title: Retrospective evaluation of enoxaparin dosing in patients 48 weeks' postmenstrual age or younger in a neonatal intensive care unit.
abstract: BACKGROUND
  Enoxaparin is the anticoagulant of choice in neonates because of the ease of administration, predictable pharmacokinetics, and reduced adverse effects when compared to heparin. The Chest guidelines recommend that therapy in patients younger than 2 months should be initiated with enoxaparin 1.5 mg/kg administered subcutaneously twice daily. This starting dosage may be inadequate, leading to a delay in achieving therapeutic anti-factor Xa plasma concentrations.
  
  
  OBJECTIVE
  To determine an enoxaparin dose for neonatal patients that achieves a therapeutic anti-factor Xa plasma concentration and compare that dose to the recommended enoxaparin dose per published guidelines for this patient population.
  
  
  METHODS
  The study was designed as a single-center chart review. Eligible patients were identified by pharmacy anticoagulation records or a search of the electronic medical record for enoxaparin orders. Patients must have received enoxaparin subcutaneously twice daily and have had a postmenstrual age of 48 weeks or younger. Patients diagnosed with renal failure and those receiving prophylactic doses of enoxaparin were excluded.
  
  
  RESULTS
  The mean (SD) initial dose of enoxaparin was 1.4 (0.3) mg/kg subcutaneously twice daily, resulting in 27 of 33 patients (81.8%) having a subtherapeutic anti-factor Xa concentration. A mean enoxaparin dose of 2.0 (0.5) mg/kg was required to achieve a therapeutic anti-factor Xa plasma concentration (p < 0.001). Patients born prematurely required a higher enoxaparin dose (2.2 [0.5] mg/kg) than did those born at full-term gestation (1.8 [0.4] mg/kg; p < 0.05).
  
  
  CONCLUSIONS
  For patients 48 weeks' postmenstrual age or younger who are treated in a neonatal intensive care unit, a higher initial dose of enoxaparin than that suggested by the Chest guidelines is required to attain a therapeutic antifactor Xa plasma concentration. Premature neonates require a larger starting dose of enoxaparin than do infants born at full-term gestation.
authors: Department of Pharmacy, Le Bonheur Children's Hospital, Memphis, TN, USA. Kevin.hicks@stjude.org
authors: J Kevin
authors: JK
authors: Hicks
authors: Chasity M
authors: CM
authors: Shelton
authors: Jasmine K
authors: JK
authors: Sahni
authors: Michael L
authors: ML
authors: Christensen
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage*; D017984:Enoxaparin / Q000008:administration & dosage*; D015951:Factor Xa / Q000378:metabolism; D065427:Factor Xa Inhibitors; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D012189:Retrospective Studies
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D065427:Factor Xa Inhibitors; D015951:Factor Xa