In the field of pharmacokinetics, the area under the curve (AUC) is the definite integral of the concentration of a drug in blood plasma as a function of time (this can be done using liquid chromatography–mass spectrometry[1]).
AUC is a useful metric when trying to determine whether two formulations of the same dose (for example a capsule and a tablet) result in equal amounts of tissue or plasma exposure.
[citation needed][4] In pharmacokinetics, bioavailability generally refers to the fraction of a drug that is absorbed systemically and is thus available to produce a biological effect.
In order to determine the respective AUCs, the serum concentration vs. time plots are typically gathered using C-14 labelled drugs and AMS (accelerated mass spectrometry).
[11] Despite the number of mathematically superior numerical integration schemes (such as those outlined in Wagner & Ayres 1977), the trapezoidal rule remains the convention for AUC calculation.
An example is a 2019 algorithm known as OTTER: it performs a fit onto sum of exponentials curve for the input data but only uses it to suggest better sample times by finding more highly sloped periods.