A Study to Assess the Effectiveness and Safety of Clonidine Extended-Release OnydaTM XR in Children With ADHD and ODD

This is a study to see how safe and effective OnydaTM XR is to treat Attention-Deficit/Hyperactivity Disorder (ADHD) in children aged 6 to 12 years who also have Oppositional Defiant Disorder (ODD). The trial will consist of a screening period of up to 28 days; a 35-day double-blind treatment period that includes a one week of the lowest dose of medication (0.1mg) given at bedtime, then three weeks at 0.2 mg, then one week at 0.1 mg and a follow-up phone call one week after stopping study medication. During the screening period, we will determine whether participants qualify to enroll in the study. Approximately 162 boys and girls aged 6 to 12 years, who are currently diagnosed with ADHD and ODD, are planned to be screened in order to complete approximately 124 subjects. Key Inclusion/Exclusion Criteria Participants will have a main diagnosis of ADHD and comorbid ODD based on a structured interview. They will also be required to have significant problems because of their ADHD and be in good health. They will not be able to take other medications for ADHD or any other mental health problems during the study. At the screening visit, participants and their parents will be asked about ADHD, ODD and other mental health symptoms. They will also give blood and urine samples, and complete an electrocardiogram and physical exam. Blood pressure and pulse rate will also be obtained. Parents will complete questionnaires about ADHD, ODD, and sleep. During the second visit, the doctor will ensure that participants continue to qualify for the study. Parents and participants will complete questionnaires. Parents will be shown how to dose the study medication. It is a liquid suspension. Participants will be seen weekly and will be asked about changes in health, new medications and parents will complete questionnaires while participants have blood pressure and pulse rate checked. At the last in-clinic study visit, participants will also have blood and urine samples taken and, complete an electrocardiogram and undergo a physical exam. Parents will complete questionnaires. One week after the last in-clinic visit