Enoxaparin Weight-Based Dosing
For therapeutic anticoagulation, enoxaparin should be dosed at 1 mg/kg subcutaneously every 12 hours, with dose adjustments required for severe renal impairment, extreme obesity, and elderly patients over 75 years.
Standard Therapeutic Dosing
The established therapeutic dose is 1 mg/kg subcutaneously every 12 hours for treatment of venous thromboembolism and acute coronary syndromes. 1, 2 This dosing has been validated in multiple large trials including ESSENCE, TIMI 11B, and SYNERGY, demonstrating equivalent or superior efficacy compared to unfractionated heparin. 1
- An alternative once-daily regimen of 1.5 mg/kg subcutaneously is approved for inpatient treatment of pulmonary embolism in some jurisdictions, though this has not been extensively tested in all populations. 1, 3
- For acute coronary syndrome, a 30 mg intravenous bolus may be given initially, followed by 1 mg/kg subcutaneously every 12 hours. 1, 2
Prophylactic Dosing
For VTE prophylaxis, the standard dose is 40 mg subcutaneously once daily. 2, 4 An alternative prophylactic regimen is 30 mg subcutaneously twice daily. 2
Critical Dose Adjustments
Severe Renal Impairment
In patients with creatinine clearance <30 mL/min, reduce the therapeutic dose to 1 mg/kg subcutaneously once daily (not twice daily). 1, 2, 4 This adjustment is essential because enoxaparin accumulation increases bleeding risk 2- to 3-fold in severe renal dysfunction. 1
Morbid Obesity (BMI ≥40 kg/m²)
For patients with BMI 40-50 kg/m², dose at approximately 0.97 mg/kg every 12 hours; for BMI 50-60 kg/m², reduce to 0.70 mg/kg; and for BMI >60 kg/m², use 0.71 mg/kg. 5 Standard 1 mg/kg dosing in morbidly obese patients results in supratherapeutic anti-Xa levels in 53-65% of cases. 5
- For prophylaxis in morbidly obese patients, weight-based dosing of 0.5 mg/kg once daily is more appropriate than fixed 40 mg dosing. 4, 6
- A dose range of 0.75-0.85 mg/kg appears safe for therapeutic anticoagulation in obesity, producing therapeutic anti-Xa levels in 62% of patients. 7
- All obese patients should have anti-Xa monitoring due to high inter-patient variability. 7
Elderly Patients
For patients ≥75 years receiving fibrinolytic therapy, enoxaparin should NOT be used as it increases bleeding risk. 1 For other indications in elderly patients, dose reduction to 0.75 mg/kg every 12 hours may be necessary. 4
Low Body Weight
For patients <50 kg, specific institutional dosing algorithms should be developed, as standard dosing may result in excessive anticoagulation. 1
Special Clinical Contexts
Cancer-Associated VTE
Dalteparin (200 units/kg daily for 30 days, then 150 units/kg daily) is preferred over enoxaparin for cancer-associated VTE. 1, 2 If enoxaparin is used, dose at 1 mg/kg every 12 hours, though long-term safety data in cancer patients are limited. 1
Critically Ill Trauma Patients
For VTE prophylaxis in trauma ICU patients, weight-based dosing at 0.6 mg/kg twice daily provides superior anti-Xa levels compared to standard 30 mg twice daily dosing. 8 This addresses the decreased bioavailability of enoxaparin in critically ill patients. 8
Monitoring and Safety
- Routine anti-Xa monitoring is not required for standard dosing but should be considered in severe renal failure, pregnancy, and obesity. 1
- Target anti-Xa range for twice-daily dosing is 0.6-1.0 IU/mL measured 4 hours post-injection. 1
- Target anti-Xa range for once-daily dosing is 1.0-2.0 IU/mL. 1
- Platelet count monitoring is necessary during treatment to detect heparin-induced thrombocytopenia. 1
Critical Pitfalls to Avoid
Never "stack" enoxaparin with unfractionated heparin or switch between them during active treatment, as this dramatically increases bleeding risk. 2, 4 If switching is necessary, allow appropriate washout periods.
Do not "dose cap" enoxaparin at arbitrary weight thresholds (e.g., 100 kg) without clinical justification, as this results in subtherapeutic dosing and increased thrombotic risk. 7 However, in extreme obesity, dose reduction based on BMI class is appropriate. 5
Avoid standard dosing in patients with creatinine clearance <30 mL/min without dose adjustment, as this significantly increases major bleeding risk. 1