Experience with intravenous enoxaparin in critically ill infants and children

Objective: Subcutaneous administration of enoxaparin is often difficult in special populations, such as premature infants and critically ill children with severe edema. The difficulty achieving adequate anticoagulation in these patients has led to the employment of intravenous enoxaparin in some cases. However, little pharmacodynamic data are available for determining the appropriate dosing and monitoring (by anti-Factor Xa levels) of intravenous enoxaparin. The objective of this study is to report our experience with the use of intravenous enoxaparin in pediatric patients in the intensive care unit. DESIGN:: Retrospective review of medical records. SETTING:: Single institution pediatric intensive care unit. PATIENTS:: All pediatric patients receiving intravenous enoxaparin in the pediatric intensive care unit at Children's Medical Center Dallas between April 1, 2005 and March 31, 2006 were identified using hospital pharmacy records. INTERVENTIONS:: None. MEASUREMENTS AND MAIN RESULTS:: Seven patients were identified as having received intravenous enoxaparin while in the intensive care unit. Higher anti-Xa levels were found at 1-2 hrs after administration of intravenous enoxaparin rather than at the 4-6 hrs documented with subcutaneous administration and these levels decreased substantially 6-8 hrs after an intravenous dose. Mean therapeutic dose for children <1 yr of age was 2.40 mg/kg/dose (±sd 0.58). For children <1 yr of age, the mean therapeutic dose was 1.11 mg/kg/dose (±sd 0.13). The mean prophylactic dose for the two children was 0.93 mg/kg/dose (±sd 0.43). CONCLUSIONS:: Our data show that the pharmacodynamics of intravenous administration is different from subcutaneous administration and deserves further study.