Dose-Normalized Bioavailability

What is this formula?

Dose-normalized bioavailability expresses drug exposure relative to the administered dose. It is calculated by dividing the area under the concentration-time curve (AUC) by the administered dose.

This parameter allows comparison of systemic exposure across studies, formulations, or dosing regimens when different doses are used.

A higher value indicates greater exposure per unit dose.

When to use it

Use this formula when comparing pharmacokinetic data obtained using different administered doses.

It is commonly used in dose proportionality studies, formulation comparisons, bioavailability research, and pharmacokinetic evaluations.

Example

A subject receives a dose of 200 mg and the measured AUC is 100 mg·h/L.

Data:

AUC = 100 mg·h/L

Dose = 200 mg

Formula:

FDN = AUC/Dose

Substitution:

FDN = 100/200

Result:

FDN = 0.50 h/L

This value can be compared directly with results obtained using other doses.

Applications

- Dose proportionality assessment

- Pharmacokinetic comparison studies

- Formulation development

- Bioavailability evaluation

- Drug development research

Note

Dose-normalized bioavailability is a comparative pharmacokinetic metric rather than a direct measure of absolute bioavailability. It is most useful when pharmacokinetics are approximately linear. In nonlinear pharmacokinetics, exposure may not increase proportionally with dose, limiting the interpretation of this parameter.