Quetiapine extended release: adjunctive treatment in major depressive disorder

Quetiapine extended release (XR) is a once-daily oral formulation of the atypical antipsychotic quetiapine that is available for use as adjunctive therapy in major depressive disorder (MDD). Systemic quetiapine exposure after orally administered quetiapine XR is similar to that of quetiapine immediate release at the same dosage, although quetiapine XR is absorbed more slowly and plasma concentrations are more stable over time. In two 6-week, randomized, double-blind, placebo-controlled, multinational trials in patients with MDD with an inadequate response to antidepressants, quetiapine XR 300 mg/day adjunctive to antidepressant reduced depressive symptoms significantly more than antidepressant plus placebo, according to changes in Montgomery-Åsberg Depression Rating Scale (MADRS) total scores. In one trial, adjunctive quetiapine XR 150 mg/day also led to significantly greater reductions in MADRS total scores than antidepressant plus placebo. MDD response rates were significantly higher with adjunctive quetiapine XR 300 mg/day (but not 150 mg/day) than with antidepressant plus placebo. The numbers needed to treat to achieve an additional response over antidepressant plus placebo were 11-18 and 8-9 in the quetiapine XR 150 and 300 mg/day dosage groups, respectively. Treatment-emergent adverse events were mostly of mild to moderate severity; 1% of adjunctive quetiapine XR and 1.3% of antidepressant plus placebo recipients reported serious adverse events.