Serial trough and peak amikacin levels in plasma as predictors of nephrotoxicity.

We studied 113 patients treated with intravenous amikacin to determine the value of determining serial trough and peak amikacin levels in plasma for predicting nephrotoxicity. Thirteen patients (11.5%) developed renal toxicity, with significant increases from 48 to 96 h in both peak and trough amikacin levels (6.7 +/- 4.7 [standard deviation] days before the serum creatinine rose). The nontoxicity group had no change or even showed decrements in amikacin levels in plasma. A higher nephrotoxicity risk was seen in patients with increments greater than 1 microgram/ml between 48 and 96 h, with odds ratios of 16.4 for trough, 8 for peak, and 7.2 for both levels. We suggest that an increment of at least 1 microgram/ml in amikacin levels in plasma from 48 to 96 h may predict the appearance of renal toxicity.