Trimethobenzamide

Absorption

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

Toxicity

Oral LD50 in mice is 1600 mg/kg.

Originator

Tigan,Beecham,US,1973

The Uses of Trimethobenzamide

Antiemetic.

Indications

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

Background

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.

Definition

ChEBI: The amide obtained by formal condensation of 3,4,5-trihydroxybenzoic acid with 4-[2-(N,N-dimethylamino)ethoxy]benzylamine. It is used to prevent nausea and vomitting in humans.

Manufacturing Process

To 122 grams (1 mol) of p-hydroxybenzaldehyde in 1 liter of chlorobenzene were added 66 grams (1.04 mols) of sodium methoxide (85%) and 108 grams (1 mol) of 2-dimethylaminoethyl chloride. The mixture was stirred and refluxed for 15 hours, then cooled and the precipitated sodium chloride filtered off. The filtrate was concentrated at steam temperature under water vacuum and the residual oil was fractionated in high vacuum, to give 4-(2- dimethylaminoethoxy)benzaldehyde, BP2.2145°C.
Two teaspoons of Raney nickel catalyst were added to a solution of 65.6 grams (0.34 mol) of 4-(2-dimethylaminoethoxy)benzaldehyde in 300 ml of 10% ammoniacal ethanol. The mixture was hydrogenated at 80°C and a pressure of 1,000 psi. The catalyst was filtered off, the volatiles were distilled off and the residual oil was fractionated in high vacuum, to obtain 4-(2- dimethylaminoethoxy)benzylamine, BP0.3120° to 123°C.
To 9.7 grams (0.05 mol) of 4-(2-dimethylaminoethoxy)benzylamine, dissolved in 100 ml of acetonitrile, was added all at once 12 grams (0.051 mol) of 3,4,5-trimethoxybenzoyl chloride, dissolved in 75 ml of acetonitrile. The mixture was stirred and refluxed for 8 hours, and then cooled. The crystalline solid, which had formed, was filtered off, washed with acetonitrile and recrystallized from acetonitrile, to give 4-(2-dimethylaminoethoxy)-N-(3,4,5- trimethoxybenzoyl)benzylamine hydrochloride, MP 185° to 186°C.

brand name

Tigan (King).

Therapeutic Function

Antinauseant

Pharmacokinetics

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.

Metabolism

Hepatic.