What is the recommended cardiology loading dose for anticoagulation therapy?

Recommended Cardiology Loading Doses for Anticoagulation Therapy

The recommended loading doses for anticoagulation therapy in acute coronary syndromes vary by specific agent and clinical scenario, with unfractionated heparin requiring a 60-70 IU/kg IV bolus (maximum 4000-5000 IU), enoxaparin requiring a 30 mg IV bolus followed by 1 mg/kg subcutaneously, and bivalirudin requiring a 0.75 mg/kg bolus for PCI support. 1

Unfractionated Heparin (UFH)

• For initial therapy in NSTE-ACS: 60 IU/kg IV bolus (maximum 4000 IU), followed by 12 IU/kg/hour infusion (maximum 1000 IU/hour), adjusted to maintain aPTT at 1.5-2.0 times control (approximately 50-70 seconds) 1
• For supporting PCI: In patients who have received prior anticoagulant therapy, additional UFH as needed to achieve ACT 250-300 seconds; in patients without prior anticoagulant therapy, 70-100 U/kg initial bolus to achieve target ACT of 250-300 seconds 1
• With fibrinolytic therapy: 60 IU/kg IV bolus (maximum 4000 IU), followed by 12 IU/kg/hour infusion (maximum 1000 IU/hour) adjusted to therapeutic aPTT range 1

Enoxaparin

• Initial therapy: 1 mg/kg subcutaneously every 12 hours (reduce dose to 1 mg/kg once daily if CrCl <30 mL/min) 1, 2
• An initial IV loading dose of 30 mg has been used in selected patients 2
• To support PCI: If last subcutaneous dose was administered 8-12 hours earlier or only one subcutaneous dose has been given, administer 0.3 mg/kg IV; if last dose was within previous 8 hours, no additional enoxaparin needed 1, 2
• With fibrinolytic therapy:
  • Age <75 years: 30 mg IV bolus, followed in 15 minutes by 1 mg/kg subcutaneously every 12 hours (maximum 100 mg for first 2 doses) 1, 2
  • Age ≥75 years: No bolus, 0.75 mg/kg subcutaneously every 12 hours (maximum 75 mg for first 2 doses) 1, 2
  • Regardless of age, if CrCl <30 mL/min: 1 mg/kg subcutaneously every 24 hours 1, 2

Bivalirudin

• To support PCI: 0.75 mg/kg bolus, followed by 1.75 mg/kg/hour IV infusion during the PCI procedure 1
• Post-PCI infusion for primary PCI: 1.75 mg/kg/hour for 2-4 hours post-PCI 1
• In patients with CrCl <30 mL/min, reduce infusion to 1 mg/kg/hour 1
• For NSTE-ACS (early invasive strategy): 0.10 mg/kg loading dose followed by 0.25 mg/kg/hour, continued until diagnostic angiography or PCI 1

Fondaparinux

• Initial therapy: 2.5 mg subcutaneously daily 1
• With fibrinolytic therapy: 2.5 mg IV, then 2.5 mg subcutaneously daily starting the following day 1
• Contraindicated if CrCl <30 mL/min 1
• Important: Fondaparinux should not be used to support PCI because of the risk of catheter thrombosis; if PCI is performed while the patient is on fondaparinux, an additional anticoagulant with anti-IIa activity (either UFH or bivalirudin) should be administered 1

Antiplatelet Loading Doses

• Aspirin: 162-325 mg loading dose (non-enteric coated preferred for initial dosing) 1
• Clopidogrel:
  • Age ≤75 years: 300-600 mg loading dose (600 mg preferred for PCI) 1
  • Age >75 years: 75 mg (no loading dose) 1
• Ticagrelor: 180 mg loading dose 1

Special Considerations

• Anticoagulation should be continued for a minimum of 48 hours and preferably for the duration of hospitalization, up to 8 days or until revascularization if performed 1
• For patients undergoing PCI, the procedure should be performed under ACT guidance with heparin given at a dose to maintain ACT of 250-350 seconds (200-250 seconds if GPIIb/IIIa inhibitors are used) 1
• The choice of anticoagulant should consider the patient's renal function, bleeding risk, and planned procedures 1
• Enteric-coated aspirin should be avoided initially because of delayed and reduced absorption 1

Common Pitfalls and Caveats

• Underdosing of anticoagulants, especially in obese patients, can lead to inadequate anticoagulation and increased risk of thrombotic events 3
• Excessive anticoagulation increases bleeding risk without improving outcomes 1
• Failure to adjust dosing for renal impairment can lead to drug accumulation and increased bleeding risk, especially with enoxaparin and fondaparinux 2
• When switching between anticoagulants, proper transition protocols should be followed to avoid periods of inadequate anticoagulation or excessive anticoagulation 4
• Fondaparinux alone is insufficient for PCI due to risk of catheter thrombosis 1