Trimethobenzamide is an oral and parenteral antiemetic agent. The products are indicated for the treatment of postoperative nausea and vomiting and for nausea associated with gastroenteritis. Structurally, the drug is a substituted benzamide with actions similar to metoclopramide, but trimethobenzamide is considered less potent. Trimethobenzamide should not be used in pediatric patients due to the risk of extrapyramidal signs and symptoms and other serious CNS effects. Trimethobenzamide rectal suppositories were discontinued from the market in 2007 after the FDA removed approval for the NDA, stating there was a lack of data supporting suppository effectiveness for the treatment of nausea and vomiting.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Oral Administration
-Trimethobenzamide capsules may be administered without regard to meals.
Injectable Administration
-Visually inspect parenteral products for particulate matter and discoloration prior to administration whenever solution and container permit.
Intramuscular Administration
-Trimethobenzamide injection is for intramuscular administration only; do not administer intravenously.
-Not for use in pediatric patients.
-No dilution is necessary.
-Intramuscular administration may cause pain, stinging, burning, redness and swelling at the site of injection. Such effects may be minimized by deep injection into the upper outer quadrant of the gluteal region, and by avoiding the escape of solution along the route.
The use of centrally acting antiemetics in children with viral infection has reportedly been associated with an increased risk of developing Reye's syndrome (characterized by abrupt onset of persistent, severe vomiting, lethargy, irrational behavior, progressive encephalopathy leading to coma, convulsions, and death); however, a causal relationship to the cause or course of Reye's syndrome has not been established. It has been suggested that drugs which are potentially hepatotoxic, including trimethobenzamide, may unfavorably alter the course of Reye's syndrome.
Generally, adverse reactions to trimethobenzamide occur infrequently at usual dosages and seldom require drug discontinuation. Drowsiness is probably the most frequent side effect. Blurred vision, diarrhea, dizziness, headache, and muscle cramps are less frequent. More serious CNS symptoms such as coma, depression of mood, disorientation, extrapyramidal symptoms (e.g., pseudoparkinsonism, tremor), opisthotonus, and seizures have been reported rarely with trimethobenzamide administration. The recent use of other CNS-depressant medications may increase the risk for some side effects. If any of these adverse reactions occur, attempts should be made to determine if the symptoms are associated with the administration of the drug or with the condition being treated. If the adverse effects are due to the drug, the dosage of trimethobenzamide should be reduced or the drug discontinued.
Hypersensitivity reactions including angioedema and allergic skin rash (unspecified) have been reported. Trimethobenzamide should be discontinued at the first sign of hypersensitivity. Blood dyscrasias (e.g., agranulocytosis, leukopenia) and jaundice (cholestasis) have also occurred in some patients receiving trimethobenzamide, and may also indicate the occurrence of hypersensitivity reactions. Patients should be instructed to report for evaluation of sore throat with fever and unusual tiredness, or symptoms of jaundice. If sensitivity reactions are detected, trimethobenzamide should be discontinued and the drug should not be reintroduced.
Hypotension has been reported following intramuscular injection of trimethobenzamide, particularly in surgical patients. Injection site reaction (pain, stinging, burning, redness, and swelling) may also occur after intramuscular injection. Local rectal irritation may occur following rectal administration.
A large portion of trimethobenzamide is excreted as unchanged drug via the kidney. In order to minimize the risk of adverse reactions, in patients with renal impairment (creatinine clearance 70 mL/minute/1.73 m2 or less) or renal failure, reduce the daily dosage by increasing the dosing interval and adjust as needed based upon therapeutic response and tolerability. Monitor renal function.
Trimethobenzamide injection is for intramuscular administration only; do not give via intravenous administration. Trimethobenzamide injection is contraindicated for use in children or infants. Trimethobenzamide suppositories are contraindicated for use in neonates and premature neonates. Trimethobenzamide suppositories contain benzocaine; avoid trimethobenzamide suppository use in patients with history of benzocaine hypersensitivity or other ester local anesthetic hypersensitivity. The safety and effectiveness of trimethobenzamide in pediatric patients has not been established. Trimethobenzamide is not recommended for use in pediatric patients due to the risk of extrapyramidal symptoms and other serious CNS effects, and the risk of exacerbation of underlying disease in pediatric patients with Reye's Syndrome, or other hepatic impairment.
