A review of vilazodone exposures with focus on serotonin syndrome effects

Vilazodone is an antidepressant with selective serotonin reuptake inhibition and partial 5HT1A agonism. Serotonin syndrome is believed to be due to excessive stimulation of 5-HT2A and 5-HT1A receptors, resulting in the clinical triad of altered mentation, autonomic instability and neuromuscular abnormalities. The goal of this study is to define serotonergic effects after vilazodone exposure.

A retrospective review of two databases: the American Association of Poison Controls Centers' National Poison Data System (NPDS) and the American College of Medical Toxicology's Toxicology Investigators Consortium (ToxIC Registry). A case series of four patients from one medical toxicology service is also presented.

During the 52-month study period, a total of 3192 vilazodone human exposures were reported to NPDS. Of these, 1734 (54%) were isolated vilazodone cases. The clinical effects of vilazodone toxicity included drowsiness (20%), vomiting (14%), tachycardia (11%) and agitation (10%). Most patients (71%) had symptoms for between 2 and 24 h, though some (14%) remained symptomatic for more than 24 h. The most common treatment was intravenous fluids (15%) and the most serious intubation (2%). From the ToxIC Registry, a total of 23 cases of vilazodone exposures were identified. Of these, 17 (74%) had vilazodone listed as the first (primary) agent and 10 (43%) involved vilazodone-only ingestions. Nine (39%) cases documented serotonin syndrome; and most (8/9; 89%) listed vilazodone as the primary agent. All (n = 4) subjects in the case series with acute vilazodone toxicity had serotonin syndrome.

Vilazodone overdose, including vilazodone-only ingestions, are associated with serotonin syndrome. Serotonergic toxicity and appropriate treatments should be considered when caring for patients with vilazodone ingestions.