Open study evaluating the onset of antipsychotic action of olanzapine in the treatment of patients with schizophrenia, schizophreniform or schizo-affective disorder

OBJECTIVE This 6-week, open-label study with olanzapine was designed to determine the onset of antipsychotic action of a 10-mg/day starting dose of olanzapine, continued as a fixed dose for at least 4 weeks. METHODS A total of 306 patients experiencing an acute exacerbation of schizophrenia were prospectively followed-up. Response was defined as a 20% improvement on the Positive And Negative Syndrome Scale (PANSS) positive score, sustained until week 6. Onset of action was defined as the time point at which a 20% improvement in positive symptoms occurred and was maintained to week 6. RESULTS Significant improvements from baseline were observed throughout the study with respect to PANSS positive and PANSS total score (P