Bioavailability

**Semantic type:** Qualitative Concept

**Definition:** The rate and extent to which the active ingredient or active moiety is absorbed from a drug product and becomes available at the site of action. For drug products that are not intended to be absorbed into the bloodstream, bioavailability may be assessed by measurements intended to reflect the rate and extent to which the active ingredient or active moiety becomes available at the site of action (21CFR320.1).

**Synonyms:** - bioavailability