Evidence for the Effectiveness of Olanzapine Among Patients Nonresponsive and/or Intolerant to Risperidone

Background: This multicenter, open-label study evaluated the efficacy and safety of olanzapine in patients with schizophrenia who had been nonresponsive or intolerant to a course of risperidone (mean duration of risperidone treatment = 46.3 days). Method: A total of 34 patients with DSM-III-R and ICD-9 schizophrenia entered this trial. Twenty-five patients were nonresponsive to previous risperidone treatment, 6 patients were intolerant to the risperidone treatment, and 3 patients listed both reasons for discontinuation of risperidone. Patients were treated across a dose range of 5 to 25mg/day of olanzapine. The primary efficacy variable was baseline to endpoint change in Positive and Negative Syndrome Scale (PANSS) score. Safety was assessed using the Clinical Global Impressions- Severity of Illness scale. Results: Improvement from baseline PANSS score (mean ± SD PANSS score = 119.4 ± 26.9) was evident at the week-6 midpoint (-22.2 ± 19.5) and at the week-14 endpoint (-28.7 ± 22.3). On average, severity ratings were reduced from baseline by 25% after 14 weeks of olanzapine therapy. Twenty olanzapine-treated patients (58.8%) achieved the a priori-defined response criterion of = 20% reduction in PANSS total score. Among patients who met the response criterion, 50% (10/20) had done so by the fourth week. These clinical improvements occurred across a broad range of symptom domains and included reductions in PANSS positive, negative, general psychopathology, and mood subscores. No statistically significant differences were found on any efficacy measure at any visit between the patients who were nonresponsive to risperidone compared with those who were intolerant to risperidone. Olanzapine was well tolerated, with no subject discontinuing early owing to an intolerable adverse event that could be conclusively linked to olanzapine. Conclusion: The results of this open-label study suggest that olanzapine may be an effective alternative for schizophrenic patients who are nonresponsive and/or intolerant to risperidone treatment. Moreover, the results underscore the differential pharmacology that exists among the newer antipsychotic agents.