Oral availability (F) is the fraction of drug that reaches the systemic circulation after oral ingestion. It is determined by 'absorption' and 'first-pass' metabolism.
Absorption refers to the ability of a drug to cross the gut wall into the portal vein.
First-pass metabolism describes presystemic drug elimination and can occur in the gut wall, portal vein or liver. The liver is usually the most important contributor.
Adjust the sliders for drug absorption and first-pass metabolism to see how these affect oral availability.
Systemic Blood Stream (Vena Cava)