Efficacy of olanzapine monotherapy for treatment of bipolar I depression: a randomized, double-blind, placebo controlled study

Depression symptoms are now recognized to be the predominant cause of disability for bipolar disorder (BD) patients. The treatment strategies for the depressed phase of BD remain more anecdotal than data-based. Olanzapine has been investigated as an alternative to antidepressants and a mood stabilizer for acute bipolar depression. The purpose of this study was to assess the efficacy of olanzapine monotherapy for bipolar I depression. Sixty-eight patients with bipolar I depression were randomly assigned to treatment with olanzapine (mean final dose 14.4 mg/day) (n = 34) or placebo (n = 34) in a double-blind parallel-group study design. Planned assessments included Montgomery-Asberg Depression Rating Scale (MADRS), Young Mania Rating Scale (YMRS), Clinical Global Impressions-Severity of Illness scale (CGI-S), Clinical Global Impressions-Improvement scale (CGI-I), Hamilton Depression scale (HAMD), Hamilton Anxiety scale (HAMA), and Treatment Emergent Symptom Scale (TESS). Of the 68 patients who were randomly assigned, 57 (83.8 %) completed treatments. Improvements in MADRS total score, CGI-S, CGI-I, and HAMD in the olanzapine group were significantly greater relative to those in the placebo group during the 8-week follow-up period (p < 0.001, p = 0.0017, p = 0.007, and p < 0.001, respectively). Rates of categorical treatment response and remission in the olanzapine group (50.0 % and 35.3 %, respectively) were significantly higher than those in the placebo group (20.6 %, p = 0.011 and 11.8 %, p = 0.022, respectively). At the 8-week treatment, the mean weight and the total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels increased significantly in the olanzapine group (p = 0.037, p = 0.029, p = 0.030, and p = 0.028, respectively). Olanzapine is effective in the treatment of bipolar I depression but is associated with significant metabolic side effects.