KP415 Open-Label Safety Study in Children (6-12 Years of Age) With ADHD

The study will consist of a Screening Period, a Dose Optimization Phase, and a Treatment Phase and a Follow-Up Visit, as follows: * Screening Period: Subjects will undergo a screening period up to 30 days prior to entering the Dose Optimization Phase. * Dose Optimization Phase: During the Dose Optimization Phase, subjects will be titrated to doses of 20, 30 or 40 mg KP415 based on tolerability and best individual dose-response in the opinion of the Investigator. * Treatment Phase: Eligible subjects will receive single daily doses of KP415 for up to approximately 360 days (up to approximately 12 months). The dose of KP415 given in the Treatment Phase will be the dose of KP415 at the end of the Dose Optimization Phase. During the Treatment Phase, the dose of KP415 may be changed based on individual tolerability and best dose response (to either 20, 30, or 40 mg KP415 capsules). Safety, efficacy and sleep behavior assessments will be performed. * Follow-Up Visit: 3 ±2 days after administration of the last dose of the Treatment Phase, subjects will enter a Follow-Up Visit to evaluate safety parameters.