Efficacy, Safety, and Tolerability of Venlafaxine Extended Release and Buspirone in Outpatients With Generalized Anxiety Disorder

Background: The objective of this randomized, double-blind study was to compare the efficacy and safety of venlafaxine extended release (XR) and buspirone in outpatients with generalized anxiety disorder (GAD) but without concomitant major depressive disorder.

Method: Male and female outpatients at least 18 years old who met the DSM-IV criteria for GAD and had scores of 18 or higher on the Hamilton Rating Scale for Anxiety (HAM-A) were randomly assigned to treatment with either venlafaxine XR (75 or 150 mg/day), buspirone (30mg/day in 3 divided doses), or placebo for 8 weeks. The primary efficacy variables were changes in anxiety as determined by final on-therapy HAM-A total and psychic anxiety scores and Clinical Global Impressions scale (CGI) scores. Other key efficacy variables were HAM-A anxious mood and tension scores and the anxiety subscale scores of the patient-rated Hospital Anxiety and Depression scale (HAD).

Results: The efficacy analysis included 365 patients and the safety analysis, 405. At week 8, adjusted mean HAM-A psychic anxiety, anxious mood, and tension scores were significantly lower for venlafaxine XR-treated patients than for placebo-treated patients. On the HAD anxiety subscale, venlafaxine XR, 75 or 150 mg/day, was significantly more efficacious than placebo at all time points except weeks 1 (both dosages) and 2 (150-mg/day dosage only) and significantly more efficacious than buspirone at all time points except week 1. On the CGI-Improvement scale, scores for venlafaxine XR (both dosages) and buspirone were numerically superior to those for placebo at all time points, and statistical significance was observed at weeks 3, 4, 6, and 8 for venlafaxine XR and at weeks 6 and 8 for buspirone. The adverse events were not essentially different between treatment groups.

Conclusion: Venlafaxine XR is an effective, safe, and well-tolerated once-daily anxiolytic agent in patients with GAD without comorbid major depressive disorder. This agent was significantly superior to buspirone on the HAD anxiety subscale. Buspirone demonstrated statistical significance versus placebo on a measure of anxiolytic response.