OBJECTIVE: To evaluate the long-term (11-month) efficacy and safety of 
desvenlafaxine (administered as desvenlafaxine succinate) at the recommended 
50-mg/d dose in preventing relapse in patients with major depressive disorder 
(MDD).
METHOD: Adult outpatients (age ≥ 18 years) with MDD (DSM-IV criteria) and a 
17-item Hamilton Depression Rating Scale (HDRS17) total score ≥ 20 at screening 
and baseline were enrolled in a multicenter, double-blind, placebo-controlled, 
randomized withdrawal trial conducted between June 2009 and March 2011. Patients 
who responded to 8-week open-label treatment with desvenlafaxine 50 mg/d with 
continuing stable response through week 20 were randomly assigned to receive 
placebo or desvenlafaxine 50 mg/d in a 6-month, double-blind, randomized 
withdrawal period. The primary efficacy endpoint was time to relapse following 
randomization to double-blind treatment, which was compared between groups using 
the log-rank test. Relapse was defined as HDRS17 total score ≥ 16, 
discontinuation for unsatisfactory response, hospitalization for depression, 
suicide attempt, or suicide. Safety and tolerability data were collected 
throughout the trial.
RESULTS: A total of 874 patients were enrolled; 548 patients were randomly 
assigned to receive placebo (n = 276) or desvenlafaxine 50 mg/d (n = 272) in the 
double-blind withdrawal period. Time to relapse was significantly shorter for 
placebo versus desvenlafaxine (P < .001). At the end of the 6-month double-blind 
treatment, the estimated probability of relapse was 30.2% for placebo versus 
14.3% for desvenlafaxine 50 mg/d. Safety and tolerability results were generally 
consistent with those in short-term studies of desvenlafaxine 50 mg/d.
CONCLUSIONS: Desvenlafaxine at the recommended dose of 50 mg/d was effective in 
relapse prevention of depression during a 6-month period in patients who 
demonstrated stable response after 20 weeks of open-label desvenlafaxine 
treatment.
TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00887224.