The necessity of increased doses of amikacin in burn patients.

Extended periods (6 to 9 hours) of subtherapeutic serum amikacin levels were observed in five burn patients receiving the recommended intravenous dose of 7.5 mg/kg every 12 hours. Kinetic studies revealed an unusually short half-life, especially in younger patients. This more rapid elimination necessitated a shorter dosing interval (every 6 hours), resulting in an increased daily dose (30 mg/kg/day). In this study of 10 patients with normal renal function, an intravenous dosage regimen of 7.5 mg/kg every 6 hours resulted in therapeutic peak concentrations and shortened intervals of subtherapeutic serum concentrations. A transient episode of tinnitus without cochlear damage occurred in one patient after the first dose. Neither ototoxicity nor nephrotoxicity occurred in any of the patients. Because of interpatient variability in amikacin elimination, frequent monitoring of serum levels with necessary dosage changes is imperative to provide optimal serum concentrations. However, it must be emphasized that these increased dosage regimens of amikacin are not suggested for routine use without previously measuring serum levels.