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In the field of pharmacokinetics, the area under the curve (AUC) is the area under the curve (mathematically known as definite integral) in a plot of concentration of drug in blood plasma against time. Typically, the area is computed starting at the time the drug is administered and ending when the concentration in plasma is negligible. In practice, the drug concentration is measured at certain discrete points in time and the trapezoidal rule is used to estimate AUC. ==Interpretation and usefulness of AUC values== The AUC (from zero to infinity) represents the ''total drug exposure over time''. Assuming linear pharmacodynamics with elimination rate constant ''K'', one can show that AUC is proportional to the ''total amount of drug absorbed by the body'' (i.e. the total amount of drug that reaches the blood circulation). The proportionality constant is 1/''K''. This is useful when trying to determine whether two formulations of the same dose (for example a capsule and a tablet) release the same dose of drug to the body. Another use is in the therapeutic monitoring of toxic drugs. For example, gentamicin is an antibiotic which displays nephro- and ototoxicities; measurement of gentamicin concentrations in a patient's plasma and calculation of the AUC is used to guide the dosage of this drug. AUC becomes useful for knowing the average concentration over a time interval, AUC/t. Also, AUC is referenced when talking about elimination. The amount eliminated by the body (mass) = clearance (volume/time) * AUC (mass *time/volume). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Area under the curve (pharmacokinetics)」の詳細全文を読む スポンサード リンク
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