Comparison between risperidone, olanzapine, and clozapine in the management of chronic schizophrenia: a naturalistic prospective 12-week observational study

Risperidone, olanzapine, and clozapine are three atypical antipsychotic medications commonly used in the management of chronic schizophrenia. While they offer advantages with regard to clinical efficacy and side‐effect profile, few studies have compared them in a naturalistic prospective observational manner. This study therefore investigated their comparative efficacy over 12 weeks including illness characteristics and adverse effects. One hundred thirty‐one patients (76 M, 55 F) with DSMI‐V schizophrenia or schizoaffective disorder were treated with risperidone (n = 38), olanzapine (n = 38), or clozapine (n = 55). All patients showed a significant decrease of Positive and Negative Syndrome Scale (PANSS)‐positive scores. Decreases in tardive dyskinesia and impulsivity scores were noted with clozapine and olanzapine, respectively. No differences between the medications were noted on depression, anxiety, EPS, or overt aggression scores. Olanzapine and clozapine appeared to be more effective in females. Males showed a decreased sexual performance irrespective of the medication and those treated with risperidone and clozapine showed greater proportional reduction of overt aggression. Clozapine‐treated patients showed significant increased weight, increased glucose levels, and lowered sexual performance. Risperidone patients tended to exhibit reduced cholesterol levels. Higher creatine kinase (CK) levels were noted in risperidone‐treated patients. While cautious given the nature of the study design, results suggest differences in the response to various atypical antipsychotic medications regarding efficacy and side‐effect susceptibility. Copyright © 2006 John Wiley & Sons, Ltd.