Concentrations of gentamicin and amikacin in human kidneys

High kidney concentrations of gentamicin or amikacin, measured by an enzymological assay, were found in 9 of 10 patients who died during therapy with these aminoglycosides. Renal cortical concentrations of gentamicin ranged from 140 to 540 μg/g of tissue, with medullary levels of 128 to 230 μg/g. Concentrations of amikacin ranged from 365 to 1,030 μg/g in the cortex and from 270 to 718 μg/g in the medulla. The only patient with low kidney concentrations was an infant who received a single dose of gentamicin. Tissue levels were high in patients with both normal and abnormal renal function. The authors' results indicate that gentamicin and amikacin are concentrated in renal cortical and medullary tissue.