Vancomycin AUC24 Calculator
Vancomycin AUC24 Calculator
Estimate AUC24 for vancomycin dosing from total daily dose and creatinine clearance, in line with the AUC-guided 2020 consensus guideline.
Vancomycin AUC24
AUC-guided dosingTotal daily dose 2000 mg, creatinine clearance 80 mL/min, clearance factor 0.75
Formula
- total daily dose
- mg, summed across all doses given in 24 hours
- CrCl
- creatinine clearance, mL/min
- factor
- vancomycin clearance as a fraction of creatinine clearance, typically about 0.75
- 0.06
- converts creatinine clearance from mL/min to L/h (× 60 ÷ 1000)
Worked example
Total daily dose 2000 mg, creatinine clearance 80 mL/min, clearance factor 0.75
CL = 0.75 × 80 × 0.06 = 3.6 L/h
AUC24 = 2000 ÷ 3.6 = 556 mg·h/L
This sits within the 400-600 target range assuming an MIC of 1 mg/L
AUC24/MIC targets
| AUC24/MIC (assuming MIC 1 mg/L) | Interpretation |
|---|---|
| Below 400 | Likely subtherapeutic |
| 400 – 600 | Target range |
| Above 600 | Increased nephrotoxicity risk without added benefit |
From trough-only monitoring to AUC-guided dosing
The 2020 consensus guideline from ASHP, IDSA, PIDS and SIDP moved vancomycin monitoring from trough-only targets to an AUC24/MIC target of 400 to 600, assuming an MIC of 1 mg/L. The change followed evidence that troughs above 15 mg/L were associated with a substantially higher rate of acute kidney injury without a corresponding improvement in clinical cure — the old target was pushing exposure higher than needed for benefit.
This calculator estimates AUC24 from total daily dose and an assumed vancomycin clearance, using the population approximation that vancomycin clearance runs at about 75% of creatinine clearance. The 0.06 factor converts creatinine clearance in mL/min into a clearance in L/h so that the units of dose and clearance are consistent. It is a first-pass estimate for planning a starting dose, not a substitute for a measured level.
The guideline’s preferred method is two measured concentrations fitted with Bayesian dosing software, which accounts for the individual patient’s actual pharmacokinetics rather than a population average. Reach for that whenever the patient is haemodynamically unstable, has rapidly changing renal function, or when the population estimate and a measured trough disagree — the population factor of 0.75 is a starting point, not a patient-specific measurement.
Frequently asked questions
What is the target AUC24/MIC for vancomycin?
400 to 600, assuming an MIC of 1 mg/L, as set out in the 2020 ASHP/IDSA/PIDS/SIDP consensus guideline.
Why did guidelines move away from trough-only monitoring?
Because troughs above 15 mg/L were associated with a higher rate of acute kidney injury without improving clinical cure, so exposure was being pushed higher than necessary.
How accurate is the population clearance factor of 0.75?
It is a population approximation, useful for planning a starting dose. Individual clearance varies, particularly in unstable renal function, so it is not a substitute for a level-guided estimate.
What is the most accurate way to determine AUC24?
Two measured vancomycin concentrations analysed with Bayesian dosing software, which the guideline identifies as more accurate than a population-based estimate from dose and creatinine clearance alone.
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References
- Rybak MJ et al. Therapeutic monitoring of vancomycin for serious MRSA infections: a revised consensus guideline. Am J Health-Syst Pharm. 2020;77(11):835-864.
- Neely MN et al. Prospective trial of vancomycin dosing by trough versus AUC. Antimicrob Agents Chemother. 2018;62(2):e02042-17.