Efficacy and Safety of a Long-Acting Multilayer-Release Methylphenidate Formulation (PRC-063) in the Treatment of Adolescent Attention-Deficit/Hyperactivity Disorder: A Randomized, Double-Blind Clinical Trial with a 6-Month Open-Label Extension

Objectives: To study the safety and efficacy of the long-acting methylphenidate formulation PRC-063 in adolescents with attention-deficit/hyperactivity disorder (ADHD). Methods: Adolescents 12 to ≤17 years who me Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 criteria for ADHD and had a baseline ADHD Rating Scale DSM-5 (ADHD-5-RS) score ≥24 participated in a randomized, double-blind, placebo-controlled, fixed-dose, parallel-group study. Participants were randomized 1:1:1:1:1 to receive placebo or one of four doses of PRC-063 once daily for 4 weeks. The primary endpoint was change from baseline in least-squares mean clinician-rated ADHD-5-RS total score for PRC-063 (all doses combined) versus placebo. Other efficacy assessments included Conners third Edition: Self-Report (C3SR) and Clinical Global Impression-Improvement (CGI-I). A subset of double-blind study participants entered a subsequent open-label, dose-optimized study. Safety outcomes in both studies included treatment-emergent adverse events (TEAEs). Results: Three hundred fifty-four participants were included in the primary analysis. The least-squares mean change from baseline in ADHD-5-RS total score was -15.17 for PRC-063 versus -10.98 for placebo (least-squares mean difference -4.2, p  = 0.0067). For individual PRC-063 doses, improvements in ADHD-5-RS total score versus placebo were significant for 45 mg ( p  = 0.0155) and 70 mg ( p  = 0.0401), but not for 25 or 85 mg. A significant improvement for PRC-063 versus placebo was recorded for C3SR Inattention ( p  = 0.0168), but not for the other C3SR subscales. About 52.7% of participants randomized to PRC-063 were responders based on CGI-I versus 32.4% of those randomized to placebo ( p  = 0.0004). Further improvements in ADHD symptoms based on ADHD-5-RS were observed from 1 month through 6 months of open-label treatment ( p  < 0.0001). There were two serious adverse events (both during the open-label study), one of which (aggressive behavior) was assessed as related to study drug. The only TEAEs that occurred in >10% of participants during double-blind treatment were decreased appetite (20.1%) and headache (15.0%). Most TEAEs were of mild or moderate severity. Conclusion: PRC-063 significantly improved ADHD symptomatology in adolescents. It was generally well tolerated, with an AE profile consistent with other long-acting stimulants. NCT02139111 and NCT02168127.