Vancomycin monitoring and dose adjustment in adults undergoing haemodialysis

Vancomycin monitoring is essential to individualise maintenance vancomycin doses in adults undergoing haemodialysis. Use of Bayesian dosing software to determine the area under the concentration–time curve over a 24-hour period (AUC24) can guide dosage adjustments; however, the utility of Bayesian software depends on the availability of a haemodialysis-specific pharmacokinetic model. A predialysis vancomycin plasma concentration can be used as a surrogate for AUC24; maintaining a predialysis plasma vancomycin concentration between 16 and 20 mg/L will likely achieve an AUC24 target of 400 to 600 mg.hr/LFu, 2018Hartinger, 2022Lewis, 2021Ogawa, 2022Zelenitsky, 2022.

After haemodialysis, vancomycin redistributes from the tissues back to the blood over 3 to 6 hoursLaunay-Vacher, 2002. Vancomycin plasma concentrations taken immediately after haemodialysis cannot be used to guide dosing because the level will be falsely low.

If a predialysis plasma sample can be obtained and the vancomycin plasma concentration returned within 90 minutes, wait for the concentration before giving the dose, and adjust the dose.

If there are delays in receiving the vancomycin plasma concentration, do not wait for the concentration before giving the dose; use the maintenance dose given at the last haemodialysis session. Adjust the dose before giving the next dose.

Advice on dosage adjustment can be obtained from an expert or, if available, a local protocol. See Adjusting the vancomycin dose in adults undergoing haemodialysis based on trough concentration for suggested dosage adjustment to achieve a target of 16 to 20 mg/L.

Some centres use dosing nomograms to determine an appropriate dosage adjustment. Examples of vancomycin dosing nomograms can be found in this American Journal of Health-System Pharmacy article and this Nephrology article; however, these nomograms use different target predialysis plasma concentrations than those recommended in this topic.

If vancomycin is given before a 72-hour interdialytic interval (eg on Friday when next haemodialysis session is on Monday), the maintenance dose should be increased by 25% to ensure adequate vancomycin exposure until the end of the interdialytic intervalRybak, 2020.

Table 1. Adjusting the vancomycin dose in adults undergoing haemodialysis based on trough concentration

[NB1]

Trough plasma concentration [NB2]

Suggested dose adjustment to achieve a target of 16 to 20 mg/L

less than 16 mg/L

increase the dose [NB3]

16 to 20 mg/L

maintain current dose

21 to 25 mg/L

reduce the dose [NB3]

more than 25 mg/L

withhold the dose and seek expert advice

Note:

NB1: The recommendations in this table do not apply to patients with central nervous system infection – seek expert advice.

NB2: The recommendations in this table assume the timing of the trough sample was appropriate (ie predose).

NB3: Dose adjustment should be made in a linear manner – a worked example calculation of linear dose adjustment for vancomycin in an adult is given in Example calculation of linear dose adjustment in an adult receiving a vancomycin intermittent infusion.