Branded versus generic clozapine for treatment of schizophrenia

OBJECTIVE: To report clinical findings resulting from a switch from branded to generic clozapine. METHODS: Twenty patients diagnosed with schizophrenia were followed in this naturalistic outpatient study. The Positive and Negative Syndrome Scale (PANSS), Beck Anxiety Inventory (BAI), Abnormal Involuntary Movement Scale, and the Movement Disorder Assessment were used to assess differences in the clinical status of patients before and after switching from Clozaril to generic clozapine (Mylan Pharmaceuticals). Results were analyzed by means of the paired t-test and by calculation of the percent change in mean scores. A clinically significant change as measured by the PANSS was defined as a +/-20% change in mean scores at final evaluation. The design was open-label and non-blinded. RESULTS: At the final evaluation, the t-test revealed no significant differences between branded and generic clozapine for the total PANSS, the positive symptom, negative symptom, and the general psychopathology subscales of the PANSS, and the BAI. There were no clinically significant changes for any measure. CONCLUSIONS: In this small group of patients with schizophrenia, no deterioration in clinical status in several domains was noted after changing from branded to generic clozapine. This finding is consistent with pharmacologic data suggesting bioequivalence of the 2 products. Results, however, must be interpreted cautiously due to the lack of optimal study controls and small sample size.