Therapeutic Dosing of Enoxaparin
The therapeutic dose of enoxaparin is 1 mg/kg subcutaneously every 12 hours for most patients, with specific adjustments required for certain populations including the elderly, those with renal impairment, and obese patients. 1, 2
Standard Therapeutic Dosing
- Standard dose: 1 mg/kg subcutaneously every 12 hours 1, 2
- Initial loading dose: In selected patients, an initial intravenous loading dose of 30 mg may be administered 1, 2
- Duration: Continue for the duration of hospitalization or until PCI is performed 1
Population-Specific Dosing Adjustments
Age-Based Adjustments
- Patients ≥75 years: 0.75 mg/kg subcutaneously every 12 hours (no initial IV bolus) 2
Renal Function Adjustments
- Severe renal impairment (CrCl <30 mL/min): 1 mg/kg subcutaneously once daily 1, 2, 3
- End-stage renal disease: Consider using unfractionated heparin instead due to its clearance by the reticuloendothelial system rather than renal elimination 1
Weight-Based Adjustments
- Morbid obesity (BMI ≥40 kg/m²): Consider 0.8 mg/kg subcutaneously every 12 hours 2
- Alternative for morbidly obese patients: Weight-based prophylactic dose of 0.5 mg/kg subcutaneously every 12 hours may achieve better anti-Xa levels 1
Clinical Context-Specific Dosing
Acute Coronary Syndrome
- Standard approach: 1 mg/kg subcutaneously every 12 hours with an initial 30 mg IV bolus in selected patients 1, 2
- PCI setting: If PCI is performed within 8 hours of last subcutaneous dose, no additional dose needed; if 8-12 hours have passed, add 0.3 mg/kg IV at time of PCI 1
Venous Thromboembolism
- Standard treatment: 1 mg/kg subcutaneously every 12 hours 4
- Alternative regimen: 1.5 mg/kg subcutaneously once daily has also shown equivalent efficacy 4
Important Clinical Considerations
- Monitoring: Routine monitoring of anti-Xa levels is not required for most patients but may be considered in severe renal impairment, extreme body weights, or prolonged therapy 2
- Neuraxial anesthesia timing: When neuraxial anesthesia is used, prophylactic doses of enoxaparin may be started 4 hours after catheter removal but not earlier than 12 hours after the block was performed 1
- Concomitant medications: Avoid "stacking" with unfractionated heparin due to increased bleeding risk 1, 2
Bleeding Risk Management
- For patients at high risk of bleeding but requiring anticoagulation, consider alternative agents such as fondaparinux or bivalirudin 1, 2
- Major bleeding rates are significantly lower with the 1 mg/kg dose compared to higher doses (1.9% vs 6.5% with 1.25 mg/kg) 5
The therapeutic dosing of enoxaparin must be carefully selected based on patient characteristics, with particular attention to age, renal function, and weight to optimize efficacy while minimizing bleeding risk.