Randomized, double-blind, controlled trial of risperidone versus clozapine in patients with chronic schizophrenia.

This study compares the antipsychotic efficacy and the tolerability of risperidone and clozapine in patients with schizophrenia. Patients were randomized to double-blind treatment with risperidone, 4 mg (N = 20), risperidone, 8 mg (N = 19), or clozapine, 400 mg (N = 20), daily for 28 days. Efficacy was assessed by improvement of psychotic symptoms, measured on the Brief Psychiatric Rating Scale, and Clinical Global Impression. The tolerability was assessed by the Simpson and Angus scale for extrapyramidal side effects (EPS), the Association for Methodology and Documentation in Psychiatry (AMDP) scale for somatic side effects, spontaneous reports of adverse events, clinical laboratory assessments, and vital signs. All treatments reduced psychotic symptoms. The global tolerability was significantly better in the risperidone than in the clozapine-treated patients (p < 0.01). There were no differences between treatments on the AMDP scale. The most frequent spontaneously reported adverse effects were dizziness, fatigue, accommodation disturbance, and EPS in all treatment groups and increased salivation, mainly in the clozapine-treated patients. Although there were no changes in vital signs during risperidone treatment, clozapine was associated with a mean reduction in heart rate of 10 beats/minute. Risperidone tolerability at endpoint was classified as "very good" by 60 and 47% of patients treated with risperidone, 4 and 8 mg daily, respectively; the corresponding figure in clozapine-treated patients was 30%. The results suggest that risperidone is at least as effective as an antipsychotic as clozapine, providing a valuable new approach for the treatment of schizophrenia.