Methazolamide is an oral carbonic anhydrase inhibitor. It is used in the treatment of glaucoma to rapidly reduce intraocular pressure. Methazolamide works by decreasing the production of aqueous humor. The drug is used off-label for the treatment of benign familial tremor and has also been used in prevention of altitude sickness. A topical ophthalmic formulation of methazolamide complexed in cyclodextrin is being investigated for ocular hypertension. Oral methazolamide (Neptazane(R)) was approved by the FDA in 1959.
General Administration Information
-For storage information, see the specific product information within the How Supplied section.
-NOTE: Methazolamide may be used concomitantly with miotics, mydriatics and osmotic agents.
Route-Specific Administration
Oral Administration
-May take with food.
-Consume extra fluids to help prevent kidney stones.
Frequent adverse GI effects of methazolamide include nausea, vomiting, diarrhea, anorexia, and weight loss. Melena, xerostomia, and excessive thirst have also been reported. Dysgeusia (often a metallic taste) is also a frequent adverse effect that may occur with all carbonic anhydrase inhibitors. Loss of smell and loss of taste have been reported.
Adverse CNS effects, such as drowsiness, seizures, irritability, libido decrease, vertigo, confusion, and paresthesias can develop. Paresthesias are manifested as numbness, tingling, or burning in the hands, fingers, feet, toes, mouth, tongue, lips, or anus. Paresthesias may be less common with methazolamide than with acetazolamide; however, complaints of paresthesias may signal the need for dosage reduction.
The inhibition of carbonic anhydrase by methazolamide affects the excretion of electrolytes. Rarely, hyperchloremia and/or metabolic acidosis can result from an increase in plasma chloride concentrations. The increased excretion of bicarbonate, potassium, and sodium decreases the extracellular fluid concentration of bicarbonate and causes metabolic acidosis and possibly hypokalemia. Xerostomia, increased thirst, arrhythmias, muscle cramps, and nausea may all be signs of hypokalemia. Malaise, fatigue, asthenia, weakness, and complaints of paresthesia or myalgia may also be signs of need for dosage reduction (i.e., acidosis). Hypokalemia may be more of a risk if potassium intake is inadequate or if multiple potassium-wasting drugs are being used, or in those patients with hepatic cirrhosis. In patients with hepatic disease, especially cirrhosis, hepatic encephalopathy can occur as a result of hypokalemia and elevations in serum ammonia concentrations. Other metabolic disturbances, like hyperglycemia, glycosuria, and hyperuricemia may occur in susceptible patients.
Tinnitus and hearing loss have been reported early in therapy with methazolamide. Transient myopia (nearsightedness) has also occurred and is usually reversible upon a reduction in dose or discontinuation of therapy. Myopia may not return if methazolamide is restarted after discontinuation.
Like other sulfonamide derivatives, photosensitivity may occur with carbonic anhydrase inhibitors including methazolamide. Patients should avoid prolonged exposure to sunlight or sunlamps.
Increased urinary frequency is a less frequent side effect of methazolamide compared to the other carbonic anhydrase inhibitors. Methazolamide has weak diuretic properties. Methazolamide has rarely caused crystalluria and sulfonamide-like nephrotoxicity characterized by renal tubular obstruction, hematuria, dysuria, and oliguria. An increase in calcium excretion or preexisting hypercalcemia can cause nephrolithiasis, although renal calculi formation is less with methazolamide than with acetazolamide.
'Sulfonamide-type' allergic reactions including urticaria, pruritus, and rash (unspecified) are relatively rare, including cross-sensitivity and anaphylactoid reactions or anaphylactic shock. Fever should be reported to the prescriber. Serious 'sulfonamide-type' skin and hematologic reactions reported with carbonic anhydrase inhibitors like methazolamide have included erythema multiforme, hemolysis (producing hemolytic anemia), leukopenia, pancytopenia, thrombocytopenia, thrombotic thrombocytopenic purpura (TTP), and other blood dyscrasias. For leukopenia and thrombocytopenia, prompt discontinuation of therapy resulted in complete recovery of white blood cell and platelet counts within five days. Rarely, fatalities have occurred due to 'sulfonamide-type' reactions including toxic epidermal necrolysis, Stevens-Johnson syndrome, fulminant hepatic necrosis, agranulocytosis, and aplastic anemia.
As sexual impotence (erectile dysfunction) and decreased libido have been reported as adverse effects of carbonic anhydrase inhibitor therapy such effects may occur in patient receiving methazolamide.
Methazolamide is a chemical sulfonamide possessing a structure and pharmacologic activity distinct from the bacteriostatic sulfonamides. Rarely, sulfonamides of any type can produce allergic reactions, some of which may be severe. Although no reports exist of cross-sensitivity between methazolamide and other sulfa-type drugs, including antibacterial sulfonamides and thiazide diuretics, one case has been reported with acetazolamide. While the risk of cross-sensitivity appears low, methazolamide should be discontinued in any person who exhibits reactions suggestive of sulfonamide hypersensitivity. Methazolamide should be avoided in patients with a history of carbonic anhydrase inhibitor hypersensitivity.
