Effexor XR - Clinical Pharmacology

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A 4-week study of inpatients meeting DSM-III-R criteria for major depressive disorder with melancholia utilizing Effexor (the immediate release form of venlafaxine) in a range of 150 to 375 mg/ day (t. i. d. schedule) demonstrated superiority of Effexor over placebo. The mean

dose in completers was 350 mg/ day. Examination of gender subsets of the population studied did not reveal any differential responsiveness on the basis of gender.

In one longer-term study, outpatients meeting DSM-IV criteria for major depressive disorder who had responded during an 8-week open trial on Effexor XR (75, 150, or 225 mg, qAM) were randomized to continuation of their same Effexor XR dose or to placebo, for up to 26 weeks of observation for relapse. Response during the open phase was defined as a CGI Severity of Illness item score of 3 and a HAM-D-21 total score of 10 at the day 56 evaluation. Relapse during the double-blind phase was defined as follows:

(1) a reappearance of major depressive disorder as defined by DSM-IV criteria and a CGI Severity of Illness item score of 4 (moderately ill),

(2) 2 consecutive CGI Severity of Illness item scores of 4, or

(3) a final CGI Severity of Illness item score of 4 for any patient who withdrew from the study for any reason. Patients receiving continued Effexor XR treatment experienced significantly lower relapse rates over the subsequent 26 weeks compared with those receiving placebo. In a second longer-term trial, outpatients meeting DSM-III-R criteria for major depressive disorder, recurrent type, who had responded (HAM-D-21 total score 12 at the day 56 evaluation) and continued to be improved [defined as the following criteria being met for days 56 through 180: (1) no HAM-D-21 total score 20; (2) no more than 2 HAM-D-21 total scores > 10, and (3) no single CGI Severity of Illness item score 4( moderately ill)] during an initial 26 weeks of treatment on Effexor (100 to 200 mg/ day, on a b. i. d. schedule) were randomized to continuation of their same Effexor dose or to placebo. The follow-up period to observe patients for relapse, defined as a CGI Severity of Illness item score 4, was for up to 52 weeks. Patients receiving continued Effexor treatment experienced significantly lower relapse rates over the subsequent 52 weeks compared with those receiving placebo.