Comparative pharmacokinetics of cefadroxil, cefaclor, cephalexin and cephradine in infants and children

The pharmacokinetics of cefadroxil, cephalexin, cephradine and cefaclor were studied in infants and children. The effects of a cow or infant milk feed upon absorption were also investigated. The serum half-lives of cephalexin and cephradine were similar (about 1 h); the cefaclor half-life was about 0·6 hand cefadroxil about 1·5 h. Because of the slower rate of absorption and elimination, the bioavailability of cefadroxil was about twice that of cefaclor and 75% greater than that of cephradine or cephalexin. The absorption of cefadroxil and cefaclor was not affected by the ingestion of milk but the peak serum concentrations and AUCs of cephalexin and cephradine were reduced after such a feed.