A Successful Experience of Individualized Vancomycin Dosing in Critically ill-Patients by Using Loading-Dose and Maintenance-Dose

Background/Objective: Vancomycin, a hydrophilic glycopeptide antibiotic with bactericidal activity against gram-positive microorganisms, is one of the most used antibiotics at the intensive care units (ICU). Different efforts have been done to achieve therapeutically effective plasma concentration of vancomycin by using loading and subsequent maintenance doses on an individual basis, but this remains on the 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®, which was subsequently validated with plasma levels of the drug through a patient’s sample. Results: The most prescribed loading dose was 1,500 mg and the most used maintenance dose was 1,000 mg, 3 times a day. The measured blood plasma concentrations of each patient (16.98 ± 5.423 g/mL) were compared with the concentrations calculated through the population pharmacokinetic model (14.33 ± 4.630 g/mL, p<0.05). Besides, a correlation was made between the software calculated trough concentration versus the measured trough concentration for vancomycin, where 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.