ABSTRACT: Major depressive disorder (MDD) is a serious illness in children and adolescents. Vilazodone is a selective serotonin reuptake inhibitor approved for MDD in adults. This study evaluated the efficacy, safety, and tolerability of vilazodone in adolescent patients, ages 12-17 years, with MDD (NCT01878292).This double-blind, randomized, placebo-controlled, parallel-group, fixed-dose study was conducted at 56 study centers in the United States and was 10 weeks in duration (a 1-week screening period, an 8-week double-blind treatment period, and a 1-week double-blind down-taper period). Outpatients with an MDD diagnosis based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria were included in the study. Clinical inclusion criteria required a Children's Depression Rating Scale-Revised (CDRS-R) total score of ? 40 and Clinical Global Impressions-Severity (CGI-S) score of ? 4. Patients were randomized 1:1:1 to 8 weeks of double-blind treatment with placebo (n = 174), vilazodone 15 mg/day (n = 175), or vilazodone 30 mg/day (n = 180). The primary and secondary efficacy parameters were change from baseline to week 8 in CDRS-R total score and CGI-S score, respectively. Safety parameters included adverse events (AEs); clinical laboratory, vital sign, and electrocardiogram parameters; and the Columbia-Suicide Severity Rating Scale.Approximately 86% of patients completed double-blind treatment. There was no statistically significant difference between vilazodone 15 mg/day or 30 mg/day and placebo in change from baseline in CDRS-R score. Change in CGI-S score was not significant after adjustment for multiple comparisons. The most common treatment-emergent AEs were nausea, upper abdominal pain, vomiting, diarrhea, nasopharyngitis, headache, and dizziness. Reports of suicidal ideation (placebo, 33.3%; vilazodone 15 mg/day, 36.0%; vilazodone 30 mg/day, 31.1%) and suicidal behavior (placebo, 1.8%; vilazodone 15 mg/day, 1.1%; vilazodone 30 mg/day, 1.1%) were similar between treatment groups. There were no deaths in the study.The efficacy of vilazodone for the treatment of MDD in adolescent patients could not be confirmed in this study. Vilazodone was generally safe and well tolerated, with treatment-emergent AEs similar to those in adult patients.NCT01878292.