Dose-Finding Study to Evaluate the Efficacy and Safety of Modafinil as Treatment for Adults With ADHD

The primary objective of the study is to determine whether modafinil at 255, 340, 425, or 510 mg'day is more effective than a placebo in alleviating the symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) in adults as determined by the change from baseline in the total score from the investigator-completed Adult ADHD Investigator Symptoms Rating Scale (AISRS) the at endpoint (last post-baseline observation \[week 9 or early termination\]).