Vancomycin dosing in complex and critically-ill patients
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Vancomycin has wide inter-individual variability, with Vd values varying from around 0.5-1.0 L/kg. This is affected by factors such as age, gender and body weight, but also by non-obvious factors. This dose-effect relationship is sufficiently variable that a population of patients receiving 1000mg bd can have trough levels ranging from 5.3–72.6mg/L.
Traditionally, vancomycin dosing and monitoring guidelines recommend levels are obtained at steady-state around day three. With a tool such as DoseMeRx, however, this is not necessary. Provided the time the level was taken is accurate, levels can be taken as soon as the first dose.
Vancomycin dosing calculator for AUC-dosing
The two-compartment vancomycin adult model implemented in DoseMeRx is derived from a retrospective study with a cohort of 1,812 patients. This model is particularly useful for AUC-based dosing as it models both the distribution and elimination phases of vancomycin.
How do you dose vancomycin for complex patients including ICU?
As our two-compartment adult vancomycin model (Goti el al) fits a more complex pharmacokinetic curve, in order to get the best individual fit, two laboratory results (not necessarily on the same dose) are ideal in order to fit and individualize both phases for the patient. For complex patients, such as those in ICU, where multiple levels are already being taken, the use of this model is highly recommended.
For patients with fewer levels taken, you may wish to consider the single compartment adult vancomycin model (Buelga et al) which has been clinically validated in a naïve population, widely used in over 10,000 patients receiving vancomycin therapy, and in DoseMeRx to be able to accurately predict future vancomycin concentrations with low mean absolute error of 1.2mg/L.
Here are some more vancomycin resources for you:
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