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

Inclusion Criteria:

1. Is male or female 4 years 0 months of age to less than or equal to 5 years 9 monthsof age at Visit 1 (Screening) and considered medically healthy.

2. Subject's parent(s) or legal guardian(s)/representative(s) is (are) willing and ableto provide written informed consent before completing any study related 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 Visit 1 (Screening) and at Visit 2 (Baseline).

5. Has a CGI-S score of ≥ 4 (moderate or worse) at Visit 1 (Screening) and at Visit 2 (Baseline).

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, summer camp or childcare program) at least 2 days a weekduring study so as to assess symptoms and impairment in a setting outside the home.

8. Has not initiated any behavioral intervention/therapy within 30 days of Visit 1 (Screening) and does not plan to initiate any new or discontinue any ongoingbehavioral intervention/therapy during the study (e.g., subject is eligible ifbehavioral intervention/therapy is initiated 30 or more days prior to Visit 1 [Screening] and continues with a similar duration/frequency throughout their study).

9. Subjects who are on ADHD medication at Visit 1 (Screening), but whose ADHD symptomsare not well controlled on current ADHD medication (e.g., meets Inclusion Criterion

#4), meet all other inclusion/exclusion criteria, and discontinues ADHD medicationat least 7 days prior to the day of Visit 2 (Baseline) are eligible to participate.

10. Has no current condition in the opinion of the Investigator that could confoundefficacy assessments, safety assessments or increase participant risk.

11. Has lived with the same parent(s) or legal guardian(s) or has lived under a sharedliving arrangement (e.g., joint legal custody) for greater than or equal to 6 monthsprior to Visit 1 (Screening).

12. Has a body weight ≥5th percentile for age and sex at Visit 1 (Screening) and Visit 2 (Baseline).

Exclusion Criteria:

1. Has a diagnosis at Screening (per K-SADS-PL) of another psychiatric disorder that isconsidered to be the primary diagnosis rather than ADHD or has a comorbidpsychiatric disorder secondary to ADHD that, in the opinion of the investigator (after consulting medical monitor), will likely interfere with study treatmentadherence and/or impact study results.

2. Has a current diagnosis of a major neurological disorder. The eligibility of thosewho have seizures, a history of seizure-like events (e.g., syncope, myoclonus,severe muscle spasms), a family history of seizure disorder (immediate family, i.e.,sibling, parent), and/or febrile seizures will be assessed on a case-by-case basisafter consulting the medical monitor.

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 sex at Visit 1 (Screening) or Visit 2 (Baseline).

7. Has a mean resting systolic and diastolic blood pressure* that are both >95thpercentile for age sex, and height and has a mean resting pulse rate* that is >95thpercentile for age and sex (males: >117 bpm; females: >122 bpm) at Visit 1 (Screening) or Visit 2 (Baseline). * Note: The mean of three measurements whileseated.

8. Has a clinically significant electrocardiogram finding(s) at Visit 1 (Screening).

9. Is currently taking SPN-812 for ADHD, has previously taken SPN-812 for ADHD, butdiscontinued due to a lack of efficacy or adverse reactions, or has history ofallergic reaction, hypersensitivity or intolerance to viloxazine.

10. Has an allergy to or cannot swallow pudding and applesauce and cannot swallow intactcapsule whole.

11. Has any food allergy, intolerance, restriction or special diet that, in the opinionof the Investigator, could contraindicate the subject's participation in the study.

12. Has received any investigational drug within the longer of 30 days or 5 half-livesprior to Visit 2 (e.g., first dose of study medication).

13. Has a positive urine drug test at Visit 1 (Screening). A positive test foramphetamines is allowed for subjects receiving a stimulant ADHD medication atScreening. The subject will be required to discontinue the stimulant for theduration of the study, beginning at least 7 days prior to Visit 2 (Baseline).

14. Is using of prohibited concomitant medications including known CYP1A2 substrates (e.g., theophylline, melatonin) during the Screening Period or (anticipated) for theduration of the study.

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

16. Has suicidal ideation ("Yes" indicated on C-SSRS question 4 or 5) or suicidalbehavior ("Yes" indicated on C-SSRS for any suicidal behavior) within 6 months priorto or the day of Visit 1 (Screening) or has attempted suicide ("Yes" indicated onC-SSRS for lifetime).