Bivalirudin is a direct thrombin inhibitor used as an anticoagulant in patients undergoing percutaneous coronary intervention (PCI), particularly for those with or at risk of heparin-induced thrombocytopenia. It is a synthetic 20-amino acid peptide that binds directly and reversibly to both the catalytic site and the exosite 1 of thrombin, thereby inhibiting thrombin-mediated conversion of fibrinogen to fibrin and platelet activation. Administered intravenously, bivalirudin offers predictable anticoagulant effects with a short half-life, allowing for rapid onset and offset of action.

Bivalirudin is a synthetic, 20-amino acid peptide analogue of hirudin. As a bivalent direct thrombin inhibitor, it binds simultaneously to both the active catalytic site and the exosite 1 of thrombin. By occupying both binding sites, bivalirudin prevents thrombin-mediated conversion of fibrinogen to fibrin, activation of coagulation factors V, VIII, and XIII, and thrombin-induced platelet activation. Importantly, it inhibits both free and clot-bound thrombin. Unlike heparin, it does not require antithrombin III as a cofactor and is not neutralized by platelet factor 4.