Objective: To evaluate the safety and tolerability of long-term treatment with olanzapine versus risperidone in schizophrenic outpatients with prominent negative symptoms.
Methods: This was a multi-center, randomised, open-label, parallel, dose-flexible, 1 year study of outpatients with schizophrenia (DSM-IV criteria) with prominent negative symptoms (SANS Global score > or =10). Safety was evaluated by recording treatment-emergent adverse events, vital signs, body weight and, when available, laboratory parameters. Extrapyramidal symptoms (EPS) were evaluated by a questionnaire based on the UKU scale, and sexual dysfunction by the Psychotropic-Related Sexual Dysfunction Questionnaire (PRSexDQ).
Results: The mean (+/- SD) modal dose throughout the study was 12.3 (+/- 6.3) mg/day for olanzapine and 5.2 (+/- 2.5) mg/day for risperidone. EPS were significantly more frequent in the risperidone-treated patients 50.4 % versus 28.9 % for olanzapine (p = 0.0006). Olanzapine patients showed significantly greater reductions (improvement) from baseline in the PRSexDQ score (p=0.0292) and risperidone patients reported significantly more sexual adverse events (21.1% versus 7.3% for olanzapine; p=0.0018). Mean body weight gain was not significantly different at endpoint (3.5 kg gained with olanzapine versus 1.9 kg gained with risperidone; p=0.3522), but the proportion of patients showing a body weight increase > or =7% was higher among the olanzapine-treated patients (37.8% versus 16.8%; p=0.0012).
Conclusions: Significantly less treatment-emergent extrapyramidal and sexual adverse events were observed in patients treated with olanzapine compared to those treated with risperidone. Mean body weight increases with both drugs were not significantly different after one year. Olanzapine patients presented a significantly higher incidence of clinically important body weight increase when compared with patients treated with risperidone.