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Anticholinergic (antimuscarinic, antiparkinsonian) Pregnancy: Avoid — limited data; theoretical fetal harm (intestinal ileus reported neonatally).

Benzatropine mesilate

Brand names: Cogentin

Adult dose

Dose: Acute drug-induced dystonia: 1–2 mg IM or IV, repeat after 30 min if needed. Drug-induced extrapyramidal symptoms (chronic): 0.5–1 mg PO ON; titrate to 1–4 mg/day in 1–2 divided doses; max 6 mg/day. Parkinson's tremor (rare indication now): 0.5 mg ON, titrate.
Route: Oral / IM / IV
Frequency: Once or twice daily
Max: 6 mg/day
Used mainly for ACUTE neuroleptic-induced dystonic reactions and drug-induced parkinsonism. NOT for tardive dyskinesia (may worsen). Avoid in elderly where possible.

Clinical pearls

  • First-line for acute drug-induced dystonic reaction (e.g., metoclopramide, prochlorperazine, haloperidol) — IV onset within 5–15 min; works within 30 min IM.
  • Procyclidine (5–10 mg IM/IV) is the more commonly stocked UK alternative for acute dystonia — same indication and class.
  • Avoid in elderly with antipsychotic-induced parkinsonism — switch to lower-potency antipsychotic or aripiprazole instead.
  • Anticholinergic burden — review periodically; not for chronic use beyond 3 months in most cases.
  • Patients on long-term antipsychotics often do not need long-term anticholinergic — taper after 3 months and reassess.

Contraindications

  • Narrow-angle glaucoma
  • Bowel obstruction, paralytic ileus
  • Toxic megacolon
  • Myasthenia gravis
  • Children <3 years
  • Severe BPH / urinary retention
  • Tardive dyskinesia (worsens)

Side effects

  • Anticholinergic: dry mouth, blurred vision, urinary retention, constipation
  • Confusion, hallucinations, agitation (esp. elderly)
  • Tachycardia
  • Heat intolerance, hyperthermia (anhidrosis)
  • Memory impairment
  • Glaucoma precipitation (narrow-angle)

Interactions

  • Other anticholinergics (TCAs, antihistamines, oxybutynin): additive toxicity
  • Antipsychotics: may reduce efficacy at high anticholinergic doses
  • Donepezil/rivastigmine: pharmacological antagonism — avoid
  • Alcohol/CNS depressants: ↑ sedation

Monitoring

  • Anticholinergic side effects
  • Cognitive status (especially elderly)

Reference: BNF 90; SmPC Cogentin; Maudsley Prescribing Guidelines 14th ed.; NICE CG178 Psychosis & Schizophrenia. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways