Pharmacokinetic analysis of cefozopran in neonatal infections: Population pharmacokinetics using nonmem

: This report describes the results on pharmacokinetics, efficacy and safety of cefozopran (CZOP) in neonatal patients. Enrolled patients were 136 in total whose informed consents to enter this study had been given by their parents. Among them, blood samples were collected from 42 neonates to analyze concentrations of CZOP by population pharmacokinetics (PPK) methods. Based on this analysis, the average pharmacokinetic parameters of CZOP and the variabilities of them in different morbid pharmacological backgrounds and in different subjects were evaluated. This PPK analysis showed that clearance (CL) and distribution volume (Vd) of CZOP could be estimated by the following equations; CL = 0.0452 x WT1.75 (in the case of the postnatal age of over than 1 day) CL = 0.623 x 0.0452 WT1.75 (in the case of the postnatal age of 1 day or less) Vd = 0.455 x WT where WT indicates body weight in kg. The coefficients of variation among individual subjects on CL and Vd were found to be 20.7% and 20.0%, respectively. From this PPK analysis it was indicated that the elimination of CZOP is dependent on the postnatal age and is approximately 38% lower in the younger group than in the older group. Therefore, it could be concluded that, though the cases of evaluation were small in number, adjustment of dosing of CZOP is necessary, particularly in prolongation of intervals of administration, in cases of postnatal age of 1 day or less.