What does the term "bioavailability" refer to?

The term "bioavailability" specifically refers to the amount of drug that is absorbed into the bloodstream after it is administered. This concept is crucial in pharmacology as it determines the extent and the rate at which the active ingredient or active moiety is available for therapeutic action. When a drug is administered, not all of it is necessarily absorbed; factors such as the route of administration, the drug formulation, and individual patient characteristics can influence this absorption.

Understanding bioavailability is essential for determining the proper dosage and effectiveness of a medication, as it directly impacts how much of the drug reaches systemic circulation and can exert its therapeutic effects. This is particularly significant for medications that have low bioavailability, where dosing adjustments may be needed to achieve desired therapeutic outcomes.