Relapse Prevention of Panic Disorder in Adult Outpatient Responders to Treatment With Venlafaxine Extended Release

Objective: To compare the long-term efficacy of venlafaxine extended release (ER) with placebo in preventing panic disorder relapse inoutpatient treatment responders.

Method: Outpatients aged >= 18 years who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for panic disorder with or without agoraphobia for at least the previous 3 months, with >= 6 full symptom panic attacks in the 2 weeks prior to screening and >= 3 in the 2 weeks before baseline and a Clinical Global Impressions-Severity of Illness rating >= 4 at screen were eligible to participate. Outpatients received flexible-dose (75-225 mg/day) venlafaxine ER for 12 weeks. Treatment responders were randomly assigned to venlafaxine ER or placebo for 26 weeks. Criteria for response were = 2 full symptom panic attacks per week for 2 consecutive weeks or discontinuation due to loss of effectiveness, was evaluated using Kaplan-Meier survival analysis. The study was conducted between December 2001 and August 2003.

Results: The intent-to-treat population had 291 patients in the open-label phase and 169 in the double-blind phase (placebo, N = 80; venlafaxine ER, N = 89; mean daily dose 165-171 mg). Time to relapse was significantly longer with venlafaxine ER than placebo (p < .001). All secondary measures of panic attack treatment efficacy, quality of life, and disability were significantly better with venlafaxine ER than placebo (p <= .005).

Conclusion: Venlafaxine ER was safe, well tolerated, and effective in preventing relapse in outpatients with panic disorder.