Efficacy and tolerability of paroxetine for the long-term treatment of generalized anxiety disorder

Background: Paroxetine has demonstrated efficacy in depression and anxiety disorders, including generalized anxiety disorder (GAD). This 32-week study evaluated the maintained efficacy and safety of paroxetine in GAD by assessing the potential for relapse after discontinuation of medication. Method: Adults (N = 652) with DSM-IV GAD and a Clinical Global Impressions-Severity of Illness (CGI-S) score greater than or equal to 4 received paroxetine (20-50 mg/day) for 8 weeks. Patients whose CGI-S score had decreased by at least 2 points to greater than or equal to 3 at week 8 were randomly assigned to double-blind treatment with paroxetine (N = 278) or placebo (N = 288) for a further 24 weeks. The primary efficacy parameter was the proportion of patients relapsing (an increase in CGI-S score of at least 2 points to a score greater than or equal to 4 or withdrawal resulting from lack of efficacy) during double-blind treatment. Results: Significantly fewer paroxetine than placebo patients relapsed during the 24-week double-blind phase (10.9% vs. 39.9%; p < .001). Placebo patients were almost 5 times more likely to relapse than paroxetine patients (estimated hazard ratio = 0.213 [95% CI = 0.1 to 0.3]; p < .001). Statistical significance in favor of paroxetine was demonstrated for all secondary efficacy parameters, including functional status. Twice as many paroxetine patients as placebo patients (73%) achieved remission. Paroxetine was well tolerated, with no unexpected adverse events reported. Conclusion: Paroxetine was found to be effective and well tolerated for both the short- and long-term treatment of DSM-IV GAD. Continued treatment with paroxetine significantly reduced the potential for relapse of GAD symptoms.