Lisdexamfetamine dimesylate augmentation for adults with major depressive disorder and inadequate response to antidepressant monotherapy: Results from 2 phase 3, multicenter, randomized, double-blind, placebo-controlled studies

•Lisdexamfetamine augmentation was not superior to placebo in reducing depressive symptoms.•The tolerability of lisdexamfetamine was consistent with published reports.•Study limitations include an inability to assess major depressive disorder symptom domains or subtypes.

BackgroundThe efficacy, safety, and tolerability of lisdexamfetamine dimesylate (LDX) augmentation of antidepressant monotherapy in adults with major depressive disorder (MDD) from two phase 3 studies are reported.MethodsAcross study 1 (placebo, n=201; LDX, n=201) and study 2 (placebo, n=213; LDX, n=211), most participants (placebo and LDX) in the safety analysis set were female (study 1: 66.2% and 64.2%; study 2: 67.1% and 66.8%); mean±SD ages were 41.8±12.04 with placebo and 42.2±12.32 with LDX in study 1 and 42.6±11.41 with placebo and 42.0±11.63 with LDX in study 2. Participants (18-65 y) had DSM-IV-TR-diagnosed MDD and lead-in baseline Montgomery-Åsberg Depression Rating Scale (MADRS) total scores ≥24. Eight-week antidepressant lead-in phases prospectively assessed antidepressant response. Then, 8 weeks of randomized (1:1), double-blind treatment with dose-optimized LDX (20-70 mg) or placebo in participants exhibiting inadequate antidepressant monotherapy responses (augmentation baseline MADRS total scores ≥18 and <50% MADRS total score reductions from lead-in baseline to augmentation baseline) was initiated. The primary endpoint was MADRS total score change from augmentation baseline to week 16. Safety and tolerability measures included the occurrence of treatment-emergent adverse events (TEAEs).ResultsLeast squares mean (95% CI) treatment differences (LDX-placebo) for MADRS total score changes from augmentation baseline to week 16 were not statistically significant in study 1 (0.1 [-1.7, 2.0], P=0.883) or study 2 (-0.5 [-2.3, 1.3], P=0.583). The only TEAE reported by >5% of LDX participants at twice the placebo rate in both studies was dry mouth.LimitationsLimitations include the exclusion of participants with psychiatric comorbidities/active medical disorders, the inability to assess specific MDD symptom domains (eg, anhedonia, cognition) or subtypes, the use of telephone-based depression assessments, and the potential influence of placebo response.ConclusionContrary to expectations, LDX augmentation was not superior to placebo in reducing depressive symptoms in individuals with MDD exhibiting inadequate responses to antidepressant monotherapy.