Vancomycin dosing and individualization of therapy in hemodialysis patients continues to be a challenge; particularly as vancomycin is a renally cleared drug. Complicating matters further, there is not only a range of different dialysis types (hemodialysis, peritoneal, continuous renal replacement therapy), but also a range of membranes with varying degrees of permeability to different sized molecules.
Vancomycin dosing and the pharmacokinetics of hemodialysis
Dosing hemodialysis patients is complex, with relatively few published studies, even though the use of vancomycin in hemodialysis patients is common. Challenges include a prolonged distribution phase as well as redistribution from tissue to serum at the end of dialysis giving a rebound effect. In addition, residual renal function, and nonrenal clearance should also be considered. 1 In addition to typical patient-specific factors that must be considered, in hemodialysis patients the timing of vancomycin administration, the timing of serum vancomycin concentrations, as well as the dialysis procedure used must be considered when creating a dosing regimen.
Calculating vancomycin doses in the hemodialysis cohort
The hemodialysis, two-compartment vancomycin adult model implemented in DoseMeRx is derived from the Goti et al retrospective study which included 336 patients on hemodialysis. It has been validated for use in patients receiving high-flux, intermittent hemodialysis. The study concluded clearance in patients undergoing hemodialysis was 35% lower than clearance in nondialysis patients, and the volume of distribution was approximately halved in dialysis patients when compared to non dialysis patients.2 Our implementation of this model for patients receiving vancomycin and intermittent hemodialysis has been built with these parameters to ensure more appropriate loading and maintenance dose recommendations are provided for this population.
How do you dose vancomycin in intermittent hemodialysis patients?
The release of the new 2019 draft IDSA/SIDP vancomycin dosing guidelines are clear that this is a challenging cohort.3 While evidence in other patient cohorts suggests that an AUC of 400-600 mg.h/L target is appropriate, outcome studies have not yet been completed in a hemodialysis-specific group. Nevertheless, this remains the recommended approach in the absence of other data. Due to the rebound effect and the challenges in the timing of levels, dosing, and dialysis, the majority of sites use a pre-dialysis level as a proxy for AUC. DoseMeRx is therefore configured with the primary dosing target to be aimed at optimizing the pre-dialysis (trough) level.
Here are some more vancomycin resources for you:
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