Bivalirudin is best described as which agent?

• A. A direct thrombin inhibitor used during PCI
• B. A glycoprotein IIb/IIIa inhibitor
• C. An antiplatelet that inhibits ADP receptors
• D. A factor Xa inhibitor

Answer: (A)

Bivalirudin is a direct thrombin inhibitor, meaning it binds thrombin itself and stops its ability to convert fibrinogen to fibrin. It blocks both free thrombin in the circulation and thrombin that is already bound in a clot, which helps prevent clot formation during percutaneous coronary intervention. This distinguishes it from other drug classes: GP IIb/IIIa inhibitors prevent platelet aggregation by blocking the final common pathway of platelet activation, not coagulation; antiplatelets that inhibit ADP receptors (like clopidogrel) reduce platelet activation rather than thrombin activity; and factor Xa inhibitors reduce thrombin generation upstream by inhibiting factor Xa, rather than inhibiting thrombin directly. Bivalirudin’s characteristics—direct, rapid action with a short half-life—make it suitable for anticoagulation during PCI.