Pharmacokinetics of Ceftriaxione, a Third-Generation Cephalosporin, in Pediatric Patients

We monitored the serum concentration of ceftriaxone (CTRX) in order to clarify its pharmacokinetics in pediatric patients. Subjects were 21 patients undergoing CTRX therapy (50 mg/kg/d) for pneumonia from January to September 2007. To determine the serum concentration of CTRX and to obtain other laboratory data, blood samples were drawn just before and after drug administration. To clarify the relationship between protein concentration and the protein binding ratio of CTRX in vitro and in vivo, the effect of human albumin on the binding ratio was investigated. Thereafter, the relationship between the protein binding ratio and the concentration of CTRX in pediatric patients was analyzed. There was no significant correlation between age and the elimination half-life of CTRX. Moreover, no significant differences were observed in the distribution volume and the clearance between pediatric patients and adults. The binding ratios increased with increased CTRX and albumin concentrations in both in vitro and in vivo studies. It was suggested that the CTRX concentration just before administration (i.e., C-trough) was sufficiently maintained above the mean inhibitory concentration against Streptococcus pneumoniae and Haemophilus influenzae. Therefore, CTRX administration once daily to pediatric patients with pneumonia was shown to be bacteriologically and pharmacokinetically superior in terms of efficacy.