Antimuscarinic antiparkinsonian drugs

Antimuscarinic drugs can be useful in drug-induced parkinsonism. This family of drugs are generally not used in idiopathic Parkinson’s disease since they are less effective than dopaminergic drugs and are associated with cognitive impairment.

Orphenadrine, procyclidine and trihexyphenidyl (all administered as their hydrochloride salts) reduce the symptoms of parkinsonism induced by antipsychotic drugs. Procyclidine can be administered parenterally as an emergency treatment for drug-induced dystonia.

In idiopathic Parkinson’s disease, antimuscarinic drugs reduce tremor and rigidity but have little effect on bradykinesia. They may be useful in reducing sialorrhoea (hypersalivation).