SPN-812 (extended-release viloxazine) is a structurally distinct, bicyclic, Serotonin Norepinephrine Modulating Agent (SNMA) in development as a treatment for attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. This Phase 3, randomized, double-blind study (P302) evaluated the efficacy and safety of once-daily SPN-812 at doses of 200 and 400 mg compared to placebo in adolescents ages 12-17yrs with ADHD.

Inclusion criteria required subjects have a confirmed Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) ADHD diagnosis, ADHD-Rating Scale-5 (ADHD-RS-5) score ≥28, Clinical Global Impression-Severity score ≥4, and be free of ADHD medication ≥1 week before randomization. This investigation was conducted at 34 study sites in the United States. Subjects (N=310) were randomized 1:1:1 to placebo:200 mg SPN-812:400 mg SPN-812. The treatment period included up to 1 week of titration and 5 weeks of maintenance (intent-to-treat population: N=301; placebo=104, 200 mg=94, 400 mg=103). The primary efficacy endpoint was change from baseline (CFB) at end of study (EOS) in ADHD-RS-5 total score. Key secondary endpoints included Clinical Global Impression-Improvement (CGI-I) score at EOS, and CFB at EOS in Conners 3-Parent Short Form (Conners 3-PS) Composite T-score and Weiss Functional Impairment Rating Scale-Parent Form (WFIRS-P) total average score. Safety assessments included adverse events (AEs), laboratory tests, vital signs, physical exams, electrocardiograms, and the Columbia-Suicide Severity Rating Scale.

Compared to placebo, a significantly greater improvement in ADHD-RS-5 total score was observed in the 200 mg and 400 mg SPN-812 treatment group at EOS (p=0.0232, p=0.0091; respectively). Significant improvement in CGI-I score at EOS for both 200 mg and 400 mg SPN-812 compared to placebo was also observed (p=0.0042, p=0.0003; respectively). No significant change was observed at either dose compared to placebo in the Conners 3-PS Composite T-score (p=0.6854, p=0.0518; respectively), or the WFIRS-P total average score (p=0.2062, p=0.0519; respectively). The most common (≥5%) treatment-related AEs were somnolence, decreased appetite, fatigue, headache, and nausea.

In this study, SPN-812 met the primary objective for both the 200 and 400 mg doses, and a key secondary objective (CGI-I) for both the 200 and 400 mg doses. AE-related dropouts were ≤5%, indicating SPN-812 treatment was well tolerated.

This study is an encore of a poster presentation at the 2019 Annual Meeting of the American Academy of Child and Adolescent Psychiatry (AACAP).

This research was funded by Supernus Pharmaceuticals, Inc., Rockville, MD.