearance was not affected by gender.
Ethnic Differences
Topiramate clearance was not affected by race.