[Pharmacokinetic interference between furosemide and cephalosporins]

The effect of furosemid was studied on rats in comparison to that of etamid with respect to circulation in the body of some cephalosporins, such as cephalotin, cephaloridin, cephazolin, cephacetrile, cephapirin, cefradin and cefalexin. Furosemid and etamid were administered to the rats intraperitoneally in a dose of 100 mg/kg 30 minutes before exposure to the cephalosporins. Cefalexin was administered intragastrically in a dose of 100 mg/kg and the other cephalosporins were administered intramuscularly in a dose of 20 mg/kg. It was found that furosemid increased the blood levels of all cephalosporins in the rats and especially those of cephaloridine and cephacetrile, the levels being increased 5-6 times. The effect of etamid was analogous but less pronounced. Furosemid significantly decreased the renal excretion of some cephalosporins, i.e. cephaloridine, cephalotin, cephacetrile and cephazolin and had an insignificant effect on renal excretion of the other antibiotics. Etamid did not inhibit renal excretion of the cephalosporins.