The risks and benefits of clozapine versus chlorpromazine.

Clozapine is an atypical antipsychotic drug with reduced risk of unwanted neurological effects in comparison with other drugs. In this multicenter study, 151 hospitalized schizophrenic patients were randomly assigned to treatment under double-blind conditions to assess the antipsychotic efficacy and safety of clozapine versus chlorpromazine. All patients exhibited tardive dyskinesia or other extrapyramidal side effects associated with at least two prior neuroleptics. Eleven patients were dropped from treatment due to extrapyramidal symptoms while being treated with chlorpromazine; only one clozapine patient's treatment was terminated for this reason. Clozapine patients exhibited clinical improvement superior to that of chlorpromazine patients as assessed by the Brief Psychiatric Rating and Clinical Global Impression scales. These results suggest that clozapine is well tolerated and may be therapeutically superior to chlorpromazine in treating psychotic behavior. Agranulocytosis potential can be minimized by frequent white blood cell counts and removing nonresponding patients from treatment prior to the peak risk period (months 2 through 6).