Evaluation of SPN-812 (Viloxazine Extended-release Capsule) in Preschool-age Children With ADHD

This study will evaluate the efficacy and safety of SPN-812 (viloxazine extended release) in children 4 to 5 years of age with ADHD.

This is a randomized, double-blind, placebo-controlled, multicenter, 2-arm (1:1), parallel-group, efficacy and safety/tolerability fixed-dose study of SPN-812 in preschool-age children (4 to 5 years old) with ADHD. Participants will be screened for eligibility for up to 4 weeks. Eligible participants will be treated with study medication for 6 weeks. The total duration of the study is up to 10 weeks.

Eligibility Criteria:
Inclusion Criteria:

1. Is male or female between 4 years 0 months and 5 years 9 months of age at Screening and considered medically healthy.
2. Subject's parent(s) or legal guardian(s)/representative(s) is (are) willing and able to provide written informed consent, including a signed Informed Consent Form and documentation of assent (if applicable) by the subject before completing any study related procedures.
3. Has a primary diagnosis of ADHD according to DSM-IV-TR criteria and confirmed with the Kiddie Schedule for Affective Disorders and Schizophrenia - Present and Lifetime Version (K-SADS-PL).
4. Has an ADHD-RS-IV-P Total Score of ≥ 28 (males) or ≥ 24 (females) at Screening and at Baseline (Day 1).
5. Has a CGI-S score of ≥ 4 (moderate or worse) at Screening and at Baseline (Day 1).
6. Has undergone an adequate course of non-pharmacologic treatment or is having symptoms severe enough to warrant pharmacologic treatment without prior non-pharmacologic treatment.
7. Is participating in a structured group activity (e.g., preschool, kindergarten, sports, Sunday school or child care program) so as to assess symptoms and impairment in a setting outside the home.
8. Is not currently receiving a behavioral intervention for ADHD at the time of screening nor plans to receiving a behavioral intervention for ADHD throughout their study (if subject is receiving a behavioral interventions for another psychiatric disorder or disorders, their eligibility will be evaluated on a case-by-case basis).
9. For subjects who are on ADHD medication at screening, but who's ADHD symptoms are not well controlled on current ADHD medication are allowed in the study if they meet all other inclusion/exclusion criteria
10. Has no current condition in the opinion of the Investigator that could confound safety assessments or increase participant risk.
11. Has lived with the same parent(s) or legal guardian(s) for greater than or equal to 6 months.
12. Has a body weight ≥5th percentile for age and sex at Screening and Baseline.

Exclusion Criteria:

1. Has a current diagnosis of a major psychiatric disorder.
2. Has a current diagnosis of a major neurological disorder. Subjects with seizures or with a history of seizure-like events, or with a family history of seizure disorder (immediate family, i.e., sibling, parent) are excluded. Febrile seizures are not exclusionary and will be assessed on a case-by-case basis, however, a history of complex febrile seizures is exclusionary. If for any reason the subject received medication for a febrile seizure, this will be exclusionary.
3. History of Bipolar Disorder diagnosed in a first degree relative.
4. Has global development delay or intellectual disability by medical history.
5. Has a current diagnosis of a significant (per Investigator's evaluation and/or judgement) systemic disease.
6. Has body mass index \> 95th percentile for the subject's age and gender.
7. Has a resting blood pressure and heart rate\* measurement (average of the 3 'sitting' vital signs readings) greater than or equal to 95th percentile for age at screening or baseline. \* Note: The heart rate obtained during Vital Signs refers to "pulse rate".
8. Has a clinically significant electrocardiogram findings at screening.
9. Has history of allergic reaction, hypersensitivity or intolerance to viloxazine.
10. Has an allergy to applesauce or cannot swallow capsules and applesauce.
11. Any food allergy, intolerance, restriction or special diet that, in the opinion of the Investigator, could contraindicate the subject's participation in the study.
12. Received any investigational drug within the longer of 30 days or 5 half-lives prior to Day 1 dosing with SM.
13. Positive drug test at Screening. A positive test for amphetamines is allowed for subjects receiving a stimulant ADHD medication at Screening. The subject will be required to discontinue the stimulant for the duration of the study, beginning at least 1 week prior to the Baseline Visit.
14. Use of prohibited concomitant medications including known CYP1A2 substrates (e.g., theophylline, melatonin) during the screening period or anticipated for the duration of the study.
15. Any reason that, in the opinion of the Investigator, would prevent the subject from participating in the study.