Bioavailability

Bioavailability is the degree to which a drug, nutrient or other biologically active substance becomes available to the target tissue after administration. For bioavailability to be verified, there must be a chemical, biological, immunologic, or other test that verifies the concentration of the drug, or its active derivative, in the body fluids of the recipient.

Bioequivalence covers the case where the initial distribution of different drug preparations may vary, but the duration and form of the active principle is delivered identically.