Abstract:
The purpose of this study was to determine pharmacokinetic parameters of
amikacin in Thai patients. One-hundred and thirty-two serum amikacin concentrations
were obtained from 71 Thai-patients (40 male and 31 female). A one-compartment model
was fitted to the population data using the computer program Kinetica version 4.0. The
model was guided by evaluation of the minimum objective function and the weighted
residuals.
The mean age of the patients was 60.2 years (ranges, 13 to 92 years). The mean
total body weight and creatinine clearance was 53.7 kg (ranges, 33 to 80 kg.) and 58.8
mL/min (ranges, 21.1 to 157.0 mL/min), respectively. Several covariates were tested for
their influence on elimination rate constant and volume of distribution. The creatinine
clearance was the potential source of variability in both volume of distribution and
elimination rate constant. The final models for volume of distribution and elimination rate
constant were Vd = 14.50 + 0.06CLcr (L) and Kel = 0.121 + 0.0015CLcr (hr-1). The
interindividual variability for Vd and Kel was 29.5% and 39.8%, respectively.
Intraindividual variability was 37.4%. Mean±SD value of volume of distribution,
elimination rate constant, clearance and half-life was 18.03±4.18 L., 0.208±0.07 hr-1,
3.92±2.09 L/hr. and 4.02±2.26 hr, respectively. To validate the final model, seventeen
serum amikacin concentrations obtained from 10 patients were considered. The predicted
concentrations calculated from individual pharmacokinetic parameters were compared with
observed concentrations, this was found to have correlation (R2=0.89; p<0.05). The mean
error (ME) was 0.78±4.05 mg/L and root mean square error (RMSE) was 4.00 mg/L.
The pharmacokinetic parameters model of amikacin from this study can be used as
basic information for further study in related fields. The proposed dosage regimen is
recommended for Thai patients who are prescribed amikacin and its should be further
investigated in a larger population. A more complete pharmacokinetic parameters model
and dosage regimen needs more Thai patients’ pharmacokinetic data.