• Mechanism of Action:
    • Binds to antithrombin III, converts to an active form, and inhibits thrombin and factor Xa
  • Dosing & Administration:
    • IV 50- to 70-U/kg then infusion based on reperfusion plan
  • Adverse Effects:
    • Bleeding & thrombocytopenia
  • Contraindications:
    • Severe thrombocytopenia & active bleeding
  • Clinical Pearls & Practical Considerations: 
    • Heparin has a short half-life and its effect can be rapidly reversed by protamine sulfate.
    • Heparin can also cause heparin-induced thrombocytopenia (HIT), an immune-mediated reaction that can lead to thrombosis. HIT can occur 5 to 10 days after initiation of heparin therapy.
    • Monitoring: aPTT, INR, CBC, platelet count



  • Mechanism of Action:
    • Binds to thrombin, preventing thrombin-mediated platelet activation and thrombus formation
  • Dosing & Administration:
    • 0.75 mg/kg IV bolus followed by infusion of 1.75 mg/kg/hr
    • Reduce infusion to 1 mg/kg/h with estimated CrCl <30 mL/min
  • Adverse Effects:
    • Bleeding, Hypotension, Nausea, & Anaphylaxis
  • PK/PD
    • Plasma half-life of 30 minutes; metabolized by liver
  • Clinical Pearls & Practical Considerations: 
    • It is often used as an alternative to heparin plus GPIIb/IIIa inhibitors in patients with high bleeding risk.
    • May be preferred in those with high risk of bleeding
    • There is no specific reversal agent for bivalirudin

Anticoagulant Drug Chart

DrugMechanism of ActionDosage and Route of AdministrationOnset of ActionElimination Half-lifeAdverse Effects
HeparinIndirect thrombin50-70 unit
IV bolus, followed by continuous infusion
Immediate1-2 hoursBleeding, HIT, thrombocytopenia, hypersensitivity, hyperkalemia, osteoporosis
EnoxaparinIndirect Factor Xa1 mg/kg
3-5 hours4-7 hoursBleeding, thrombocytopenia, HIT, hyperkalemia, hypersensitivity, osteoporosis
BivalirudinDirect thrombin0.75 mg/kg IV bolus followed by infusion of 1.75 mg/kg/hrImmediate25 minutesBleeding, anemia, hypotension, thrombocytopenia, angina, dyspnea, allergic reaction
FondaparinuxIndirect Factor XaSubcutaneous3 hours17-21 hoursBleeding, thrombocytopenia, anemia, injection site reaction, hypersensitivity, caution in renal impairment

AHA STEMI Guidelines- Anticoagulants Prior to PCI

UFH•With GP IIb/IIIa receptor antagonist planned: 50- to 70-U/kg IV bolus to achieve therapeutic ACT of 200 to 250 s. •GP IIb/IIIa receptor antagonist planned: 70- to 100-U/kg bolus to achieve therapeutic ACT is 250 to 300 s (HemoTec device) or 300 to 350 s (Hemochron device).IC
Bivalirudin0.75-mg/kg IV bolus, then 1.75-mg/kg/h infusion with or without prior treatment with UFH. •An additional bolus of 0.3 mg/kg can be given if needed. •Reduce infusion to 1 mg/kg/h with estimated CrCl <30 mL/minIIaB
Preferred over UFH with GP IIb/IIIa receptor antagonist in patients at high risk of bleedingIIaB
FondaparinuxNot recommended as sole anticoagulant for primary PCIIIIHarm B