Vancomycin AUC Dosing Calculator | AUC24 from 2 Levels

Scope: adults on intermittent IV vancomycin, stable kidney function, not on dialysis. The 400–600 target is the guideline’s target for serious invasive MRSA infection — it excluded MSSA, coagulase-negative staphylococci and other pathogens. Not for children, CRRT/dialysis, continuous infusions, intervals over 24 hours, or unstable renal function (deteriorating or improving) — this page takes no creatinine and cannot detect instability. Method: two-level first-order equations, not Bayesian.

What do you have?

Current Dose per Administration mg

Dosing Interval hours

Infusion Duration hours, as actually given

Measured Levels mg/L = mcg/mL

Peak Level mg/L

Peak Drawn After End of Infusion hours — an offset, not a clock time

Trough Level mg/L

Trough Drawn Before the Next Dose hours — 0 if right before

Enter levels in mg/L (identical to mcg/mL) and times as offsets, not clock times. The dose above must be the one that produced these levels. A pre-dose trough from the previous interval works too: at steady state an interval starts at the same concentration it ends at. Draw only at steady state — after the third or fourth dose. Levels drawn earlier read low, and this page will then suggest a dose that is too high. A whole-scale unit error is invisible to the checks here: they compare the two levels to each other, not to an absolute scale.

Estimated AUC₂₄

— mg·h/L

Total Daily Dose for AUC 400–600

— mg/daynot an order — redistribute into a practical regimen and re-measure levels

Derived Pharmacokinetics

Parameter	Value
Enter both levels to derive the patient’s kinetics.

Show calculation steps

Recent Updates

The current ASHP/IDSA/PIDS/SIDP consensus guideline replaced trough-based monitoring with an individualized AUC/MIC target of 400 to 600 (assuming a broth-microdilution MIC of 1 mg/L) for serious MRSA infections, naming two acceptable routes to the AUC: Bayesian software, or two timed steady-state levels with first-order equations — the method this page implements.
The prospective multicentre observational PROVIDE study sharpened the upper bound: higher vancomycin exposures did not lower treatment failure but did raise acute kidney injury, and in a post hoc analysis patients with a day-2 AUC of 515 or lower had the best combined outcomes — a reason to aim at the middle of the target range, not its ceiling.

Sources: Rybak, M. J., et al. 2020 consensus guideline, Am J Health-Syst Pharm 2020;77(11):835-864 · Lodise, T. P., et al. PROVIDE, Clin Infect Dis 2020;70(8):1536-1545.

Key Knowledge Points

A 15–20 mg/L trough is no longer the goal in serious MRSA infection. Troughs correlate poorly with true exposure: many patients whose troughs sit in that range already carry AUC values beyond the therapeutic threshold and inside the nephrotoxicity range. For non-invasive MRSA or other infections the guideline says the evidence is insufficient to recommend either route.
This page is the guideline’s equation route, not its Bayesian route. Two timed steady-state levels estimate the AUC accurately, but the result is a snapshot — it cannot adapt to changing kinetics. The guideline also asks for target exposure within the first 24 to 48 hours and calls Bayesian estimation prudent there precisely because it does not need steady-state levels; this page does.
Timing is part of the method. The peak must be post-distributional — 1 to 2 hours after the end of the infusion — and the trough should come from the same interval near its end. Both time boxes take offsets, not clock times, and this page flags draws outside that window.
Retargeting is proportional. At steady state, changing the total daily dose changes the observed AUC₂₄ in direct proportion — that is how the suggested range is derived. Redistribute it, keep every infusion at or below the label rate of 10 mg/min, and re-measure on a schedule: weekly if the patient is stable, daily if not, and for anyone past 3 to 5 days of therapy.
The upper bound is a kidney limit, not a stretch goal. The guideline’s own words are that daily AUC should be held between 400 and 600 mg·h/L; the 650 often quoted alongside it is a meta-analysis AKI cutpoint, not a target ceiling. AUC-guided monitoring itself lowered nephrotoxicity against trough-guided practice in a 1,280-patient quasi-experiment, pooled odds ratio 0.68.

About This Vancomycin AUC Dosing Calculator

This Vancomycin AUC Dosing Calculator estimates the 24-hour area under the concentration-time curve (AUC₂₄) for adults on intermittent IV vancomycin, using the two-level first-order method the 2020 ASHP/IDSA/PIDS/SIDP consensus guideline names as the alternative to Bayesian software. It extrapolates a steady-state peak and trough to the true end-of-infusion and end-of-interval concentrations, integrates one dosing interval, scales to 24 hours, and applies the guideline’s dose-proportionality principle to suggest the total daily dose that lands the AUC in the 400–600 target.

The Formulas Explained

kₑ = ln(Cₚ/Cₜ) ÷ Δt   (Δt = time between the two draws)
True peak Cₘₐₓ = Cₚ × e^(kₑ × tₚ)   ·   True trough Cₘₖₙ = Cₜ × e^(−kₑ × tₜ)
AUC per interval = tₖₙₗ × (Cₘₐₓ + Cₘₖₙ) ÷ 2 + (Cₘₐₓ − Cₘₖₙ) ÷ kₑ
AUC₂₄ = AUC per interval × (24 ÷ interval)   ·   New daily dose = current daily dose × (target AUC ÷ estimated AUC)

The elimination rate constant is the classic two-point log-linear slope (the Sawchuk–Zaske method); the interval AUC is a linear trapezoid over the infusion plus a log-linear decay area after it, as published for two-concentration AUC estimation by Pai and colleagues — the review the 2020 guideline cites for this approach, crediting Begg, Barclay, and Duffull as modified by Pai and Rodvold.

