A double-blind, placebo-controlled study of edivoxetine as an adjunctive treatment for patients with major depressive disorder who are partial responders to selective serotonin reuptake inhibitor treatment

BackgroundThis phase 2 study examined the efficacy and tolerability of edivoxetine, a highly selective norepinephrine reuptake inhibitor, as an adjunctive treatment for patients with major depressive disorder (MDD) who have a partial response to selective serotonin reuptake inhibitor (SSRI) treatment.MethodsStudy design consisted of double-blind, 10-week therapy of adjunctive edivoxetine (6-18 mg once daily) or adjunctive placebo with SSRI. Inclusion/entry criteria included partial response to current SSRI by investigator opinion and a GRID 17-item Hamilton Rating Scale for Depression (HAMD17) total score ≥16. The primary efficacy measure was the Montgomery-Asberg Depression Rating Scale (MADRS). Safety measures included treatment-emergent adverse events (TEAE) and vital signs.ResultsFor the primary evaluable population (n=63 for adjunctive edivoxetine and n=68 for adjunctive placebo), the treatment groups did not differ significantly on the primary outcome of change from baseline to week 8 in the MADRS total score; the effect size of edivoxetine treatment was 0.26. Significant treatment differences, favoring adjunctive edivoxetine (p≤.05), were shown for improvements in role functioning and the functional impact of fatigue. For the adjunctive edivoxetine randomized group (N=111), the most frequent TEAEs were hyperhidrosis (7.2%), nausea (7.2%), erectile dysfunction (6.3%) and testicular pain (6.3%). Hemodynamic changes were observed in blood pressure and pulse rate between treatment groups.LimitationsStudy was underpowered for an alpha 2-sided 0.05 significance level for the primary outcome.ConclusionsFor patients with MDD who had a partial response to SSRIs, adjunctive edivoxetine treatment was not statistically superior to adjunctive placebo on the primary outcome measure. However, pending further study, improved functioning and remission rate suggest a potential role for edivoxetine for patients with depression.