Methazolamide use is contraindicated in patients with uncorrected electrolyte imbalance (e.g., hyponatremia, hypokalemia, hyperchloremia), acid/base imbalance (metabolic acidosis, acidemia), or adrenal insufficiency (e.g., Addison's disease). Baseline serum electrolytes should be monitored prior to drug initiation and repeated at regular intervals. Methazolamide is contraindicated in patients with severe renal disease (renal failure, anuria). Dosage reduction is warranted in patients with renal impairment. Methazolamide may potentiate acidosis and cause neurologic side effects in dialysis patients. The drug may also cause or worsen kidney stones (nephrolithiasis).
Methazolamide may cause hyperglycemia and should be used cautiously in patients with diabetes mellitus.
Methazolamide is contraindicated in patients with significant hepatic disease. The excretion of potassium is increased initially upon administration methazolamide. In patients with severe hepatic disease such as cirrhosis the use of methazolamide may precipitate hepatic encephalopathy or coma.
Geriatric patients may be more likely to develop hyperchloremic non-anion gap metabolic acidosis from the use of carbonic anhydrase inhibitors; reduced dosage may be needed due to an age-related decline in renal function. As methazolamide may cause drowsiness or confusion, especially in the elderly, performing hazardous tasks like driving or operating machinery should be delayed until the effects of the medication are known.
Long-term use of methazolamide is contraindicated in closed-angle glaucoma; however, the medication may temporarily be used preoperatively. Organic closure of the angle may occur in patients with closed-angle glaucoma despite methazolamide lowered intraocular pressure. Worsening glaucoma would be masked by a lowered IOP.
In patients with pulmonary disease or obstruction, like chronic obstructive pulmonary disease (COPD) (e.g., chronic bronchitis or emphysema) or any condition where alveolar ventilation may be impaired, methazolamide should be used with caution because it may precipitate or aggravate acidosis and/or acute respiratory failure.
Methazolamide has been reported to induce bone marrow suppression, agranulocytosis, neutropenia, aplastic anemia, purpura and thrombocytopenia so patients with a pre-existing hematological disease should have periodic hematologic evaluations.
There are no adequate and well controlled studies to assess potential risks during human pregnancy. Skeletal anomalies have occurred in rats at doses 40 times the human dose. Methazolamide should be used during pregnancy only when the benefit clearly outweighs the risk.
It is not known whether methazolamide is excreted in human milk. Since many drugs are excreted in human milk and because there is a potential for serious adverse reactions in a nursing infant, a decision should be made to either discontinue breast-feeding or discontinue methazolamide therapy depending on the importance of the therapy to the breast-feeding individual.
The safety and effectiveness of methazolamide in pediatric patients including children and infants have not been established.
Like other sulfonamide derivatives, photosensitivity may occur with carbonic anhydrase inhibitors including methazolamide. Some patients may be more sensitive to sunlight (UV) exposure while receiving methazolamide. Advise patients to avoid prolonged exposure to sunlight or sunlamps.
Although methazolamide's action results in increased output of urine and excretion of sodium, potassium and chloride, methazolamide should not be used as a diuretic to treat edema or other related conditions. The diuretic effect is weak and transient.
For the adjunctive treatment of open-angle glaucoma, for the treatment of secondary glaucoma, and for use pre-operatively for acute angle-closure glaucoma:
Oral dosage:
Adults, including the Geriatric: 50 to 100 mg PO 2 to 3 times per day. Methazolamide may be used temporarily in patients with elevated IOPs (e.g., postsurgery or post-laser), or continuously in patients with glaucoma resistant to other treatment.
Adolescents and Children: Safety and efficacy have not been established.
For the treatment of benign familial tremor* (essential tremor*):
Oral dosage:
Adults, including the Geriatric: 50 to 75 mg PO daily appears more efficacious than higher doses (150 to 300 mg daily) in essential tremor.
For the prevention of altitude sickness* (acute mountain sickness):
Oral dosage:
Adults, including the Geriatric: 150 to 200 mg PO daily. There appears to be no advantage to starting therapy prior to ascent. Methazolamide (150 mg/day) has been shown to be as effective as acetazolamide (500 mg/day) in preventing the symptoms of acute mountain sickness at 4,985 meters (16,351 feet). Methazolamide has not been shown effective in the treatment of acute symptoms of altitude sickness, although it may be preferable to acetazolamide due to a quicker onset of action.
Maximum Dosage Limits:
-Adults
300 mg/day PO.
-Elderly
300 mg/day PO.
-Adolescents
Safety and efficacy have not been established.
-Children
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Use not recommended in patients with severe hepatic impairment (e.g., cirrhosis); the use of methazolamide may precipitate hepatic encephalopathy or coma.
Patients with Renal Impairment Dosing
CrCl > 50 ml/min: No dosage adjustment needed.
CrCl 10-50 ml/min: Extend dosage interval; no quantitative recommendations available.
CrCl < 10 ml/min: Avoid use.
