Extended-release quetiapine fumarate (quetiapine XR) as adjunctive therapy in major depressive disorder (MDD) in patients with an inadequate response to ongoing antidepressant treatment: a multicentre, randomized, double-blind, placebo-controlled study

This study evaluated once-daily extended-release quetiapine fumarate (quetiapine XR) as adjunctive therapy in patients with major depressive disorder (MDD) with inadequate response to ongoing antidepressant treatment. In this 8-wk (6-wk active treatment/2-wk post-treatment drug-discontinuation/follow-up), multicentre, double-blind, placebo-controlled, Phase III study, 446 patients were randomized to quetiapine XR 150 mg/d, 300 mg/d, or placebo adjunct to ongoing antidepressant treatment. The primary endpoint was the change from randomization to week 6 in Montgomery-Asberg Depression Rating Scale (MADRS) total score. At week 6, MADRS total scores significantly improved with quetiapine XR 300 mg/d vs. placebo (-14.7 vs. -11.7, p or = 50% total score reduction) 58.9% vs. 46.2%, p10%) with quetiapine XR were dry mouth, somnolence, sedation, dizziness, constipation, nausea, insomnia, headache, and fatigue. In this study, quetiapine XR 300 mg/d as adjunctive therapy in patients with MDD with an inadequate response to ongoing antidepressant treatment was effective at week 6. However, the difference from placebo for quetiapine XR 150 mg/d at week 6 was not statistically significant. Both doses studied (150 and 300 mg/d) were effective at week 1 and generally well tolerated.