A Study of Delayed and Extended Release Formulation of Dextroamphetamine Sulfate (HLD100) in Children With ADHD

Inclusion Criteria: * Subjects must have a diagnosis of ADHD as defined by DSM-5 criteria with confirmation using the Mini International Neuropsychiatric Interview for Children and Adolescents (MINI-KID). * Subjects must demonstrate mild-to-moderate impairment of ADHD symptoms and function per the following at screening (V1) and/or baseline (V2): * ADHD-RS-IV score at or above the 90th percentile normalized for sex and age in total score and ≥24 at Baseline; * CGI-S score ≥4; * Subject body weight must be ≥20 kg. * Subject must be considered clinically appropriate for treatment with amphetamine and HLD100, including prior treatment experience with an amphetamine product, and ability to swallow treatment capsules. Exclusion Criteria: * History of, or current, medical condition or laboratory result which, in the opinion of the investigator, unfavorably alters the risk-benefit of study participation, may jeopardize subject safety, or may interfere with the satisfactory completion of the study and study-related procedures. * Serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, or other cardiac problems that may place the subject at increased vulnerability to the sympathomimetic effects of a stimulant drug. * History of seizure disorder (except febrile seizures prior to age 5 and with last occurrence at least 1 year prior to study participation), Tourette's disorder, or intellectual disability of minor severity or greater (DSM-5 criteria). * History of psychosis, bipolar disorder, anorexia nervosa, bulimia, or suicide attempt. Current depression, anxiety, conduct/behavior disorder, substance use disorder, or other psychiatric condition which, in the investigator's opinion, may jeopardize subject safety or may interfere with the satisfactory completion of the study and study-related procedures. * Active suicidal ideation as evidenced by an ideation score of 2 or greater on the C-SSRS. * History of severe allergic reaction or intolerance to amphetamine.