Safety and Efficacy of Centanafadine Sustained-Release in Adults With Attention-Deficit Hyperactivity Disorder: Results of Phase 2 Studies

PURPOSE: Two phase 2 studies evaluated the efficacy and tolerability of centanafadine sustained-release (SR) for adults with attention-deficit/hyperactivity disorder (ADHD). PATIENTS AND METHODS: In a phase 2a, flexible-dose, single-blind study, 41 male patients (aged 18‒55 years) with a diagnosis of ADHD (based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) were titrated with centanafadine-SR 200‒300, 400, or 500 mg/d for 2 weeks, and then were treated with the titrated dose for 2 weeks. In a phase 2b, randomized, double-blind, placebo-controlled, crossover study, 85 male and female patients (aged 18‒60 years) with a diagnosis of ADHD (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) were titrated to target doses of centanafadine-SR 400, 500, 600, or 800 mg/d over the course of 1 week, and then received their titrated dose for 3 weeks. The primary outcome in both studies was mean total ADHD Rating Scale-IV (ADHD-RS-IV) score. RESULTS: In the phase 2a study, mean ADHD-RS-IV total score decreased by 21.41 (standard deviation 10.74) from the start of active centanafadine-SR treatment to the end of week 4 (P<0.001). In the phase 2b study, centanafadine-SR treatment resulted in a statistically significant improvement in ADHD-RS-IV from baseline to week 3 compared with placebo (least-squares mean −16.5 vs −8.4; P<0.001; effect size 0.66), with significant efficacy demonstrated as early as week 1. Centanafadine-SR was generally well tolerated at doses ≤400 mg. Most treatment-emergent adverse events (TEAEs) were mild or moderate; decreased appetite, headache, and nausea were the most frequently reported. In the 2 studies, 13 of 120 patients discontinued centanafadine-SR due to TEAEs; however, only 1 patient who received ≤400 mg discontinued due to a TEAE. No serious TEAEs were reported at any dose. CONCLUSION: These results support the continued development of centanafadine-SR at doses up to 400 mg/d.