Clopidogrel is an antithrombic compound whose active metabolite is a selective, irreversible antagonist of the platelet purinergic P2Y12 receptor (IC50 = 100 nM). Clopidogrel inhibits ADP-induced platelet aggregation ex vivo and functions as a prodrug whereupon biotransformation to its active metabolite via CYP2C19 in the liver enables its anti-aggregating activity. Marketed under the name Plavix , clopidogrel in combination with aspirin has been shown to be beneficial in the prevention of vascular ischemic events for patients without deficiencies in CYP2C19-related metabolism.