indication

For the treatment of postoperative nausea and vomiting and for nausea associated with gastroenteritis.

pharmacology

Trimethobenzamide is a novel antiemetic which prevents nausea and vomiting in humans. Its actions are unclear but most likely involves the chemoreceptor trigger zone (CTZ). In dogs pretreated with trimethobenzamide HCl, the emetic response to apomorphine is inhibited, while little or no protection is afforded against emesis induced by intragastric copper sulfate.

mechanism of action

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.

toxicity

Oral LD₅₀ in mice is 1600 mg/kg.

biotransformation

Hepatic.

absorption

The relative bioavailability of the capsule formulation compared to the solution is 100%.

half life

The mean elimination half-life of trimethobenzamide is 7 to 9 hours.

route of elimination

Between 30 – 50% of a single dose in humans is excreted unchanged in the urine within 48–72 hours.

drug interactions

Acetophenazine: Trimethobenzamide and Acetophenazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Amitriptyline: Trimethobenzamide and Amitriptyline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Amoxapine: Trimethobenzamide and Amoxapine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Atropine: Trimethobenzamide and Atropine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Azelastine: Trimethobenzamide and Azelastine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Benzatropine: Trimethobenzamide and Benztropine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Biperiden: Trimethobenzamide and Biperiden, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Bromodiphenhydramine: Trimethobenzamide and Bromodiphenhydramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Brompheniramine: Trimethobenzamide and Brompheniramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Carbinoxamine: Trimethobenzamide and Carbinoxamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Chlorpheniramine: Trimethobenzamide and Chlorpheniramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Chlorpromazine: Trimethobenzamide and Chlorpromazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Clemastine: Trimethobenzamide and Clemastine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Clidinium: Trimethobenzamide and Clidinium, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Clomipramine: Trimethobenzamide and Clomipramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Clozapine: Trimethobenzamide and Clozapine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Cyclizine: Trimethobenzamide and Cyclizine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Dexbrompheniramine: Trimethobenzamide and Dexbrompheniramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Dicyclomine: Trimethobenzamide and Dicyclomine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Dimenhydrinate: Trimethobenzamide and Dimenhydrinate, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Diphenhydramine: Trimethobenzamide and Diphenhydramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Donepezil: The therapeutic effects of the anticholinergic, Trimethobenzamide, and/or the acetylcholinesterase inhibitor (central), Donepezil, may be reduced due to antagonism. Monitor therapeutic effects of both agents.

Doxepin: Trimethobenzamide and Doxepin, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Doxylamine: Trimethobenzamide and Doxylamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Dronabinol: Anticholinergics, such as Trimethobenzamide, may increase the tachycardic effect of cannabinoids such as Marinol. Close monitoring of cardiovascular effects is recommended.

Droperidol: Trimethobenzamide and Droperidol, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Fexofenadine: Trimethobenzamide and Fexofenadine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Flavoxate: Trimethobenzamide and Flavoxate, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Flupenthixol: Trimethobenzamide and Flupenthixol, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Fluphenazine: Trimethobenzamide and Fluphenazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Galantamine: The therapeutic effects of the anticholinergic, Trimethobenzamide, and/or the acetylcholinesterase inhibitor (central), Galantamine, may be reduced due to antagonism. Monitor therapeutic effects of both agents.

Glycopyrrolate: Trimethobenzamide and Glycopyrrolate, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Haloperidol: Trimethobenzamide and Haloperidol, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Homatropine Methylbromide: Trimethobenzamide and Homatropine Methylbromide, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Hydroxyzine: Trimethobenzamide and Hydroxyzine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Hyoscyamine: Trimethobenzamide and Hyoscyamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Imipramine: Trimethobenzamide and Imipramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Ipratropium bromide: Trimethobenzamide and Ipratropium, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Isocarboxazid: Trimethobenzamide and Isocarboxazid, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Ketotifen: Trimethobenzamide and Ketotifen, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Loratadine: Trimethobenzamide and Loratadine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Loxapine: Trimethobenzamide and Loxapine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Maprotiline: Trimethobenzamide and Maprotiline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Meclizine: Trimethobenzamide and Meclizine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Mepenzolate: Trimethobenzamide and Mepenzolate, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Mesoridazine: Trimethobenzamide and Mesoridazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Methantheline: Trimethobenzamide and Methantheline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Methylscopolamine: Trimethobenzamide and Methylscopolamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Moclobemide: Trimethobenzamide and Moclobemide, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Molindone: Trimethobenzamide and Molindone, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Nabilone: Anticholinergics, such as Trimethobenzamide, may increase the tachycardic effect of cannabinoids such as Nabilone. Close monitoring of cardiovascular effects is recommended.

