Subjective muscle weakness and hypotonia during clozapine treatment.

Four cases of patients who described an unpleasant subjective experience of weakness and reduced muscle tone during treatment with clozapine are presented. An exacerbation of muscular dystrophy during clozapine treatment is also described. It is hypothesized that these adverse effects are related to the muscle relaxant properties of clozapine. The differential diagnosis of sedation, fatigue, asthenia, and reduced muscle tone is discussed.