Clinical and pharmacokinetic characteristics of aminoglycoside nephrotoxicity in 201 critically ill patients.

We studied 201 critically ill patients during 267 courses of gentamicin (139 courses) or tobramycin (128 courses) therapy. Clinical and pharmacokinetic data were obtained on 240 of 267 courses (120 courses each of gentamicin and tobramycin). Two judgments of nephrotoxicity and its cause were made independently in this study, using a clinical and a pharmacokinetic definition of nephrotoxicity. The two sets of criteria were generally in good agreement, as all but 10 of 41 patients who were judged nephrotoxic by pharmacokinetic criteria were independently judged nephrotoxic by the clinical definition. Groups of patients judged nontoxic did not differ from groups judged nephrotoxic in age, sex, weight, initial creatinine clearance, total dose given, duration of treatment, initial aminoglycoside trough serum levels, number of dosage adjustments, concurrent use of furosemide, or concurrent cephalosporins. Prior aminoglycosides (usually gentamicin) had been used more frequently in the nontoxic group (P less than 0.05). Two major conclusions of this study are at variance with those of previous investigators; (i) we found no clinical parameters of value in predicting nephrotoxicity in critically ill patients; and (ii) aminoglycoside serum concentrations, once in the therapeutic range, were of limited value in prevention of aminoglycoside nephrotoxicity in our patients.