Tigan

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

• Tigan^®

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Trimethobenzamide is usually taken 3 or 4 times per day. You may also be using the medicine only when needed. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Store at room temperature away from moisture and heat.

Contraindications

• Known hypersensitivity to trimethobenzamide.100 101 a c

• Injection contraindicated in children.100 101 a

Warnings/Precautions

Warnings

May impair ability to perform activities requiring mental alertness or physical coordination (e.g., operating machinery, driving a motor vehicle); avoid concomitant use with alcohol.100 101 a c

Possible neurologic reactions (e.g., opisthotonos, seizures, coma, extrapyramidal reactions); may be similar to CNS signs and symptoms accompanying certain disorders (e.g., acute febrile illness, encephalitis, Reye’s syndrome, encephalopathy, gastroenteritis, dehydration, electrolyte imbalance), especially in children and in geriatric or debilitated patients.100 101 a c Diagnosis of these disorders may be obscured or the disease-associated signs and symptoms may be incorrectly diagnosed as drug induced.100 101 a c

Use with caution in patients with such disorders, particularly in those who have recently received other CNS drugs (e.g., phenothiazines, barbiturates, belladonna derivatives).100 101 a c (See Specific Drugs under Interactions.)

Avoid use in pediatric patients with signs and symptoms suggestive of Reye’s syndrome.100 101 a c (See Pediatric Use under Cautions.)

Discontinue drug if CNS symptoms occur.100 101 a c

Sensitivity Reactions

Hypersensitivity reactions including allergic skin reactions have been reported; discontinue at the first sign of sensitization.100 101 a c

General Precautions

Jaundice reported; discontinue drug if jaundice occurs.100 101 a c

Potential hepatotoxic effects may unfavorably alter the course of Reye’s syndrome.100 101 a c (See Pediatric Use under Cautions.)

Blood dyscrasias reported; discontinue drug if blood dyscrasia occurs.100 101 a c

Antiemetic effect may mask signs of overdosage of other drugs or may obscure the cause of vomiting in various disorders (e.g., appendicitis).100 101 a c

Discontinue drug if exaggeration of preexisting nausea occurs.100 101 a c

Specific Populations

Category C.e

Not known whether trimethobenzamide is distributed into milk.a e Safety not established.100 101 a c

Injection contraindicated in children.100 101 a Suitable oral dosage forms and rectal suppositories for pediatric use no longer are commercially available in the US.102 103 a c (See Preparations.)

Use trimethobenzamide with caution in children.a c Not recommended for treatment of uncomplicated vomiting in children; limit use to treatment of prolonged vomiting of known etiology.100 101 c Avoid use in pediatric patients with signs and symptoms suggestive of Reye’s syndrome.100 101 a c

Extrapyramidal effects of trimethobenzamide may obscure the diagnosis of or be confused with CNS manifestations of Reye’s syndrome or other encephalopathies.100 101 a c (See Neurologic Effects under Cautions.)

Potential hepatotoxic effects of trimethobenzamide may unfavorably alter the course of Reye’s syndrome.100 101 a c

Children with acute febrile illnesses, encephalitides, gastroenteritis, dehydration, or electrolyte imbalance may be at increased risk for adverse CNS effects (e.g., extrapyramidal reactions, opisthotonos, seizures, coma).100 101 a c Use with caution in such children, especially those who recently have received other CNS agents.100 101 a c

Geriatric and debilitated patients with acute febrile illnesses, encephalitides, gastroenteritis, dehydration, or electrolyte imbalance may be at increased risk for adverse CNS effects (e.g., extrapyramidal reactions, opisthotonos, seizures, coma).100 101 a c Use with caution in such individuals, especially those who recently have received other CNS agents.100 101 a c

Common Adverse Effects

Adverse effects may include blurred vision,100 101 a c depression,100 101 a c disorientation,100 101 a c dizziness,100 101 a c drowsiness,100 101 a c headache,100 101 a c extrapyramidal symptoms,100 101 a c diarrhea,100 a c opisthotonos,100 101 a c and muscle cramps.100 101 a c In addition, injection site reactions (pain,100 101 a stinging,100 101 a redness,100 101 a swelling100 101 a ) and hypotension100 101 a may occur following IM injection.

• Appears to directly affect the medullary chemoreceptor trigger zone (CTZ) by inhibiting stimuli at the CTZ.100 101 a c

• Inhibits the emetic effect of apomorphine in animals; however, does not appear to inhibit direct impulses to the vomiting center in the lateral reticular formation and does not act peripherally to decrease the sensitivity of visceral nerves that transmit afferent impulses from the GI tract to the vomiting center.100 101 a c

• Structurally related to the substituted ethanolamine antihistamines (e.g., diphenhydramine) but exhibits only weak antihistaminic activity.a

Trimethobenzamide is used to treat nausea and vomiting after surgery. It is also used to treat nausea caused by gastroenteritis.

