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Area under the curve (AUC): total drug exposure
Medically reviewed by Javeria Muneer, Pharmacist · Last reviewed:
The area under the concentration–time curve, AUC, measures total exposure to a drug over a period. Its units are concentration × time, such as mg·h/L. Two regimens with very different peaks can have the same AUC if they deliver the same total amount.
The key relationship
For a single dose, or one interval at steady state, AUC = F × Dose / CL. Exposure rises in proportion to the dose and the fraction absorbed, and falls as clearance increases. Volume of distribution does not appear in this equation: it changes the shape of the curve but not the area under it.
Rearranged, CL = F × Dose / AUC. This is how clearance is measured in clinical studies.
Where AUC is used
Bioequivalence studies compare AUC and peak concentration between a generic and the original brand. A generic is accepted when the 90% confidence interval of the ratio falls within 80–125%.
Vancomycin dosing guidelines now target an AUC24 of roughly 400–600 mg·h/L rather than a trough level, because AUC predicts both effect and kidney toxicity more reliably.
See it in the simulator
Change the volume and notice the peak moves while the AUC tile stays the same.
