Indications
Bivalirudin is primarily indicated for managing patients with heparin-induced thrombocytopenia and for preventing thrombosis. It is also recommended for individuals undergoing percutaneous coronary intervention (PCI). Moreover, bivalirudin is used in cases of moderate to high-risk acute coronary syndromes, particularly in instances of unstable angina or non-ST segment elevation, when a PCI is planned.
Pharmacodynamics
Bivalirudin functions by directly inhibiting thrombin, a key enzyme in the coagulation process. It achieves this by specifically binding to both the catalytic site and the anion-binding exosite of thrombin, affecting both circulating and clot-bound forms. This binding is reversible; thrombin can slowly cleave the bond with bivalirudin, thus restoring its active configuration.
Absorption
Upon intravenous administration, bivalirudin demonstrates linear pharmacokinetics. When a 1 mg/kg intravenous bolus is followed by a continuous 2.5 mg/kg/hr infusion over four hours, the mean steady state concentration of bivalirudin is approximately 12.3 ± 1.7 mcg/mL.
Metabolism
Bivalirudin primarily undergoes proteolytic cleavage, with approximately 80% of the drug being metabolized through this process.
Mechanism of Action
Bivalirudin functions by inhibiting thrombin through binding simultaneously to its catalytic site and anion-binding exosite. Thrombin, a serine proteinase, is pivotal in thrombosis, as it facilitates the conversion of fibrinogen into fibrin monomers and the activation of Factor XIII to XIIIa, enabling the formation of a covalently cross-linked fibrin framework that stabilizes the thrombus. Moreover, thrombin's role extends to activating Factors V and VIII, which further propagate thrombin generation, as well as activating platelets, thereby enhancing aggregation and granule release.
