Bauer L A, Blouin R A
Eur J Clin Pharmacol. 1983;24(5):639-42. doi: 10.1007/BF00542214.
The influence of age on amikacin pharmacokinetics was examined in 87 patients with normal renal function. All patients had a gram negative infection, were febrile, weighed within 20% of their ideal body weight, did not receive penicillin antibiotics concurrently, had normal hematocrits and had a measured 24 h creatinine clearance greater than 80 ml/min/1.73 m2. 31 patients were 20-39 years old, 27 patients were between the ages of 40-59 years, and 29 patients were 60-79 years old. These patients were compared to patients in similar previous studies who received gentamicin or tobramycin. No significant differences in clearance, volume of distribution or half-life were found due to age within a single drug group (amikacin, gentamicin, or tobramycin) or among the 3 drug groups. However, a substantial amount of intersubject variability existed in the calculated pharmacokinetic parameters. Patients over 40 years old tended to be underdosed with amikacin and the other 2 aminoglycosides. The average amikacin dose needed to achieve the desired steady-state concentrations was 18.9 mg/kg/day. 52% of the amikacin patients required doses greater than the recommended maximum (15 mg/kg/day). Since aminoglycoside pharmacokinetics do not change as age increases, doses do not need to be arbitrarily changed in older patients with normal renal function.
