Extended Release Quetiapine Fumarate (Quetiapine XR) as Adjunct Therapy in Patients with Generalized Anxiety Disorder and a History of Inadequate Treatment Response: A Randomized,Double-Blind Study

Objective

To evaluate the efficacy and tolerability of adjunct extended release quetiapine fumarate (quetiapine XR) in patients with generalized anxiety disorder (GAD) and inadequate response to selective serotonin reuptake inhibitors/ serotonin norepinephrine reuptake inhibitors (SSRI/SNRIs).

Methods

11-week (1-week single-blind placebo run-in; 8-week randomized treatment; 2-week post-treatment period), double-blind, placebo-controlled study. Patients were randomized to quetiapine XR or placebo adjunct to SSRI/SNRI. 50 mg initial dose; 150 mg/day, Day 3; 300 mg/day, Weeks × and 4 if indicated (Clinical Global Impressions-Severity of Illness [CGI-S] ≥ 4; 150 mg/day tolerated). Primary endpoint: change from randomization to Week 8 in HAM-A total score. Secondary variables: Hamilton Rating Scale for Anxiety (HAM-A) psychic/somatic clusters, response and remission; and CGI-S.

Results

409 patients were randomized to quetiapine XR (n = 209) or placebo (n = 200); 41% and 55% of patients, respectively, had dose increases (300 mg/day). Week 8 mean change in HAM-A total score was not statistically significant for quetiapine XR (–10.74; p = 0.079) versus placebo (–9.61). Secondary variables were generally consistent with the primary analysis, except a significant reduction in HAM-A total score at Week 1 (–6.45, quetiapine XR versus –4.47, placebo; p < 0.001); significant improvements in HAM-A psychic cluster (p < 0.05) and CGI-S total (p < 0.05) scores at Week 8. Adverse events (.10% either group) were dry mouth, somnolence, sedation, headache, and dizziness.

Conclusions

In patients with GAD and inadequate response to SSRI/SNRI, adjunct quetiapine XR did not show a statistically significant effect for the primary endpoint at Week 8, although some secondary endpoints were statistically significant versus placebo. Quetiapine XR was generally well tolerated.