Efficacy of Duloxetine for the Treatment of Generalized Anxiety Disorder: Implications for Primary Care Physicians

Objective: This study examined the efficacy and tolerability of duloxetine, a dual reuptake inhibitor of serotonin and norepinephrine, for the treatment of patients with generalized anxiety disorder (GAD).

Method: Patients were ≥ 18 years old and recruited from 5 European countries, the United States, and South Africa. The study had a 9-week, multicenter, randomized, double-blind, fixed-dose, placebo-controlled, parallel-group design. A total of 513 patients (mean age = 43.8 years; 67.8% female) with a DSM-IV-defined GAD diagnosis received treatment with duloxetine 60 mg/day (N = 168), duloxetine 120 mg/day (N = 170), or placebo (N = 175). The primary efficacy measure was the Hamilton Rating Scale for Anxiety (HAM-A) total score. Secondary measures included the Sheehan Disability Scale, HAM-A psychic and somatic anxiety factor scores, and HAM-A response, remission, and sustained improvement rates. The study was conducted from July 2004 to September 2005.

Results: Both groups of duloxetine-treated patients demonstrated significantly greater improvements in anxiety symptom severity compared with placebo-treated patients as measured by HAM-A total score and HAM-A psychic and somatic anxiety factor scores (p values ranged from ≤ .01 to ≤ .001). Duloxetine-treated patients had greater functional improvements in Sheehan Disability Scale global and specific domain scores (p ≤ .001) than placebo-treated patients. Both duloxetine doses also resulted in significantly greater HAM-A response, remission, and sustained improvement rates compared with placebo (p values ranged from ≤ .01 to ≤ .001). The rate of study discontinuation due to adverse events was 11.3% for duloxetine 60 mg and 15.3% for duloxetine 120 mg versus 2.3% for placebo (p ≤ .001).

Conclusion: The results of this study demonstrate that duloxetine 60 mg/day and 120 mg/day were efficacious and well tolerated and thus may provide primary care physicians with a useful pharmacologic intervention for GAD.

Clinical Trials Registration: ClinicalTrials.gov identifier NCT00122824.