A Phase 4, Multicenter, 2-part Study Composed of a Randomized, Double-blind, Parallel-group, Placebo-controlled, Active-comparator, Dose-optimization Evaluation followed by a Open-label Evaluation to Assess the Safety and Efficacy of Guanfacine Hydrochloride Prolonged-release (SPD503) in Children and Adolescents aged 6 to 17 Years with Attention-deficit/Hyperactivity Disorder

This study is open to children and teenagers of all genders who are between 6 and 17 years old and have been diagnosed with ADHD.

There might be other specific health requirements or conditions that would mean someone could or could not join the study. These are important for safety and to make sure the study results are clear.

If you are interested, a study doctor would talk with you and your child to figure out if they meet all the necessary requirements to take part.

If you or your child decides to take part, the study will involve several visits to a clinic. You or your child might receive Intuniv at different doses, another ADHD medicine called atomoxetine, or a dummy pill. Neither you nor your study doctor will know which treatment is being given during the first part of the study; this is called 'double-blind'.

There will be regular assessments, which include things like checking their heart rate, blood pressure, weight, and height. They might also complete questionnaires about their ADHD symptoms and how they are feeling, and do some tasks on a computer or tablet that look at things like attention and reaction time. These assessments help the study team understand how the medicine is working and if there are any side effects.

After the first comparison part, there will be an 'open-label' part, where everyone will know they are receiving Intuniv. The total duration of the study will involve several months of treatment and follow-up appointments.