Objective: Pregabalin has demonstrated robust, rapid efficacy in reducing symptoms of generalized anxiety disorder (GAD) in 4 placebo-controlled clinical trials. The current study compared the efficacy and safety of pregabalin and venlafaxine in patients diagnosed with moderate to severe GAD.
Method: The study was conducted from December 21, 1999, to July 31, 2001. Outpatients (N = 421) in primary care or psychiatry settings meeting DSM-IV criteria for GAD were randomly assigned to 6 weeks of double-blind treatment with pregabalin 400 or 600 mg/day, venlafaxine 75 mg/day, or placebo. The primary analysis was change in Hamilton Rating Scale for Anxiety (HAM-A) total score from baseline to last-observation-carried-forward (LOCF) endpoint. Secondary analyses included the change in HAM-A psychic (emotional) and somatic (physical) factor scores, significant improvement at week 1, and week 1 improvement sustained at every visit through endpoint.
Results: Pregabalin at both dosages (400 mg/day, p = .008; 600 mg/day, p = .03) and venlafaxine (p = .03) produced significantly-greater improvement in HAM-A total score at LOCF endpoint than did placebo. Only the pregabalin 400-mg/day treatment group experienced significant improvement in all a priori primary and secondary efficacy measures. Pregabalin in both dosage treatment groups (400 mg/day, p < .01; 600 mg/day, p < .001) significantly improved HAM-A total score at week 1, with significant improvement through LOCF endpoint. Statistically significant improvement began at week 2 for venlafaxine. Discontinuation rates due to associated adverse events were greatest in the venlafaxine treatment group: venlafaxine, 20.4%; pregabalin 400 mg/day, 6.2%; pregabalin 600 mg/day, 13.6%; placebo, 9.9%.
Conclusion: Pregabalin was safe, well tolerated, and rapidly efficacious across the physical-somatic as well as the emotional symptoms of GAD in the majority of patients studied in primary care and psychiatric settings.