The Effect of Asphyxia on the Pharmacokinetics of Ceftazidime in the Term Newborn

The multiple-dose pharmacokinetics of ceftazidime (CAZ) (administered twice daily in a 50 mg/kg of body weight i.v. dose) were studied in 10 severely asphyxiated term infants with suspected septicemia on d 3 of life. Nine term infants with suspected septicemia but without asphyxia served as controls. Blood samples were collected from an arterial catheter at 0, 0.5, 1, 2, 4, 8, and 12 h after an i.v. bolus injection. A high performance liquid chromatography method was used to determine CAZ concentrations from serum. CAZ pharmacokinetics followed a one-compartment open model. The GFRs of all infants were simultaneously studied by means of the 24-h continuous inulin infusion technique. Elimination serum half-life (5.86 ± 1.13 h versus3.85 ± 0.40 h) and serum trough concentrations (46 ± 14 mg/L versus23 ± 7 mg/L) of CAZ were significantly (p< 0.001) increased in the asphyxiated newborn, whereas total body clearance of CAZ (128.4 ± 25.1 mL/h versus205.7 ± 55.4 mL/h), CAZ clearance per kg (40.9 ± 6.1 mL/h/kg versus60.8 ± 8.3 mL/h/kg), and the GFR expressed in mL/min (3.14 ± 0.43 versus4.73 ± 0.89) were significantly (p< 0.001) decreased in the asphyxiated newborn. We conclude that twice daily administration of 50 mg/kg of body weight CAZ given to asphyxiated term newborns in the first days of life results in significantly higher serum trough levels in comparison with control infants. The impaired CAZ clearance is a result of a significantly decreased GFR.