Trimethobenzamide is contraindicated for use in patients with known hypersensitivity to trimethobenzamide. This contraindication includes patients who have experienced agranulocytosis or other blood dyscrasias; skin reactions indicative of sensitization or jaundice due to trimethobenzamide therapy. Patients should be instructed to report sore throat, fever and unusual tiredness, or symptoms of jaundice to their health care professional. Trimethobenzamide should be used with caution in patients with preexisting bone marrow suppression. Drug-induced bone marrow suppression is rare, but preexisting neutropenia could be worsened by the administration of this drug.
The use of trimethobenzamide during pregnancy should only be considered when non-drug measures to control vomiting have failed and the risk-benefit ratio for the patient and fetus has been determined. The limited available data with trimethobenzamide in pregnant women are not sufficient to inform a drug-associated risk for major birth defects and miscarriage. Animal studies suggest no teratogenic risk. In one human study from the 1970s, the incidence of severe congenital defects was increased in trimethobenzamide-exposed infants compared to non-treated controls, but the use of other antiemetics in some patients may have influenced the results of the study. The authors concluded that the risk of congenital malformations due to trimethobenzamide was low. Other case-control studies have been published which have reported no increased incidence in malformations during human pregnancy. The American College of Obstetricians and Gynecologists (ACOG) include trimethobenzamide as a third-line pharmacologic treatment option for nausea and vomiting of pregnancy in patients who have failed other primary and secondary therapies but for whom dehydration is not evident.
There are no data available on the use of trimethobenzamide in human milk, the effects of trimethobenzamide on the breastfed infant or the effects of the drug on milk production. The molecular weight of the drug is within the range that would be expected to pass into breast milk. An antiemetic such as prochlorperazine or promethazine may be preferred when short-term antiemetic therapy is necessary in the mother. Occasional short-term use is probably compatible with posing little risk to a nursing infant. However, regardless of agent chosen, if multiple doses are to be used the infant should be monitored for excess sedation or other adverse effects. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.
Trimethobenzamide should be used with caution in patients with certain disorders such as acute fever, encephalitis, Reye's syndrome, encephalopathy, gastroenteritis, dehydration, and electrolyte imbalance, especially in children, older patients, or debilitated patients because neurologic reactions resulting from trimethobenzamide therapy may be similar to CNS signs and symptoms accompanying these disorders. The diagnosis of these disorders may be obscured or the disease-associated signs and symptoms may be incorrectly diagnosed as drug induced. The use of centrally acting antiemetics in children with viral infection has reportedly been associated with an increased risk of developing Reye's syndrome (characterized by abrupt onset of persistent, severe vomiting; lethargy; irrational behavior; progressive encephalopathy leading to coma; seizures; and death); however, a causal relationship to the cause or course of Reye's syndrome has not been established. It has been suggested that drugs which are potentially hepatotoxic, including trimethobenzamide, may unfavorably alter the course of Reye's syndrome.
Clinical studies of trimethobenzamide did not include sufficient numbers of geriatric patients to determine if they respond differently than younger adult patients. Trimethobenzamide is largely excreted by the kidney, and the risk of toxic reactions may be greater in geriatric patients with impaired renal function. Because geriatric patients are more likely to have decreased renal function, reduce the daily dosage of trimethobenzamide by increasing the dosing interval and adjust as needed based upon therapeutic response and tolerability. Monitor renal function. Additionally, use with caution because neurologic reactions resulting from trimethobenzamide may be similar to CNS signs and symptoms accompanying fever, encephalitis, Reye's syndrome, gastroenteritis, dehydration, and electrolyte imbalances. The diagnosis of these disorders may be obscured or the disease-associated symptoms may be incorrectly diagnosed as drug-induced. The federal Omnibus Budget Reconciliation Act (OBRA) regulates medication use in residents of long-term care facilities (LTCFs). According to OBRA, trimethobenzamide is a relatively ineffective antiemetic that can cause significant extrapyramidal side effects, lethargy, sedation, and confusion; however, trimethobenzamide may be indicated in patients with Parkinson's disease taking apomorphine.
The antiemetic effects of trimethobenzamide may mask the symptoms of overdosage of other drugs or may obscure the cause of vomiting in various disorders such as appendicitis.
Trimethobenzamide can cause blurred vision, disorientation, dizziness, and drowsiness. Trimethobenzamide may impair the ability to perform activities requiring mental alertness or physical coordination (e.g., driving or operating machinery). Concomitant use with alcohol (ethanol intoxication) should be avoided. Trimethobenzamide should also be used cautiously in patients who have recently received other drugs which act on the CNS (see Drug Interactions).
