Vilazodone for major depressive disorder: a systematic review of the efficacy and safety profile for this newly approved antidepressant - what is the number needed to treat, number needed to harm and likelihood to be helped or harmed?

Objective: To describe the efficacy and safety of vilazodone for the treatment of major depressive disorder (MDD).

Data sources: The pivotal registration trials were accessed by querying http://www.ncbi.nlm.nih.gov/pubmed/, http://www.fda.gov and http://www.clinicaltrials.gov for the search term 'vilazodone'. Product labeling provided additional information.

Study selection: All available clinical reports of studies were identified.

Data extraction: Descriptions of the principal results and calculation of number needed to treat (NNT) and number needed to harm (NNH) for relevant dichotomous outcomes were extracted from the available study reports and other sources of information.

Data synthesis: Vilazodone is a specific serotonin reuptake inhibitor and serotonin 5HT1A receptor partial agonist. In needs to be administered with food to ensure adequate bioavailability. Approval for the treatment of MDD was based on a clinical development programme that included two 8-week placebo-controlled randomised clinical trials in outpatients with MDD where vilazodone was titrated to a target dose of 40 mg/d over the first 2 weeks. Both trials evidenced efficacy for vilazodone as measured by the Montgomery Asberg Depression Rating Scale. NNT for response vs. placebo was 8 (95% CI 6-16) and for remission was 14 (95% CI 8-55). NNH vs. placebo for discontinuation because of an adverse event (AE) was 27 (95% CI 15-104). The most commonly encountered AEs (incidence ≥ 5% and at least twice the rate of placebo) were diarrhoea, nausea, vomiting and insomnia, with NNH values vs. placebo of 6 (95% CI 5-8), 6 (95% CI 5-8), 30 (95% CI 18-82) and 26 (95% CI 16-78), respectively. NNH vs. placebo for any sexual AE was 12 (95% CI 9-18), but systematically collected data using rating scales of sexual function did not reveal treatment associated effects. Vilazodone was not associated with clinically relevant weight change in the short-term trials. In an open-label 1-year study of vilazodone, mean weight increased by 1.7 kg among the observed cases.

Conclusions: Vilazodone represents another option for the treatment of MDD. Vilazodone appears to have a favourable weight-gain profile based on short-term studies. Sexual side-effects were not consistently demonstrated when assessed using clinical rating scales but spontaneously reported AEs related to sexual functioning were observed. Additional controlled data regarding long-term efficacy and effectiveness will help characterise this new agent when used in maintenance treatment.