This is a randomized, double-blind, parallel group, placebo-controlled, dose optimized, phase 3 study to evaluate the safety and efficacy of PRC-063 in the treatment of ADHD in adults

Inclusion Criteria:

1. Males or females 18 to 60 years of age
2. Diagnosis of ADHD (any type: combined, predominately hyperactive impulsive type or predominately inattentive type) by a psychiatrist, psychologist, or licensed allied healthcare professional
3. Subject is willing and able to comply with all the protocol requirements.

Exclusion Criteria:

1. Primary and/or comorbid psychiatric diagnosis other than ADHD
2. Has a current or recent history of hypertension, symptomatic cardiovascular disease, advanced arteriosclerosis, structural cardiac abnormality, cardiomyopathy, serious heart rhythm abnormalities, coronary artery disease, or other serious cardiac problems that may place them at increased vulnerability to the sympathomimetic effects of a stimulant drug;
3. Has used any investigational drug within 30 days of the screening visit;