Chemically, trimethobenzamide HCl is N-[p -[2-(dimethylamino)ethoxy]benzyl]-3,4,5-
trimethoxybenzamide monohydrochloride. It has a molecular weight of
424.93 and the following structural formula:
Capsules: Each 300-mg Tigan® capsule for oral use contains trimethobenzamide hydrochloride equivalent
to 300 mg. The capsule has an opaque purple cap marked “Tigan”
and an opaque purple body marked “M079”.
Inactive Ingredients: D&C Red No. 28, FD&C Blue No.1, lactose, magnesium stearate,
starch and titanium dioxide.
Single-Dose Vials: Each 2-mL single-dose
vial contains 200 mg trimethobenzamide hydrochloride compounded with
1 mg sodium citrate and 0.4 mg citric acid as buffers and pH adjusted
to approximately 5.0 with sodium hydroxide.
Multi-Dose Vials: Each mL contains
100 mg trimethobenzamide hydrochloride compounded with 0.45% phenol
as preservative, 0.5 mg sodium citrate and 0.2 mg citric acid as buffers
and pH adjusted to approximately 5.0 with sodium hydroxide.
Mechanism of Action
The mechanism of action of Tigan® 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
HCl, the emetic response to apomorphine is inhibited, while little
or no protection is afforded against emesis induced by intragastric
The pharmacokinetics of trimethobenzamide have been
studied in healthy adult subjects. Following administration of 200
mg (100 mg/mL) Tigan I.M. injection, the time to reach maximum plasma
concentration (Tmax) was about half an hour, about 15 minutes
longer for Tigan 300 mg oral capsule than an I.M. injection. A single
dose of Tigan 300 mg oral capsule provided a plasma concentration
prole of trimethobenzamide similar to Tigan 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.
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).
Indications and Usage
Tigan® is indicated for the treatment of postoperative nausea
and vomiting and for nausea associated with gastroenteritis.
Use of the injectable form of Tigan® in children and
use of any dosage form in patients with known hypersensitivity to
trimethobenzamide are contraindicated.
Caution should be exercised when administering Tigan® 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
The extrapyramidal symptoms which can occur secondary
to Tigan® may
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.
It has been suspected that drugs with hepatotoxic
potential, such as Tigan®, 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.
Tigan® may 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 Tigan® 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 Tigan® (trimethobenzamide hydrochloride) or other
antiemetic agents. In such disorders caution should be exercised in
administering Tigan®, 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 uids
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 Tigan® may render diagnosis
more difcult in such conditions as appendicitis and obscure
signs of toxicity due to overdosage 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 rst 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.
CAPSULES , 300 mg
Usual Adult Dosage
One 300 mg capsule t.i.d. or q.i.d.
INJECTABLE, 100 mg/mL (not for use in children)
Usual Adult Dosage
2 mL (200 mg) t.i.d. or q.i.d. intramuscularly.
NOTE: The injectable
form is intended for intramuscular administration only; it is not
recommended for intravenous use.
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.
Store at 25°C (77°F).
Excursions permitted to 15–30°C (59–86°F).
[See USP Controlled Room Temperature]
Capsules, 300 mg trimethobenzamide hydrochloride
each, bottles of 100
61570-079-01 300 mg 100’s
Vials, 2 mL, trays of 25
61570-543-25 100 mg/mL in 2 mL
Vials Multi-Dose Vials, 20 mL
61570-541-20 100 mg/mL in 20 mL Multi-Dose Vials