Intermittent hemodialysis
Contraindicated in patients with severe renal disease; may potentiate acidosis and may cause CNS adverse effects in dialysis patients.
*non-FDA-approved indication
Acarbose: (Minor) Carbonic anhydrase inhibitors, such as methazolamide, may cause hyperglycemia and glycosuria that may decrease the hypoglycemic effect of oral antidiabetic agents. Additional serum glucose monitoring may be required with dose adjustment of acarbose if indicated.
Acetaminophen; Aspirin, ASA; Caffeine: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Acetaminophen; Aspirin: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Acetaminophen; Aspirin; Diphenhydramine: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Acetaminophen; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Acetazolamide: (Contraindicated) The combination of acetazolamide and methazolamide would constitute duplicate therapy. Additive hypokalemic effects may occur with if two carbonic anhydrase inhibitors are coadministered.
Acrivastine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Albuterol: (Moderate) Albuterol may cause additive hypokalemia when coadministered with carbonic anhydrase inhibitors. These combinations can lead to symptomatic hypokalemia and associated ECG changes in some susceptible individuals. Monitoring of potassium levels would be advisable.
Albuterol; Budesonide: (Moderate) Albuterol may cause additive hypokalemia when coadministered with carbonic anhydrase inhibitors. These combinations can lead to symptomatic hypokalemia and associated ECG changes in some susceptible individuals. Monitoring of potassium levels would be advisable. (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Alogliptin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Alogliptin; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Alogliptin; Pioglitazone: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Aluminum Hydroxide; Magnesium Hydroxide: (Moderate) Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia.
Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Moderate) Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia.
Amiloride: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy. (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Aminosalicylate sodium, Aminosalicylic acid: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Amobarbital: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Amphetamine: (Moderate) Urinary alkalinizers, such as methazolamide, result in decreased renal excretion of amphetamines. Monitor for amphetamine-related side effects. Avoid concomitant use in amphetamine overdose situations.
Amphetamine; Dextroamphetamine Salts: (Moderate) Urinary alkalinizers, such as methazolamide, result in decreased renal excretion of amphetamines. Monitor for amphetamine-related side effects. Avoid concomitant use in amphetamine overdose situations.
Amphetamine; Dextroamphetamine: (Moderate) Urinary alkalinizers, such as methazolamide, result in decreased renal excretion of amphetamines. Monitor for amphetamine-related side effects. Avoid concomitant use in amphetamine overdose situations.
Amphotericin B lipid complex (ABLC): (Moderate) Amphotericin B may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy.
Amphotericin B liposomal (LAmB): (Moderate) Amphotericin B may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy.
Amphotericin B: (Moderate) Amphotericin B may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy.
Arsenic Trioxide: (Moderate) Caution is advisable during concurrent use of arsenic trioxide and methazolamide as electrolyte imbalance caused by diuretics may increase the risk of QT prolongation with arsenic trioxide.
Aspirin, ASA: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Aspirin, ASA; Butalbital; Caffeine: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate. (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Aspirin, ASA; Caffeine: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Aspirin, ASA; Caffeine; Orphenadrine: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Aspirin, ASA; Carisoprodol; Codeine: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Aspirin, ASA; Citric Acid; Sodium Bicarbonate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Aspirin, ASA; Dipyridamole: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Aspirin, ASA; Omeprazole: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Aspirin, ASA; Oxycodone: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Atenolol; Chlorthalidone: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Atracurium: (Moderate) Nondepolarizing neuromuscular blockers when combined with carbonic anhydrase inhibitors may lead to prolonged respiratory depression. This action is due to enhanced neural blockade as a result of potential hypokalemia from the carbonic anhydrase inhibitor. Serum potassium concentrations should be checked and adjusted prior to the administration of nondepolarizing neuromuscular blockers.
Azelastine; Fluticasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Azilsartan; Chlorthalidone: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Barbiturates: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Beclomethasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate. (Major) The therapeutic action of methenamine requires an acidic urine. Methazolamide can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
Benzphetamine: (Moderate) Urinary alkalinizers, such as methazolamide, result in decreased renal excretion of amphetamines. Monitor for amphetamine-related side effects. Avoid concomitant use in amphetamine overdose situations.
Betamethasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Bexagliflozin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Bismuth Subsalicylate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Bismuth Subsalicylate; Metronidazole; Tetracycline: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Brompheniramine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Budesonide: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Budesonide; Formoterol: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Bumetanide: (Moderate) Loop diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Butalbital; Acetaminophen: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Butalbital; Acetaminophen; Caffeine: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Butalbital; Acetaminophen; Caffeine; Codeine: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Butalbital; Aspirin; Caffeine; Codeine: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate. (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Calcium Phosphate, Supersaturated: (Moderate) Concomitant use of medicines with potential to alter renal perfusion or function such as carbonic anhydrase inhibitors may increase the risk of acute phosphate nephropathy in patients receiving sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous.
