Efficacy and tolerability of lisdexamfetamine dimesylate (NRP-104) in children with attention-deficit/hyperactivity disorder: A Phase III, multicenter, randomized, double-blind, forced-dose, parallel-group study

Abstract Background: Lisdexamfetamme dimesylate (LDX) is a therapeutically inactive amphetamine prodrug. It was developed with the goal of providing an extended duration of effect that is consistent throughout the day, with a reduced potential for abuse, overdose toxicity, and drug tampering. Following ingestion, the pharmacologically active d-amphetamine molecule is gradually released by rate-limited hydrolysis. Objectives: The aims of this study were to assess the efficacy and tolerability of LDX in school-aged children with attention-deficit/hyperactivity disorder (ADHD) treated in the community, and to characterize the duration of action of LDX compared with placebo. Methods: This Phase III, multicenter, randomized, double-blind, forced-dose, parallel-group study was conducted at 40 centers across the United States. Male and female children aged 6 to 12 years with ADHD were randomly assigned to receive LDX 30, 50, or 70 mg with forced-dose titration, or placebo, PO QD for 4 weeks. Efficacy was assessed using the ADHD Rating Scale Version IV (ADHD-RS-IV), the Conners' Parent Rating Scale (CPR′), and the Clinical Global Impression of Improvement scale. Tolerability was assessed throughout the study. Results: Of the 290 randomized patients (201 boys, 89 girls; mean [SD] age, 9 [1.8] years), 230 completed the trial (LDX 30 mg, n=56; LDX 50 mg, n=60; LDX 70 mg, n=60; and placebo, n=54). The most common reasons for study discontinuation (n = 60) were lack of efficacy (LDX 30 mg, 1%; LDX 50 mg, 0%; LDX 70 mg, 1 %; and placebo, 17%) and adverse events (AEs) (LDX 30 mg, 9%; LDX 50 mg, 5%; LDX 70 mg, 14%; and placebo, 1%). Significant improvements in ADHD-RS-IV scores were seen with all doses of LDX compared with placebo (all, P P Conclusion: In this population of children with ADHD, treatment once daily with the prodrug LDX at doses of 30 to 70 mg appeared to be effective and had a tolerability profile similar to those of currently marketed extended-release stimulants.