Which medication directly inhibits glycoprotein IIb/IIIa receptors on platelets to prevent aggregation?

• A. Abciximab
• B. Warfarin
• C. Heparin
• D. Clopidogrel

Answer: (A)

Directly inhibiting glycoprotein IIb/IIIa receptors on platelets blocks the final common pathway of platelet aggregation, since fibrinogen and von Willebrand factor can no longer bridge adjacent platelets. The medication that does this is abciximab, a monoclonal antibody fragment that binds to GPIIb/IIIa and prevents platelet–platelet crosslinking. It’s given intravenously in acute coronary syndromes and during percutaneous coronary intervention to reduce thrombotic complications, though it carries a significant bleeding risk and is used for a limited duration. The other drugs work through different mechanisms: warfarin and heparin target the coagulation cascade rather than the platelet receptor, while clopidogrel blocks the P2Y12 ADP receptor to reduce platelet activation without directly inhibiting GPIIb/IIIa.