Purpose: The present study aimed to establish a population pharmacokinetic model of vancomycin, including adult critically ill septic patients, with normal and impaired renal function.
Materials and methods: A prospective analysis of 146 concentrations from 73 adult critically ill septic patients treated with 1-h intravenous infusion of vancomycin were included in the study. A nonlinear mixed effects modeling (NONMEM) approach was applied for data analysis and evaluation of the final model. The influence of creatinine clearance calculated by the Cockcroft-Gault equation (CrCl), and other potential covariates on vancomycin clearance (CL) were evaluated.
Results: The final one-compartment pharmacokinetic model includes the effect of CrCl on CL. Population pharmacokinetic values for a typical subject were estimated at 0.024 l/h for CL dependent on renal function (CLCrCl), 1.93 l/h for residual portion of CL (not dependent on renal function), and 0.511 l/kg for volume of distribution (V). According to the final model, for patients with CrCl = 120 ml/min, the median vancomycin total CL is 4.81 l/h, while CrCl-dependent fraction accounts for approximately 60% of CL.
Conclusions: The developed population vancomycin model may be used in estimating individual CL for adult critically ill septic patients, and could be applied for individualizing dosage regimens taking into account the continuous effect of CrCl.
Keywords: Antibiotics; Creatinine clearance; NONMEM; Renal function; TDM.
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