Vancomycin Pharmacokinetics in Obese Patients: Insights from Bayesian Modeling

Area of Science:

• Pharmacology
• Clinical Pharmacy
• Obesity Medicine

Background:

• Vancomycin dosing in obese patients presents pharmacokinetic challenges.
• Achieving therapeutic vancomycin exposure is difficult due to altered drug handling.
• The relationship between vancomycin trough concentrations and efficacy in obesity is variable.

Purpose of the Study:

• To evaluate vancomycin pharmacokinetics in obese patients.
• To assess the attainment of therapeutic vancomycin targets using Bayesian software.
• To compare vancomycin exposure across different body mass index (BMI) categories.

Main Methods:

• Retrospective cohort study of adult inpatients receiving intravenous vancomycin.
• Exclusion of patients on renal replacement therapy, with AKI, pregnant, or on ECMO.
• Bayesian pharmacokinetic analysis using PrecisePK software, categorizing patients by BMI.

Main Results:

• Mean vancomycin clearance and volume of distribution increased with BMI.
• Therapeutic AUC0-24 values were achieved in approximately half of patients across all BMI groups.
• Trough concentrations were higher in obese patients but showed moderate correlation with AUC, with greater variability.

Conclusions:

• Obesity significantly alters vancomycin clearance and distribution.
• Target AUC0-24 values are achievable in obese patients, irrespective of BMI.
• Vancomycin trough concentrations are unreliable for predicting exposure in obese patients, necessitating AUC-guided Bayesian dosing.