Effectiveness of the Extended Release Formulation of Quetiapine As Monotherapy for the Treatment of Acute Bipolar Depression

Background: To evaluate the effectiveness of quetiapine extended release once daily in bipolar depression.

Methods: Double-blind, placebo-controlled study in acutely depressed adults with bipolar I or II disorder, with or without rapid cycling. Patients were randomized to 8 weeks of quetiapine extended release (XR) 300 mg daily monotherapy or placebo. The primary outcome measure was change from baseline to Week 8 in MADRS total score.

Results: Quetiapine XR 300 mg once daily (N=133) showed significantly greater improvement in depressive symptoms compared with placebo (N=137) from Week 1 (p<0.001) through to Week 8 (p<0.001). Mean change in MADRS total score at Week 8 was -17.4 in the quetiapine XR group and -11.9 in the placebo group (p<0.001). Response (>or=50 reduction in MADRS total score) and remission (MADRS total score<or=12) rates at Week 8 were significantly higher with quetiapine XR (p<0.001) compared with placebo (p<0.05). Quetiapine XR improved core symptoms of depression. The most common adverse events associated with quetiapine XR were dry mouth, somnolence, and sedation. Greater weight gain was observed in patients on quetiapine XR relative to placebo.

Limitations: Fewer patients with bipolar II disorder included, only one fixed dose tested and the lack of an active comparator.

Conclusions: Quetiapine XR (300 mg) once daily monotherapy was significantly more effective than placebo for treating episodes of depression in bipolar I disorder, throughout the 8-week study, with significance observed as early as Day 7. Adverse events were consistent with the known effects of quetiapine.