Trimethobenzamide
TIGAN
Pronunciation: trye-meth-oe-BEN-za-mide
“Trim bendy Tigger”
rainbow spray → antiemetic
What it isWeak central D2-antagonist antiemetic; adult postoperative and gastroenteritis nausea and vomiting.
Why this oneUsed for dopaminergic-drug nausea in Parkinson disease, notably apomorphine, where metoclopramide and prochlorperazine are avoided.
What limits itDrowsiness and acute dystonic or other extrapyramidal reactions limit use; avoid pediatric use and reduce dosing when renal clearance is impaired.
Pearls
- Typically started 3 days before apomorphine initiation.
Trimethobenzamide prescription history
Animated chart of estimated U.S. prescriptions per year, Antiemetics (1946–2026). Trimethobenzamide enters in 1959 (estimated).
FDA-approved for
- nausea (~1959)
Principal riskacute dystonia and other extrapyramidal reactions
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Nausea and vomiting | Adults | 300 mg TID–QID | 300 mg TID–QID | 1200 mg/day |
Renal CrCl ≤70 mL/min/1.73m2: reduce daily dose by increasing the dosing interval; monitor renal function
Hepatic Avoid in suspected hepatic impairment (hepatotoxicity risk); discontinue if impaired liver function develops
Instructions
- Oral; select the lowest effective daily dosage and adjust to response/tolerability
Available strengths
- cap 300 mg
- inj 100 mg/mL
Cautions
- Acute dystonic reactions/EPS — reduce dose or discontinue; avoid with other EPS-causing drugs
- May mask CNS signs of undiagnosed disease (e.g., encephalopathy, Reye's syndrome)
- Other serious CNS reactions: coma, mood depression, disorientation, seizures
- Hepatotoxicity — avoid in hepatic impairment, discontinue if liver function worsens
- Drowsiness — may impair driving/operating machinery
Adverse reactions
- Parkinson-like symptoms
- Drowsiness, dizziness, headache
- Blurred vision
- Diarrhea, muscle cramps
- Jaundice
- Blood dyscrasias
- Hypersensitivity (angioedema, skin reactions)
Pregnancy Limited human data insufficient to assess risk; no adverse developmental effects in animal studies
Lactation No human data; weigh benefits of breastfeeding against maternal need
Cost
| Strength | #/mo | generic $ | CostPlus | |
|---|---|---|---|---|
| 300 mg | cap | 90 TID | $1,619.97/mo | not offered |
| 100 mg/mL | inj | per unit | not offered |
Generic entry1982
Open Trimethobenzamide in the interactive console ↗
Memory aids: interaction avatars
Open Trimethobenzamide in the interactive console ↗
Self-check
- What is trimethobenzamide’s proposed central mechanism?
Probably dopamine antagonism in the chemoreceptor trigger zone. - When should trimethobenzamide dosing be reduced?
When renal clearance is impaired.