Canagliflozin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Canagliflozin; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Carbamazepine: (Minor) Methazolamide can induce osteomalacia in patients being concomitantly treated with carbamazepine. Potential mechanisms for this interaction include an methazolamide-induced increase in the urinary excretion of calcium and effects resulting from metabolic acidosis.
Central-acting adrenergic agents: (Moderate) The concomitant administration of diuretics with other antihypertensive agents can result in additive hypotensive effects. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Cetirizine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Chlorothiazide: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Chlorpheniramine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Chlorthalidone: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Choline Salicylate; Magnesium Salicylate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Ciclesonide: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Ciprofloxacin: (Minor) A large proportion of ciprofloxacin is normally excreted unchanged in the urine. If urinary alkalinizing agents such as carbonic anhydrase inhibitors are used concomitantly, the solubility of ciprofloxacin can be decreased because of alkaline urine. Patients should be monitored for crystalluria and nephrotoxicity.
Cisapride: (Major) Cisapride should be used with great caution in patients receiving potassium-wasting diuretic therapies, including carbonic anhydrase inhibitors. Drugs that are associated with depletion of electrolytes may cause cisapride-induced cardiac arrhythmias. Serum electrolytes (potassium, calcium, and magnesium) and creatinine should be assessed prior to administration of cisapride and whenever conditions develop that may affect electrolyte imbalance or renal function. Cisapride is contraindicated for use in patients with known serum electrolyte imbalances; cisapride should be discontinued if such imbalances occur.
Cisatracurium: (Moderate) Nondepolarizing neuromuscular blockers when combined with carbonic anhydrase inhibitors may lead to prolonged respiratory depression. This action is due to enhanced neural blockade as a result of potential hypokalemia from the carbonic anhydrase inhibitor. Serum potassium concentrations should be checked and adjusted prior to the administration of nondepolarizing neuromuscular blockers.
Citalopram: (Moderate) Caution is advisable during concurrent use of citalopram and methazolamide as electrolyte imbalance caused by diuretics may increase the risk of QT prolongation with citalopram.
Clonidine: (Moderate) The concomitant administration of diuretics with other antihypertensive agents can result in additive hypotensive effects. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Clozapine: (Moderate) Caution is advisable during concurrent use of clozapine and methazolamide as electrolyte imbalance caused by diuretics may increase the risk of QT prolongation with clozapine. In addition, clozapine, in combination with methazolamide, has been reported to cause agranulocytosis. As with clozapine-induced agranulocytosis, the agranulocytosis that occurs with carbonic anhydrase inhibitors is neither dose related or predictable, but is reversible.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Corticosteroids: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Cortisone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Cyclosporine: (Minor) Acetazolamide may increase serum cyclosporine concentrations. Data are not available regarding an interaction between cyclosporine and other carbonic anhydrase inhibitors (e.g., methazolamide), although monitoring is warranted.
Dapagliflozin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Dapagliflozin; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Dapagliflozin; Saxagliptin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Deflazacort: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Desloratadine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Dexamethasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Dexbrompheniramine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Dextroamphetamine: (Moderate) Urinary alkalinizers, such as methazolamide, result in decreased renal excretion of amphetamines. Monitor for amphetamine-related side effects. Avoid concomitant use in amphetamine overdose situations.
Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Dextromethorphan; Quinidine: (Major) Methazolamide can decrease the urinary excretion and enhance the clinical effects of quinidine. Carbonic anhydrase inhibitors increase the alkalinity of the urine, thereby increasing the amount of nonionized drug available for renal tubular reabsorption into the systemic circulation.
Dichlorphenamide: (Major) Use dichlorphenamide and methazolamide, 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.
Diflunisal: (Moderate) The concomitant use of diflunisal and methazolamide has resulted in a decrease in intraocular pressure due to increased concentrations of methazolamide. If diflunisal and methazolamide are used concurrently, monitor the patient for signs and symptoms of toxicity.
Digoxin: (Moderate) Carbonic anhydrase inhibitors can result in hypokalemia. Patients receiving these drugs concurrently with cardiac glycosides are at an increased risk for digitalis toxicity if hypokalemia develops during treatment. Ventricular irritability may occur. Monitor for hypokalemia and supplement with potassium if needed.
Donepezil; Memantine: (Moderate) Systemic carbonic anhydrous inhibitors have the potential to increase urine pH, and potentially reduce the renal clearance of memantine. The clearance of memantine is reduced by about 80% under alkaline urine conditions at pH 8. Increases in urinary pH may decrease elimination of memantine, resulting in drug accumulation and potential toxicity.
Droperidol: (Moderate) Caution is advised when using droperidol in combination with other agents that may lead to electrolyte abnormalities, such as carbonic anhydrase inhibitors, especially hypokalemia or hypomagnesemia, as such abnormalities may increase the risk for QT prolongation or cardiac arrhythmias.
Dulaglutide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Empagliflozin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Empagliflozin; Linagliptin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Empagliflozin; Linagliptin; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Empagliflozin; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Ephedrine: (Major) Acetazolamide or methazolamide can decrease excretion and enhance the effects of ephedrine. Carbonic anhydrase inhibitors increase the alkalinity of the urine, thereby increasing the amount of nonionized ephedrine available for renal tubular reabsorption. If concurrent use cannot be avoided, monitor for the appearance of ephedrine-related toxicity.
