Prophylactic Use of Enoxaparin in Adolescents During Bariatric Surgery—a Prospective Clinical Study

INTRODUCTION: Severe obesity predisposes youth to a higher risk of venous thromboembolism (VTE). This study evaluates a BMI-stratified prophylactic dosing regimen of enoxaparin in adolescents with severe obesity undergoing surgery. METHODS: Adolescents aged 12-20 years received prophylactic enoxaparin at 40 mg SC (for a BMI < 50 kg/m(2)) and 60 mg SC (for a BMI ≥ 50 kg/m(2)) every 12 hours until discharge. Blood samples were drawn at pre-dose, 1, 2, 4, 6, and 12 hrs. Plasma Anti-Factor Xa (Anti-FXa) activity was used as a surrogate marker for enoxaparin pharmacokinetics. RESULTS: Ten female and two male obese adolescents (age range 14-19 years) had a mean BMI of 49.9 kg/m(2) (38.4-58 kg/m(2)). Four patients had a BMI of less than 50 kg/m(2) and received 40 mg enoxaparin, resulting in a mean dosage of 0.352 ± 0.070 mg/kg body weight. Eight patients were dosed with 60 mg enoxaparin every 12 hours, resulting in a mean dosage of 0.395 ± 0.028 mg/kg. Peak plasma anti-FXa activity (C(max)) ranged from 0.14 to 0.30 IU/mL, median C(max) was 0.205 IU/mL. Median T(max) was 5.67 hours (range 3.78 to 7.52 hours). Median AUC(i) was 1.00 h*IU/mL (range 0.42 to 1.67 h*IU/mL). 10 out of 12 patients (83%) reached the primary endpoint with anti-FXa activity in the range for VTE prevention (0.1-0.3 IU/mL). CONCLUSIONS: Our dosing scheme of 40 mg vs 60 mg enoxaparin stratified according to BMI proved to be effective in reaching prophylactic anti-FXa activity in 83% of adolescent patients.