Mechanism of Action

Viibryd (vilazodone hydrochloride) is a selective serotonin reuptake inhibitor and a 5HT1A receptor partial agonist. The mechanism of the antidepressant effect of vilazodone is not fully understood but is thought to be related to its enhancement of serotonergic activity in the CNS through selective inhibition of serotonin reuptake. Vilazodone is also a partial agonist at serotonergic 5-HT1A receptors; however, the net result of this action on serotonergic transmission and its role in vilazodone’s antidepressant effect are unknown.

Side Effects

Adverse events associated with the use of Viibryd may include, but are not limited to, the following:

Diarrhea

Nausea

Vomiting

Insomnia

Dosing/Administration

The recommended initial dose of Viibryd is 40 mg once daily. Treatment should be titrated, starting with an initial dose of 10 mg once daily for seven days, followed by 20 mg once daily for an additional seven days and then an increase to 40 mg once daily.

Clinical Trial Results

FDA Approval
The FDA approval of Viibryd was based on two eight-week, multicenter, randomized, double-blind, placebo-controlled studies in adults meeting the criteria for major depressive disorder. The subjects were titrated over two weeks to a dose of 40 mg (n=436) or placebo (n=433) once daily. Viibryd was superior to placebo in the improvement of depressive symptoms as measured by the mean change from baseline to Week 8 in the Montgomery-Asberg Depression Rating Scale (MADRS) total score. In Study 1, the Least Squares Mean difference from placebo in change from baseline was -3.2 and in Study 2, the difference was -2.5.