clopidogrel

Clopidogrel is a thienopyridine antiplatelet agent that irreversibly blocks the P2Y12 ADP receptor on platelets, preventing ADP-mediated platelet activation and aggregation. As a prodrug, it requires hepatic metabolism primarily by CYP2C19 to form its active metabolite. This mechanism complements aspirin's COX-1 inhibition, making dual antiplatelet therapy highly effective. Clinically, clopidogrel is used for secondary prevention in patients with established cardiovascular disease, including post-MI, stroke, or peripheral arterial disease. It's also essential in patients receiving coronary stents to prevent thrombosis. Key considerations include CYP2C19 genetic polymorphisms that can reduce drug efficacy (poor metabolizers have decreased cardiovascular protection), drug interactions with proton pump inhibitors (especially omeprazole), and increased bleeding risk. The drug has a slow onset (3-7 days to maximal effect) and prolonged duration of action (5-7 days after discontinuation due to irreversible binding). Loading doses (300-600mg) are used in acute settings to achieve faster antiplatelet effects.