Urinary Precipitate During Cephalothin-Cephaloridine Treatment

To the Editor.— The cephalosporins are semisynthetic congeners of cephalosporin C which is produced by the fungusCephalosporium acremonium. The most commonly used representatives of this group of new antibiotics are cephalothin sodium and cephaloridine; both are excreted unchanged in the urine.¹,²Urinary recovery studies on normal subjects given single intramuscular injections of 1.0 gm of either cephalothin sodium or cephaloridine indicate that about 75% of the injected material is eliminated in an active form during the first six hours.²Cephaloridine is excreted almost entirely by glomerular filtration³although tubular excretion also occurs.⁴Renal dysfunction may occur during treatment with cephaloridine and, less frequently, with cephalothin.⁵Acute toxic effects of cephaloridine include necrosis of the proximal convoluted tubules in mice, rats, guinea pigs, rabbits, monkeys, and man.⁵⁻⁹Repeated administration in rats of 50 to 150 mg/kg/day of cephaloridine produces proteinuria,¹⁰while moderate to large