A randomised, placebo-controlled 52-week trial of continued quetiapine treatment in recently depressed patients with bipolar I and bipolar II disorder.

Objectives: To examine the longer-term efficacy of quetiapine monotherapy in bipolar depression in a preplanned pooling of data from the EMBOLDEN I and II studies.

Methods: Patients (N = 584) with bipolar I or II disorder (most recent episode: depressed) who achieved remission after 8 weeks of treatment with quetiapine (300 or 600 mg/day) were randomised to the same quetiapine dose or placebo for 26-52 weeks or until mood event recurrence.

Results: The risk for recurrence of a mood event was significantly lower with quetiapine than placebo (HR 0.51 (95% CI: 0.38-0.69); < 0.001). Quetiapine was associated with a lower risk for recurrence of depressive events (HR 0.43 (95% CI: 0.30-0.62); P < 0.001) but recurrence of manic/hypomanic events was not significantly reduced (HR 0.75 (95% CI: 0.45-1.24; P = 0.263). There was a lower risk of recurrence of mood events in bipolar I (HR 0.58 (95% CI: 0.41-0.82), P = 0.002) and bipolar II patients (HR 0.33 (95% CI: 0.18-0.60), P < 0.001). Discontinuation rates due to adverse events were 4.3, 4.0 and 1.7% for quetiapine 300 mg/day, 600 mg/day and placebo, respectively. Safety data, including changes in lipid and glucose parameters, were consistent with the recognized profile of quetiapine.

Conclusions: The efficacy of quetiapine monotherapy in bipolar depression is maintained during continued treatment for 26-52 weeks. Quetiapine was generally well tolerated.