OBJECTIVE

The aim of this study was to compare the efficacy and tolerability of quetiapine and lithium monotherapy with that of placebo for a major depressive episode in bipolar disorder.

METHOD

802 patients with DSM-IV-defined bipolar disorder (499 bipolar I, 303 bipolar II) were randomly allocated to quetiapine 300 mg/d (n = 265), quetiapine 600 mg/d (n = 268), lithium 600 to 1800 mg/d (n = 136), or placebo (n = 133) for 8 weeks. Primary endpoint was the change in Montgomery-Asberg Depression Rating Scale (MADRS) total score. The study was conducted from August 2005 to May 2007.

RESULTS

Mean MADRS total score change from baseline at week 8 was -15.4 for quetiapine 300 mg/d, -16.1 for quetiapine 600 mg/d, -13.6 for lithium, and -11.8 for placebo (P < .001 for both quetiapine doses, P = .123 for lithium, vs placebo). Quetiapine 600 mg/d was significantly more effective than lithium in improving MADRS total score at week 8 (P = .013). Quetiapine-treated (both doses), but not lithium-treated, patients showed significant improvements (P < .05) in MADRS response and remission rates, Hamilton Depression Rating Scale (HDRS), Clinical Global Impressions-Bipolar-Severity of Illness and -Change, and Hamilton Anxiety Rating Scale (HARS) scores at week 8 versus placebo. Both quetiapine doses were more effective than lithium at week 8 on the HDRS and HARS. The most common adverse events were somnolence, dry mouth, and dizziness with quetiapine (both doses) and nausea with lithium.

CONCLUSIONS

Quetiapine (300 or 600 mg/d) was more effective than placebo for the treatment of episodes of acute depression in bipolar disorder. Lithium did not significantly differ from placebo on the main measures of efficacy. Both treatments were generally well tolerated.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00206141.