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

Inclusion Criteria:

1. Is male or female between 4 years 0 months and 5 years 9 months of age at Screeningand considered medically healthy.

2. Subject's parent(s) or legal guardian(s)/representative(s) is (are) willing and ableto provide written informed consent, including a signed Informed Consent Form anddocumentation of assent (if applicable) by the subject before completing any studyrelated procedures.

3. Has a primary diagnosis of ADHD according to DSM-IV-TR criteria and confirmed withthe Kiddie Schedule for Affective Disorders and Schizophrenia - Present and LifetimeVersion (K-SADS-PL).

4. Has an ADHD-RS-IV-P Total Score of ≥ 28 (males) or ≥ 24 (females) at Screening andat 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 havingsymptoms severe enough to warrant pharmacologic treatment without priornon-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 impairmentin a setting outside the home.

8. Is not currently receiving a behavioral intervention for ADHD at the time ofscreening nor plans to receiving a behavioral intervention for ADHD throughout theirstudy (if subject is receiving a behavioral interventions for another psychiatricdisorder 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 arenot well controlled on current ADHD medication are allowed in the study if they meetall other inclusion/exclusion criteria

10. Has no current condition in the opinion of the Investigator that could confoundsafety 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 orwith 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 notexclusionary and will be assessed on a case-by-case basis, however, a history ofcomplex febrile seizures is exclusionary. If for any reason the subject receivedmedication 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/orjudgement) 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 screeningor baseline. * Note: The heart rate obtained during Vital Signs refers to "pulserate".

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 ofthe 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 priorto Day 1 dosing with SM.

13. Positive drug test at Screening. A positive test for amphetamines is allowed forsubjects receiving a stimulant ADHD medication at Screening. The subject will berequired to discontinue the stimulant for the duration of the study, beginning atleast 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 durationof the study.

15. Any reason that, in the opinion of the Investigator, would prevent the subject fromparticipating in the study.