Quetiapine extended release (XR) was developed to provide convenient, once-daily dosing and rapid dose escalation when compared to the immediate-release (IR) formulation.

To review preclinical and clinical study data on the efficacy and safety of quetiapine XR in bipolar depression and major depressive disorder (MDD).

Review of published studies and presentations at scientific congresses.

Quetiapine fumarate demonstrates a broad spectrum of efficacy in psychotic and mood disorders. In pharmacologic studies, quetiapine and its major active metabolite, norquetiapine, have actions on 5-HT2A receptors and D2 receptors, considered to explain efficacy in psychosis and mania. Norquetiapine, unlike quetiapine and other atypical antipsychotics at relevant doses, has affinity for the norepinephrine transporter in-vitro and demonstrates binding in-vivo, which may contribute to antidepressant efficacy. Quetiapine XR as monotherapy (300 mg/day) was significantly more effective than placebo in a study of patients with acute bipolar depression, with onset of effect as early as 1 week. In large, placebo-controlled studies, quetiapine XR as monotherapy (50-300 mg/day), or adjunct therapy (150-300 mg/day) to antidepressants, has demonstrated efficacy against depressive and comorbid symptoms in MDD, with rapid onset of effect. The safety profile of quetiapine XR in these studies was broadly consistent with quetiapine IR. Sedation intensity during initial dose escalation was significantly lower with quetiapine XR than IR in 1 study in patients with bipolar depression.

Quetiapine XR is effective in bipolar depression and MDD and has a safety profile consistent with quetiapine IR.

By funding from AstraZeneca Pharmaceuticals LP.