Bioavailability is a subcategory of absorption and is the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered intravenously, its bioavailability is 100%. However, when a medication is administered via other routes (such as orally), its bioavailability generally TH [›] decreases (due to incomplete absorption and first-pass metabolism) or may vary from patient to patient. Bioavailability is one of the essential tools in pharmacokinetics, as bioavailability must be considered when calculating dosages for non-intravenous routes of administration.

Bioequivalence is a term in pharmacokinetics used to evaluate the normal in vivo organic equality of two restrictive arrangements of a medication. On the off chance that two items are said to be bioequivalent it implies that they would be relied upon to be, in every practical sense, the same.