Efficacy of venlafaxine extended-release capsules in nondepressed outpatients with generalized anxiety disorder - A 6-month randomized controlled trial

Context Generalized anxiety disorder (GAD) is a chronic disorder that is as sociated with debilitating psychic and somatic symptoms. Venlafaxine extend ed-release (XR) capsules have been shown to be effective in short-term trea tment of patients with GAD without major depressive disorder (MDD), but lon g-term data are needed to establish whether this agent confers persistent b enefits. Objective To compare the 6-month efficacy and safety of a flexible dosage o f venlafaxine XR in outpatients with GAD without associated MDD. Design Six-month, randomized, double-blind, placebo-controlled, parallel-gr oup trial conducted May 1996 to October 1997. Setting Fourteen outpatient clinics and private psychiatric practices in th e United States. Participants A total of 251 outpatients aged 18 years or older who met Diag nostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for GAD, had sufficient symptoms to require treatment, and did not have coexisting MDD. Interventions Participants were randomly assigned to receive either placebo (n=127) or venlafaxine XR (75, 150, or 225 mg/d, as required to control sy mptoms; n=124) for 28 weeks. Main Outcome Measures Changes from baseline in the Hamilton Rating Scale fo r Anxiety (HAM-A) total score, the HAM-A psychic anxiety factor score, and the Clinical Global Impressions (CGI) scale Severity of Illness and Global Improvement scores, compared by intervention group. Results During weeks 6 through 28, response rates in the venlafaxine XR gro up were 69% or higher compared with rates of 42% to 46% in the placebo grou p (P<.001). By an evaluable-patient analysis, venlafaxine XR compared with placebo significantly improved anxiety scores from week 1 or 2 through week 28 on all primary efficacy measures, including the HAM-A total (P<.001), t he HAM-A psychic anxiety factor (P<.001), and the CGI scale scores (P<.001) . Adjusted mean changes from baseline to week 28 using last-observation-car ried-forward methods were for HAM-A, venlafaxine XR -13.4, placebo -8.7 (P< .001); for HAM-A psychic anxiety score, venlafaxine XR -7.4, placebo -4.2 ( P<.001); and for CGI-Improvement, venlafaxine XR 2,2, placebo 3.0 (P<.001). The most common treatment-emergent adverse event was nausea, followed by s omnolence and dry mouth. Conclusions This study is the first placebo-controlled demonstration of the longterm efficacy of any drug class in treating outpatients with DSM-IV-di agnosed GAD. Venlafaxine XR is an effective, rapidly acting, safe, once-dai ly agent for both the short-and long-term treatment of anxiety and may prov ide an important alternative to currently available anxiolytics.