[The autoradiographic studies on the distribution of 14C-labelled sodium 7-[D(-)-alpha-(4-ethyl-2, 3-dioxo-1-piperazinecarboxamido)-alpha-(4-hydroxyphenyl)-acetamido]-3-[(1-methyl -1 H-tetrazol-5-yl) thiomethyl]-3-cephem-4-carboxylate (14C-cefoperazone) in rats and mice].

The distribution of cefoperazone (CPZ), a new semisynthetic cephalosporin antibiotic, was studied by macroautoradiography following a single intravenous or subcutaneous administration of 100 mg/kg 14C-CPZ to rats, mice, pregnant mice and experimental pyelonephritic mice. (1) In whole body autoradiograms of rats administered subcutaneously and mice administered subcutaneously and intravenously, their distribution patterns of the radioactivity were found to be similar to each case. The radioactivity was distributed at high concentration in liver, kidney, lung, tongue, salivary gland, skin, gastrointestinal tracts and retina. The radioactivity was rapidly excreted in urine and bile. And it was observed that the radioactivity excreted through bile was not reabsorbed from gastrointestinal tracts. (2) In pregnant mice administered intravenously, the radioactivity was observed the same level as whole blood level in placenta, while was hardly observed in fetuses. (3) In the experimental pyelonephritic mice administered intravenously, a considerable radioactivity was concentrated on the acute inflammatory area.