How do orally administered drugs primarily absorb into the body?

Orally administered drugs primarily absorb into the body through the stomach or intestinal lining because the gastrointestinal (GI) tract is designed to facilitate the absorption of nutrients and medications. When a medication is taken orally, it passes through the digestive system, where it is broken down and dissolved in the stomach and intestinal fluids.

Once dissolved, the active ingredients in the medication can then permeate through the epithelial cells of the stomach and intestinal lining. This absorption process often occurs in the small intestine, where the surface area is significantly larger, allowing for more efficient uptake into the bloodstream. The absorbed drugs then enter the portal circulation before reaching systemic circulation, thus making them available for therapeutic action throughout the body.

Other methods of absorption, such as through the skin, directly into the bloodstream, or via the lungs, are not relevant for orally administered drugs since they typically rely on the digestive system for the initial breakdown and absorption into the body.