Comparative low-dose nephrotoxicities of gentamicin, tobramycin, and amikacin.

Most investigations of the comparative nephrotoxicities of aminoglycosides in animals have utilized large multiples of the human dose. Furthermore, many of these assessments have used only one or two dose levels and have not described a dose-response comparison among antibiotics. Because of this lack of comparative dose-response data over a range of low multiples of the human dose, the nephrotoxicities of gentamicin, tobramycin, and amikacin were investigated in 180 rats, utilizing doses ranging from one to seven times the equivalent human clinical doses. Histopathological evaluations of both kidneys from each rat were scored without knowledge of the treatment, and statistical analyses of the results indicated that a linear and parallel dose-response relationship existed for each drug, the relative nephrotoxicity over the range of doses analyzed was gentamicin > tobramycin > amikacin (P = 0.0001), and, unlike amikacin, the human dose equivalents (milligrams per kilogram) of gentamicin and tobramycin were significantly nephrotoxic in rats (P < 0.05).