TRIMEPRAZINE TARTRATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TRIMEPRAZINE TARTRATE (TRIMEPRAZINE TARTRATE).
Trimeprazine is a phenothiazine derivative that acts as an antagonist at histamine H1 receptors, dopamine D2 receptors, and muscarinic acetylcholine receptors, exerting antihistaminic, antiemetic, sedative, and anticholinergic effects.
| Metabolism | Hepatic metabolism via cytochrome P450 enzymes, primarily CYP2D6; metabolites include sulfoxides and N-demethylated derivatives. |
| Excretion | Primarily renal excretion of metabolites (approximately 70-80% as conjugated metabolites), with about 5-10% unchanged. Biliary/fecal elimination accounts for less than 20%. |
| Half-life | Terminal elimination half-life is approximately 3.5 to 4 hours in adults; may be prolonged in elderly or hepatic impairment, necessitating dose adjustment. |
| Protein binding | Approximately 90-95% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Approximately 2.5-3.5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: 25-40% due to extensive first-pass metabolism; IM: 75-85%; IV: 100%. |
| Onset of Action | Oral: 30-60 minutes; Intramuscular: 15-30 minutes; Intravenous: 5-10 minutes. |
| Duration of Action | Oral: 4-6 hours; IM/IV: 3-4 hours. Duration may be shorter in children and longer in elderly due to altered clearance. |
| Molecular Weight | 446.56 Da |
10-20 mg orally 3-4 times daily; maximum 100 mg/day.
| Dosage form | SYRUP |
| Renal impairment | GFR ≥50 mL/min: no adjustment; GFR 10-49 mL/min: administer 50% of usual dose; GFR <10 mL/min: avoid use. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use. |
| Pediatric use | Children 2-12 years: 0.5-1 mg/kg/day orally in divided doses every 4-6 hours; maximum 40 mg/day. |
| Geriatric use | Initiate at 5 mg 3 times daily; increase cautiously to avoid sedation and hypotension; maximum 50 mg/day. |
| 1st trimester | Avoid; limited human data; animal studies show developmental toxicity at high doses. Potential for teratogenicity based on phenothiazine class effects. |
| 2nd trimester | Use only if benefit outweighs risk; may cause maternal hypotension and fetal hypoxia. |
| 3rd trimester | Avoid near term; risk of neonatal respiratory depression, extrapyramidal symptoms, and withdrawal. |
Clinical note
Comprehensive clinical and safety monograph for TRIMEPRAZINE TARTRATE (TRIMEPRAZINE TARTRATE).
| Placental transfer | Crosses placenta; phenothiazines are known to reach fetal circulation with potential for neonatal effects. |
| Breastfeeding | Trimeprazine is excreted into breast milk in small amounts; however, due to potential for infant sedation and irritability, use with caution and monitor infant for drowsiness and feeding difficulties. |
■ FDA Black Box Warning
None
| Serious Effects |
Comatose statesCNS depressionHypersensitivity to trimeprazine or other phenothiazinesSevere bone marrow depressionAngle-closure glaucoma
| Precautions | May cause QT interval prolongation; use with caution in patients with cardiac disease or electrolyte disturbances., May cause extrapyramidal symptoms, especially in elderly or debilitated patients., May cause tardive dyskinesia with prolonged use., May cause neuroleptic malignant syndrome (rare)., Sedation and dizziness may impair ability to drive or operate machinery., May cause anticholinergic effects (dry mouth, urinary retention, constipation, blurred vision)., Use with caution in patients with glaucoma, prostate hypertrophy, or hepatic impairment. |
| Food/Dietary | No specific food interactions are documented; however, grapefruit juice may increase phenothiazine levels at high intake; advise moderation. Avoid ethanol. |
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| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Limited human data; animal studies not conducted. First trimester: insufficient evidence to exclude risk. Second and third trimesters: potential for neonatal respiratory depression and hypotonia if used near term. Avoid in pregnancy unless clearly needed. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and respiratory status. In third trimester, observe neonate for signs of withdrawal, respiratory depression, or hypotonia. |
| Fertility Effects | No specific data on fertility. Anticholinergic and antihistaminic effects may theoretically impact fertility. |
| Clinical Pearls | Trimeprazine is a phenothiazine antihistamine with sedative, antipruritic, and antiemetic properties; use cautiously in elderly due to anticholinergic effects and risk of sedation; monitor for extrapyramidal symptoms in children; avoid in patients with severe CNS depression, narrow-angle glaucoma, or prostatic hyperplasia; taper dosing to avoid rebound pruritus. |
| Patient Advice | May cause drowsiness; avoid driving or operating machinery until you know how this medication affects you. · Avoid alcohol and other CNS depressants (e.g., sedatives, tranquilizers) as they may increase dizziness and drowsiness. · Do not take with other antihistamines or cold medications without consulting your doctor. · Report any unusual muscle movements, stiffness, or persistent sedation to your doctor. · Use sunscreen and protective clothing; this drug may increase sensitivity to sunlight. · Take exactly as prescribed; do not increase dose or frequency without medical advice. |