Bioavailability (BA) is the extent and rate to which the active drug ingredient or active moiety from the drug product delivered in a non-intravenous way is absorbed and becomes available at the site of drug action. Assessing BA early in the drug discovery process reduces attrition rates and guides subsequent drug development processes. As a critical indicator of drug absorption, BA is determined by comparing the pharmacokinetic (PK) measurements of the drug target in the system following extravascular dosing or intravenous dosing.