Area under the curve (pharmacokinetics)

In the field of

Bioavailability can be measured in terms of "absolute bioavailability" or "relative bioavailability".

Absolute bioavailability

Absolute bioavailability refers to the bioavailability of a drug when administered via an extravascular dosage form (i.e. oral tablet, suppository, subcutaneous, etc.) compared with the bioavailability of the same drug administered intravenously (IV). This is done by comparing the AUC of the non-intravenous dosage form with the AUC for the drug administered intravenously. This fraction is normalized by multiplying by each dosage form's respective dose.^[6]

${\displaystyle F_{\text{abs}}=\left({\frac {{\text{AUC}}_{\text{non-IV}}}{{\text{AUC}}_{\text{ IV}}}}\ \right)\times \left({\frac {{\text{Dose}}_{\text{ IV}}}{{\text{Dose}}_{\text{non-IV}}}}\ \right)}$

Relative bioavailability

Relative bioavailability compares the bioavailability between two different dosage forms. Again, the relative AUCs are used to make this comparison and relative doses are used to normalize the calculation.

${\displaystyle F_{\text{rel}}=\left({\frac {{\text{AUC}}_{\text{dosageA}}}{{\text{AUC}}_{\text{dosageB}}}}\ \right)\times \left({\frac {{\text{Dose}}_{\text{B}}}{{\text{Dose}}_{\text{A}}}}\ \right)}$

Other applications

AUC of glucose concentration change following food intake is used to calculate the glycemic index.^[7]

Variations

Methodology

The use of

Despite the number of mathematically superior

sum of exponentials curve for the input data but only uses it to suggest better sample times by finding more highly sloped periods.^[12]

Extensions

The area under the effect curve (AUEC) is an integral of the effect of a drug over time, estimated as a previously-established function of concentration. It was proposed to be used instead of AUC in animal-to-human dose translation, as computer simulation shows that it could cope better with half-life and dosing schedule variations than AUC. This is an example of a PK/PD model, which combines pharmacokinetics and pharmacodynamics.^[13]

See also

• C_max (pharmacology)
• C_mean (pharmacology)
• "Area Under Curve" of the Receiver operating characteristic

References

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4. ^ "Useful Pharmacokinetic Equations" (PDF). University of Florida.
5. S2CID 2383402
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6. ^ Srinivasan, V. Srini (2001). [1] "Bioavailability of Nutrients: A Practical Approach to In Vitro Demonstration of the Availability of Nutrients in Multivitamin-Mineral Combination Products". The Journal of Nutrition 131 (4 Suppl): 1349S–1350S.
7. PMID 19079901
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8. S2CID 24170738
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9. S2CID 42761923
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10. S2CID 27930861
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11. ^ Knapp, Alex (2011). "Apparently, Calculus Was Invented In 1994". Forbes.
12. PMID 31412422
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13. PMID 35638366
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