TREMIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TREMIN (TREMIN).
Trihexyphenidyl is a centrally acting anticholinergic agent that blocks muscarinic acetylcholine receptors in the basal ganglia, restoring the balance between dopaminergic and cholinergic activity, thereby reducing extrapyramidal symptoms.
| Metabolism | Primarily hepatic via hydroxylation and N-dealkylation, with involvement of CYP2D6 and CYP3A4 isoenzymes. |
| Excretion | Renal: 40% unchanged; fecal: 60% as metabolites |
| Half-life | Terminal elimination half-life: 16 hours (range 12–20 hours) in adults, supporting twice-daily dosing; 35 hours in elderly patients |
| Protein binding | 15% bound to albumin |
| Volume of Distribution | 2.5 L/kg (indicating extensive tissue distribution) |
| Bioavailability | Oral: 80–90% (first-pass metabolism limited) |
| Onset of Action | Oral: 1–2 hours for tremor reduction; IV: 5–10 minutes |
| Duration of Action | Oral: 6–12 hours; IV: 2–4 hours |
| Molecular Weight | 387.87 |
1 mg orally 1-2 times daily, gradually increasing by 1 mg every 5-7 days up to 12 mg/day in divided doses. Maximum dose 12 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-89 mL/min: no adjustment needed. GFR <30 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: use with caution; maximum 6 mg/day. Child-Pugh C: contraindicated. |
| Pediatric use | Not recommended for use in children. |
| Geriatric use | Initial dose 1 mg once daily; increase slowly due to increased sensitivity; monitor for CNS side effects. |
| 1st trimester | Avoid. Teratogenic effects observed in animal studies; human data limited but risk cannot be excluded. |
| 2nd trimester | Avoid. Use only if benefit outweighs risk; may affect fetal motor development. |
| 3rd trimester | Avoid. Risk of neonatal withdrawal syndrome and extrapyramidal symptoms. |
Clinical note
Comprehensive clinical and safety monograph for TREMIN (TREMIN).
| Placental transfer | Crosses placenta; achieves fetal concentrations approximately 50% of maternal serum levels. |
| Breastfeeding | Excreted into breast milk in low amounts; monitor infant for extrapyramidal symptoms, sedation, and poor weight gain. Use with caution. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to tremin or any excipientNarrow-angle glaucomaMyasthenia gravisSevere hepatic impairmentParkinson's disease (relative, but caution)
| Precautions | May cause CNS depression, confusion, and hallucinations, especially in elderly patients., Use with caution in patients with glaucoma, prostatic hypertrophy, or obstructive gastrointestinal disorders due to anticholinergic effects., Abrupt discontinuation may precipitate parkinsonian crisis or withdrawal symptoms., May exacerbate tardive dyskinesia. |
| Food/Dietary | No specific food interactions; however, high-fat meals may delay absorption. Avoid excessive alcohol consumption. |
Loading safety data…
| L3 (Moderately Safe) |
| Teratogenic Risk | Tremin is an anticholinergic with potential fetal risks: first trimester exposure may be associated with minor malformations; second and third trimester exposure can cause neonatal anticholinergic effects including tachycardia, urinary retention, and ileus. Avoid use in pregnancy unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal heart rate, urine output, and bowel sounds. Fetal assessment includes ultrasound for growth and amniotic fluid volume; nonstress test or biophysical profile in third trimester if used long-term. |
| Fertility Effects | No human data; animal studies show no impairment of fertility. Theoretical risk from anticholinergic effects on reproductive tract motility. |
| Clinical Pearls |
| TREMIN (trihexyphenidyl) is an anticholinergic agent used for Parkinsonism and extrapyramidal symptoms. Monitor for cognitive impairment, especially in elderly. Taper slowly to avoid withdrawal. Use with caution in patients with glaucoma, urinary retention, or myasthenia gravis. May reduce effect of antipsychotics if used for EPS. |
| Patient Advice | Take with or after meals to reduce gastrointestinal upset. · Avoid alcohol and CNS depressants as they may increase drowsiness. · Do not discontinue abruptly; taper under medical supervision to avoid withdrawal symptoms. · Report any difficulty urinating, vision changes, or confusion. · Use caution when driving or operating machinery until effects are known. · Drink plenty of fluids to prevent constipation. |