A Study to Evaluate the Efficacy and Safety of Two Doses of PF-03654746 in Adults With Attention Deficit Hyperactivity Disorder (ADHD).

• Drug: PF-03654746
  
  Dosage Form: 0.5 mg capsules of PF-03654746 Dosage: 0.5 mg QD for Days 1-7, then 1.0 mg QD Days 8-14, then 2.0 mg QD Days 15-21
• Drug: Placebo capsules
  
  Dosage Form: matching placebo capsules Dosage: Subjects will take two placebo capsules each morning throughout the 3 week double-blind treatment placebo treatment period.
• Drug: PF-03654746
  
  Dosage Form: 0.5 mg capsules of PF-03654746 Dosage: 1 mg (2 x 0.5 mg capsules) of PF-03654746 given daily for three weeks

• Experimental: Flexible Dose
  
  Intervention: Drug: PF-03654746
• Placebo Comparator: Placebo
  
  Intervention: Drug: Placebo capsules
• Experimental: Fixed Dose
  
  Intervention: Drug: PF-03654746

Inclusion Criteria:

Subjects with a diagnosis of Attention Deficit Hyperactivity Disorder, based on clinical assessment and interview.

Male and female outpatients. Subjects with a diagnosis of Attention Deficit Hyperactivity Disorder, based on clinical assessment and interview.

Female subjects must be of non-childbearing potential.

Exclusion Criteria:

Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular (including hypertension), hepatic, neurologic, or allergic disease.

Current or lifetime history of psychosis or bipolar disorder; any current anxiety disorder (with the exception of social or specific phobia), or substance abuse or dependence in the past 6 months.

Current episode of Major Depression or episode within the last 6 months.