Ephedrine; Guaifenesin: (Major) Acetazolamide or methazolamide can decrease excretion and enhance the effects of ephedrine. Carbonic anhydrase inhibitors increase the alkalinity of the urine, thereby increasing the amount of nonionized ephedrine available for renal tubular reabsorption. If concurrent use cannot be avoided, monitor for the appearance of ephedrine-related toxicity.
Epoprostenol: (Moderate) Further reductions in blood pressure may occur when epoprostenol is administered with other antihypertensive agents.
Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Ertugliflozin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Ertugliflozin; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Ertugliflozin; Sitagliptin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Ethacrynic Acid: (Moderate) Loop diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Ethotoin: (Minor) Acetazolamide or methazolamide can induce osteomalacia in patients being concomitantly treated with hydantoin anticonvulsants. The carbonic anhydrase inhibitors increase the rate of urinary calcium excretion; phenytoin increases the metabolism of the D vitamins. When combined, the effects on bone catabolism can be additive.
Exenatide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Fexofenadine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Flecainide: (Moderate) Carbonic anhydrase inhibitors can decrease the urinary excretion and enhance the clinical effects of flecainide. Carbonic anhydrase inhibitors increase the alkalinity of the urine, thereby increasing the amount of nonionized drug available for renal tubular reabsorption into the systemic circulation.
Fludrocortisone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Flunisolide: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Fluticasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Fluticasone; Salmeterol: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Fluticasone; Umeclidinium; Vilanterol: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Fluticasone; Vilanterol: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Formoterol; Mometasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Fosphenytoin: (Minor) Acetazolamide or methazolamide can induce osteomalacia in patients being concomitantly treated with hydantoin anticonvulsants. The carbonic anhydrase inhibitors increase the rate of urinary calcium excretion; phenytoin increases the metabolism of the D vitamins. When combined, the effects on bone catabolism can be additive.
Furosemide: (Moderate) Loop diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Glimepiride: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Glipizide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Glipizide; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Glyburide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Glyburide; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Guaifenesin; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Guanfacine: (Moderate) The concomitant administration of diuretics with other antihypertensive agents can result in additive hypotensive effects. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Haloperidol: (Moderate) Caution is advisable during concurrent use of haloperidol and methazolamide as electrolyte imbalance caused by diuretics may increase the risk of QT prolongation with haloperidol.
Hydantoins: (Minor) Acetazolamide or methazolamide can induce osteomalacia in patients being concomitantly treated with hydantoin anticonvulsants. The carbonic anhydrase inhibitors increase the rate of urinary calcium excretion; phenytoin increases the metabolism of the D vitamins. When combined, the effects on bone catabolism can be additive.
Hydralazine; Isosorbide Dinitrate, ISDN: (Moderate) Nitrates can cause hypotension. This action may be additive with other agents that can cause hypotension such as diuretics.
Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Hydrocortisone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate. (Major) The therapeutic action of methenamine requires an acidic urine. Methazolamide can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
Ibuprofen; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Iloprost: (Moderate) Further reductions in blood pressure may occur when inhaled iloprost is administered to patients receiving other antihypertensive agents.
Incretin Mimetics: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Indapamide: (Moderate) Other diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Insulin Aspart: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Aspart; Insulin Aspart Protamine: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Degludec: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Degludec; Liraglutide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Detemir: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Glargine: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Glargine; Lixisenatide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Glulisine: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Lispro: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin Lispro; Insulin Lispro Protamine: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulin, Inhaled: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Insulins: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Ipratropium; Albuterol: (Moderate) Albuterol may cause additive hypokalemia when coadministered with carbonic anhydrase inhibitors. These combinations can lead to symptomatic hypokalemia and associated ECG changes in some susceptible individuals. Monitoring of potassium levels would be advisable.
Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Isocarboxazid: (Moderate) Exaggerated hypotensive effects may result when MAOIs are used in combination with other antihypertensive drugs, including diuretics. Patients should be observed for symptoms of orthostatic hypotension. Dose adjustments of the antihypertensive may be required.
Isophane Insulin (NPH): (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Isosorbide Dinitrate, ISDN: (Moderate) Nitrates can cause hypotension. This action may be additive with other agents that can cause hypotension such as diuretics.
Isosorbide Mononitrate: (Moderate) Nitrates can cause hypotension. This action may be additive with other agents that can cause hypotension such as diuretics.
Levalbuterol: (Moderate) Albuterol may cause additive hypokalemia when coadministered with carbonic anhydrase inhibitors. These combinations can lead to symptomatic hypokalemia and associated ECG changes in some susceptible individuals. Monitoring of potassium levels would be advisable.
