# A Successful Experience of Individualized Vancomycin Dosing in Critically Ill Patients by Using a Loading Dose and Maintenance Dose

## TL;DR

This study shows how individualized dosing of vancomycin in ICU patients can be successfully implemented using a population pharmacokinetic model.

## Contribution

The study successfully implemented a population pharmacokinetic model for individualized vancomycin dosing in a Chilean ICU.

## Key findings

- A loading dose of 1500 mg and maintenance dose of 1000 mg three times a day were most commonly used.
- Measured plasma concentrations correlated well with model predictions (R2 = 0.65).
- No renal side effects were observed in patients receiving the individualized dosing regimen.

## Abstract

Background/Objective: Vancomycin, a hydrophilic glycopeptide antibiotic with bactericidal activity against Gram-positive microorganisms, is one of the most commonly used antibiotics un the intensive care unit (ICU). Different efforts have been made to achieve a therapeutically effective plasma concentration of vancomycin by using loading and subsequent maintenance doses on an individual basis, but this remains subject to debate. Our objective was to individualize a dosage regimen in a Chilean ICU to optimize the pharmacological treatment of vancomycin by using a population pharmacokinetic model. Methods: A quantitative descriptive study was carried out in 51 patients at the adult ICU, San Borja Arriarán Clinical Hospital in Santiago, Chile. The dose of vancomycin was calculated by using a population pharmacokinetic software, the Antibiotic Kinetics®, and was subsequently validated with plasma trough levels of the drug through a patient sample. Results: The most commonly prescribed loading dose was 1500 mg and the most commonly used maintenance dose was 1000 mg, three times a day. The measured blood plasma concentrations of each patient (16.98 ± 5.423 μg/mL) were compared with the concentrations calculated through the population pharmacokinetic model (14.33 ± 4.630 μg/mL, p < 0.05). In addition, a correlation was found between the software-calculated trough concentration versus the measured trough concentration for vancomycin, with a positive correlation between both variables established (R2 = 0.65; p < 0.0001). No renal side effects were observed in the treated patient group. Conclusions: In the present study, a vancomycin dosing model for critically ill patients, based on a population pharmacokinetic model, was successfully implemented for routine clinical practice.