klopidogrel

Klopidogrel, commonly known as clopidogrel, is an oral antiplatelet medication in the thienopyridine class. It is a prodrug that is activated in the liver by cytochrome P450 enzymes, principally CYP2C19. The active metabolites irreversibly inhibit the P2Y12 adenosine diphosphate (ADP) receptor on platelets, reducing platelet aggregation for the life of the platelet.

Clinically, clopidogrel is used to reduce the risk of stroke, myocardial infarction, and other vascular events in patients with atherosclerotic disease or after acute coronary syndromes. It is routinely prescribed with aspirin after certain cardiovascular procedures, such as percutaneous coronary intervention with stent placement, to prevent stent thrombosis. Typical maintenance dosing is 75 mg once daily, with a loading dose of 300–600 mg given in the setting of acute coronary syndrome or before PCI; duration of therapy depends on the indication and balancing of bleeding risk.

Adverse effects are dominated by bleeding. Common events include easy bruising, epistaxis, and gastrointestinal bleeding. Other potential effects include rash, and in rare cases neutropenia or thrombotic thrombocytopenic purpura. Clopidogrel is contraindicated in active major bleeding and used with caution in patients with high bleeding risk or significant hepatic impairment. Drug interactions that increase bleeding risk include NSAIDs and anticoagulants; some proton pump inhibitors may reduce activation of clopidogrel through CYP2C19 inhibition, leading clinicians to favor alternatives when feasible.

Klopidogrel was developed by collaboration between Sanofi and Bristol-Myers Squibb and was approved in the 1990s. It remains a widely used antiplatelet therapy, available under various brand names, with Plavix being the best known.