Dyanavel® XR Extended-Release Oral Suspension in the Treatment of Children With ADHD: A Laboratory School Study

Inclusion Criteria: 1. Males or females aged 6 to 12 years at the time of screening, inclusive 2. Diagnosed with ADHD by a psychiatrist within 6 months of study enrolment or newly diagnosed with ADHD using the DSM-5 criteria for ADHD 3. An ADHD-RS-5 score at Screening ≥90th percentile for sex and age in at least one of the following categories: 1. Hyperactive-impulsive subscale, 2. Inattentive subscale, or 3. Total score. Subjects who do not meet this criteria at screening can have ADHD-RS-5 repeated at baseline, after washout of stimulant medication for a minimum of 24 hours prior to baseline. 4. In the clinical judgment of the Investigator, the subject must be in need of pharmacological treatment for ADHD. 5. Females of childbearing potential must be non-lactating and must have a negative serum pregnancy test at screening 6. Provide written informed consent (parent/guardian) and assent (child aged 10 - 12 years only) prior to participation in the study Exclusion Criteria: 1. Diagnosed with any DSM-5 active disorder (other than ADHD) with the exception of specific phobias, learning disorders, motor skills disorders, communication disorders, oppositional defiant disorder, elimination disorders, and sleep disorders 2. Known history of chronic medical illnesses including severe hypertension, untreated thyroid disease, peripheral vasculopathy, known structural cardiac disorders, serious cardiac conditions, serious arrhythmias, cardiomyopathy, known family history of sudden death 3. Known history or presence of significant renal or hepatic disease, as indicated by clinical laboratory assessment (liver function test results ≥ two times the upper limit of normal, blood urea nitrogen, or creatinine). 4. Clinically significant abnormal ECG or cardiac findings on physical examination (including the presence of a pathologic murmur) 5. Use of the following medications within 30 days of Baseline Visit: * MAOI - monoamine oxidase inhibitors (e.g., Selegiline, isocarboxazid, phenelzine, tranylcypromine) * Tricyclic Antidepressants (e.g. Desipramine, protriptyline) 6. Use of the following medications within 3 days of Baseline Visit * Gastrointestinal acidifying agents (e.g., guanethidine, reserpine, glutamic acid HCl, ascorbic acid) * Urinary acidifying agents (e.g., ammonium chloride, sodium acid phosphate, methenamine salts) 7. Use of atomoxetine within 14 days of Baseline Visit 8. Planned use of prohibited drugs or agents from the Screening visit through the end of the study 9. Abnormal clinically significantly laboratory test value at screening that, in the opinion of the Investigator, would preclude study participation 10. Known history of allergy/hypersensitivity to amphetamine or any of the components of Dyanavel XR, or topical anaesthetics 11. Known history of lack of response to amphetamine 12. Parent or guardian's inability or unwillingness to follow directions of the Investigator or study research staff. 13. Any uncontrolled medical condition that in the opinion of the Investigator would preclude study participation 14. History of significant illness requiring hospitalization, or surgery requiring anaesthetics within 30 days of Baseline Visit