Trimethobenzamide may cause hepatotoxicity; therefore, avoid use of trimethobenzamide in patients with existing hepatic disease or in patients whose signs and symptoms suggest the presence of hepatic impairment. Discontinue trimethobenzamide in patients who develop impaired liver function while taking the medicine.
For the control of nausea/vomiting due to gastroenteritis or post-operative nausea/vomiting (PONV):
Oral dosage:
Adults: 300 mg PO 3 to 4 times per day as needed.
Geriatric: 300 mg PO 3 to 4 times per day PRN. Reduce the daily dosage by increasing the dosing interval and adjust as needed based upon therapeutic response and tolerability.
Intramuscular dosage:
Adults: 200 mg IM 3 to 4 times per day as needed.
For the treatment of pregnancy-induced nausea/vomiting*:
Intramuscular dosage:
Adult Pregnant females: 200 mg IM every 6 to 8 hours as needed. Per ACOG, trimethobenzamide is a third-line pharmacologic option if the patient is still experiencing persistent symptoms after a trial of nonpharmacologic options and other pharmacologic options (e.g., vitamin B6, doxylamine, promethazine, prochlorperzine, dimenhydrinate, diphenhydramine).
Maximum Dosage Limits:
-Adults
1200 mg/day PO; or 800 mg/day IM or PR.
-Elderly
1200 mg/day PO; or 800 mg/day IM or PR.
-Adolescents
(weight 13.6-40.9 kg): 800 mg/day PO or PR.
-Children
(weight 13.6-40.9 kg): 800 mg/day PO or PR or 15 mg/kg/day PO or PR.
(weight < 13.6 kg): 400 mg/day PR or 15 mg/kg/day PR.
-Infants
Not indicated by any route.
Patients with Hepatic Impairment Dosing
Use caution; specific guidelines for dosage adjustments in hepatic impairment are not available. Do not use in patients with jaundice or a history of trimethobenzamide-induced jaundice.
Patients with Renal Impairment Dosing
CrCl greater than 70 mL/minute: No dosage adjustment needed.
CrCl 70 mL/minute or less: Reduce the daily dosage by increasing the dosing interval and adjust as needed based upon therapeutic response and tolerability.
*non-FDA-approved indication
Acetaminophen; Aspirin; Diphenhydramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Acetaminophen; Caffeine; Pyrilamine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Chlorpheniramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Codeine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Diphenhydramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acetaminophen; Hydrocodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Acetaminophen; Oxycodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Acetaminophen; Pamabrom; Pyrilamine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Acrivastine; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Alfentanil: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Alprazolam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Amikacin: (Minor) Because of trimethobenzamide's antiemetic pharmacology, the drug may effectively mask dizziness, tinnitus, or vertigo that are associated with ototoxicity induced by various medications, including the aminoglycosides. Clinicians should be aware of this potential interaction and take it into consideration when monitoring for aminoglycoside-induced side effects.
Aminoglycosides: (Minor) Because of trimethobenzamide's antiemetic pharmacology, the drug may effectively mask dizziness, tinnitus, or vertigo that are associated with ototoxicity induced by various medications, including the aminoglycosides. Clinicians should be aware of this potential interaction and take it into consideration when monitoring for aminoglycoside-induced side effects.
Amobarbital: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Anticholinergics: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Anxiolytics; Sedatives; and Hypnotics: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like anxiolytics, sedatives and hypnotics, may potentiate the effects of either trimethobenzamide or the anxiolytics, sedatives and hypnotics.
Apomorphine: (Moderate) Because apomorphine may cause somnolence or dizziness, monitor for additive sedation or dizziness when trimethobenzamide or other sedating anti-emetics are used with apomorphine.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Aspirin, ASA; Carisoprodol; Codeine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Aspirin, ASA; Oxycodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Atropine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Atropine; Difenoxin: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Barbiturates: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Belladonna; Opium: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist. (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Benzhydrocodone; Acetaminophen: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Benzodiazepines: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Benztropine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Brompheniramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Brompheniramine; Phenylephrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Brompheniramine; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Buprenorphine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like buprenorphine, may potentiate the effects of either trimethobenzamide or buprenorphine.
Buprenorphine; Naloxone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like buprenorphine, may potentiate the effects of either trimethobenzamide or buprenorphine.
Buspirone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like buspirone, may potentiate the effects of either trimethobenzamide or buspirone.
