Post hoc Responder and Remission Analyses from Two Studies of SHP465 Mixed Amphetamine Salts Extended-Release Among Adults with Attention-Deficit/Hyperactivity Disorder

Objectives: In two studies of adult attention-deficit/hyperactivity disorder (ADHD), SHP465 mixed amphetamine salts (MAS) extended-release significantly reduced ADHD-Rating Scale, 4th Edition total score (ADHD-RS-IV-TS) versus placebo (PBO). This report describes post hoc analyses of SHP465 MAS treatment response and remission rates from those studies. Methods: Adults with Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision–defined ADHD were randomized to SHP465 MAS (12.5–75 mg) or PBO in a 7-week dose-optimization study and to SHP465 MAS (25, 50, or 75 mg) or PBO in a 6-week fixed-dose study. Response was examined using three definitions (definition 1: ≥30% ADHD-RS-IV-TS reduction + Clinical Global Impressions-Improvement [CGI-I] rating of 1 or 2; definition 2: ≥50% ADHD-RS-IV-TS reduction + CGI-I rating of 1 or 2; definition 3: ADHD-RS-IV-TS ≤18). Remission was defined as ADHD-RS-IV-TS ≤12. The Kaplan–Meier analyses assessed time to response or remission. Results: The intent-to-treat populations included 136 SHP465 MAS and 132 PBO participants in the dose-optimization study and 302 SHP465 MAS and 103 PBO participants in the fixed-dose study. Percentages of participants meeting response criteria (SHP465 MAS vs. PBO) at the final treatment week in the dose-optimization and fixed-dose studies, respectively, were 66.0% versus 31.6% and 72.7% versus 28.3% (definition 1); 47.9% versus 27.6% and 60.6% versus 16.7% (definition 2); and 54.3% versus 30.3% and 52.6% versus 18.3% (definition 3). The remission criterion (SHP465 MAS vs. PBO) at the final treatment week was met by 37.2% versus 19.7% of participants in the dose-optimization study and 39.7% versus 10.0% of participants in the fixed-dose study. Times to response and remission favored SHP465 MAS over PBO in both studies (all nominal log-rank p < 0.0001). Conclusion: These post hoc analyses indicate that SHP465 MAS was associated with greater response and remission rates than PBO in adults with ADHD, with times to response and remission also nominally favoring SHP465 MAS.