View source for Area Under the Curve (AUC)

The '''Area Under the Curve''' ('''AUC''') is a critical parameter in pharmacokinetics, representing the integral of the drug concentration-time curve. It quantifies the total drug exposure over time, providing vital information on drug absorption, distribution, metabolism, and elimination.

===Definition===
<math>\text{AUC} = \int_0^\infty C(t) \,dt </math>

Where:
*<math>C(t)</math> is the drug concentration at time <math>t</math>

AUC offers insight into the extent and rate of drug absorption, making it a fundamental measure to assess bioavailability and bioequivalence of drugs.

==Types of AUC==
Several types of AUC values exist, each serving unique purposes in pharmacokinetic studies:
{| class="wikitable"
!Type
!Description
!Application
|-
|<math>\text{AUC}_{\text{last}}</math>
|Area under the concentration-time curve up to the last measurable concentration.
|Used to determine the total exposure of the body to the drug until the last measurable concentration.
|-
|<math>\text{AUC}_{0\to\infty}</math>
|Represents the total area under the concentration-time curve from administration to infinity.
|Provides an estimate of the total exposure of the body to a drug. Useful for evaluating the overall efficacy of a drug.
|-
|<math>\text{AUC}_{0\to t}</math>
|Area under the concentration-time curve from the administration up to a specific time 't'.
|Useful for focusing on drug exposure within specific time windows.
|-
|<math>\text{AUC}_{0\to24}</math>
|Area under the concentration-time curve from administration up to 24 hours.
|Often used when drugs are administered once a day.
|-
|<math>\text{AUC}_{\tau}</math>
|Area under the concentration-time curve over a dosing interval 'tau', for example in repeated dosing every 12 or 24 hours.
|Helpful in evaluating steady-state pharmacokinetics in multiple dosing regimens.
|-
|<math>\text{AUC}_{\text{micro}}</math>
|Utilizes microdosing studies and mass spectrometric analyses to determine the AUC for drugs administered in very low concentrations.
|Suitable for studying the pharmacokinetics of drugs at subtherapeutic, micro-level doses.
|}

===Application===
AUC is indispensable in pharmacology and drug development:
*It is pivotal for determining the dosage and frequency of drug administration.
*It aids in evaluating the bioequivalence of generic drugs to brand-name counterparts.
*It enables researchers to study the pharmacokinetics of new drug candidates.

===See Also===

* [[Wikipedia:Area under the curve (pharmacokinetics)|Wikipedia article]]

*[[Pharmacokinetics]]
*Drug Metabolism
*[[Bioavailability]]
*[[Bioequivalence]]