Rationale : Clopidogrel is a specific and irreversible of the P2Y12 platelet receptor leading to an inhibition of platelet aggregation. Clopidogrel is a prodrug that must be converted into an active metabolite that selectively and irreversibly binds to the P2Y12 platelet membrane receptor. As a consequence, a loading dose of 300 mg is necessary in percutaneous coronary intervention and in acute coronary syndrome, situations which require a rapid inhibition of platelet aggregation due to the high thrombotic risk.