CC11 – Drug bioavailability

CC11. Drug bioavailability is the fraction of administered dose of the parent drug that reaches the systemic circulation.

11.1. The bioavailability of an intravenous dose is defined as 1 (or 100%).

11.2. Absolute bioavailability, F, can be obtained by comparing the area under the curve (AUC) of a concentration–time relationship of one route of administration with that of the same drug given intravenously.

11.3. Relative bioavailability compares the proportion of parent drug reaching the systemic circulation from one non-intravenous route of administration to another non-intravenous route.

11.4. A formulation is the form in which the drug is administered (e.g., dermal patch, capsule and injectable) and can alter the rate and extent of release of soluble drug and, therefore, the bioavailability.

11.5. First-pass metabolism of drug in the liver or gut before it reaches the systemic circulation may decrease parent drug bioavailability as can other factors that decrease drug absorption.