Enoxaparin Dose Requirements to Achieve Therapeutic Low-molecular-weight Heparin Anti-factor Xa Levels in Infants and Young Children.

Abstract

Enoxaparin is commonly used to treat pediatric thrombosis. Several small retrospective studies have suggested that infants and young children require higher enoxaparin doses to achieve therapeutic anti-factor Xa levels compared with adults. This is a retrospective study of hospitalized children who received enoxaparin for the treatment of thrombosis at a free-standing children's hospital. The primary objective was to ascertain the enoxaparin dose required to achieve an anti-factor Xa level of 0.5 to 1.0 U/mL among 4 age groups in a large cohort of infants and young children between 60 days and 5 years of age. A total of 176 infants and children were evaluated. The majority of patients were less than 1 year of age (n=104). An inverse relationship between enoxaparin dose needed to achieve therapeutic anti-factor Xa levels and patient age was noted, particularly in the first year of life. Patients who were 60 days to less than 7 months at the time of enoxaparin initiation (n=73) required the highest mean dose among the age groups at 1.73 mg/kg subcutaneously every 12 hours (P<0.0001). Infants and young children require higher doses of enoxaparin to achieve therapeutic anti-factor Xa levels compared with adults.