Nortriptyline: Trimethobenzamide and Nortriptyline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Olanzapine: Trimethobenzamide and Olanzapine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Orphenadrine: Trimethobenzamide and Orphenadrine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Oxybutynin: Trimethobenzamide and Oxybutynin, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Perphenazine: Trimethobenzamide and Perphenazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Phenelzine: Trimethobenzamide and Phenelzine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Phenindamine: Trimethobenzamide and Phenindamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Pimozide: Trimethobenzamide and Pimozide, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Potassium Chloride: The ulcerative effects of solid oral dosage forms of KCl may be enhanced by Trimethobenzamide, an anticholinergic. Anticholinergics slow gastric emptying, increasing the contact time between the gastrointestinal mucosa and KCl. Prolonged exposure to KCl increases the risk of gastric and intestinal irritation and ulceration. Solid oral dosage forms of KCl should be avoided; alternatives include liquid or effervescent potassium preparations.

Pramlintide: The anticholinergic effects of Trimethobenzamide may be enhanced by Pramlintide. Additive effects of reduced GI motility may occur. Pramlintide slows gastic emptying and should not be used with drugs that alter GI motility (e.g. anticholinergics). Consider alternative treatments or use caution during concomitant therapy.

Prochlorperazine: Trimethobenzamide and Prochlorperazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Procyclidine: Trimethobenzamide and Procyclidine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Promethazine: Trimethobenzamide and Promethazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Propantheline: Trimethobenzamide and Propantheline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Protriptyline: Trimethobenzamide and Protriptyline, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Quetiapine: Trimethobenzamide and Quetiapine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Risperidone: Trimethobenzamide and Risperidone, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Rivastigmine: The therapeutic effects of the anticholinergic, Trimethobenzamide, and/or the acetylcholinesterase inhibitor (central), Rivastigmine, may be reduced due to antagonism. Monitor therapeutic effects of both agents.

Scopolamine: Trimethobenzamide and Scopolamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Secretin: The stimulatory effect of Secretin may be reduced by anticholinergics such as Trimethobenzamide. Concomitant use of Secretin and drugs with substantial anticholinergic effects should be avoided. If combination therapy must be used, Secretin efficacy should be closely monitored.

Solifenacin: Trimethobenzamide and Solifenacin, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Tacrine: The therapeutic effects of the central acetylcholinesterase inhibitor, Tacrine, and/or the anticholinergic, Trimethobenzamide, may be reduced due to antagonism. The interaction may be beneficial when the anticholinergic action is a side effect. Monitor for decreased efficacy of both agents.

Thioridazine: Trimethobenzamide and Thioridazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Thiothixene: Trimethobenzamide and Thiothixene, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Tiotropium: Trimethobenzamide and Tiotropium, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Tolterodine: Trimethobenzamide and Tolterodine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Tranylcypromine: Trimethobenzamide and Tranylcypromine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Trifluoperazine: Trimethobenzamide and Trifluoperazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Trihexyphenidyl: Trimethobenzamide and Trihexyphenidyl, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Trimeprazine: Trimethobenzamide and Trimeprazine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Trimipramine: Trimethobenzamide and Trimipramine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Triprolidine: Concomitant therapy with Triprolidine and Trimethobenzamide, two anticholinergics, may result in additive anticholinergic effects. Monitor for enhanced anticholinergic effects.

Trospium: Trospium and Trimethobenzamide, two anticholinergics, may cause additive anticholinergic effects and enhanced adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Zuclopenthixol: Trimethobenzamide and Zuclopenthixol, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.