Butalbital; Acetaminophen: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Butalbital; Acetaminophen; Caffeine: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate. (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Butalbital; Aspirin; Caffeine; Codeine: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate. (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Butorphanol: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, such as butorphanol, may potentiate the effects of either trimethobenzamide or the other medication.
Calcium, Magnesium, Potassium, Sodium Oxybates: (Major) Sodium oxybate should not be used in combination with CNS depressants. Additive CNS depressant effects may be possible when sodium oxybate is used concurrently with drugs like trimethobenzamide.
Carbinoxamine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Celecoxib; Tramadol: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Chlophedianol; Dexbrompheniramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorcyclizine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlordiazepoxide: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Chlordiazepoxide; Amitriptyline: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Chlordiazepoxide; Clidinium: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine. (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Chlorpheniramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Codeine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist. (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Dextromethorphan: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Hydrocodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist. (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Phenylephrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpheniramine; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Chlorpromazine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Clemastine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Clonazepam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Clorazepate: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Codeine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Codeine; Guaifenesin: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Codeine; Phenylephrine; Promethazine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist. (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Codeine; Promethazine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist. (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Cyproheptadine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Dexbrompheniramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Dexbrompheniramine; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Dexchlorpheniramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Diazepam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Dicyclomine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Dimenhydrinate: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Diphenhydramine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Diphenhydramine; Ibuprofen: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Diphenhydramine; Naproxen: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Diphenhydramine; Phenylephrine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Diphenoxylate; Atropine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Doxylamine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Doxylamine; Pyridoxine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Dronabinol: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, such as dronabinol, may potentiate the effects of either trimethobenzamide or dronabinol.
Droperidol: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like droperidol, may potentiate the effects of either trimethobenzamide or droperidol.
Estazolam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Eszopiclone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like anxiolytics, sedatives and hypnotics, may potentiate the effects of either trimethobenzamide or the anxiolytics, sedatives and hypnotics.
Ethanol: (Major) Advise patients to avoid alcohol consumption while taking CNS depressants. Alcohol consumption may result in additive CNS depression.
Fentanyl: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Flavoxate: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Fluphenazine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Flurazepam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Gentamicin: (Minor) Because of trimethobenzamide's antiemetic pharmacology, the drug may effectively mask dizziness, tinnitus, or vertigo that are associated with ototoxicity induced by various medications, including the aminoglycosides. Clinicians should be aware of this potential interaction and take it into consideration when monitoring for aminoglycoside-induced side effects.
Glycopyrrolate: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Glycopyrrolate; Formoterol: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Homatropine; Hydrocodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist. (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Hydrocodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Hydrocodone; Ibuprofen: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Hydromorphone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Hydroxyzine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Hyoscyamine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Ibuprofen; Oxycodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Indacaterol; Glycopyrrolate: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Ipecac: (Major) Ipecac has been shown to be effective in producing emesis in patients who have ingested antiemetics, provided ipecac is given promptly (usually within 1 hour of antiemetic consumption). If ipecac is administered after antiemetic therapy has begun to exert therapeutic effects, ipecac may be less effective. It is suggested the irritating GI effects of ipecac lead to emesis following antiemetic consumption.
Levorphanol: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Lorazepam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Meclizine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Meperidine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Meprobamate: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like anxiolytics, sedatives and hypnotics, may potentiate the effects of either trimethobenzamide or the anxiolytics, sedatives and hypnotics.
Methadone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Methohexital: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Methscopolamine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Midazolam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Morphine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Morphine; Naltrexone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Nabilone: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression like nabilone may potentiate the effects of either medication.
Nalbuphine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like nalbuphine, may potentiate the effects of either trimethobenzamide or nalbuphine.
Neostigmine; Glycopyrrolate: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Oliceridine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Opiate Agonists: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Oxazepam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Oxybutynin: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Oxycodone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Oxymorphone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Paromomycin: (Minor) Because of trimethobenzamide's antiemetic pharmacology, the drug may effectively mask dizziness, tinnitus, or vertigo that are associated with ototoxicity induced by various medications, including the aminoglycosides. Clinicians should be aware of this potential interaction and take it into consideration when monitoring for aminoglycoside-induced side effects.
Pentazocine; Naloxone: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like pentazocine, may potentiate the effects of either trimethobenzamide or pentazocine.
Pentobarbital: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Perphenazine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Perphenazine; Amitriptyline: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Phenobarbital: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate. (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Phenothiazines: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Plazomicin: (Minor) Because of trimethobenzamide's antiemetic pharmacology, the drug may effectively mask dizziness, tinnitus, or vertigo that are associated with ototoxicity induced by various medications, including the aminoglycosides. Clinicians should be aware of this potential interaction and take it into consideration when monitoring for aminoglycoside-induced side effects.
