Abstract
OBJECTIVES: The purpose of this study was to describe the enoxaparin dose required by preterm neonates and infants to achieve therapeutic anti-Xa levels. STUDY DESIGN: Retrospective chart review of preterm infants, <12 weeks postnatal age, born before 37 weeks gestation, receiving subcutaneous (SUBQ) enoxaparin every 12 h (q12h) with an anti-Xa goal of 0.5-1 units/mL. The primary endpoint was the enoxaparin dose required to achieve a therapeutic anti-Xa level. Secondary endpoints included initial enoxaparin dose and the frequency of achieving therapeutic anti-Xa levels with the initial dose, index thrombus progression, formation of new thrombi, and suspected or confirmed bleeding. RESULTS: Fifty-six patients were included for analysis. At time of enoxaparin initiation, the median gestational age, post-menstrual age, and weight were 34 weeks and 2 days, 38 weeks and 4 days, and 2.5 kg (kg), respectively. The median dose required to achieve a therapeutic anti-Xa was 2 mg/kg (IQR 1.7-2.6 mg/kg) SUBQ q12h. The median initial enoxaparin dose of 1.7 mg/kg SUBQ q12h aligned with formulary recommendations. Twenty-three patients (41 %) achieved a therapeutic anti-Xa with the initial dose. Follow-up ultrasounds were available for 38 patients, of which 3 (8 %) showed progression of the index thrombus and 5 (13 %) showed formation of a new thrombus. One patient discontinued enoxaparin due to pulmonary hemorrhage, necessitating protamine administration. CONCLUSIONS: Preterm neonates appear to require a median enoxaparin dose of 2 mg/kg subcutaneously every 12 h to achieve therapeutic anti-Xa levels.