A Double-Blind, Placebo-Controlled, Parallel-Group, Flexible-Dose Study of Venlafaxine Extended Release Capsules in Adult Outpatients With Panic Disorder

Objective: To evaluate the efficacy, safety, and tolerability of venlafaxine extended release (ER) in short-term treatment of panic disorder. Method: In this multicenter, double-blind study, conducted from April 2001 to December 2002, 343 adult outpatients who met criteria for panic disorder (with and without agoraphobia) according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, were randomly assigned to flexible-dose venlafaxine ER (75-225 mg/d) or placebo for 10 weeks (N = 155 per group, intent-to-treat population). The primary outcome measure was the percentage of panic-free patients as assessed using the Sheehan Panic and Anticipatory Anxiety Scale. Key secondary measures included the Panic Disorder Severity Scale (PDSS) score and Clinical Global Impress ions-Improvement (CGI-I) scale response (score = 1 or 2). Last-observation-carried-forward data were analyzed, and statistical significance was set at p <= .05. Results: At week 10, the percentage of patients who were free from full-symptom panic attacks was 52% in the venlafaxine ER group and 43% in the placebo group (p = .11). Mean change from baseline in PDSS total score was significantly (p = .006) greater for the venlafaxine ER group (-9.3) than for the placebo group (-7.5), and significantly (p = .03) more venlafaxine ER-treated patients achieved CGI-I. response (71%) than did those receiving placebo (59%) at week 10. Treatment with venlafaxine ER was generally safe and well tolerated. Adverse events were the primary or secondary cause for discontinuation for 7 placebo patients (4%) and 12 venlafaxine ER patients (7%). Conclusions: Venlafaxine ER appears to be effective, safe, and well tolerated in short-term treatment of panic disorder, although the results fell just short of significance on the primary outcome measure.