Tobramycin and Amikacin Nephrotoxicity

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Abstract
108 patients who received tobramycin or amikacin could be evaluated for nephrotoxicity in a prospective randomized trial. Both groups had similar illnesses, and causative agents, concurrent drug administration, ages, sex ratios, initial serum creatinine and aminoglycoside levels and total dose and duration of therapy. Using urinary concentration of β2microglobulin (β2m) as a marker, nephrotoxicity was detected in 13 (22.4%) of 58 patients given tobramycin and 13 (26%) of 50 given amikacin (n.s.). Using serum creatinine as a marker, nephrotoxicity was detected in 3 (5.2%) of 58 patients given tobramycin and in 7 (14%) of 50 given amikacin (n.s.). The whole group of 108 patients was used to compare the usefulness of serum creatinine levels versus urinary concentration of β2m. An elevation of serum creatinine was detected in 10 of 108 patients (9.3%). In 5 of these 10 patients the β2m remained normal, suggesting a functional renal failure. In 21 of the 108 patients (19.4%) the β2m increased while the serum creatinine remained normal, suggesting an aminoglycoside nephrotoxicity which would have remained undetected if only serum creatinine had been measured. In the remaining patients (77 of the 108; 71.3%) serum creatinine and urinary concentration of β2m both remained normal throughout the treatment. In conclusion no statistically significant differences were found between tobramycin and amikacin nephrotoxicity. Urinary β2m is more sensitive than serum creatinine and furthermore it allows one to differentiate aminoglycoside nephrotoxicity from functional renal failure.