Pharmacokinetics. What is the area under the curve (AUC)?

The following pharmacological definition has been taken from the Pharmacology and Experimental Therapeutics Department Glossary at Boston University School of Medicine .

Area Under the Curve (AUC):

The area under the plot of plasma concentration of drug (not logarithm of the concentration) against time after drug administration. The area is conveniently determined by the “trapezoidal rule”: the data points are connected by straight line segments, perpendiculars are erected from the abscissa to each data point, and the sum of the areas of the triangles and trapezoids so constructed is computed. When the last measured concentration (Cn, at time tn) is not zero, the AUC from tn to infinite time is estimated by Cn/kel.

The AUC is of particular use in estimating bioavailability of drugs, and in estimating total clearance of drugs (ClT). Following single intravenous doses, AUC = D/ClT, for single compartment systems obeying first-order elimination kinetics; alternatively, AUC = C0/kel. With routes other than the intravenous, for such systems, AUC = F · D/ClT, where F is the bioavailability of the drug. The ratio of the AUC after oral administration of a drug formulation to that after the intravenous injection of the same dose to the same subject is used during drug development to assess a drug’s oral bioavailability.

The copyright of the text is held by Trustees of Boston University. Permission has been granted for its use in this blog.

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