Olanzapine versus haloperidol in the treatment of patients with chronic schizophrenia: Results of the Japan multicenter, double‐blind olanzapine trial

This randomized double-blind trial was conducted to test the efficacy and safety of olanzapine in Japanese patients with schizophrenia. Importantly, this study also represents the first large clinical trial of olanzapine conducted in an Asian population. Patients (n = 182) were randomly assigned to treatment with olanzapine or haloperidol over a period of 8 weeks. The primary analyses included: (i) a test of non-inferiority of olanzapine compared with haloperidol in efficacy using the Final Global Improvement Rating (FGIR); and (ii) comparison between the treatment groups in extrapyramidal symptom severity using the Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). Olanzapine was comparable to haloperidol in efficacy in treating positive symptoms and significantly superior in treating negative symptoms. Extrapyramidal symptom severity was significantly improved for olanzapine-treated patients versus haloperidol-treated patients. Olanzapine was shown to be more effective and better tolerated than haloperidol in the treatment of Japanese patients suffering from chronic schizophrenia.