Efficacy of olanzapine monotherapy in the treatment of bipolar depression with mixed features

Background This analysis investigated the correlations between the efficacy of olanzapine monotherapy and the number of concurrent manic symptoms in patients treated for bipolar depression. Methods Pooled data from 2 placebo-controlled olanzapine studies in patients with bipolar I depression were analyzed (total 1214 patients; 690 olanzapine monotherapy patients and 524 placebo patients). Patients were categorized for mixed features by the number of concurrent manic symptoms at baseline (0, 1 or 2, and ≥3, respectively, as measured by a Young Mania Rating Scale item score ≥1). Efficacy was evaluated by change in Montgomery-Åsberg Depression Rating Scale (MADRS) total score from baseline to 6 weeks. Results Least-squares mean differences between olanzapine and placebo in the change of MADRS total scores were -3.76 (p=0.002), -3.20 (p<0.001), and -3.44 (p=0.002) for mixed features 0, 1 or 2, and ≥3, respectively. The response rates for olanzapine versus (vs.) placebo were 52.6% vs. 39.8%, 50.3% vs. 40.0%, and 42.2% vs. 33.7% for mixed features 0, 1 or 2, and ≥3, respectively. The remission rates for olanzapine vs. placebo group were 46.1% vs. 34.3%, 39.5% vs. 32.0%, and 34.8% vs. 24.1% for mixed features 0, 1 or 2, and ≥3, respectively. No significant interaction between mixed features and treatment was seen in the MADRS changes or response and remission rates. Limitations Post hoc analyses of the data from 2 previous randomized clinical studies. Conclusions Olanzapine monotherapy was shown to be effective in the treatment of bipolar depression irrespective of the presence of concurrent manic symptoms.