4.9.2 Antimuscarinic drugs used in parkinsonism

ChoiceDrugDosage
1st choiceProcyclidine tablets 5mgDose:
See BNF - seek specialist advice
Or
Trihexyphenidyl hydrochloride tablets 2mg, 5mgDose:
See BNF - seek specialist advice

Prescribing Notes

  • Antimuscarinics are sometimes used as a first line therapy in young onset Parkinson’s Disease under specialist supervision, but not generally recommended in older patients – see cautions.
  • Antimuscarinics may occasionally be useful in patients with tremor which is unresponsive to other drugs, on the advice of a specialist.
  • Procyclidine is mainly used in the management of drug-induced parkinsonism.
  • Tardive dyskinesia is not improved by antimuscarinic drugs and may be made worse.

Cautions

  • Antimuscarinics may cause cognitive impairment and urinary retention. They should be avoided in older patients.
  • Antimuscarinics are not generally recommended for use in Parkinson’s Disease because of toxicity in the elderly and the risk of aggravating dementia.
  • Abrupt withdrawal of antimuscarinics should be avoided.