Low-molecular-weight heparin in thrombotic disease in children and adolescents

Purpose: The use of unfractionated heparin (UFH) in children is problematic . In adults, subcutaneous low-molecular-weight heparin (LMWH) is as effecti ve as UFH in the treatment of thrombosis. Because pediatric data are limite d, the authors studied the use of enoxaparin in children. Patients and Methods: Nineteen children (ages 18 days to 19 years; median a ge, 40 months) with indications for thrombosis treatment or prophylaxis wer e studied. Six patients (median age, 33 months), treated on a protocol that included pharmacokinetic studies, initially received enoxaparin 1 mg/kg su bcutaneously every 12 hours; doses then were adjusted until target plasma l evels of 0.5 to 1.2 anti-Xa U/mL were achieved. The records of 13 additiona l patients treated with enoxaparin off study were reviewed. Results: In the first six patients, enoxaparin pharmacokinetics was found t o be similar to that in adults; once targeted levels were achieved, these r emained stable. Among all 19 subjects, 14 had treatment of active thrombosi s and 5 underwent thrombosis prophylaxis. For treatment of thrombosis, enox aparin 1 mg/kg initially was administered subcutaneously every 12 hours. Target anti-Xa levels were achieved with 0.55 to 1.5 mg/kg every 12 hours ( mean, 0.98 mg/kg; median, 1.0 mg/kg) in 1 to 7 days (median, 1 day). All pa tients in the treatment group had clinical improvement within 2 to 5 days, and 12 had follow-up radiological studies that confirmed this. For prophyla xis, enoxaparin was given at 1 mg/kg subcutaneously every 24 hours. No new thrombi were clinically evident in this group. There was no major bleeding with enoxaparin; one patient had transient mild mucosal oozing. Conclusion: In this limited population, enoxaparin seems to be a safe, effe ctive, and convenient alternative to UFH in children and adolescents. The a dult therapeutic target range of 0.5 to 1.2 anti-Xa:U/mL is readily achieva ble with a starting dose of 1 mg/kg every 12 hours in most children. Initia l close monitoring with plasma anti-Xa activity should be done and doses ad justed to achieve target range, particularly in neonates. In the population of this study, enoxaparin seems as effective as UFH in the period immediat ely thrombotic episode. These results should be confirmed in the ongoing ra ndomized trial comparing LMWH with UFH in children.