The effects of risperidone and olanzapine on the indications for clozapine.

The effects of the availability of risperidone and olanzapine on the indications for which clozapine is prescribed (treatment-resistance, treatment-intolerance, and/or negative symptoms) were examined for 252 patients with schizophrenia who began treatment at our hospital between June 1990 and June 1997. There were no statistical differences in the indications for clozapine treatment before and after the availability of either risperidone or olanzapine. Furthermore, there were no significant differences in the frequencies of the indications in subgroups of patients who had previously received a trial with risperidone or olanzapine, as compared with the remaining patients. The indications for clozapine appear to have been unaffected by the advent of risperidone and olanzapine; however, we noted a decrease in the absolute number of patients starting clozapine after risperidone became available. More recently, the majority of patients referred for treatment with clozapine had received previous trials with risperidone or olanzapine.