Renal excretion of cephapirin and cephaloridine: evidence for saturable tubular reabsorption.
Drug concentrations in plasma and urine were determined in 5 healthy subjects after intravenous infusion of 1 gm cephapirin and cephaloridine. Sampling of blood and urine was frequent and prolonged. Specimens were analyzed by high-pressure liquid chromatography (HPLC). Renal clearance of cephapirin decreased to less than 5% of control in all subjects when drug concentrations in plasma and urine declined. Cephaloridine clearance decreased to a lesser extent. Our findings suggest that, besides tubular secretion and glomerular filtration, a saturable and probably active tubular reabsorption is also involved in the renal handling of these two cephalosporins. The saturable reabsorption process was characterized by its Michaelis-Menten constant Km and its maximum transport capacity Tm.
D000042:Absorption; D000328:Adult; D001798:Blood Proteins / Q000378:metabolism; D002509:Cephaloridine / Q000097:blood / Q000378:metabolism* / Q000652:urine; D002511:Cephalosporins / Q000378:metabolism*; D002514:Cephapirin / Q000097:blood / Q000378:metabolism* / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007684:Kidney Tubules / Q000378:metabolism*; D007700:Kinetics; D008875:Middle Aged; D011485:Protein Binding
D001798:Blood Proteins; D002511:Cephalosporins; D002514:Cephapirin; D002509:Cephaloridine