Population pharmacokinetics of vancomycin in patients with diabetic foot infection: a comparison of five models.

PURPOSE: This study aimed to compare individual pharmacokinetic (PK) parameters of vancomycin with predicted values from five population PK models in patients with diabetic foot infections (DFIs).

METHODS: Patients with a diagnosis of DFI and an estimated glomerular filtration rate (eGFR) ≥ 30 mL/min were included in the study. Individual PK data was carried on by collecting three vancomycin serum concentrations in a steady-state condition. Five published population-based nomograms were assumed to predict PK parameters. Optimal vancomycin exposure was considered as a trough level of 15-20 mg/L or the area under the curve over 24 h/minimum inhibitory concentration (AUC24 /MIC) ≥ 400.

RESULTS: A total of 48 samples from 16 patients were analyzed. There was a statistically significant difference between the volume of distribution (Vd ) obtained from population methods and the individual estimations (P ≤ 0.001 in Ambrose and Burton, P = 0.010 and 0.006 in Bauer and Burton revised models, respectively). AUC/MIC ≥ 400 was achieved in 68.7% of patients while 50% had a trough level of less than 15 mg/L.

CONCLUSIONS: Vancomycin PK parameters, particularly individualized Vd , may not be predictable by population nomograms in patients with DFI and stable renal function. Moreover, the weak correlation between AUC24 values and trough concentrations underlines the starting practice of vancomycin AUC24 -based monitoring and dosing in the clinical setting.