Studies on Oxacephem Antibiotics: Comparison of the Effects of 1-Oxa and 1-Thia Cephalosporins on Blood Coagulation Activities and Vitamin K Metabolism in Rats

Abstract

Oxacephem antibiotics have been developed to increase the antibacterial activity of cephem antibiotics, but the effect of 1-oxygen replacement of cephem antibiotics on blood coagulation activities is not yet known. Therefore, latamoxef (LMOX), flomoxef (FMOX) and their 1-S congeners were examined for their effects on prothrombin time, activated partial thromboplastin time, plasma prothrombin and Factor VII levels, plasma and liver descarboxyprothrombin (PIVKA-II) levels, and liver microsomal vitamin K epoxide reductase activities in rats kept on a vitamin K-deficient diet. Under the vitamin-deficient states, LMOX, FMOX and their 1-S congeners inhibited the vitamin K epoxide reductase, although the effect of FMOX or its congener was much less than that of LMOX, and they decreased the blood clotting activities in rats fed a vitamin K-deficient diet. However, no difference was found in these effects between LMOX and its 1-S congener or between FMOX and its 1-S congener. This result suggests that the 1-oxygen replacement of cephem antibiotics is not responsible for the hypoprothrombinemic effect of the antibiotics.