CEFAZOLIN, A NEW SEMISYNTHETIC CEPHALOSPORIN ANTIBIOTIC. VI

EXCRETION AND METABOLISM OF CEFAZOLIN-¹⁴C IN RATS AFTER INTRAMUSCULAR ADMINISTRATION

Abstract

Cefazolin is a new semisynthetic cephalosporin antibiotic. The urinary and biliary excretion and tissue levels of cefazolin were determined in rats by a simultaneous assaying of the biological and radiological activity following intramuscular injection of ¹⁴C-labeled cefazolin sodium to investigate the metabolism in vivo. The results of both determinations coincided in many aspects. Paper chromatography and subsequent autoradiography and bioautography revealed that the great majority of urinary and biliary radioactivities were derived from unchanged cefazolin. Thin-layer chromatography and inverse isotope dilution analysis indicated the same fact. These data proved that there is little biotransformation of parenterally administered cefazolin in the animal body.