A Phase 3 Placebo-Controlled Trial of Once-Daily 400-mg and 600-mg SPN-812 (Viloxazine Extended-Release) in Adolescents with ADHD

Objectives: Three Phase 3 trials have demonstrated the efficacy and safety of SPN-812 in pediatric subjects with ADHD. Here, we report the results of a fourth trial.

Methods: Eligible adolescent subjects (N = 297) were randomized to SPN-812 (400- or 600-mg/day) or placebo. The primary efficacy endpoint was change from baseline (CFB) at end of study (EOS) in the ADHD Rating Scale-5 (ADHD-RS-5) Total score. Statistical analyses included sequential testing for multiple treatment comparisons. Key secondary endpoints included: Clinical Global Impression-Improvement (CGI-I) score at EOS and CFB at EOS in the Conners 3-Parent Short Form (Conners 3-PS) Composite T-score and Weiss Functional Impairment Rating Scale-Parent (WFIRS-P) Total average score.

Results: The CFB at EOS ADHD-RS-5 Total score (least square [LS] means ± SE) for 400-mg/day, 600-mg/day SPN-812, and placebo was -18.3 ± 1.36, -16.7 ± 1.39, and -13.2 ± 1.38, respectively. The difference vs. placebo was statistically significant only for the 400-mg/day SPN-812 treatment group (600 mg/day: p = 0.0712; 400 mg/day: p = 0.0082). Neither dose could be considered superior to placebo due to the use of statistical method of sequential testing. Significant improvements were observed on a number of secondary endpoints. SPN-812 was well tolerated at both doses, with <5% discontinuation rate due to adverse events.

Conclusions: Treatment with 400- but not 600-mg/day SPN-812 resulted in statistically significant improvement in the primary endpoint. The negative result seen in the 600-mg/day SPN-812 group was likely due to an unusually high placebo response. Safety data were consistent across all doses in the SPN-812 trials.