Linagliptin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Linagliptin; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Liraglutide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Lisdexamfetamine: (Moderate) Urinary alkalinizers, such as acetazolamide and methazolamide, result in decreased renal excretion of amphetamines. Monitor for amphetamine-related side effects. Avoid concomitant use in amphetamine overdose situations. Urinary alkalinizers increase the proportion of non-ionized metabolites of the amphetamine molecule, resulting in decreased renal excretion of these compounds. Alkaline urine will significantly increase the half-life of lisdexamfetamine.
Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Lithium: (Moderate) Carbonic anhydrase inhibitors interfere with lithium reabsorption at the proximal tubule, the primary site of lithium reabsorption. Thus, lithium serum concentrations are likely to decrease during administration of carbonic anhydrase inhibitors. In one small study evaluating the pharmacokinetic effects of several different medications on a single 600 mg dose of lithium carbonate, administration of acetazolamide resulted in a 31% increase in lithium clearance. If carbonic anhydrase inhibitor therapy is needed during lithium administration, monitoring of lithium concentrations is recommended, along with clinical monitoring for evidence of a decrease in lithium efficacy. Patients should promptly report persistent changes in moods or behaviors.
Lixisenatide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Loop diuretics: (Moderate) Loop diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Loratadine; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Magnesium Hydroxide: (Moderate) Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia.
Magnesium Salicylate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Magnesium Salts: (Moderate) Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia. (Minor) Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia.
Mannitol: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy.
Mecamylamine: (Major) Methazolamide can decrease the urinary excretion and enhance the clinical effects of mecamylamine. Carbonic anhydrase inhibitors increase the alkalinity of the urine, thereby increasing the amount of nonionized drug available for renal tubular reabsorption into the systemic circulation.
Mefloquine: (Moderate) Coadministration of mefloquine and anticonvulsants may result in lower than expected anticonvulsant concentrations and loss of seizure control. Monitoring of the anticonvulsant serum concentration is recommended. Dosage adjustments may be required during and after therapy with mefloquine.
Memantine: (Moderate) Systemic carbonic anhydrous inhibitors have the potential to increase urine pH, and potentially reduce the renal clearance of memantine. The clearance of memantine is reduced by about 80% under alkaline urine conditions at pH 8. Increases in urinary pH may decrease elimination of memantine, resulting in drug accumulation and potential toxicity.
Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Metformin; Repaglinide: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors, such as methazolamide, may cause hyperglycemia and glycosuria that may decrease the hypoglycemic effect of oral antidiabetic agents, such as repaglinide. Additional serum glucose monitoring may be required with dose adjustment of repaglinide if indicated.
Metformin; Saxagliptin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Metformin; Sitagliptin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Methadone: (Moderate) Carbonic anhydrase inhibitors can cause electrolyte disturbances such as hypomagnesemia and hypokalemia, which may prolong the QT interval. As methadone may also prolong the QT interval, cautious coadministration with diuretics is needed.
Methamphetamine: (Moderate) Urinary alkalinizers, such as methazolamide, result in decreased renal excretion of amphetamines. Monitor for amphetamine-related side effects. Avoid concomitant use in amphetamine overdose situations.
Methenamine: (Major) The therapeutic action of methenamine requires an acidic urine. Methazolamide can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Major) The therapeutic action of methenamine requires an acidic urine. Methazolamide can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
Methenamine; Sodium Salicylate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate. (Major) The therapeutic action of methenamine requires an acidic urine. Methazolamide can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
Methohexital: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Methyldopa: (Moderate) The concomitant administration of diuretics with other antihypertensive agents can result in additive hypotensive effects. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Methylprednisolone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Metolazone: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Mexiletine: (Major) If acidifying or alkalinizing agents, such as carbonic anhydrase inhibitors, are administered concomitantly with mexiletine, urinary excretion and plasma half-life of the antiarrhythmic can be altered. Elimination of mexiletine is decreased when the urine is alkaline and increased when it is acidic. Dosage adjustments should be made as necessary.
Miglitol: (Minor) Carbonic anhydrase inhibitors, such as methazolamide, may cause hyperglycemia and glycosuria that may decrease the hypoglycemic effect of miglitol. Additional serum glucose monitoring may be required with dose adjustment of migltol if indicated.
Mometasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Monoamine oxidase inhibitors: (Moderate) Exaggerated hypotensive effects may result when MAOIs are used in combination with other antihypertensive drugs, including diuretics. Patients should be observed for symptoms of orthostatic hypotension. Dose adjustments of the antihypertensive may be required.
Naproxen; Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Nateglinide: (Minor) Carbonic anhydrase inhibitors, such as methazolamide, may cause hyperglycemia and glycosuria that may decrease the hypoglycemic effect of nateglinide. Additional serum glucose monitoring may be required with dose adjustment of nateglinide if indicated.
NIFEdipine: (Moderate) Nifedipine can have additive hypotensive effects with other antihypertensive agents (including carbonic anhydrase inhibitors). This additive effect can be desirable, but the patient should be monitored carefully and the dosage should be adjusted based on clinical response.
Nitrates: (Moderate) Nitrates can cause hypotension. This action may be additive with other agents that can cause hypotension such as diuretics.