Worked example — 1,000 mg q12h over 1 h; peak 25 mg/L at 1.0 h after the end of infusion; trough 8 mg/L at 0.5 h before the next dose. Δt = 9.5 h; kₑ = ln(25/8)/9.5 = 0.1199 h⁻¹ (t½ 5.78 h); true peak 28.19, true trough 7.53 mg/L; interval AUC = 17.86 + 172.18 = 190.0; AUC₂₄ = 380 mg·h/L. To reach 400–600, the 2,000 mg/day regimen scales to roughly 2,100–3,150 mg/day — e.g., 1,250 mg q12h, then re-measure.

Clinical Interpretation & Limitations

The estimate is only as good as its inputs. The method assumes steady state — the guideline places that after the third or fourth dose — mono-exponential decay between the draws, and stable renal function, deteriorating or significantly improving alike; the guideline is explicit that the calculation will not be correct if a physiologic change such as renal dysfunction occurs during or after the sampling period. Steady state takes about five half-lives, so at the 20 to 40 hour half-lives of stable chronic kidney disease that is four to eight days, and day-2 levels do not qualify. Repeat it when the dose, the interval, or the patient changes.

The 400–600 target assumes a broth-microdilution MIC of 1 mg/L. The guideline notes that standard doses may not reach the target when the MIC is 2 mg/L — a stewardship conversation, not a reason to push the AUC past 600. The reverse move is blocked as well: below a BMD MIC of 1 mg/L the guideline does not recommend cutting the dose to hold the same ratio. Etest MICs read higher than broth microdilution and must not be plugged into this ratio uncritically.

An in-target AUC is not the whole kidney risk. The guideline names increased weight, pre-existing renal dysfunction and critical illness as host factors, and concurrent aminoglycosides, loop diuretics, amphotericin B, IV contrast, vasopressors and piperacillin/tazobactam as agents shown to raise nephrotoxicity in patients receiving vancomycin. The target does not change; the monitoring intensity should.

Administration safety is unchanged by AUC dosing: the label directs each dose to run at no more than 10 mg/min or over at least 60 minutes, whichever is longer, at no more than 5 mg/mL — so 1,000 mg needs 1.7 hours and a 3,000 mg load needs 5. In obese adults the guideline lowers loading to 20–25 mg/kg of actual body weight under the same 3,000 mg cap, and does not extend the mg/kg rule to maintenance: it computes that from a population clearance estimate and the target AUC, rarely above 4,500 mg/day, because maintenance doses set on actual body weight are themselves a route to supratherapeutic exposure.

Frequently Asked Questions (FAQ)

Why does this calculator use AUC instead of trough levels?

The 2020 ASHP/IDSA/PIDS/SIDP consensus guideline moved vancomycin monitoring from trough targets to an AUC24/MIC target of 400 to 600, because a trough is a poor stand-in for total exposure. In one prospective trial only 19% of troughs were therapeutic versus 70% of AUCs, and AUC-guided monitoring is associated with less nephrotoxicity than trough-guided dosing (pooled odds ratio 0.68).

When should the two vancomycin levels be drawn?

Both near steady state. The guideline prefers a post-distributional peak 1 to 2 hours after the end of the infusion and a trough within the same dosing interval, near its end. Enter the actual offsets – this page extrapolates each level to the true end-of-infusion peak and true end-of-interval trough before computing the AUC.

Can I use this for dialysis, CRRT, children, or unstable kidney function?

No. The first-order method assumes one stable elimination rate, and the guideline warns the calculation will not be correct if a physiologic change such as renal dysfunction occurs during or after sampling. Dialysis, CRRT, pediatric and rapidly changing patients need Bayesian software or specialist dosing – this page covers stable adult intermittent dosing only.

Why is the AUC target 400 to 600 mg·h/L?

Below an AUC/MIC of 400 (broth-microdilution MIC of 1 mg/L), bactericidal exposure for MRSA is not reliably reached in PK/PD models. Above roughly 600, kidney injury climbs: a meta-analysis found less AKI below about 650, and the observational PROVIDE study saw the best combined outcomes, post hoc, at day-2 AUCs of 515 or lower. The guideline therefore brackets 400 to 600.

Is this the same as Bayesian AUC software?

No. The guideline’s preferred approach is Bayesian software, which can work from one or two levels and adapt as kinetics change. This page implements the guideline’s stated alternative: two timed steady-state levels run through first-order equations – simpler and fully transparent, but a snapshot. Recheck levels after any dose change or renal shift.

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📖 Sources:

📝 How to cite this page:

DosePilot Medical Team. Vancomycin AUC Dosing Calculator. DosePilot. Published August 16, 2026. Last medically reviewed August 2026. https://dosepilot.com/calc/vancomycin-auc-dosing-calculator/

⚠️ Disclaimer:

This tool is for informational and educational purposes only and is not a substitute for professional clinical judgment. AUC estimates derived from two concentrations depend entirely on accurate levels, draw times, and stable renal function; the suggested dose range is a proportional projection, not a prescription. All dosing decisions must be made by a qualified healthcare professional considering the individual patient’s full clinical context, institutional protocols, and repeat level monitoring.