The objective of this study was to evaluate the anxiolytic efficacy, and speed of onset of efficacy, of pregabalin (PGB) and venlafaxine-XR (VXR) in patients with generalized anxiety disorder (GAD). In this double-blind trial, outpatients, ages 18-65 years, who met Diagnostic and Statistical Manual of Mental Disorders, 4th edition, criteria for GAD were randomized to 8 weeks of flexible-dose treatment with PGB (300-600 mg/day), VXR (75-225 mg/day), or placebo (PBO). The intent-to-treat sample consisted of 121 patients on PGB [least square (LS) mean ± SE baseline Hamilton Anxiety Rating Scale (HAM-A), 27.6 ± 0.4], 125 patients on VXR (baseline HAM-A, 27.4 ± 0.4), and 128 patients on PBO (baseline HAM-A, 26.8 ± 0.4). Treatment with PGB was associated with a significantly greater LS mean change in the HAM-A total score at last observation carried forward endpoint versus PBO (-14.5 ± 0.9 vs. -11.7 ± 0.9; P = 0.028). Treatment with VXR was not significant versus PBO at endpoint (-12.0 ± 0.9; -11.7 ± 0.9; P =0.968). Treatment with PGB showed an early onset of improvement, with significantly greater LS mean change in the HAM-A by day 4 versus both PBO (-5.3 ± 0.5 vs. -3.4± 0.5; P = 0.008) and VXR (-2.9 ± 0.5; P = 0.0012). The proportion of patients reporting a severe adverse event was similar for PGB (9.1%) and PBO (7.8%), but higher for VXR (20.0%; P < 0.05). In conclusion, PGB was a safe and effective treatment of GAD, with a significantly earlier onset of anxiolytic activity than VXR.
Trial registration: ClinicalTrials.gov NCT00151450.