Rx Drugs Info

trimethobenzamide hydrochloride (Trimethobenzamide Hydrochloridecapsule 
[Actavis Totowa LLC]


Chemically, trimethobenzamide hydrochloride is N-[ρ-[2-(dimethylamino)ethoxy]benzyl]-3,4,5-trimethoxybenzamide monohydrochloride. It has a molecular weight of 424.92 and the following structural formula:

Image from Drug Label Content

Each capsule for oral use contains trimethobenzamide hydrochloride equivalent to 300 mg.

Inactive Ingredients: Lactose monohydrate, magnesium stearate and pregelatinized starch. The capsule shell contains the following ingredients, D&C Red #28, FD&C Blue #1, FD&C Red #40, gelatin and titanium dioxide.

White ink contains the following ingredients: ammonium hydroxide, isopropyl alcohol, n-butyl alcohol, pharmaceutical glaze, propylene glycol, simethicone and titanium dioxide.


Mechanism of Action

The mechanism of action of trimethobenzamide hydrochloride 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 hydrochloride, the emetic response to apomorphine is inhibited, while little or no protection is afforded against emesis induced by intragastric copper sulfate.


The pharmacokinetics of trimethobenzamide have been studied in healthy adult subjects. Following administration of 200 mg (100 mg/mL) trimethobenzamide I.M. injection, the time to reach maximum plasma concentration (Tmax) was about half an hour, about 15 minutes longer for trimethobenzamide 300 mg oral capsule than an I.M. injection. A single dose of trimethobenzamide 300 mg oral capsule provided a plasma concentration profile of trimethobenzamide similar to trimethobenzamide 200 mg I.M. The relative bioavailability of the capsule formulation compared to the solution is 100%. The mean elimination half-life of trimethobenzamide is 7 to 9 hours.

Special Populations


Systemic exposure to trimethobenzamide was similar between men (N=40) and women (N=28).


Pharmacokinetics appeared to be similar for Caucasians (N=53) and African Americans (N=12).


Trimethobenzamide hydrochloride capsule, USP 300 mg is indicated for the treatment of postoperative nausea and vomiting and for nausea associated with gastroenteritis.


Use in patients with known hypersensitivity to trimethobenzamide is contraindicated.


Caution should be exercised when administering trimethobenzamide hydrochloride capsules to children for the treatment of vomiting.

Antiemetics are not recommended for treatment of uncomplicated vomiting in children and their use should be limited to prolonged vomiting of known etiology. There are two principal reasons for caution:

  1. The extrapyramidal symptoms which can occur secondary to trimethobenzamide hydrochloride capsulesmay be confused with the central nervous system signs of an undiagnosed primary disease responsible for the vomiting, e.g., Reye’s syndrome or other encephalopathy.

  2. It has been suspected that drugs with hepatotoxic potential, such as trimethobenzamide hydrochloride capsules, may unfavorably alter the course of Reye’s syndrome. Such drugs should therefore be avoided in children whose signs and symptoms (vomiting) could represent Reye’s syndrome.

Trimethobenzamide hydrochloride capsulesmay produce drowsiness. Patients should not operate motor vehicles or other dangerous machinery until their individual responses have been determined.

Usage in Pregnancy:

Trimethobenzamide hydrochloride was studied in reproduction experiments in rats and rabbits and no teratogenicity was suggested. The only effects observed were an increased percentage of embryonic resorptions or stillborn pups in rats administered 20 mg and 100 mg/kg and increased resorptions in rabbits receiving 100 mg/kg. In each study these adverse effects were attributed to one or two dams. The relevance to humans is not known. Since there is no adequate experience in pregnant or lactating women who have received this drug, safety in pregnancy or in nursing mothers has not been established.

Usage with Alcohol: Concomitant use of alcohol with trimethobenzamide hydrochloride capsules, USP 300 mg may result in an adverse drug interaction.


During the course of acute febrile illness, encephalitides, gastroenteritis, dehydration and electrolyte imbalance, especially in children and the elderly or debilitated, CNS reactions such as opisthotonos, convulsions, coma and extrapyramidal symptoms have been reported with and without use of trimethobenzamide hydrochloride capsules or other antiemetic agents. In such disorders caution should be exercised in administering trimethobenzamide hydrochloride capsules, particularly to patients who have recently received other CNS acting agents (phenothiazines, barbiturates, belladonna derivatives). Primary emphasis should be directed toward the restoration of body fluids and electrolyte balance, the relief of fever and relief of the causative disease process. Overhydration should be avoided since it may result in cerebral edema.

The antiemetic effects of trimethobenzamide hydrochloride capsules may render diagnosis more difficult in such conditions as appendicitis and obscure signs of toxicity due to over dosage of other drugs.


There have been reports of hypersensitivity reactions and Parkinson-like symptoms. There have been instances of hypotension reported following parenteral administration to surgical patients. There have been reports of blood dyscrasias, blurring of vision, coma, convulsions, depression of mood, diarrhea, disorientation, dizziness, drowsiness, headache, jaundice, muscle cramps and opisthotonos. If these occur, the administration of the drug should be discontinued. Allergic-type skin reactions have been observed; therefore, the drug should be discontinued at the first sign of sensitization. While these symptoms will usually disappear spontaneously, symptomatic treatment may be indicated in some cases.



Dosage should be adjusted according to the indication for therapy, severity of symptoms and the response of the patient.

Usual Adult Dosage: One 300 mg capsule t.i.d. or q.i.d.


Trimethobenzamide hydrochloride capsules, USP 300 mg are filled gelatin capsules size 1 lavender opaque cap/lavender opaque body with a white imprint “A-185” on cap and body. Available in bottles of 100’s and 500’s.

Store at 20° to 25°C (68° to 77°F)[See USP Controlled Room Temperature].

Image from Drug Label Content

Manufactured by: Actavis Totowa LLC

990 Riverview Drive, Totowa, NJ 07512 USA



Trimethobenzamide Hydrochloride (Trimethobenzamide Hydrochloride)
Product Code 52152-185 Dosage Form CAPSULE
Route Of Administration ORAL DEA Schedule
Name (Active Moiety) Type Strength
Trimethobenzamide Hydrochloride (Trimethobenzamide) Active 300 MILLIGRAM  In 1 CAPSULE
lactose monohydrate Inactive  
magnesium stearate Inactive  
pregelatinized starch Inactive  
d&c red #28 Inactive  
fd&c blue #1 Inactive  
fd&c red # 40 Inactive  
gelatin Inactive  
titanium dioxide Inactive  
ammonium hydroxide Inactive  
isopropyl alcohol Inactive  
n-butyl alcohol Inactive  
pharmaceutical glaze Inactive  
propylene glycol Inactive  
simethicone Inactive  
Characteristic Appearance Characteristic Appearance
Color PURPLE (lavender opaque) Score 1
Shape CAPSULE Symbol true
Imprint Code A-185 Coating true
Size 19mm
# NDC Package Description Multilevel Packaging
1 52152-185-02 100 CAPSULE In 1 BOTTLE None
2 52152-185-04 500 CAPSULE In 1 BOTTLE None

Revised: 11/2007Actavis Totowa LLC

Data are from FDA and U.S. National Library of Medicine.