Objective: To evaluate the efficacy and tolerability of once-daily extended release quetiapine fumarate (quetiapine XR) as monotherapy treatment for major depressive disorder (MDD).

Method: This 8-week (6-week active-treatment, randomized phase; 2-week posttreatment drug-discontinuation/tapering phase), multicenter, double-blind, randomized, parallel-group, placebo- and active-controlled, phase 3 study was conducted between April 2006 and May 2007. In total, 612 patients with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)-defined MDD were randomly assigned to quetiapine XR 150 mg/day or 300 mg/day, duloxetine 60 mg/day (active control), or placebo. The primary endpoint was the change from baseline to week 6 in Montgomery-Asberg Depression Rating Scale (MADRS) total score.

Results: At week 6, both doses of quetiapine XR (p

Conclusion: Quetiapine XR monotherapy (150 mg/day and 300 mg/day) is effective, with safety and tolerability consistent with the known profile of quetiapine XR, in the treatment of patients with MDD, with onset of symptom improvement demonstrated at week 1.

Trial Registration: clinicaltrials.gov Identifier: NCT00321490

J Clin Psychiatry 2009;70(4):526-539

https://doi.org/10.4088/JCP.08m04592