A 24-Week Open-Label Extension Study of Olanzapine-Fluoxetine Combination and Olanzapine Monotherapy in the Treatment of Bipolar Depression

Abstract

Olanzapine-fluoxetine combination has shown efficacy in the acute treatment of depressive episodes in patients with bipolar I disorder. The present analyses examined the efficacy and safety of longer term treatment with olanzapine-fluoxetine combination or olanzapine monotherapy in a 6-month open-label extension study. 376 patients with DSM-IV bipolar I disorder, depressed, who completed an acute trial entered the open-label study and received 1 week of olanzapine monotherapy (5-20 mg/day). At all subsequent visits, patients could choose between olanzapine monotherapy or olanzapine-fluoxetine combination (6/25, 6/50, or 12/50 mg/day). Three treatment groups were defined retrospectively according to the medication course taken from week 1: olanzapine, olanzapine-fluoxetine combination, or switched. The efficacy measures were the Montgomery-Asberg Depression Rating Scale (MADRS), Clinical Global Impressions-Bipolar Version, and Young Mania Rating Scale. The study was conducted from July 2000 to May 2002. Among patients who started in remission, MADRS total scores did not change significantly from baseline to endpoint in the olanzapine-fluoxetine combination (0.8) or olanzapine (0.3) groups, but increased slightly in the switched (2.3, p = .02) group. For patients who started in nonremission, MADRS total scores decreased significantly in all groups (olanzapine-fluoxetine combination: -5.7, p = .001; olanzapine: -11.6, p = .004; switched: -6.4, p = .015). The majority of patients who entered the study in nonremission achieved remission (MADRS total score < or = 12) during the trial (olanzapine-fluoxetine combination: 66.7%, olanzapine: 64.7%, switched: 62.5%). The overall rate of depressive relapse was 27.4%, and the overall incidence of mania emergence was 5.9%. The present findings suggest that long-term treatment with olanzapine-fluoxetine combination may be a useful option for the management of depressive symptoms and carries a low risk of mania emergence.