Atypical antipsychotics in primary generalized anxiety disorder or comorbid with mood disorders

Generalized anxiety disorder (GAD) is a chronic, highly prevalent and debilitating disorder that commonly co-occurrs with mood disorders. Current available agents for GAD are limited either by their slow onsets of actions, unsatisfactory anxiolytic effects or potential for abuse/dependence. Atypical antipsychotics have been studied as alternatives. Olanzapine, risperidone and quetiapine immediate release have been explored in the treatment of refractory GAD and risperidone in bipolar anxiety with randomized, double-blind, placebo-controlled trials, but the results were not consistent. By contrast, quetiapine extended release (quetiapine-XR) 150 mg/day monotherapy yielded consistent anxiolytic effects across three studies that were superior to placebo and as effective as paroxetine 20 mg/day and escitalopram 10 mg/day but with an earlier onset of action. In a 52-week treatment of GAD, quetiapine-XR was superior to placebo in the prevention of anxiety relapses. Overall, atypical antipsychotics were relatively well tolerated, with common side effects of somnolence and sedation. However, in contrast to antidepressants and benzodiazepines, the long-term risk and benefit of atypical antipsychotics in the treatment of GAD is yet to be determined.