Primidone: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Prochlorperazine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Promethazine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Promethazine; Dextromethorphan: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Promethazine; Phenylephrine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Propantheline: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Pseudoephedrine; Triprolidine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Quazepam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Remifentanil: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Remimazolam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Scopolamine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Secobarbital: (Moderate) The concurrent use of trimethobenzamide with barbiturates may potentiate the CNS effects of either trimethobenzamide or the barbiturate.
Sedating H1-blockers: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Sodium Oxybate: (Major) Sodium oxybate should not be used in combination with CNS depressants. Additive CNS depressant effects may be possible when sodium oxybate is used concurrently with drugs like trimethobenzamide.
Streptomycin: (Minor) Because of trimethobenzamide's antiemetic pharmacology, the drug may effectively mask dizziness, tinnitus, or vertigo that are associated with ototoxicity induced by various medications, including the aminoglycosides. Clinicians should be aware of this potential interaction and take it into consideration when monitoring for aminoglycoside-induced side effects.
Sufentanil: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Tapentadol: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Temazepam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Thioridazine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Tobramycin: (Minor) Because of trimethobenzamide's antiemetic pharmacology, the drug may effectively mask dizziness, tinnitus, or vertigo that are associated with ototoxicity induced by various medications, including the aminoglycosides. Clinicians should be aware of this potential interaction and take it into consideration when monitoring for aminoglycoside-induced side effects.
Tramadol: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Tramadol; Acetaminophen: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like opiate agonists, may potentiate the effects of either trimethobenzamide or the opiate agonist.
Triazolam: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the benzodiazepines, may potentiate the effects of either trimethobenzamide or the benzodiazepine.
Trifluoperazine: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression such as the phenothiazines may potentiate drowsiness or other common side effects of either medication. In addition, the administration of trimethobenzamide to patients who have recently received CNS-depressive drugs has resulted in opisthotonus, seizures, coma, and extrapyramidal symptoms.
Trihexyphenidyl: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Triprolidine: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the sedating h1-blockers, may potentiate the effects of either trimethobenzamide or the sedating h1-blocker.
Trospium: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
Zaleplon: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like anxiolytics, sedatives and hypnotics, may potentiate the effects of either trimethobenzamide or the anxiolytics, sedatives and hypnotics.
Zolpidem: (Moderate) The concurrent use of trimethobenzamide with other medications that cause CNS depression, like anxiolytics, sedatives and hypnotics, may potentiate the effects of either trimethobenzamide or the anxiolytics, sedatives and hypnotics.
The mechanism of action of trimethobenzamide as determined in animals is obscure, but may involve the chemoreceptor trigger zone (CTZ), an area in the medulla oblongata through which emetic impulses are conveyed to the vomiting center; direct impulses to the vomiting center apparently are not similarly inhibited. In dogs pretreated with trimethobenzamide, the emetic response to apomorphine is inhibited, while little or no protection is afforded against emesis induced by intragastric copper sulfate.
Trimethobenzamide is administered orally, intramuscularly, and rectally.
Distribution of the drug into human body fluids and tissues has not been determined. Animal data suggest that trimethobenzamide and its metabolites are distributed mainly into the liver, kidneys, and lungs. Trimethobenzamide is generally cleared from the blood within 2 hours after a single dose; however, measurable concentrations may persist for over 24 hours in some patients. The exact route of metabolism in humans has not been clearly established. In animals, trimethobenzamide is metabolized primarily in the liver to the N-desmethyl and N-oxide metabolites and excreted in urine and feces (via biliary elimination). In humans, approximately 30-50% of a single dose is excreted in urine as unchanged drug within 48-72 hours following administration; 20% of an administered dose is excreted within 24 hours.
-Route-Specific Pharmacokinetics
Oral Route
Following oral administration, the onset of action occurs within 10-40 minutes and lasts for approximately 3-4 hours. The relative systemic bioavailability of an oral dose is about 60% that of an IM dose; plasma concentrations of trimethobenzamide attained after a 400-mg oral dose are approximately equivalent to those attained following a 200-mg IM dose.
Intramuscular Route
After IM injection, the onset of action of trimethobenzamide is within 15-35 minutes and persists for 2-3 hours.
Other Route(s)
Rectal Route
The onset and duration of action of trimethobenzamide following rectal administration is not known.