TRIMETHOBENZAMIDE: 145 Adverse Event Reports & Safety Profile

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: Capsules: Each capsule for oral use contains trimethobenzamide hydrochloride USP equivalent to 300 mg. The capsule has an opaque purple cap marked “HP” and an opaque purple body marked “180”. The inactive ingredients are lactose monohydrate, magnesium stearate, and corn starch. The capsule shell contains the following ingredients: gelatin, titanium dioxide, D&C Red No. 28, and FDC Blue No. 1, and sodium lauryl sulfate. White ink contains the following ingredients: Shellac, dehydrated alcohol, isopropyl alcohol, butyl alcohol, propylene glycol, ammonium hydroxide, potassium hydroxide and titanium dioxide. chemical-structure

AND USAGE Trimethobenzamide hydrochloride capsules is indicated in adults for the treatment of postoperative nausea and vomiting and for nausea associated with gastroenteritis. Limitation of Use: Trimethobenzamide hydrochloride capsules is not recommended for use in pediatric patients due to the risk of extrapyramidal signs and symptoms and other serious central nervous system (CNS) effects, and the risk of exacerbation of the underlying disease in pediatric patients with Reye's syndrome or other hepatic impairment. Trimethobenzamide hydrochloride capsules are an antiemetic indicated in adults for the treatment of postoperative nausea and vomiting and for nausea associated with gastroenteritis. ( 1 ) Limitation of Use:

• Trimethobenzamide hydrochloride capsules are not recommended for use in pediatric patients due to the risk of extrapyramidal signs and symptoms and other serious central nervous system (CNS) effects and the risk of exacerbation of the underlying disease in pediatric patients with Reye's syndrome or other hepatic impairment. ( 1 , 8.4 )

DOSAGE AND ADMINISTRATION (See WARNINGS and PRECAUTIONS .) Dosage should be adjusted according to the indication for therapy, severity of symptoms and the response of the patient.

Geriatric Patients

Dose adjustment such as reducing the total dose administered at each dosing or increasing the dosing interval should be considered in elderly patients with renal impairment (creatinine clearance ≤ 70 mL/min/1.73m 2 ). Final dose adjustment should be based upon integration of clinical efficacy and safety considerations. (See CLINICAL PHARMACOLOGY and PRECAUTIONS ). Patients with Renal Impairment In subjects with renal impairment (creatinine clearance ≤ 70 mL/min/1.73m 2 ), dose adjustment such as reducing the total dose administered at each dosing or increasing the dosing interval should be considered. (See CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION ). INJECTABLE, 100 mg/mL (Not for use in pediatric patients)

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. Intramuscular 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.

Contraindications The injectable form of Tigan ® is contraindicated in pediatric patients and in patients with known hypersensitivity to trimethobenzamide.

Contraindications

The injectable form of Tigan ® is contraindicated in pediatric patients and in patients with known hypersensitivity to trimethobenzamide.

REACTIONS The following adverse reactions from voluntary reports or clinical studies have been reported with trimethobenzamide. Because many of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Nervous system disorders: Parkinson-like symptoms, coma, convulsions, opisthotonos, dizziness, drowsiness, headache, [see Warnings and Precautions ( 5.1 , 5.2 , 5.3 )] Psychiatric disorders: disorientation, depression of mood Eye disorders: blurred vision Hematologic disorders: blood dyscrasias Hepatobiliary disorders: jaundice [see Warnings and Precautions ( 5.4 )] Immune system disorders: hypersensitivity, including angioedema and allergic-type skin reactions Gastrointestinal disorders: diarrhea Musculoskeletal disorders: muscle cramps Adverse reactions include hypersensitivity reactions and Parkinson-like symptoms; blood dyscrasias, blurring of vision, coma, convulsions, depression of mood, diarrhea, disorientation, dizziness, drowsiness, headache, jaundice, muscle cramps, and opisthotonos. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Avet Pharmaceuticals Inc. at 1-866-901-DRUG (3784) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

AND PRECAUTIONS Acute Dystonic Reactions and Other Extrapyramidal Symptoms (EPS) : Depending on the severity of symptoms, reduce the dosage or discontinue the drug. Treat acute dystonic reactions with anticholinergics. Avoid trimethobenzamide hydrochloride capsules in patients receiving other drugs that are likely to cause EPS. ( 5.1 , 7.2 ) Masking of Other Serious Disorders : EPS and other CNS symptoms in patients treated with trimethobenzamide hydrochloride capsules may be confused with CNS signs of undiagnosed primary disease (e.g., encephalopathy, metabolic imbalance, Reye's Syndrome). If CNS symptoms occur, evaluate the risks and benefits of continuing trimethobenzamide hydrochloride capsules. ( 5.2 , 7.2 ) Other CNS Reactions : Coma, depression of mood, disorientation, and seizures have been reported. The recent use of other drugs that cause CNS depression or EPS symptoms may also increase the risk; consider reducing the dosage or discontinuing the drug. ( 5.3 , 7.1 , 7.2 ) Hepatotoxicity : Avoid use in patients whose signs and symptoms suggest the presence of hepatic impairment. Discontinue trimethobenzamide hydrochloride capsules in patients who develop impaired liver function while on treatment. ( 5.4 , 8.7 ) Effects on the Ability to Drive or Operate Machinery : Mental and/or physical abilities may be impaired. Concomitant use of other drugs that cause CNS depression or EPS symptoms may increase this effect; either trimethobenzamide hydrochloride capsules or the other interacting drug should be chosen, depending on the importance of the drug to the patient. ( 5.5 , 7.1 , 7.2 )

