KEMADRIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for KEMADRIN (KEMADRIN).
Centrally acting anticholinergic agent that blocks muscarinic receptors in the basal ganglia, reducing cholinergic overactivity and restoring dopamine-acetylcholine balance.
| Metabolism | Primarily metabolized by hepatic microsomal enzymes; metabolites are excreted in urine. |
| Excretion | Primarily renal as unchanged drug and metabolites (approximately 50% unchanged); minor biliary/fecal elimination (<10%). |
| Half-life | 6-10 hours in adults (terminal elimination half-life); may be prolonged in elderly or renal impairment. |
| Protein binding | ~90%, primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 4-8 L/kg; indicates extensive tissue distribution (high lipophilicity). |
| Bioavailability | Oral: ~80% with first-pass metabolism reducing systemic exposure. |
| Onset of Action | Oral: 1 hour; IV: immediate (within minutes). |
| Duration of Action | Oral: 6-12 hours; IV: 2-4 hours (dose-dependent efficacy in extrapyramidal symptoms). |
| Action Class | Anticholinergic- centrally acting |
| Brand Substitutes | Trodin 5mg Tablet, Ocyl 5mg Tablet, Prolid 5mg Tablet, Prodine 5mg Tablet, Dine 5mg Tablet |
2.5 mg orally three times daily, increased gradually to 5 mg three to four times daily if necessary; maximum 15-20 mg daily.
| Dosage form | TABLET |
| Renal impairment | GFR >50 mL/min: no adjustment. GFR 10-50 mL/min: administer every 6 hours. GFR <10 mL/min: avoid use or administer every 12 hours. |
| Liver impairment | Contraindicated in severe hepatic impairment. In mild to moderate (Child-Pugh A or B): use with caution, reduce dose or extend dosing interval. |
| Pediatric use | Not established. Safety and efficacy in children under 12 years have not been determined. |
| Geriatric use | Initiate at low end of dosing range (2.5 mg once or twice daily); increase slowly. Monitor for confusion, urinary retention, constipation. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for KEMADRIN (KEMADRIN).
| Breastfeeding | Excretion into breast milk is unknown; M/P ratio not established. Due to potential anticholinergic effects (e.g., drowsiness, gastrointestinal disturbances) in the infant, avoid use during breastfeeding or use with caution. Monitor infant for anticholinergic side effects. |
| Teratogenic Risk | Procyclidine (Kemadrin) is Pregnancy Category C. Animal studies are insufficient; no adequate human studies. First trimester: Avoid unless benefit outweighs risk; potential anticholinergic effects may cause fetal tachycardia. Second and third trimesters: Use with caution; neonatal anticholinergic effects (e.g., ileus, respiratory depression) reported near term. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Known hypersensitivity to trihexyphenidyl","Narrow-angle glaucoma","Obstructive gastrointestinal disorders","Myasthenia gravis","Severe prostatic hypertrophy","Megaesophagus or esophageal achalasia"]
| Precautions | ["May cause anticholinergic effects: confusion, hallucinations, urinary retention, constipation, blurred vision, heat stroke in hot weather","Use with caution in elderly patients due to CNS effects","Tardive dyskinesia: avoid abrupt withdrawal of antipsychotics when used for extrapyramidal symptoms","May exacerbate glaucoma, myasthenia gravis, gastrointestinal obstruction, and prostatic hypertrophy"] |
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| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and anticholinergic effects (dry mouth, blurred vision, urinary retention). Fetal monitoring: assess fetal heart rate and growth parameters. Neonatal monitoring for anticholinergic withdrawal (irritability, hyperactivity) if used near term. |
| Fertility Effects | Procyclidine may impair fertility in both males and females due to anticholinergic effects on ejaculation (decreased seminal volume) and possible menstrual irregularities. Decreased libido and erectile dysfunction reported. Effects are reversible upon discontinuation. |