Individualized pharmacokinetic versus standard dosing of amikacin: a comparison of therapeutic outcomes

We compared the therapeutic outcome in patients with normal renal function managed with either individualized pharmacokinetic (PK) dosing or standard (every 12 h) dosing of amikacin. A total of 82 patients with confirmed or suspected infectious processes were entered into the study. There was no difference in therapeutic outcomes (P = 0.47) with one patient from each group dying. The duration of hospital stay (15.8 days vs 11.3 days, P = 0.052) and the mean duration of therapy (8.9 days vs 7.4 days, P = 0.20) were not significantly different, although a trend was seen towards longer time periods in the PK group. The incidence of nephrotoxicity (3 vs 1, P = 0.61), and calculated PK parameters were not different between the PK and standard groups, respectively. Upon evaluation of amikacin serum concentrations in individual patients, we found that five of 82 patients (6.1%) were or might have been at risk for toxicity with standard, unmonitored doses of amikacin, when compared to published literature. Although equivalent therapeutic outcomes may be achieved with standard or individualized PK dosing, the risk of toxicity with standard dosing is substantial. The routine use of standard dosing regimens cannot be recommended. Definition of specific patients subtypes in whom standard regimens utilizing lower doses can safely and effectively be used is necessary.