This is a open-label, single ascending dose, pharmacokinetic, and tolerability study of NFC-1 in Children and Adolescents (Ages 6-17 Years) with ADHD.

Inclusion Criteria:

1. Subject and parent/legally authorized representative (LAR) are able to speak English fluently and have provided written informed consent, and assent (as applicable) for this study.
2. Subject is 6 to 17 years inclusive at the time of consent/assent.
3. Subject is male, female of non-childbearing potential or non-pregnant, non-lactating female of childbearing potential who agrees to comply with any applicable contraceptive requirements 2 weeks prior to administration of IP and throughout the study.
4. Subject meets Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for a primary diagnosis of ADHD based on a M.I.N.I. International Neuropsychiatric Interview.
5. Subject is considered "healthy". Healthy status is defined by absence of evidence of any active or chronic disease other than their ADHD following a detailed medical and surgical history, a complete physical examination.
6. Subject has the ability to swallow a capsule of investigational product whole.

Exclusion Criteria:

1. Subject has a history of any hematological, hepatic, respiratory, cardiovascular, renal, neurological, or psychiatric disease, gall bladder removal, or current or recurrent disease other than their ADHD.
2. Subject has a current or relevant history of physical or psychiatric illness, or any medical disorder that may require treatment.
3. Subject has a current, controlled or uncontrolled, comorbid psychiatric diagnosis with significant symptoms.
4. Subject is considered a suicide risk in the opinion of the investigator, has previously made a suicide attempt, or is currently demonstrating active suicidal ideation.
5. Subject has used an investigational product, been enrolled in a clinical study including vaccines, or had any changes in eating habits, within 30 days prior to the first dose of investigational product.
6. Subject has a positive screen for alcohol or drugs of abuse, or a positive hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV), or HIV antibody screen.
7. Subject previously was an adolescent (12-17) who was either a screen failure, or enrolled or participated in this study or another NFC1 clinical study.
8. Subject is currently taking any medication that might confound the results of safety assessments conducted in the study.
9. Subject has a concurrent chronic or acute illness, disability, or other condition that might confound the results of safety assessments conducted in the study.
10. Subject is unwilling to discontinue current ADHD medication to participate in the study.
11. Subject has a clinical laboratory abnormality that indicates clinically significant hematologic, hepatobiliary, or renal disease.