Clozapine-induced myopathy

The induction of a myopathy is an uncommon form of the side-effects of the antipsychotic drug clozapine and largely unrecognised. We report on a 70-year old male patient who had been treated with 25 mg clozapine daily for 3 years and who presented with a 2-year history of progressive proximal muscle weakness. Blood level of creatine kinase was elevated. Withdrawal of clozapine resulted in rapid improvement of muscle strength after 14 days and prompt normalisation of enzyme levels.