Prasugrel/Clopidogrel Maintenance Dose Washout Study

Inclusion Criteria

• Male or female subjects >/= 18 years and /= 60 kg
• On aspirin therapy (81 mg to 325 mg daily) at the time of screening and able to maintain a consistent aspirin dosing regimen from the baseline visit through the final study visit
• Subjects who do not have contraindications for a thienopyridine (ie, prasugrel, clopidogrel or ticlopidine), and have a history of stable atherosclerosis represented by Coronary Artery disease, defined as any of the following:
• chronic stable angina
• Prior history of acute coronary syndrome (>/= 30 days before screening) including unstable angina or acute myocardial infarction (ST elevation Myocardial Infarction [STEMI] or non-ST elevation Myocardial Infarction [NSTEMI]), not currently prescribed or currently on thienopyridine therapy;
• Previous coronary revascularization including percutaneous transluminal coronary angioplasty (PTCA), stent, or coronary artery bypass grafting (CABG) coronary artery disease (>/= 50% obstruction) in at least one coronary vessel after angiography
• Female subjects who meet one of the following:
• Women of childbearing potential with a negative serum pregnancy test at screening who are not breast feeding, do not plan to become pregnant during the study, and agree to use an approved method of birth control during the study. Approved methods of birth control are oral, path, injectable or implantable hormonal contraception, intrauterine device, diaphragm plus spermicide, or female condom plus spermicide. Abstinence, partner's use of condoms, and partner's vasectomy are NOT acceptable methods of contraception.
• Women who have been postmenopausal for at least 1 year or have had a hysterectomy, bilateral salpingo-oophorectomy, or tubal ligation at least 6 months prior to signing the informed consent form.
• Subjects with a competent mental condition to provide written informed consent before entering the study.

Exclusion Criteria

• Any other formal indication for the use of a thienopyridine.
• Subjects with a history of refractory ventricular arrhythmias.
• Subjects with a history of an implantable defibrillator device.
• Subjects with a history or evidence of congestive heart failure (New York Heart Association [NYHA] Class III or above) within 6 months prior to screening.
• Subjects with significant hypertension (systolic blood pressure >180 mmHg or diastolic blood pressure >110 mmHg) at either the time of screening or baseline assessment.
• Bleeding Risk Exclusion Criteria:
• Any known contraindication to treatment with an anticoagulant or antiplatelet agent
• Prior history or clinical suspicion of cerebral vascular malformations, intracranial tumor, transient ischemic attack (TIA), or stroke, or recent history (within 3 months) of head trauma
• Prior history or presence of significant bleeding disorders (eg, hematemesis, melena, severe or recurrent epistaxis, hemoptysis, hematuria, or intraocular bleeding)
• History (within the last 5 years) or presence of gastric ulcers. Previous history of duodenal ulcer is acceptable but must have been successfully surgically or medically treated with no further evidence of disease in the past 6 months (from screening).
• Prior history of abnormal bleeding tendency (ie, prolonged bleeding on dental extraction, tonsillectomy, or previous surgical procedure)
• Known prior history of thrombocytopenia (platelet count 500,000/mm³) or recent history (within six months) of hemoglobin /= 3 times the upper limit of normal (ULN) laboratory reference range; or bilirubin >/= 2 times the ULN of laboratory reference range at screening
• Subjects who are unreliable and unwilling to make themselves available for the duration of the study and who will not abide by the research unit policy and procedure and study restrictions
• Subjects who have had an angiogram </= 7 days before randomization