Switching to Olanzapine From Previous Antipsychotics: A Regional Collaborative Multicenter Trial Assessing 2 Switching Techniques in Asia Pacific

Background:This open-label, multicenter, randomized study compared the efficacy and safety of switching moderately ill Asian patients with schizophreniafrom their current regimen of antipsychotic medication to the atypical antipsychotic olanzapine using either a direct switch method or a start-taper switch method.

Method: Asian inpatients and outpatients with DSM-IV schizophrenia (N = 108) currently treated with predominantly typical antipsychotics were switched to olanzapine (initial dose of 10 mg/day) for 6 weeks. Patients were randomly assigned to 1 of 2 groups: the direct switch group (N = 54) received only olanzapine, while the start-taper switch group (N = 54) received olanzapine and their usual antipsychotic in decreasing doses for the first 2 weeks. A successful switch was defined as completing 6 weeks of therapy without worsening of symptoms (Clinical Global Impressions-Severity of Illness scale [CGI-S]) or extrapyramidal side effects (Simpson-Angus Scale). Overall efficacy was assessed using the Positive and Negative Syndrome Scale (PANSS), and safety was assessed by recording adverse events and measuring vital signs.

Results:Statistically significant (p < .001) improvements from baseline to endpoint occurred in both switch groups in the CGI-S score and the PANSS total score and subscores. However, no significant differences were observed between the switch groups for any efficacy measure. Both techniques had comparable rates of successful switching (direct switch, 74.1% vs. start-taper switch, 67.9%).The frequency of treatment-emergent adverse events was similar between switch groups with no clinically significant differences in any laboratory value or vital sign. Weight gain occurred in both switch groups (p < .001), but the groups were not statistically different from each other. Both switch groups showed statistically significant (p < .01) improvements from baseline to endpoint on the Simpson-Angus Scale and Barnes Akathisia Scale.

Conclusion:Moderately ill Asian patients with schizophrenia may experience a decrease in symptom severity and improvement in extrapyramidal symptoms when switched from their current medication to olanzapine therapy.