AUC (area under the concentration–time curve)
AUC is the area under the drug concentration–time curve over a period, a measure of total exposure. Divided by the length of a dosing interval it gives the average concentration.
Definition
AUC is the area under the drug concentration–time curve. It measures how much drug the body is exposed to over time, in units such as mg·h/L. AUC0–τ is the AUC over one dosing interval τ; AUC0–∞ is the AUC after a single dose extrapolated to infinity.
Link to dose and clearance
For linear PK, the AUC after an intravenous dose is the dose divided by clearance. At steady state, AUC0–τ is the dose per interval divided by clearance, so the average concentration is Cavg,ss = AUC0–τ / τ, that is, the dose rate divided by clearance.
On this site
In the anti-PD-1 dosing analysis, the average concentration was computed from the AUC. Two regimens with the same dose rate (pembrolizumab 200 mg every 3 weeks and 400 mg every 6 weeks) had the same average concentration but different troughs. See also Ctrough and Cmax.
Frequently asked questions
How is AUC related to the average concentration?
The average concentration over a dosing interval is the AUC over that interval divided by its length.
Does the same AUC mean the same trough?
No. Regimens with the same dose rate have the same average concentration, but a longer interval gives a higher peak and a lower trough.