Increased enoxaparin dosing is required for obese children.

Weight-based dosing for enoxaparin is recommended in the 2008 American College of Chest Physicians (ACCP) guidelines for venous thromboembolism (VTE) prophylaxis. Enoxaparin 0.5 mg/kg per dose administered subcutaneously every 12 hours is recommended for this indication in children. There is no established upper dosing limit of enoxaparin for prophylaxis in children, and the US Food and Drug Administration-approved enoxaparin dose for adults for VTE prophylaxis is 30 mg subcutaneously every 12 hours or 40 mg subcutaneously daily. Therefore, we assumed that the upper limit for children is 40 mg subcutaneously daily. We reviewed 3 cases of obese adolescent boys who required large doses of enoxaparin to achieve the ACCP-recommended anti-factor Xa range of 0.1 to 0.3 IU/mL for the prevention of VTE. All 3 patients required doses of enoxaparin that are higher than that recommended for adults for VTE prophylaxis: patient A (BMI: 105.9) required >0.28 mg/kg per dose, patient B (BMI: 95.7) required 0.15 mg/kg per dose, and patient C (BMI: 29.9) required 0.49 mg/kg per dose. The desired anti-factor Xa range was achieved when enoxaparin was administered every 12 hours in each patient with no reported episodes of VTE. One patient had minor bruising, but no other adverse events were noted. Because of the variability in dose requirements and unpredictability in patient responses demonstrated in our 3 adolescents, prospective studies are needed to provide definitive recommendations on dosing of enoxaparin for VTE prophylaxis in this subset of obese pediatric patients.