Bivalirudin

Cardiovascular / Anticoagulation

Also known as: Angiomax, Angiox, BG-8967, Hirulog

Direct Thrombin InhibitorsResearch phase: Extensive human data; FDA-approvedRegulatory: FDA-approved (2000) for use in patients with unstable angina undergoing PCI, and for patients with or at risk for HIT undergoing PCI. EMA-approved as Angiox. Marketed by The Medicines Company (now Novartis).

Mechanism

A synthetic blood thinner based on hirudin, a protein found in leech saliva. Unlike heparin (the traditional blood thinner used during heart procedures), bivalirudin directly blocks thrombin (the key clotting enzyme) and wears off quickly — its effects last only about 25 minutes. This makes it safer for procedures like coronary stenting, where you need precise control over blood clotting.

Technical detail

20-amino-acid synthetic peptide (D-Phe-Pro-Arg-Pro-Gly-Gly-Gly-Gly-Asn-Gly-Asp-Phe-Glu-Glu-Ile-Pro-Glu-Glu-Tyr-Leu) based on the binding regions of hirudin, a 65-residue thrombin inhibitor from Hirudo medicinalis. Bivalent mechanism: the N-terminal D-Phe-Pro-Arg sequence binds the thrombin active site (catalytic triad), while the C-terminal sequence binds exosite 1 (fibrinogen-binding site). Thrombin slowly cleaves the Arg-Pro bond in the N-terminal region, creating a self-limiting mechanism — half-life approximately 25 minutes. Inhibits both free and clot-bound thrombin (unlike heparin, which cannot inhibit clot-bound thrombin). Does not activate platelets, does not cause HIT (heparin-induced thrombocytopenia). HORIZONS-AMI trial showed reduced bleeding and 30-day mortality vs. heparin + GP IIb/IIIa inhibitor in primary PCI.

Effects

CARDIOVASCULAR SYSTEM (HEMOSTASIS): Direct thrombin inhibitor — bivalirudin binds both the catalytic active site and the anion-binding exosite 1 of thrombin, providing potent and specific anticoagulation [RCT]. Unlike heparin, it inhibits both free and clot-bound thrombin (heparin only inhibits free thrombin) [in vitro, clinical]. Does NOT require antithrombin III as a cofactor — works independently [pharmacological]. Predictable, linear pharmacokinetics — no need for routine monitoring (though ACT is used procedurally) [RCT, pharmacokinetic studies]. Short half-life (~25 minutes in normal renal function) — rapid offset of anticoagulation, reducing bleeding complications [RCT]. Does NOT activate platelets (unlike heparin, which can cause HIT) — safe in heparin-induced thrombocytopenia [RCT]. Does NOT interact with platelet factor 4 — zero risk of HIT [pharmacological]. Proteolytic clearance (80%) + renal clearance (20%) — thrombin itself cleaves bivalirudin at the Arg3-Pro4 bond, a unique self-limiting mechanism [pharmacokinetic]. CLINICAL OUTCOMES: Reduced major bleeding compared to heparin + GP IIb/IIIa inhibitors in PCI (HORIZONS-AMI — 40% reduction in major bleeding; EUROMAX — confirmed in STEMI) [RCT]. Similar or improved 30-day mortality in STEMI PCI vs. heparin [RCT]. Reduced net adverse clinical events (composite of ischemic + bleeding) [RCT]. However: higher acute stent thrombosis rate in some trials (HORIZONS-AMI — 1.3% vs. 0.3% with heparin + GP IIb/IIIa), mitigated by prolonged post-PCI infusion [RCT].