Nitroglycerin: (Moderate) Nitrates can cause hypotension. This action may be additive with other agents that can cause hypotension such as diuretics.
Octreotide: (Moderate) Patients receiving diuretics or other agents to control fluid and electrolyte balance may require dosage adjustments while receiving octreotide due to additive effects.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Olopatadine; Mometasone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Pancuronium: (Moderate) Nondepolarizing neuromuscular blockers when combined with carbonic anhydrase inhibitors may lead to prolonged respiratory depression. This action is due to enhanced neural blockade as a result of potential hypokalemia from the carbonic anhydrase inhibitor. Serum potassium concentrations should be checked and adjusted prior to the administration of nondepolarizing neuromuscular blockers.
Pentobarbital: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Phenelzine: (Moderate) Exaggerated hypotensive effects may result when MAOIs are used in combination with other antihypertensive drugs, including diuretics. Patients should be observed for symptoms of orthostatic hypotension. Dose adjustments of the antihypertensive may be required.
Phenobarbital: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Phentermine; Topiramate: (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.
Phenytoin: (Minor) Acetazolamide or methazolamide can induce osteomalacia in patients being concomitantly treated with hydantoin anticonvulsants. The carbonic anhydrase inhibitors increase the rate of urinary calcium excretion; phenytoin increases the metabolism of the D vitamins. When combined, the effects on bone catabolism can be additive.
Pimozide: (Moderate) Caution is advisable during concurrent use of pimozide and methazolamide as electrolyte imbalance caused by diuretics may increase the risk of QT prolongation with pimozide. Potassium deficiencies should be corrected prior to treatment with pimozide and normalized potassium levels should be maintained during treatment.
Pioglitazone: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Pioglitazone; Glimepiride: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Pioglitazone; Metformin: (Moderate) Carbonic anhydrase inhibitors such as methazolamide frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of methazolamide with metformin may increase the risk for lactic acidosis; consider more frequent monitoring. Carbonic anhydrase inhibitors may also alter blood sugar; both hyperglycemia and hypoglycemia have been described. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction. (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Potassium-sparing diuretics: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy.
Pramlintide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Prednisolone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Prednisone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Primidone: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Pseudoephedrine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Pseudoephedrine; Triprolidine: (Moderate) Methazolamide can decrease the urinary excretion and enhance the clinical effects of pseudoephedrine. Use caution if methazolamide is coadministered; monitor for excessive pseudoephedrine-related adverse effects.
Quetiapine: (Moderate) Caution is advisable during concurrent use of quetiapine and methazolamide as electrolyte imbalance caused by diuretics may increase the risk of QT prolongation with quetiapine.
Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Quinidine: (Major) Methazolamide can decrease the urinary excretion and enhance the clinical effects of quinidine. Carbonic anhydrase inhibitors increase the alkalinity of the urine, thereby increasing the amount of nonionized drug available for renal tubular reabsorption into the systemic circulation.
Quinine: (Moderate) Use caution if using carbonic anhydrase inhibitors and quinine concomitantly. Urinary alkalinizing agents may increase plasma quinine concentrations because quinine is reabsorbed when the urine is alkaline.
Regular Insulin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Regular Insulin; Isophane Insulin (NPH): (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Repaglinide: (Minor) Carbonic anhydrase inhibitors, such as methazolamide, may cause hyperglycemia and glycosuria that may decrease the hypoglycemic effect of oral antidiabetic agents, such as repaglinide. Additional serum glucose monitoring may be required with dose adjustment of repaglinide if indicated.
Rocuronium: (Moderate) Nondepolarizing neuromuscular blockers when combined with carbonic anhydrase inhibitors may lead to prolonged respiratory depression. This action is due to enhanced neural blockade as a result of potential hypokalemia from the carbonic anhydrase inhibitor. Serum potassium concentrations should be checked and adjusted prior to the administration of nondepolarizing neuromuscular blockers.
Rosiglitazone: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Salicylates: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Salsalate: (Major) Avoid the coadministration of high-dose salicylates and carbonic anhydrase inhibitors, like methazolamide, whenever possible. The combination yielded reports of anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death. The mechanism appears to be accumulation of the carbonic anhydrase inhibitor, resulting in increased CNS depression and metabolic acidosis. The acidosis may allow greater CNS penetration of the salicylate.
Saxagliptin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Secobarbital: (Minor) Methazolamide can induce osteomalacia in patients treated chronically with barbiturates. Potential mechanisms for this interaction include a carbonic anhydrase inhibitor induced increase in the urinary excretion of calcium and an increase in barbiturate effects resulting from metabolic acidosis. Methazolamide can also increase the rate of excretion of weakly acidic drugs, such as barbiturates.
Semaglutide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
SGLT2 Inhibitors: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Sitagliptin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Sodium Phosphate Monobasic Monohydrate; Sodium Phosphate Dibasic Anhydrous: (Moderate) Concomitant use of medicines with potential to alter renal perfusion or function such as carbonic anhydrase inhibitors may increase the risk of acute phosphate nephropathy in patients receiving sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous.
