Efficacy and Safety of Dexmethylphenidate Extended-Release Capsules in Adults with Attention-Deficit/Hyperactivity Disorder

Background This multicenter, randomized, fixed-dose, double-blind, placebo-controlled study evaluated efficacy of extended-release dexmethylphenidate (d-MPH-ER) in adults with attention-deficit/hyperactivity disorder (ADHD). Methods Randomized adults with ADHD (n = 221) received once-daily d-MPH-ER 20 mg, 30 mg, or 40 mg or placebo for 5 weeks. The primary efficacy variable was change from baseline to final visit in DSM-IV ADHD Rating Scale (ADHD-RS) total score. Secondary efficacy parameters included the proportion of patients with improvement ≥30% in ADHD-RS total score and final scores on Clinical Global Impressions-Improvement (CGI-I) scale. Results Of 218 evaluable patients, 184 completed the study. All d-MPH-ER doses were significantly superior to placebo in improving ADHD-RS total scores. Placebo scores improved by 7.9; d-MPH-ER, 20 mg, improved by 13.7 (p = .006); d-MPH-ER, 30 mg, improved by 13.4 (p = .012); and d-MPH-ER, 40 mg, improved by 16.9 (p < .001). Overall distribution of CGI-I ratings at final visit was significantly better with each d-MPH-ER dosage than with placebo. There were no unexpected safety or tolerability concerns, based on experience with racemic methylphenidate (MPH) in adults and dexmethylphenidate (d-MPH) in children. Conclusions Once-daily d-MPH-ER at 20 mg, 30 mg, or 40 mg is a safe and effective treatment for adults with ADHD.