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 |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TREMIN (TREMIN).
| Breastfeeding | Excretion into human milk is unknown; however, anticholinergic agents may suppress lactation. M/P ratio not established. Use caution in nursing mothers; consider risk of infant anticholinergic effects. |
| 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. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to trihexyphenidyl or any component","Narrow-angle glaucoma","Obstructive gastrointestinal disorders (e.g., pyloric stenosis, paralytic ileus)","Myasthenia gravis","Severe ulcerative colitis or toxic megacolon"]
| 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."] |
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| 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. |