Methods of determining the area under the concentration–time curve (AUC) for vancomycin in adults

The 2 main methods used to measure the area under the concentration–time curve over a 24-hour period (AUC₂₄) are manual AUC₂₄ calculations and model-informed precision dosing using Bayesian dosing software. A comparison of various methods for optimising vancomycin dosing (with a focus on Bayesian dosing software) can be found in this article.

Manual AUC₂₄ calculations can be performed with a minimum of 2 measured vancomycin plasma concentrations after steady state has been reached. The first (peak) concentration is usually measured 1 to 2 hours after the infusion has finished, and the second (trough) concentration is usually measured immediately before the next scheduled dose. For vancomycin continuous infusions, the AUC₂₄ is the random plasma concentration (mg/L) multiplied by 24 hours.

Model-informed precision dosing uses Bayesian dosing software to predict an individual’s drug exposure based on prespecified population pharmacokinetic models. It incorporates relevant patient characteristics (such as weight, height and serum creatinine) to determine the patient’s likely drug exposure and predict the initial dose or the required maintenance dose when a vancomycin plasma concentration is available. A single concentration, taken any time after the first dose is administered, is often adequatePai 2017. In practice, the plasma sample is often taken immediately before the next dose is due; however, recent data suggest that a plasma sample taken earlier in the dosing interval may be preferredUster 2022. The utility of model-informed precision dosing depends on the availability of appropriate predictive models for specific patient populations.

Approaches to AUC₂₄ monitoring may differ between institutions because of differences in expertise and resourcing; the use of AUC₂₄ monitoring should be based on local protocols. If resources and appropriate training are not available to implement AUC₂₄ monitoring, use target trough concentration monitoring.