The selective serotonin reuptake inhibitor (SSRI) and 5-HT1A receptor partial agonist vilazodone (Viibryd, Forest Laboratories, Inc), currently approved for the treatment of major depressive disorder (MDD) in adults, is also effective in relieving anxiety symptoms in patients with generalized anxiety disorder (GAD).
The finding, from a double-blind, randomized clinical trial, was presented here at the American Society of Clinical Psychopharmacology (ASCP) 2015 Annual Meeting.
“Some physicians assume that all antidepressants work for anxiety disorders, and that is not the case,” lead author David Sheehan, MD, professor emeritus, University of South Florida College of Medicine, Tampa, told Medscape Medical News.
“There is always a question when a new antidepressant comes on the market, does it work for generalized anxiety disorder? Vilazodone is an antidepressant that has some main mechanisms of action that look like a standard SSRI like Paxil [Apotex Corp], Prozac [Eli Lilly and Company], and Zoloft [Pfizer Inc], but in addition, it has an action that is like an old antianxiety drug called buspirone, or Buspar [Bristol-Myers Squibb Company],” Dr Sheehan said.
The multicenter study compared vilazodone 20-40 mg/day vs placebo in patients aged 18 to 70 years who had GAD.
The study was of 10 weeks’ duration and consisted of a 1-week screening period, 8 weeks of treatment, and a 1-week down-taper period. Therapy was initiated at the 20-mg dose; increases to 40 mg per day were permitted at the end of week 2 or week 4 for patients with inadequate response or who experienced difficulty with tolerance, but no dose increases were allowed after week 4.
The primary efficacy outcome was total score change from baseline to week 8 on the Hamilton Rating Scale for Anxiety (HAMA); the secondary efficacy outcome was change in score on the Sheehan Disability Scale (SDS).
The study randomly assigned 202 patients to receive vilazodone, and 202 to receive placebo.
Of the patients who who received placebo, 81% (n = 163) completed the study, compared with 71% (n = 144) of the patients who received vilazodone.
At the end of 8 weeks, patients receiving vilazodone were worrying much less and had fewer anxiety symptoms than patients who received placebo, Dr Sheehan reported.
The least square mean difference (LSMD) between vilazodone and placebo with regard to the HAMA score from baseline to week 8 was statistically significant in favor of vilazodone (-2.20, 95% confidence interval [CI], 3.72 to -0.68; P = .0048).
A similar result was seen in change on the SDS score (LSMD, -1.89; 95% CI, -3.52 to -0.26; P = .0236).
Statistically significant differences at week 8 for vilazodone vs placebo were also seen on each SDS domain score, the HAMA Psychic and Somatic Anxiety subscales, and the HAMA Anxious Mood and Tension items.
Most of the patients in the study (64% of patients receiving placebo and 79% of patients receiving vilazodone) reported side effects from treatment. Most of these were mild to moderate in severity.
Treatment-emergent adverse events that were reported in ≥5% of patients receiving vilazodone at twice the rate of those receiving placebo were nausea, diarrhea, dizziness, fatigue, delayed ejaculation, and erectile dysfunction.
Mean changes in laboratory values and vital signs were low and were similar between the two groups. No patient experienced an increase in heart rate.
“Vilazodone is not FDA approved for anxiety, so it remains to be seen if it will get approval for that indication, but this study was a step for researchers to understand that the drug does at least have the hope of providing some relief from anxiety symptoms,” Dr Sheehan said.
Good News for Clinicians
“GAD is a very common problem that is associated with significant impairment. When it occurs in combination with depression, it is associated with worse outcomes and a lower response rate to treatment. So, whether it occurs by itself or in combination with other psychiatric disorders, GAD poses a significant mental health burden on many people,” Holly A. Swartz, MD, professor, University of Pittsburgh School of Medicine, in Pennsylvania, told Medscape Medical News.
“We do not have enough well-tolerated, effective treatments available to manage GAD, so clinicians will be glad to know that another treatment shows evidence of efficacy,” Dr Swartz, who was not involved in the research, said.
“My only concern about this particular study is that although vilazodone was statistically better than placebo, the least square mean difference between the two treatments was not very large,” she added. “When seeking to alleviate suffering, we look for large differences between placebo and active treatment.”
This study was supported by funding from Forest Laboratories, LLC. Dr Sheehan reports multiple financial relationships with industry. Dr Swartz reports no relevant financial relationships.
American Society of Clinical Psychopharmacology (ASCP) 2015 Annual Meeting. Abstract 3000210. Presented June 23, 2015.