Procyclidine hydrochloride

How it works

It blocks central muscarinic acetylcholine receptors, helping to correct the relative cholinergic excess in the basal ganglia that produces parkinsonian and dystonic symptoms.

Prescribing in practice

• Its antimuscarinic effects make it hazardous in glaucoma, prostatic enlargement, urinary retention and gastrointestinal obstruction, and it should not be withdrawn abruptly.
• It can impair memory and precipitate confusion, so it is used cautiously in older people and avoided where there is cognitive impairment.
• It is generally ineffective against tardive dyskinesia and may worsen it, so it should not be used for that indication.

Monitoring

Monitor for antimuscarinic effects including dry mouth, blurred vision, constipation, urinary retention and confusion, particularly in older patients.

Counselling the patient

• This medicine can cause dry mouth, blurred vision, constipation, or difficulty passing urine.
• It may affect alertness; take care driving and do not stop it suddenly without advice.
• Report any new confusion or memory problems to your team.

Evidence & guidelines

Antimuscarinics such as procyclidine are long-established for drug-induced parkinsonism and acute dystonia, with their use reflected in current prescribing references and NICE guidance.