Delirium secondary to anticholinergics

Abstract

In conjunction with BMJ Case Reports , DTB will feature occasional drug-related cases that are likely to be of interest to readers. These will include cases that involve recently marketed drugs for which there is limited knowledge of adverse effects and cases that highlight unusual reactions to drugs that have been marketed for several years. We present a case of a young man who developed sudden deterioration in his physical and mental state whilst being treated as an inpatient for substance-induced psychosis. This deterioration was manifested by sudden disorientation, change in behaviour and visual hallucinations. It was only after excluding other potential causes that this presentation was attributed to the regular administration of procyclidine that was being used to counteract the extrapyramidal side effects from antipsychotics. The patient showed a dramatic improvement on stopping procyclidine. This case highlights the importance of awareness of rare adverse drug reactions and the resultant distressing effect for the patient himself. Antipsychotics are the mainstay of treatment of psychosis. They are well known for their extrapyramidal side effects (EPSEs) that greatly impact a patient’s well-being, including stiffness, tremor, difficulty eating and writing. Procyclidine is commonly prescribed to alleviate EPSEs. It does so by inhibiting the action of acetylcholine at the muscarinic receptor, hence minimising its excitatory effects.1 Reported side effects of procyclidine include most commonly drowsiness, dizziness, constipation, flushing, nausea, nervousness, blurred vision and dry mouth. Rarely, it is reported to cause abdominal pain, difficulty swallowing, urinary retention, weakness, chest pain, fainting, fever, tachycardia, arrhythmias, change in mental state (such as confusion, hallucinations, memory problems), mydriasis and visual changes.1 2 Being an anticholinergic, anticholinergic delirium is a possible, although rare, adverse effect of procyclidine. Following the use of Adverse Drug Reaction Probability Scale,3 this case report illustrates a probable procyclidine-induced delirium in …