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) and 60 mg SC (for a BMI ≥ 50 kg/m) every 12 h until discharge. Blood samples were drawn at pre-dose, 1, 2, 4, 6, and 12 h. 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 (38.4-58 kg/m). Four patients had a BMI of less than 50 kg/m 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 h, resulting in a mean dosage of 0.395 ± 0.028 mg/kg. Peak plasma anti-FXa activity (C) ranged from 0.14 to 0.30 IU/mL, median C was 0.205 IU/mL. Median T was 5.67 h (range 3.78-7.52 h). Median AUC was 1.00 h IU/mL (range 0.42-1.67 h IU/mL). Ten 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.