Differential effect of clozapine on weight: a controlled study.

OBJECTIVE

This study examined whether clozapine induces more weight gain than haloperidol and whether weight gain is related to clinical improvement.

METHOD

The weight and symptoms of 39 outpatients with schizophrenia who were randomly assigned to double-blind treatment with either clozapine or haloperidol were assessed. The weight and symptoms of 33 of the patients who chose to take clozapine during a 1-year follow-up after the study ended were also assessed.

RESULTS

The patients treated with clozapine gained significantly more weight over baseline (7%) than the haloperidol-treated patients (1%). Weight gain was not significantly correlated with improvements in either positive or negative symptoms. Fifty-eight percent of the patients followed for 1 year gained at least 10% over their baseline weight.

CONCLUSIONS

Weight gain is an important side effect of clozapine and is unrelated to the drug's differential antipsychotic efficacy.