Bivalirudin
Synthetic 20-amino-acid analog of hirudin that directly and reversibly inhibits thrombin, used as an intravenous anticoagulant during percutaneous coronary intervention.
Overview
Thrombin is the central enzyme of the coagulation cascade, converting fibrinogen to fibrin and activating platelets. Bivalirudin is a bivalent, directly acting inhibitor: one end binds thrombin's catalytic site while the other binds its fibrinogen-recognition exosite, blocking both free and clot-bound thrombin. Unlike heparin, it does not require antithrombin and is not inactivated by platelet factor 4.
In the HORIZONS-AMI trial, bivalirudin monotherapy during primary PCI for ST-elevation myocardial infarction reduced major bleeding and mortality compared with heparin plus a glycoprotein IIb/IIIa inhibitor, and this benefit persisted at 3 years.
Bivalirudin has predictable, linear pharmacokinetics and a short half-life (~25 minutes), being cleared partly by proteolysis and partly renally, so its effect wanes quickly after the infusion stops. Its main risk, as with all anticoagulants, is bleeding; dose is reduced in significant renal impairment.
Mechanism of Action
Its N-terminal D-Phe-Pro-Arg-Pro segment occupies the catalytic cleft while a glycine-linked C-terminal sequence engages exosite I. Binding is reversible: thrombin slowly cleaves the Arg-Pro bond, restoring enzyme activity, which contributes to the drug's short duration of action. Independence from antithrombin gives a more predictable anticoagulant response than heparin.
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References (2)
- [1]Stone GW, Witzenbichler B, Guagliumi G, et al. Bivalirudin during primary PCI in acute myocardial infarction New England Journal of Medicine (2008)
→ In HORIZONS-AMI, bivalirudin monotherapy during primary PCI reduced major bleeding and 30-day mortality versus heparin plus a glycoprotein IIb/IIIa inhibitor.
- [2]Stone GW, Witzenbichler B, Guagliumi G, et al. Heparin plus a glycoprotein IIb/IIIa inhibitor versus bivalirudin monotherapy and paclitaxel-eluting stents versus bare-metal stents in acute myocardial infarction (HORIZONS-AMI): final 3-year results The Lancet (2011)
→ The mortality and bleeding benefit of bivalirudin over heparin plus GPI in STEMI persisted through 3 years of follow-up.
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