Abstract
Serdexmethylphenidate/dexmethylphenidate (SDX/d-MPH) is a novel methylphenidate formulation designed to provide rapid onset and sustained symptom control in attention-deficit/hyperactivity disorder (ADHD). This phase 3 study evaluated its efficacy, safety, and tolerability in Chinese children with ADHD. This multicenter, randomized, double-blind, placebo-controlled bridging study enrolled children aged 6-12 years who met DSM-5 criteria for ADHD. The primary endpoint was least squares mean (LSM) change from baseline to week 3 in ADHD Rating Scale-5 (ADHD-RS-5) total score, an 18-item DSM-5-based scale rating symptoms from 0 (never/rarely) to 3 (very often). Secondary endpoints included change from baseline to week 4 in ADHD-RS-5, and weekly changes in Clinical Global Impressions-Severity (CGI-S), Clinical Global Impressions-Improvement (CGI-I), and Weekly Ratings of Evening and Morning Behavior-Revised (WREMB-R). Safety was assessed throughout the study. Overall, 55 participants were randomized (SDX/d-MPH, n = 28; placebo, n = 27). At week 3, SDX/d-MPH demonstrated significantly greater improvement in ADHD-RS-5 total score versus placebo (between-group LSM change [standard error]: - 5.8 [2.58], p = 0.0292), with an effect size of 0.61, meeting the prespecified efficacy consistency criterion (≥ 0.25). At week 4, significant improvements versus placebo were observed across ADHD-RS-5 total score (- 8.4 [2.69]), inattention and hyperactivity-impulsivity sub-scores (- 4.4 [1.69] and - 3.7 [1.27], respectively), CGI-S (- 0.8 [0.28]), CGI-I (0.9 [0.27]), and WREMB-R total (- 3.7 [1.35]) and evening scores (- 3.2 [1.03]). Most treatment-emergent adverse events were mild to moderate, with no new safety signals. SDX/d-MPH significantly improved ADHD symptoms and was generally well tolerated in Chinese children, supporting extension of global trial results to this population. gov identifier: NCT06359899 (registered on 25 March 2024).