Cefoxitin, a semi-synthetic cephamycin antibiotic. Metabolism in rats with renal insufficiency

The metabolism of cefoxitin, a new semi-synthetic cephamycin antibiotic, in rats with renal insufficiency was examined in comparison with that in control. Ascending urinary tract infection was produced in rats by intra-cystic inoculation with a virulent strain of Escherichia coli. In rats with severe infection progressed into purulent inflammation in the pelvis and medullar and cortical abscess formation, the urinary excretion of the antibiotic was reduced till the first 2 h after an i.v. dose of 40 mg/kg, while its serum levels and biliary excretion during this period were contrarily higher than those in rats with mild infection limited to pelvic inflammation and in control. On the other hand, in rats with renal arteriarctia produced by constriction of the renal artery with silver clip, blood levels of the antibiotic were higher than those in control. In the former animals, the urinary excretion was reduced to about a half, while the biliary excretion was increased up to twofold of that in control through the whole experimental period. In animals either with severe infection or with renal arteriarctia, the total recovery in the urine and the bile during 6 h of the experimental period was almost equal to those in mild infection or control groups.