A higher degree of platelet inhibition remains the goal of peri-interventional and long-term anti-thrombotic therapy in patients with coronary artery disease. In clinical practice, patients undergoing percutaneous coronary intervention with stent implantation who are already on clopidogrel therapy get re-loaded with clopidogrel. This is based on prior observations showing that higher inhibition of platelet aggregation may be achieved by giving a loading dose of clopidogrel in patients with coronary artery disease while on chronic clopidogrel therapy. However, to date it is unknown if greater inhibition of platelet aggregation can be achieved by adding a prasugrel loading dose in patients on chronic prasugrel therapy. Therefore, understanding the pharmacodynamic implications of a prasugrel re-load strategy in patients on already on chronic prasugrel therapy will be useful.

Inclusion Criteria:

1. Patients with angiographically documented coronary artery disease.
2. Age between 18 to 74 years
3. On treatment with prasugrel 10mg/daily for at least 14 days.

Exclusion Criteria:

1. Blood dyscrasias or bleeding diathesis
2. Antiplatelet treatment with clopidogrel or ticlopidine
3. Recent antiplatelet treatment (< 14 days) with a glycoprotein IIb/IIIa antagonist
4. Platelet count <100x106/µL
5. Active bleeding or hemodynamic instability.
6. Unstable angina, acute or recent (<14 days) myocardial infarction.
7. Serum creatinine >2 mg/dL
8. Baseline ALT >2.5 times the upper limit of normal
9. Oral anticoagulation with a coumarin derivative
10. History of stroke, TIA or intracranial bleeding
11. Weight <60kg
12. Pregnant females