trimethobenzamide hydrochloride

Action

Unclear. Thought to block dopamine receptors and emetic impulses in chemoreceptor trigger zone, preventing nausea and vomiting.

Availability

Capsules: 300 mg

Injection: 100 mg/ml in 2-ml ampules and prefilled syringes and in 20-ml vials

Indications and dosages

➣ Nausea and vomiting

Adults: 300 mg P.O. three to four times daily or 200 mg I.M. three to four times daily

Dosage adjustment

• Renal impairment

Contraindications

• Hypersensitivity to drug

• Parenteral form in children

Precautions

Use cautiously in:

• renal impairment, arrhythmias, encephalitis, gastroenteritis, dehydration, electrolyte imbalances

• concurrent alcohol use

• elderly or debilitated patients

• pregnant or breastfeeding patients

• children with known or suspected viral illnesses.

Administration

• In I.M. use, inject deep into upper outer quadrant of gluteus maximus.

• Withhold drug in children with signs or symptoms of Reye's syndrome.

Adverse reactions

CNS: drowsiness, dizziness, headache, depression, disorientation, parkinsonian symptoms, coma, seizures

CV: hypotension

EENT: blurred vision

Hematologic: blood dyscrasias

Hepatic: jaundice

Musculoskeletal: muscle cramps, opisthotonos

Skin: rash, urticaria, flushing

Other: pain and stinging at I.M. injection site, hypersensitivity reaction

Interactions

Drug-drug. Antidepressants, antihistamines, CNS depressants, opioids, sedative-hypnotics: additive CNS depression

Drug-behaviors. Alcohol use: additive CNS depression

Patient monitoring

• Monitor neurologic status, especially for parkinsonian symptoms and other serious adverse reactions.

• Assess CBC and liver function tests. Watch for blood dyscrasias and jaundice.

• Evaluate injection site for pain and stinging.

• Closely monitor patient's nutritional and hydration status. Report continuing nausea.

Patient teaching

• Advise patient to take as needed for nausea and vomiting, but only as prescribed.

• Tell patient to contact prescriber promptly if nausea persists despite therapy.

• Instruct patient to minimize nausea and vomiting by eating small, frequent servings of healthy food and drinking plenty of fluids.

• Advise patient to avoid alcohol.

• Caution patient to avoid driving and other hazardous activities until drug effects are known.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and behaviors mentioned above.