Where does the absorption of oral medication primarily take place?

The absorption of oral medication primarily takes place in the small intestine due to its extensive surface area and rich blood supply, which facilitate effective absorption of nutrients and drugs. The inner lining of the small intestine is coated with villi and microvilli, which increase the surface area and allow for a greater amount of medication to enter the bloodstream.

While the stomach does carry out some initial breakdown of medications, it has a limited capacity for absorption due to its acidic environment and relatively small surface area compared to the small intestine. The colon and large intestine are predominantly involved in water reabsorption and do not play a significant role in the absorption of oral medications. Instead, by the time substances reach these areas, they are typically in a form that is less amenable to absorption. This makes the small intestine the primary site for the absorption of orally administered drugs.