This medicine is available only with your doctor's prescription.

Acute Dystonic Reactions and Other Extrapyramidal Symptoms (EPS)

Extrapyramidal symptoms (EPS), manifested primarily as acute dystonic reactions, may occur with Tigan. Dystonic reactions may include sudden onset of muscular spasms, especially in the head and neck or opisthotonos. Other EPS include laryngospasm, dysphagia, and oculogyric crisis. Involuntary spasms of the tongue and mouth may lead to difficulty in speaking and swallowing. Anticholinergic drugs can be used to treat acute dystonic reactions.

EPS may also include akathisia, restlessness, akinesia, and other parkinsonian-like symptoms (e.g., tremor). Depending on the severity of symptoms, reduce the daily dosage of Tigan by increasing the dosing interval or discontinue Tigan [see Dosage and Administration (2.1)].

Avoid Tigan in patients receiving other drugs that are likely to cause EPS (e.g. antipsychotics) [see Drug Interactions (7.2)].

Masking of Other Serious Disorders

EPS and other CNS symptoms which can occur in patients treated with Tigan may be confused with CNS signs of undiagnosed primary disease (e.g., encephalopathy, metabolic imbalance, Reye's syndrome) [see Warnings and Precautions (5.1, 5.3)]. If CNS symptoms occur, evaluate the risks and benefits of continuing Tigan for each patient.

Other CNS Reactions

Other serious CNS adverse reactions such as coma, depression of mood, disorientation, and seizures have been reported with Tigan administration. The recent use of other drugs that cause CNS depression or EPS symptoms (e.g., alcohol, sedatives, hypnotics, opiates, anxiolytics, antipsychotics, and anticholinergics) may also increase the risk for these serious CNS reactions [see Warnings and Precautions (5.1, 5.5)]. Consider reducing the daily dosage of Tigan by increasing the dosing interval or discontinuing the drug [see Dosage and Administration (2.1), Drug Interactions (7.1, 7.2)].

Hepatotoxicity

Tigan is potentially hepatotoxic [see Adverse Reactions (6)]. Avoid use of Tigan in patients whose signs and symptoms suggest the presence of hepatic impairment. Discontinue Tigan in patients who develop impaired liver function while taking Tigan.

Effects on the Ability to Drive or Operate Machinery

Tigan can cause drowsiness and may impair the mental and/or physical abilities required for the performance of hazardous tasks such as driving a motor vehicle or operating machinery [see Warnings and Precautions (5.1, 5.3)]. Concomitant use of other drugs that cause CNS depression or EPS symptoms (e.g., alcohol, sedatives, hypnotics, opiates, anxiolytics, antipsychotics, and anticholinergics) may increase this effect. Either Tigan or the other interacting drug should be chosen, depending on the importance of the drug to the patient [Drug Interactions (7.1, 7.2)]. Inform patients not to operate motor vehicles or other dangerous machinery until they are reasonably certain that Tigan does not affect them adversely.

Chemically, trimethobenzamide hydrochloride 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:

Each 300-mg Tigan capsule for oral use contains 300 mg trimethobenzamide hydrochloride (equivalent to 274.3 mg of trimethobenzamide) as the active ingredient. The inactive ingredients are D&C Red No. 28, FD&C Blue No. 1, lactose, magnesium stearate, starch and titanium dioxide.

NDC 61570-079-01

Pfizer

Tigan®
(trimethobenzamide
HCl capsules)

300 mg

100 Capsules
Rx only

Applies to trimethobenzamide: compounding powder, intramuscular solution, oral capsule, rectal suppository

Nervous system

Frequency not reported: Parkinson-like/extrapyramidal symptoms, coma, convulsions, disorientation, dizziness, drowsiness, headache, opisthotonos[Ref]

Hypersensitivity

Frequency not reported: Hypersensitivity reactions[Ref]

Cardiovascular

Frequency not reported: Hypotension[Ref]

Psychiatric

Frequency not reported: Depression[Ref]

Gastrointestinal

Frequency not reported: Diarrhea[Ref]

Hepatic

Frequency not reported: Jaundice[Ref]

Musculoskeletal

Frequency not reported: Muscle cramps[Ref]

Hematologic

Frequency not reported: Blood dyscrasias[Ref]

Ocular

Frequency not reported: Blurred vision[Ref]

Immunologic

Frequency not reported: Allergic-type skin reactions[Ref]

Some side effects of Tigan may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.