Comparison of quetiapine and risperidone in Chinese Han patients with schizophrenia: results of a single-blind, randomized study

Objective: To evaluate the efficacy and safety of 750 mg/day quetiapine fumarate (Seroquel*) in the treatment of Chinese Han patients with schizophrenia. Methods: In this 6-week, multicenter, randomized, rater single-blind study, a total of 119 patients with schizophrenia were randomly assigned to quetiapine (n=60, 750 mg/day) or risperidone (n=59, 4 mg/day). The efficacy was assessed by the Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression-Change (CGI-C) and the Calgary Depression Scale for Schizophrenia (CDSS). Safety and tolerability assessments included treatment-emergent adverse events, laboratory tests and electrocardiograms. Results: The primary analysis demonstrated no significant difference between treatment in the two groups (quetiapine vs. risperidone: 31.9 +/- 17.5 vs. 33.3 +/- 17.3; P=0.668). Improvements with both treatments were comparable for total PANSS, positive and negative subscores, general psychopathology subscales, and excitement and attack symptoms. Improvements in CGI-S were similar between treatment groups (P=0.046). A more favorable trend was detected for quetiapine than risperidone in the reduction of CDSS scores from baseline, especially at week 1 (1.1 +/- 2.2 vs. 0.3 +/- 2.1, P<0.050). The rate of extrapyramidal symptom (EPS) and hyperprolactinemia-related adverse events was significantly lower in the quetiapine group than the risperidone group (13.3% vs. 43.3%, P<0.001). Dizziness and somnolence were more common in the quetiapine group than the risperidone group. Conclusion: Quetiapine fumarate (750 mg/day) has broad clinical efficacy comparable to 4 mg/day risperidone. Dizziness was common in the quetiapine group (P=0.029), but the rate of somnolence was similar between the two groups (P=0.114). EPS and hyperprolactinemia rates were significantly higher with risperidone (P<0.001). Key limitations of this study include small sample size, short treatment periods, and no increase to 6 mg/day for risperidone because of its safety profile.