Abstract: AIM: To compare the efficacy and safety between quetiapine and clozapine. METHODS: There were 85 patients with first on-set schizophrenia in this study, 43 patients treated with quetiapine 425 ± 56 mg·d-1 and 42 patients treated with clozapine 350 ± 73 mg·d-1.The study lasted for 8 wk.The Positive and Negative Symptom Scale (PANSS) and Treatment Emergent Symptom Scale (TESS) were used to evaluate therapeutic and side effects. RESULTS: The PANSS scores in both groups decreased significantly after treatment with those two drugs(P <0.05 or P <0.01).The rates of improvement were similar in quetiapine group and in clozapine group (88.4 % vs 83.8 %).The efficient dosages ranged from 375 to 600 mg·d-1 for quetiapine and from 300 to 475 mg·d-1 for clozapine.TESS showed quetiapine had fewer side effects than clozapine. CONCLUSION: Quetiapine has similar efficacy and the time before effect to clozapine in the treatment of schizophrenic with fewer side effects than clozapine.

Key words: quetiapine, clozapine, schizophrenia, efficacy