Venlafaxine May Be Effective in Social Anxiety Disorder

Venlafaxine is comparable to paroxetine, and each is superior to placebo for the treatment of social anxiety disorder (SAD), according to the results of a randomized study published in the February issue of the Archives of General Psychiatry.

"Evidence has shown that the serotonin-norepinephrine reuptake inhibitor venlafaxine hydrochloride extended release (ER) is also effective for ameliorating symptoms of anxiety, including generalized anxiety disorder, symptoms of anxiety in patients with major depressive disorder, and comorbid major depressive disorder and generalized anxiety disorder," write Michael R. Liebowitz, MD, from New York State Psychiatric Institute in New York, and colleagues.

"This study is one of a series of studies designed to determine if serotonin-norepinephrine reuptake inhibitors are also a viable treatment option for symptoms of social anxiety."

At 26 U.S. centers, 440 adult outpatients meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), criteria for generalized SAD for at least six months were randomized to receive venlafaxine hydrochloride ER (75-225 mg/day), paroxetine (20-50 mg/day), or placebo for 12 weeks or less.

The primary outcome was the total Liebowitz Social Anxiety Scale (LSAS) score; and secondary outcomes were response rates as determined by the Clinical Global Impression-Improvement (CGI-I) score of 1 or 2, Clinical Global Impression (CGI)-Severity of Illness, and Social Phobia Inventory (SPI) scores.

Of 440 patients treated, 413 (93.9%) were included in the last-observation-carried-forward efficacy analysis. Of 429 patients evaluated for safety, 318 (74.1%) completed the study. Mean daily doses were 201.7 ± 38.1 mg for venlafaxine ER and 46.0 ± 7.9 mg for paroxetine.

Compared with placebo, venlafaxine ER treatment was superior at weeks 1 through 12 on the LSAS and SPI, and at week 2 and weeks 6 through 12 for CGI-Severity of Illness and responder status (P < .05 for all).

Compared with paroxetine treatment, venlafaxine ER treatment was superior at weeks 1 and 2 for the SPI (P < .05 for both).

Paroxetine treatment was superior to placebo at weeks 3 through 12 on the LSAS, the CGI-Severity of Illness scale, and the SPI, and at weeks 4 through 12 for response (P < .05 for all). Response rates at week 12 were greater for venlafaxine ER and for paroxetine (58.6% and 62.5%, respectively) than for placebo (36.1%; P < .001 for both).

Study limitations include the 12-week duration, and exclusion of patients with comorbid psychiatric disorders.

"Venlafaxine ER is effective in the short term treatment of generalized social anxiety disorder, with efficacy and tolerability comparable to paroxetine," the authors write. "In addition to its established efficacy in the treatment of depression and generalized anxiety disorder, the results indicate that is a viable first-line treatment option for patients with generalized SAD."