5.1 Acute Dystonic Reactions and Other Extrapyramidal Symptoms (EPS) Extrapyramidal symptoms (EPS), manifested primarily as acute dystonic reactions, may occur with trimethobenzamide hydrochloride capsules. 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 trimethobenzamide hydrochloride capsules by increasing the dosing interval or discontinue trimethobenzamide hydrochloride capsules <span class="opacity-50 text-xs">[see Dosage and Administration (2.1) ]</span> . Avoid trimethobenzamide hydrochloride capsules in patients receiving other drugs that are likely to cause EPS (e.g. antipsychotics) <span class="opacity-50 text-xs">[see Drug Interactions (7.2) ]</span> .

5.2 Masking of Other Serious Disorders EPS and other CNS symptoms which can occur in patients treated with trimethobenzamide hydrochloride capsules may be confused with CNS signs of undiagnosed primary disease (e.g., encephalopathy, metabolic imbalance, Reye&apos;s syndrome)) <span class="opacity-50 text-xs">[see Warnings and Precautions ( 5.1 , 5.3 )]</span>. If CNS symptoms occur, evaluate the risks and benefits of continuing trimethobenzamide hydrochloride capsules for each patient.

5.3 Other CNS Reactions Other serious CNS adverse reactions such as coma, depression of mood, disorientation, and seizures have been reported with trimethobenzamide hydrochloride capsules 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 <span class="opacity-50 text-xs">[see Warnings and Precautions (5.1 , 5.5 )]</span>. Consider reducing the daily dosage of trimethobenzamide hydrochloride capsules by increasing the dosing interval or discontinuing the drug <span class="opacity-50 text-xs">[see Dosage and Administration (2.1) , Drug Interactions (7.1 , 7.2 )]</span> .

5.4 Hepatotoxicity Trimethobenzamide hydrochloride capsules is potentially hepatotoxic <span class="opacity-50 text-xs">[see Adverse Reactions (6) ]</span> . Avoid use of trimethobenzamide hydrochloride capsules in patients whose signs and symptoms suggest the presence of hepatic impairment . Discontinue trimethobenzamide hydrochloride capsules in patients who develop impaired liver function while taking trimethobenzamide hydrochloride capsules.

5.5 Effects on the Ability to Drive or Operate Machinery Trimethobenzamide hydrochloride capsules 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 <span class="opacity-50 text-xs">[see Warnings and Precautions (5.1 , 5.3 )]</span> . 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 trimethobenzamide hydrochloride capsules 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 trimethobenzamide hydrochloride capsules does not affect them adversely.

Precautions 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 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 Tigan ® may render diagnosis more difficult in such conditions as appendicitis and obscure signs of toxicity due to overdosage of other drugs.

General

Adjustment of Dose in Renal Failure A substantial route of elimination of unchanged trimethobenzamide is via the kidney. Dosage adjustment should be considered in patients with reduced renal function including some elderly patients. (See CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION ).

Geriatric Use

Clinical studies of trimethobenzamide hydrochloride did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently from younger patients. Although there are studies reported in the literature that included elderly patients > 65 years old with younger patients, it is not known if there are differences in efficacy or safety parameters for elderly and non-elderly patients treated with trimethobenzamide. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. (See CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION ).

INTERACTIONS

• Alcohol : May cause drowsiness; avoid concomitant use. ( 7.1 )
• Other Drugs that Cause CNS Depression or EPS : Either trimethobenzamide hydrochloride capsules or the other interacting drug should be chosen, depending on the importance of the drug to the patient. If CNS-acting drugs cannot be avoided, monitor patients for CNS adverse reactions. ( 7.2 )

7.1 Alcohol Alcohol may increase the CNS depressant effects of trimethobenzamide hydrochloride capsules and may cause drowsiness <span class="opacity-50 text-xs">[see Warnings and Precautions ( 5.3 , 5.5 )]</span>. Avoid concomitant use of trimethobenzamide hydrochloride capsules with alcohol.

7.2 Other Drugs that Cause CNS Depression or EPS The concurrent use of trimethobenzamide hydrochloride capsules with other drugs that cause CNS depression or EPS (e.g., sedatives, hypnotics, opiates, anxiolytics, antipsychotics, and anticholinergics, may potentiate the effects of trimethobenzamide hydrochloride capsules <span class="opacity-50 text-xs">[see Warnings and Precautions ( 5.1 , 5.2 , 5.3 , 5.5 )]</span> . Either trimethobenzamide hydrochloride capsules or the other interacting drug should be chosen, depending on the importance of the drug to the patient. If CNS-acting drugs cannot be avoided, monitor patients for CNS adverse reactions.