Comparison of quetiapine and risperidone in the treatment of schizophrenia : A randomized, double-blind, flexible-dose, 8-week study

Objective: To compare the efficacy and tolerability of quetiapine and risperidone in the treatment of schizophrenia. Method: In this 8-week, double-blind, multicenter, flexible-dose study, patients with schizophrenia (DSM-IV diagnosis) were randomly assigned to quetiapine (200-800 mg/day) or risperidone (2-8 mg/day). The primary hypothesis was that quetiapine was not inferior to risperidone. The primary efficacy measure was change from baseline in Positive and Negative Syndrome Scale (PANSS) total scores; secondary outcomes included response rate (≥ 40% reduction in PANSS scores), Clinical Global Impression-Change (CGI-C), and cognitive and social functioning. Tolerability assessments included treatment-emergent adverse events and changes in weight, glucose, and prolactin. Patients were recruited from June 2001 to September 2002. Results: Patients (N = 673) were randomly assigned to quetiapine (N = 338, mean dose = 525 mg/day) or risperidone (N = 335, mean dose = 5.2 mg/day). The primary analysis demonstrated noninferiority between treatments (p <.05). Improvements with both treatments were comparable on PANSS total, negative, and general psychopathology subscales. Risperidone-treated patients had a significantly (p =.03) greater improvement in PANSS positive subscale score among all patients, but not among completers. Improvements in PANSS response rates, CGI-C, and cognitive function were similar between treatment groups. Changes in serum glucose and weight were minimal and comparable. The rate of extrapyramidal symptom (EPS)-related adverse events was significantly higher with risperidone (22%) than quetiapine (13%; p <.01). Somnolence was more common with quetiapine (26%) than risperidone (20%; p =.04). Prolactin levels increased with risperidone (+35.5 ng/mL), but decreased with quetiapine (-11.5 ng/mL; p<.001). Conclusions: Quetiapine and risperidone had broadly comparable clinical efficacy. Both agents improved cognitive and social functioning, and neither had a clinically significant effect on weight or glucose. Somnolence was more common with quetiapine; EPS and elevated prolactin rates were significantly higher with risperidone.