Relapse Prevention Study Of Desvenlafaxine Succinate Sustained Release In Outpatients With Major Depressive Disorder

The primary purpose of this study is to compare the long-term efficacy and safety of
desvenlafaxine succinate sustained release versus placebo in adults with Major Depressive
Disorder, using a randomized withdrawal design. Randomized withdrawal means that after
receiving desvenlafaxine succinate sustained release for a predetermined period of time,
subjects will be selected by chance to either continue receiving the study drug or to be
withdrawn from the study drug and receive placebo for the remainder of their participation
in the trial. Subjects will not know to which group they have been assigned.

The study consists of an up to 14-day screening period followed by an 8-week open-label
period in which subjects will knowingly receive 50 mg/day of desvenlafaxine succinate
sustained release. Subjects who do not respond to treatment, demonstrating no significant
change in their depressive symptoms, will be withdrawn from participation at the end of this
period. Responding subjects will receive an additional 3 months of open-label desvenlafaxine
succinate sustained release at the same dose. Subjects with stable response to treatment at
the conclusion of this 3 month period will be randomized to either desvenlafaxine succinate
sustained release at 50 mg/day or placebo in a blinded manner for an additional 6 months or
until symptoms of depression return. Following discontinuation at any point after enrollment
in the study, subjects will receive two weeks of follow-up monitoring, including one week of
blinded taper with 25 mg/day of desvenlafaxine succinate sustained release treatment for any
subjects who have been taking desvenlafaxine succinate sustained release prior to
discontinuation. Subjects assigned to placebo will receive a blinded placebo taper.
Following taper, subjects will be evaluated for one additional week to monitor safety.