- Safety and efficacy of long-term olanzapine treatment in Japanese patients with bipolar depression were assessed.An integrated analysis of data from two studies was performed in olanzapine-treated patients (n = 165) with bipolar depression. Study 1 was a 6-week, double-blind, global study. Patients were randomly assigned to olanzapine or placebo followed by 18 weeks of open-label treatment. Study 2 was an open-label extension of Study 1 involving only Japanese patients. Patients assigned to Pre-olanzapine and Pre-placebo in Study 1 were treated for 24 weeks (total olanzapine exposure 42 or 48 weeks) and newly recruited patients (New-olanzapine) were treated for 48 weeks. Safety outcomes included treatment-emergent adverse events and changes in metabolic parameters. Efficacy outcome was assessed with Montgomery-Åsberg Depression Rating Scale score.Forty-three percent of patients completed the 42- or 48-week olanzapine treatment period. The most common treatment-emergent adverse event was weight increased (47.9%). Significant increases were seen in weight (3.5 kg), and in fasting glucose (3.5 mg/dL), fasting total cholesterol (8.1 mg/dL), and fasting triglycerides (35.1 mg/dL). Remission rates (Montgomery-Åsberg Depression Rating Scale total score ≤12 at any time) were 79.8% for the Pre-olanzapine group, 90.2% for the Pre-placebo group, and 85.0% for the New-olanzapine group. No patents developed mania during treatment.Long-term use of olanzapine in a Japanese population with bipolar depression is associated with increases in weight and fasting metabolic measures, and also with improved depressive symptoms with avoidance of mania. Clinicians must carefully consider the benefits and risks of long-term therapy with olanzapine.© 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.