Extended-release quetiapine fumarate (quetiapine XR) as adjunctive therapy in patients with generalized anxiety disorder and a history of inadequate treatment response: a randomized, double-blind study.

Background: For many patients with generalized anxiety disorder (GAD), first-line treatment does not lead to remission. This study investigated the efficacy and tolerability of adjunctive extended-release quetiapine fumarate (quetiapine XR) in patients with GAD and an inadequate response to selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs).

Methods: Patients were randomized to quetiapine XR or placebo adjunctive to SSRI/SNRIs in an 11-week study. The primary endpoint was change from randomization to week 8 in Hamilton Anxiety Rating Scale (HAM-A) total score. Secondary variables were HAM-A psychic/somatic clusters, response, and remission, and Clinical Global Impression–Severity of Illness (CGI-S) score.

Results: A total of 409 patients received quetiapine XR (n = 209) or placebo (n = 200). The week 8 mean change in HAM-A total score was not statistically significant for quetiapine XR (–10.74; P = .079) vs placebo (–9.61). Secondary variables were generally consistent with the primary analysis, except for a significant reduction in HAM-A total score (week 1) and significant improvements in HAM-A psychic cluster and CGI-S total scores (week 8). Adverse events included dry mouth, somnolence, sedation, headache, and dizziness.

Conclusions: In patients with GAD and an inadequate response to SSRI/ SNRIs, adjunctive quetiapine XR did not show a statistically significant effect for the primary endpoint at week 8, although some secondary endpoints were statistically significant vs placebo. Quetiapine XR was generally well tolerated.