From the Guidelines
Lovenox (enoxaparin) dosing in obesity should be adjusted to 1 mg/kg twice daily with no maximum dose cap for treatment of venous thromboembolism, and 40 mg twice daily or 0.5 mg/kg once daily for prophylactic dosing, to ensure therapeutic anticoagulation while minimizing bleeding risks. For obese patients (BMI >30 kg/m² or weight >100 kg), standard fixed dosing is often inadequate, as enoxaparin is primarily distributed in blood volume rather than total body weight, and standard dosing may lead to subtherapeutic levels in obesity 1.
Key Considerations
- Anti-Xa monitoring should be considered for patients weighing >150 kg to ensure therapeutic levels, with target peak anti-Xa levels of 0.5-1.0 IU/mL for therapeutic dosing and 0.2-0.5 IU/mL for prophylactic dosing 1.
- Renal function should be monitored closely as obesity can mask declining kidney function when using weight-based dosing calculations 1.
- The use of low-molecular-weight heparin (LMWH) is likely the preferred option in obese patients, as direct oral anticoagulants (DOACs) have limited data in this population and may require caution in patients weighing over 120 kg 1.
Dosing Recommendations
- Treatment of venous thromboembolism: 1 mg/kg twice daily with no maximum dose cap
- Prophylactic dosing: 40 mg twice daily or 0.5 mg/kg once daily
- Anti-Xa monitoring: consider for patients weighing >150 kg, with target peak anti-Xa levels of 0.5-1.0 IU/mL for therapeutic dosing and 0.2-0.5 IU/mL for prophylactic dosing.
From the Research
Lovenox in Obesity
- Lovenox, also known as enoxaparin, is a low-molecular-weight heparin (LMWH) used as thromboprophylaxis and in patients with atrial fibrillation (AF) or venous thromboembolism (VTE) 2.
- The optimal dosage for obese patients has not been established for most anticoagulants, including LMWH, non-vitamin K antagonist oral anticoagulants (NOAC), and pentasaccharides (fondaparinux) 2.
- For thromboprophylaxis with LMWH in bariatric surgery, enoxaparin 40 mg twice daily, dalteparin 5,000 IE twice daily, or tinzaparin 75 IU/kg once daily should be considered for patients with BMI ≥ 40 kg/m2 2.
- For treatment with LMWH, a reduced weight-based dose of enoxaparin 0.8 mg/kg twice daily should be considered in patients with BMI ≥ 40 kg/m2, and no dose capping of dalteparin and tinzaparin should be applied for body weight < 140 kg 2.
Dosing of Enoxaparin in Obese Patients
- Appropriate enoxaparin dosing for thromboprophylaxis in adult patients is 40 mg subcutaneously daily or 30 mg subcutaneously twice daily 3.
- However, the appropriate dose of enoxaparin for VTE prophylaxis in obese patients is not clear, and varying doses of enoxaparin are used in clinical practice 3.
- A study found that clinicians tend to use reduced weight-based doses of enoxaparin in overweight and obese patients, and that the use of the recommended enoxaparin dose of 1 mg/kg is associated with a higher bleeding risk in those weighing more than 150 kg 4.
Fondaparinux in Obesity
- Fondaparinux is a synthetic pentasaccharide that inhibits thrombin formation by inhibiting Factor Xa, and has a favorable pharmacokinetic profile 5.
- Current evidence suggests that fondaparinux is as effective as, if not more than, enoxaparin in the prevention of venous thromboembolism in the postoperative period 5.
- However, there is limited evidence on the use of fondaparinux in obese patients, and further studies are needed to determine its safety and efficacy in this population 2, 5.