Comparison of the renal excretory mechanisms of cefmenoxime and other cephalosporins: renal clearance in rats and rabbits.

The renal excretory mechanism of cefmenoxime was compared with those of 6 other cephalosporins (cefotaxime, deacetylcefotaxime, cefotiam, cefazolin, cephaloridine and cefsulodin) in rats and rabbits. In rats, renal clearance (Cf-Drug: corrected for serum protein binding) of cefmenoxime (4.06 ml/minute) was lower than that of cefazolin, similar to that of cefotiam, and higher than those of cefotaxime, deacetylcefotaxime, cephaloridine, and cefsulodin. In rabbits, the value for cefmenoxime (2,519 ml/minute) was markedly higher than those for the other drugs. If the clearance ratio (Cf-Drug/CInulin = CRf) is more than unity, tubular secretion of a drug is indicated. In rats, the tubular secretion of cefmenoxime equalled the glomerular filtration (CRf = 2.17). The tubular secretion of cefmenoxime was lower than that of cefazolin but similar to that of cefotiam. None of the other cephalosporins seemed to be secreted significantly. In rabbits, a large amount of cefmenoxime was secreted (CRf = 208). The tubular secretion was larger than those of the other cephalosporins. All the drugs except cefsulodin showed significant tubular secretion. A species difference was observed in the CRf of the cephalosporins: the values were generally higher in rabbits than in rats.