Trade names Tigan, Tebamide MedlinePlus a682693 | AHFS/Drugs.com Monograph ATC code R06AA10 (WHO) | |
 | ||
Pregnancy
category US: C (Risk not ruled out) Routes of
administration Oral, rectal, intramuscular | ||
Trimethobenzamide (trade names Tebamide, Tigan) is an antiemetic used to prevent nausea and vomiting. It is often prescribed for patients with gastroenteritis, medication-induced nausea, and other illnesses. Trimethobenzamide is generally considered the most potent antiemetic that does not have effects on the serotonergic, dopaminergic, or histaminergic systems, so it has a lower likelihood of causing undesired side effects. In the United States, it requires a prescription.
Contents
Mechanism of action
Trimethobenzamide is an antagonist of the D2 receptor. It is believed to affect the chemoreceptor trigger zone (CTZ) of the medulla oblongata to suppress nausea and vomiting.
Side effects
Possible side effects include drowsiness, dizziness, headache, diarrhea, muscle cramps, and blurred vision. More serious adverse effects include skin rash, tremors, parkinsonism, and jaundice.
Formulations
Trimethobenzamide is marketed under the brand names Tebamide and Tigan, manufactured by GlaxoSmithKline and King Pharmaceuticals, respectively. It is available as oral capsules and injectable formulations.
Trimethobenzamide was also available as a rectal suppository, but such formulations were banned by the U.S. Food and Drug Administration on April 6, 2007 due to unproven efficacy.
Synthesis
Alkylation of the sodium salt of p-hydroxybenzaldehyde (1) with 2-dimethylaminoethyl chloride affords the ether (2). Reductive amination of the aldehyde in the presence of ammonia gives diamine (3). Acylation of that product with 3,4,5-trimethoxybenzoyl chloride affords trimethobenzamide (4).