Vancomycin Calculator

Patient Data

years

Settings

mg/hr
mcg/mL

Estimated PK Parameters

mL/min
L/hr
L
hr-1
hrs

Loading Dose

mg
hrs
mcg/mL

Estimated & Alternative Dose

mg
hrs
mcg/mL
mcg/mL
mg*hr/L
mg*hr/L

Random level → Dose → Random level

mcg/mL
hrs
mcg/ml
mg
hrs
mcg/mL

PK Parameters

hr-1
L
L/hr

Estimating a One-Time Dose

mcg/mL
hrs
mg once
mg*hr/L
mg*hr/L
  • If Ke is known then use the Supplemental Calculator "AUC During Elimination"
  • Accuracy of this calculator depends on 1) the estimated level at the start of the dose, and 2) the estimated Vd. These values are used to calculate a new Ke. The graphic shows the AUC starting from the second random level at hour “0”.

Patient Data

mg
hrs
mcg/mL
hrs

PK Parameters

L
mg*hr/L
mcg/mL
hr-1
hrs
L/hr

Estimated & Alternative Dose

mg
hrs
mcg/mL
mcg/mL
mg*hr/L
mg*hr/L

Steady-state occurs when peak and trough levels are stable after each dose. Conditions for this include: administering doses on time, having stable kidney function, and measuring the trough prior to the 4th or 5th dose.

Patient Data

mg
mcg/mL
hrs
mcg/mL
hrs

PK Parameters

hr-1
hrs
mcg/mL
L

Estimated & Alternative Dose

mg
hrs
mcg/mL
mcg/mL
mg*hr/L
mg*hr/L
  • Consider measuring two levels after the first dose for patients who have a stable yet unreliable SCr, such as for bed bound patients.
  • Draw the first level ≥ 60 minutes after the end of infusion and the second level at least 4 hours after the first level.

Patient Data

mg
hrs
mcg/mL
hrs
mcg/mL
hrs
hrs

PK Parameters

hr-1
hrs
mcg/mL
mcg/mL
L
mg*hr/L

Estimated & Alternative Dose

mg
hrs
mcg/mL
mcg/mL
mg*hr/L
mg*hr/L
  • These calculations only use vanco levels and when they were drawn, not patient variables like age or body weight, so the results can be difficult to interpret. Compare this calculator’s AUC to the AUC estimated by the Steady-State Trough calculator; if the difference between the AUCs is >100 points then there may be an issue with how the levels were drawn, reported, or entered in the calculator.
  • Vd and Ke fluctuate greatly within patients over time, but CLv remains fairly stable as long as CrCl is stable.
  • Draw the peak ≥ 60 minutes after the end of infusion and the trough at least 4 hours after the peak.

Patient Data

mg
hr-1
mcg/mL
hrs
mcg/mL
hrs

PK Parameters

hrs
mcg/mL
mcg/mL
L

Estimated & Alternative Dose

mg
hrs
mcg/mL
mcg/mL
mg*hr/L
mg*hr/L

Estimated PK Parameters

L
L
hr-1

First Dose

hrs
mg
mcg/mL
mcg/mL

Dosing by Pre-dialysis Level

mcg/mL
%
days
mg
mcg/mL
mg*hr/L
mg*hr/L
  • Select a dose so that the pre-dialysis trough is about 20 mcg/ml because this will give a daily AUC of about 500.
  • This calculator is for high-flux dialysis which removes 30-40% of vancomycin over 3-4 hours

AUC During Elimination

hr-1
mcg/mL

Time

AUC24

mg*hr/L
mg*hr/L
mg*hr/L

Peak After Single Dose

mg
L
hr-1
mcg/mL
mcg/mL

Clow = Chigh*e-K*t

mcg/mL
mcg/mL
hrs
hr -1

Time Math

hrs

Goal SS Level

mcg/mL
mg
mL
mg*hr/L

Initial Dosing

L/hr
L
hr-1
mg
mg/hr
mL/hr

Dosing by SS Level

mcg/mL
mg/hr
L
hr-1
L/hr
mL/hr
mg/hr

  

Initial Dosing Calculator: The maintenance dose is calculated based on CrCl. Clinical judgment can be used to adjust SCr and CrCl if needed. Use the loading dose calculator to achieve therapeutic levels quickly and make the first trough closer to full steady state. Note that the calculator increases Vd by 25% for the loading dose because Vd is larger at the start of therapy.

Two Levels After First Dose Calculator: This calculator may be useful for bed bound patients, when the Cockcroft-Gault equation may not be reliable to estimate CrCl.

Steady-State Trough Calculator: The trough does not have to be a trough, it can be drawn any time after distribution has finished (at least 60 minutes after the end of infusion). This calculator uses a population Vd model in first-order PK equations estimate the AUC. The correlation between peak-trough AUCs and trough-only estimated AUCs is about 0.926.  The standard deviation of the difference between peak-trough and estimated AUCs is about 50, meaning that approximately 95% of patients have an estimated AUC within 100 points of the actual AUC.  See the publications below for details:

  1. Fewel N. Vancomycin area under the curves estimated with pharmacokinetic equations using trough-only data. J Clin Pharm Ther. 2021
  2. Fewel N. Accuracy of vancomycin AUC values estimated with trough-only data in a veteran population. AJHP. 2023
  3. Arensman Hannan KN, Rivera CG, Fewel N. Vancomycin AUC values estimated with trough-only data: Accuracy in an adult academic medical center population. AJHP. 2023
  4. Keil E, Wrenn RH, Deri CR, et al. Comparison of open-access, trough-only online calculators versus trapezoidal method for calculation of vancomycin AUC. Ann Pharmacother. 2023

Steady-State Peak and Trough Calculator: Although reliable, this method requires obtaining an additional blood sample and the results can be difficult to interpret. To help evaluate the results, compare the peak-trough AUC to the AUC estimated with the Steady State Trough calculator. If the difference between the AUCs is >100 points there may be a problem with how the peak and trough levels were drawn, reported, or entered into the calculator.

Intermittent Hemodialysis Calculator: The key to this calculator is to target a pre-dialysis level of about 20 mcg/ml because this will give a daily AUC of about 500. Enter a pre-dialysis level into the calculator to estimate a post-dialysis dose.

Continuous Infusion Calculator: This dosing method is the easiest way to measure an AUC: AUC24 =  SS level * 24 hrs. The calculator has a feature where it suggests a bolus dose or hold time when a measured level is below or above the goal SS level.

Dosing by Random Levels Calculator: This calculator uses a population Vd to calculate Ke based on a random level. The results are limited to calculating a one-time dose rather than a maintenance dose.