Bioavailability
Definition
The fraction of an administered substance that reaches systemic circulation unchanged; it is measured for a particular formulation and route.
By PurePeptideHub Editorial Team · Updated . Educational source review; independent clinical review pending.
How exposure is compared
Absolute bioavailability compares dose-adjusted systemic exposure after a non-intravenous route with intravenous exposure. Researchers commonly use the area under the plasma concentration-time curve, or AUC. Route, formulation and study conditions belong with the reported percentage.
References: [1]
A worked example
In a hypothetical experiment, an oral product produces an AUC of 20 after a 10 mg dose. An intravenous reference produces an AUC of 10 after a 1 mg dose. The dose-adjusted ratio is (20/10) divided by (10/1), or 0.2: 20% absolute bioavailability. These invented numbers demonstrate the calculation, not a dose recommendation.
What a percentage cannot tell you
Higher bioavailability does not by itself mean greater safety or a better clinical result. It also differs from potency: one measures exposure, while the other concerns the concentration needed for an effect. Comparisons between products require compatible measurement methods.