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Extended-Release Venlafaxine Efficacious for Generalized Anxiety

The chronic condition of generalized anxiety disorder (GAD), marked by persistent, excessive worry and associated somatic symptoms of anxiety, is frequently comorbid with other mood and anxiety disorders. Although it responds to benzodiazepines, tricyclic antidepressants, and buspirone, no medication studies of GAD have been longer than 3 months. This multisite, randomized, double-blind, 6-month study examined efficacy of the mixed serotonin-norepinephrine reuptake inhibitor venlafaxine (75, 150, or 225 mg) with that of placebo in 251 patients with GAD but without comorbid major depression, other significant Axis I disorder, or severe somatic symptoms (mean Hamilton anxiety score 25).

Based on a last-observation-carried-forward analysis on the 238 patients receiving at least one assessment, venlafaxine patients showed significantly greater response from week 1 or 2 through week 28 than did placebo patients and a significantly overall higher response rate (69 percent vs. 44 percent). Analysis of the smaller set of completers (41 percent of participants) showed similar efficacy. Common side effects included somnolence, nausea, and dry mouth.

Comment: This is the first long-term study to show efficacy for any medication in patients with this condition. Venlafaxine, a powerful antidepressant with efficacy in treatment-resistant depression, was more effective than placebo despite a high placebo response rate. Most primary care patients with this condition have somatic symptoms and frequent comorbidity, however; the study's exclusion of patients with these severely limits the generalizability of the results -- even though exclusion was necessary to prove that the drug targeted generalized anxiety symptoms. Based on previous efficacy studies of venlafaxine in depressed or panic-disordered patients, it is probable that venlafaxine also would be effective in patients with these comorbidities.

— P Roy-Byrne

Published in Journal Watch Psychiatry August 8, 2000

Citation(s):

Gelenberg AJ et al. Efficacy of venlafaxine extended-release capsules in nondepressed outpatients with generalized anxiety disorder. JAMA 2000 Jun 21 283 3082 -3088.

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