In the terminology of pharmacokinetics, the bioavailability (BA) of a drug product refers to the rate and extent of its absorbed active ingredient or active moiety that becomes available at the site of action. A new/test drug product (T) is considered bioequivalent to an existing/reference product ( R) if there is no significant difference in the bioavailabilities between the two products when they are administered at the same dose under similar conditions in an appropriately designed study.