Sodium Sulfate; Magnesium Sulfate; Potassium Chloride: (Minor) Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia.
Sotagliflozin: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Sotalol: (Major) Diuretics should be used cautiously with sotalol and should be accompanied by close monitoring of electrolyte balance because hypokalemia and hypomagnesemia have been associated with an increased risk of proarrhythmia.
Spironolactone: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy.
Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy. (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Succinylcholine: (Moderate) Nondepolarizing neuromuscular blockers when combined with carbonic anhydrase inhibitors may lead to prolonged respiratory depression. This action is due to enhanced neural blockade as a result of potential hypokalemia from the carbonic anhydrase inhibitor. Serum potassium concentrations should be checked and adjusted prior to the administration of nondepolarizing neuromuscular blockers.
Sulfonylureas: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Thiazide diuretics: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Thiazolidinediones: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Tirzepatide: (Minor) Carbonic anhydrase inhibitors may alter blood sugar. Both hyperglycemia and hypoglycemia have been described in patients treated with acetazolamide. This should be taken into consideration in patients with impaired glucose tolerance or diabetes mellitus who are receiving antidiabetic agents. Monitor blood glucose and for changes in glycemic control and be alert for evidence of an interaction.
Tolterodine: (Minor) Diuretics can increase urinary frequency, which may aggravate bladder symptoms.
Topiramate: (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.
Torsemide: (Moderate) Loop diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Tranylcypromine: (Moderate) Exaggerated hypotensive effects may result when MAOIs are used in combination with other antihypertensive drugs, including diuretics. Patients should be observed for symptoms of orthostatic hypotension. Dose adjustments of the antihypertensive may be required.
Triamcinolone: (Moderate) Corticosteroids may increase the risk of hypokalemia if used concurrently with methazolamide. Hypokalemia may be especially severe with prolonged use of corticotropin, ACTH. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. The chronic use of corticosteroids may augment calcium excretion with methazolamide leading to increased risk for hypocalcemia and/or osteoporosis.
Triamterene: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy.
Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy. (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Urea: (Moderate) Carbonic anhydrase inhibitors promote electrolyte excretion including hydrogen ions, sodium, and potassium. They can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
Vecuronium: (Moderate) Nondepolarizing neuromuscular blockers when combined with carbonic anhydrase inhibitors may lead to prolonged respiratory depression. This action is due to enhanced neural blockade as a result of potential hypokalemia from the carbonic anhydrase inhibitor. Serum potassium concentrations should be checked and adjusted prior to the administration of nondepolarizing neuromuscular blockers.
Vorinostat: (Moderate) Use vorinostat and carbonic anhydrase inhibitors together with caution; the risk of QT prolongation and arrhythmias may be increased if electrolyte abnormalities occur. Carbonic anhydrase inhibitors increase the excretion of some electrolytes including potassium; electrolyte abnormalities such as hypomagnesemia, hypokalemia, or hypocalcemia may increase the risk of QT prolongation with vorinostat. Frequently monitor serum electrolytes if concomitant use of these drugs is necessary.
Zonisamide: (Moderate) Monitor for the appearance or worsening of metabolic acidosis if zonisamide is given concomitantly with other carbonic anhydrase inhibitors. Concomitant use of zonisamide with another carbonic anhydrase inhibitor 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.
Carbonic anhydrase is an enzyme responsible for forming hydrogen and bicarbonate ions from carbon dioxide and water. By inhibiting this enzyme, methazolamide reduces the availability of these ions for active transport. Hydrogen ion concentrations in the renal tubule lumen are reduced by methazolamide, leading to alkaline urine and an increased excretion of bicarbonate, sodium, potassium, and water. A reduction in plasma bicarbonate results in metabolic acidosis, which rapidly reverses the diuretic effect. Reduced intraocular pressure (IOP) is the result of a 50-60% reduction in aqueous humor production and is likely due to decreased bicarbonate ion concentrations in ocular fluid. For altitude sickness prophylaxis, methazolamide produces respiratory and metabolic acidosis, which increases ventilation and binding of oxygen to hemoglobin. This occurs because the drug decreases carbon dioxide tension in the pulmonary alveoli, thus increasing arterial oxygen tension.
Methazolamide is administered orally. Due to low protein-binding and high lipid solubility, there is extensive distribution of methazolamide, including the plasma, cerebrospinal fluid, aqueous humor, red blood cells, bile and extracellular fluid. The elimination half-life is 14 hours, but with twice- to three-times daily dosing, steady-state concentrations are reached at approximately 7 days. About 25% of methazolamide is recovered in the urine as the parent drug, and renal clearance accounts for about 20% of total drug clearance.
-Route-Specific Pharmacokinetics
Oral Route
After oral administration, methazolamide is well absorbed from the GI tract. There is a linear relationship between dose and plasma levels. Peak plasma concentrations are observed 1 to 2 hours after dosing. For elevated intraocular pressure, methazolamide has a rapid onset of action of 2-3 hours, with peak effect at 6-8 hours, and a duration of 10-16 hours.