Trimethobenzamide

12.1 Mechanism of Action The mechanism of action of trimethobenzamide 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 copper sulfate.

1 INDICATIONS 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 )

2 DOSAGE AND ADMINISTRATION • The recommended adult dosage is 300 mg orally three or four times daily. ( 2.1 ) • Geriatric patients and/or patients with renal impairment (creatinine clearance 70 mL/min/1.73m2 or less): Reduce the daily dosage by increasing the dosing interval; monitor renal function. ( 2.2 , 8.5 , 8.6 ) • Select the lowest effective daily dosage and adjust as needed based upon therapeutic response and tolerability. ( 2.1 , 2.2 ) 2.1 Recommended Adult Dosage The recommended adult dosage is 300 mg orally three or four times daily. Select the lowest effective daily dosage and adjust as needed based upon therapeutic response and tolerability. 2.2 Dosage Adjustment for Geriatric Patients and/or Patients with Renal Impairment In geriatric patients and/or in patients with renal impairment (creatinine clearance 70 mL/min/1.73m2 or less), reduce the daily dosage of trimethobenzamide hydrochloride capsules by increasing the dosing interval and adjust as needed based upon therapeutic response and tolerability. Monitor renal function [see Use in Specific Populations ( 8.5 , 8.6 )] .

6 ADVERSE 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 Lupin Pharmaceuticals, Inc. at 1-866-403-7592 or FDA at 1-800-FDA-1088 or WWW.FDA.GOV/MEDWATCH .

7 DRUG 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 [see Warnings and Precautions ( 5.3 , 5.5 )]. 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 [see Warnings and Precautions ( 5.1 , 5.2 , 5.3 , 5.5 )] . 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.