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Antimuscarinic (Parkinsonian)

Orphenadrine hydrochloride

Brand names: Disipal, Biorphen

Orphenadrine hydrochloride is an antimuscarinic agent used to relieve the symptoms of Parkinson's disease, particularly tremor and rigidity, and drug-induced parkinsonism.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It blocks central muscarinic acetylcholine receptors, helping to restore the dopamine-acetylcholine balance within the basal ganglia.

Prescribing in practice

  • Marked antimuscarinic effects make it hazardous in older adults and in those with glaucoma, prostatic enlargement or urinary retention, and abrupt withdrawal should be avoided.
  • Use cautiously alongside other anticholinergic, sedating, or serotonergic drugs because of additive adverse effects.
  • It can impair cognition and worsen confusion, so it is generally avoided where dementia or significant cognitive impairment is present.

Monitoring

Monitor for antimuscarinic effects such as dry mouth, blurred vision, constipation, urinary retention and confusion, especially in older patients.

Counselling the patient

  • This medicine may cause dry mouth, blurred vision, constipation or difficulty passing urine.
  • It can affect alertness, so take care with driving and avoid stopping it suddenly without advice.

Evidence & guidelines

Antimuscarinics like orphenadrine are long-established for parkinsonian tremor; NICE advises caution given limited evidence and a poor tolerability profile in older people.

Reference: NICE NG71; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways