Extended-Release Venlafaxine for General Anxiety Disorder
abstract & commentary
Source: Rickels K, et al. Efficacy of extended-release venlafaxine in nondepressed outpatients with generalized anxiety disorder. Am J Psychiatry 2000;157:968-974.
General anxiety disorder (gad) has an esti-mated life prevalence of 5.1%. As is typical of other anxiety disorders, it appears more common in women than men. Benzodiazepines and buspirone (Buspar) are the most commonly used medications for this disorder. Other antidepressants are being evaluated for GAD, but data are few, particularly in patients without concurrent depression.
This study is a multicenter, randomized, double-blind, parallel group, placebo-controlled trial of extended-release venlafaxine (Effexor XR) for GAD in nondepressed patients. Patients were randomly assigned to placebo or the study drug at fixed doses of 75 mg, 150 mg, or 225 mg/d; patients started at 75 mg/d and increased (if applicable) to higher doses by 75 mg/wk. Patients were excluded if they: had a 20% reduction in anxiety between screening and randomization; had concurrent depression, bipolar disorder, or psychosis; used a benzodiazepine or medication with psychotropic effects within 30 days of randomization; or had an acute medical problem by history, examination, or laboratory findings. Primary efficacy measurements were done weekly and included the final total and psychic anxiety factor scores on the Hamilton Anxiety Scale (HAS) and the final severity and improvement scores on the Clinical Global Improvement Scale. Secondary efficacy measurements included the somatic anxiety, anxious mood, and tension factors of the HAS, as well as the anxiety subscale of the Hospital Anxiety and Depression Scale. Adverse events were measured by self-report and physical examinations.
A total of 102 patients discontinued treatment: placebo, 19 (20%), 75 mg/d, 26 (30%), 150 mg/d, 29 (36%), and 225 mg/d, 28 (33%). The most common reason for discontinuation was adverse events in 7, 14, 18, and 17 of the groups, respectively. The most common side effects were nausea, insomnia, dry mouth, and somnolence. The mean scores of the outcome measurements were significantly lower in 4/4 primary and 3/4 for the venlafaxine groups compared to the placebo group, with changes beginning as early as week 1 and being maintained through week 8. The most positive results occurred in the 225 mg/d venlafaxine group.
Comment by Donald M. Hilty, MD
This controlled trial shows that GAD in nondepressed patients responds more favorably to extended-release venlafaxine than placebo. This finding is expected, given prior data with the immediate-release preparation. Clinical experience indicates that extended-release venlafaxine (Effexor XR) is easier to tolerate than immediate release (Effexor). Because of the common comorbidity of depression and GAD, venlafaxine and perhaps other antidepressants are often good first-line treatments. Benzodiazepines are recommended for short-term use only, which is typically not applicable to GAD, which is a chronic disorder. Buspirone is another agent indicated for the treatment of GAD. Although a prior report found venlafaxine superior to buspirone and placebo, the buspirone dose in that study was limited to 30 mg/d, which may not be sufficient for some patients.
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