Practitioner Guide

ADMINISTRATION: IV bolus + continuous infusion. Standard PCI protocol: 0.75 mg/kg IV bolus, then 1.75 mg/kg/hr infusion for the duration of the procedure. For STEMI PCI: consider extended post-PCI infusion at full dose (1.75 mg/kg/hr) for 3-4 hours to mitigate acute stent thrombosis risk. HIT protocol: 0.15-0.2 mg/kg/hr continuous infusion (no bolus), titrate to aPTT 1.5-2.5x baseline. MONITORING: ACT (activated clotting time) during PCI — target 300-350 seconds. aPTT for non-PCI anticoagulation (HIT) — target 1.5-2.5x baseline. Check ACT 5 minutes after bolus. RENAL DOSING: Reduce infusion rate in renal impairment — CrCl 10-30 mL/min: reduce infusion to 1.0 mg/kg/hr. Dialysis patients: reduce to 0.25 mg/kg/hr. Monitor aPTT closely. Bolus dose does NOT change in renal impairment. REVERSAL: No specific antidote, but the 25-minute half-life means anticoagulation resolves rapidly after stopping infusion. In emergencies: hemodialysis removes ~25% (limited utility). Recombinant Factor VIIa has been used off-label for life-threatening bleeding. TRANSITION: When transitioning to warfarin (e.g., in HIT), start warfarin when platelets recover >150K, overlap for 5+ days, stop bivalirudin when INR is therapeutic for 2 consecutive days. For DOAC transition: stop bivalirudin, start DOAC when aPTT normalizes. PRACTICAL CATH LAB TIPS: Mix with D5W or NS — stable for 24 hours at room temperature once reconstituted. If ACT is subtherapeutic after bolus, give additional 0.3 mg/kg bolus. Can increase infusion to 2.5 mg/kg/hr during PCI if needed. Watch for acute stent thrombosis (first 4 hours post-PCI) — extended infusion is key. CONTRAINDICATIONS: Active major bleeding, severe uncontrolled hypertension. Use with caution in severe hepatic impairment (reduced proteolytic clearance). COST CONSIDERATION: Significantly more expensive than unfractionated heparin — cost-effectiveness depends on reduction in bleeding complications (generally favorable in high-risk bleeding populations). STORAGE: Reconstituted solution stable 24 hours at room temperature. Lyophilized vials at room temperature.

Evidence

Research Summary

TIER 1: HORIZONS-AMI (2008, Stone et al.) — landmark RCT: bivalirudin vs. heparin + GP IIb/IIIa in primary PCI for STEMI. 40% reduction in major bleeding, similar ischemic outcomes, reduced 30-day and 3-year mortality. EUROMAX (2014) — confirmed bleeding reduction in pre-hospital STEMI setting. ACUITY (2006) — bivalirudin non-inferior to heparin + GP IIb/IIIa in moderate-high risk ACS with less bleeding. HEAT-PPCI (2014, Shahzad et al.) — challenged bivalirudin superiority: heparin alone was non-inferior with lower stent thrombosis. BRIGHT (2015) — Chinese RCT: bivalirudin + post-PCI infusion reduced net adverse events. MATRIX (2015) — bivalirudin reduced bleeding but increased stent thrombosis vs. heparin in ACS patients. FDA-approved (Angiomax) for PCI and HIT. TIER 2: Meta-analyses (Shah et al., 2016; Bangalore et al., 2014) — consistent bleeding reduction, increased acute stent thrombosis, neutral mortality. Cochrane reviews of direct thrombin inhibitors vs. heparin for ACS. Guidelines: ACC/AHA give bivalirudin Class I recommendation for PCI in HIT, Class IIa for STEMI PCI. TIER 3: Case series of bivalirudin use in HIT with thrombosis. ICU reports of prolonged bivalirudin infusion for HIT anticoagulation. Interventional cardiology registry data. KEY FINDINGS: Bivalirudin reliably reduces bleeding compared to heparin + GP IIb/IIIa, but the benefit narrows when compared to heparin alone (without GP IIb/IIIa). Acute stent thrombosis is a real risk mitigated by extended post-PCI infusion. Best niche: HIT patients and high bleeding-risk patients. GAPS: Optimal duration of post-PCI infusion debated. Role diminished as radial access (which also reduces bleeding) became standard. ACTIVE TRIALS: Comparisons with newer anticoagulants, bivalirudin in TAVR procedures, and optimization of post-PCI infusion protocols.

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