What is the dose adjustment of Enoxaparin (low molecular weight heparin) in relation to patient weight?

From the Guidelines

Enoxaparin dosing should be adjusted based on patient weight, with a recommended dose of 1 mg/kg twice daily or 1.5 mg/kg once daily for treatment of venous thromboembolism, as supported by the most recent and highest quality study 1. When considering dose adjustments, several factors come into play, including patient weight, renal function, and body mass index (BMI).

• For patients weighing over 45 kg, standard prophylactic dosing is typically 40 mg once daily.
• For treatment of venous thromboembolism, the recommended dose is 1 mg/kg twice daily or 1.5 mg/kg once daily.
• Obese patients (BMI >30 kg/m²) may require higher prophylactic doses of 40 mg twice daily or weight-based dosing at 0.5 mg/kg twice daily, while treatment doses should be based on actual body weight without capping.
• For patients with low body weight (<45 kg), dose reduction to 30 mg once daily for prophylaxis may be appropriate.
• In patients with severe renal impairment (creatinine clearance <30 mL/min), dose reduction is necessary - typically 30 mg once daily for prophylaxis and 1 mg/kg once daily for treatment, as recommended by the manufacturer and supported by studies 1. Weight-based dosing is important because enoxaparin's volume of distribution correlates with body weight, and inappropriate dosing can lead to either treatment failure with underdosing or increased bleeding risk with overdosing 1. Regular monitoring of anti-Xa levels may be beneficial in extreme weight categories or renal impairment to ensure therapeutic efficacy and safety, particularly in patients with severe renal insufficiency, where the risk of bleeding is increased 1.

From the Research

Enoxaparin Dose Adjustment in Relation to Weight

• The current treatment dose of enoxaparin is based on total body weight (TBW), but dosage in obesity remains unclear 2.
• "Dose capping" commonly occurs if TBW > 100 kg to minimize bleeding risk, but this may result in under-dosing and increasing embolization risk 2.
• A retrospective study found that dosing at 0.75-0.85 mg/kg results in 62% of therapeutic, 14% sub-therapeutic, and 24% supra-therapeutic anti-Xa levels, which appears to be a "safe" starting dose-range 2.
• A systematic review found that utilization of a reduced weight-based dosing strategy for therapeutic enoxaparin in obese patients may increase the percentage of patients with a therapeutic anti-Xa level 3.
• The review also found that overall rates of total bleeding and thrombosis were assessed in 798 patients, with 29 bleedings (3.6%) occurring, and 27 reported a relationship to dose 3.

Obesity and Enoxaparin Dosing

• Enoxaparin dosing recommendations for morbidly obese patients are lacking, and retrospective and observational studies reported goal anti-Xa levels with a median dose of 0.8 mg/kg using total body weight 4.
• A prospective, randomized, controlled study found that reduced dose enoxaparin (0.8 mg/kg) may be a reasonable dosing strategy in morbidly obese patients, with 89% of patients achieving a goal anti-Xa level 4.
• A retrospective cohort study found that standard dosing of enoxaparin in morbidly obese patients will most likely lead to supratherapeutic anti-Xa levels, and further investigation is warranted to better determine appropriate dosing 5.
• The study also found that the median therapeutic dose of enoxaparin varied by BMI class, with a median therapeutic dose of 0.97 mg/kg for patients with a BMI of 40-50 kg/m2, 0.70 mg/kg for patients with a BMI of 50-60 kg/m2, and 0.71 mg/kg for patients with a BMI over 60 kg/m2 5.

Renal Insufficiency and Enoxaparin Dosing

• A meta-analysis found that non-dialysis-dependent patients with a creatinine clearance of 30 mL/min or less who are treated with standard therapeutic doses of enoxaparin have elevated levels of anti-Xa and an increased risk for major bleeding 6.
• The meta-analysis also found that empirical dose adjustment of enoxaparin may reduce the risk for bleeding and merits additional evaluation 6.
• However, the data for tinzaparin and dalteparin were limited, and no conclusions can be made regarding other low-molecular-weight heparins (LMWHs) 6.