3.15 : 影响药物吸收的因素：解剖学参数

Drug absorption entails transporting drugs from the administration site to the bloodstream.

GI motility moves drugs through the digestive tract, entering the stomach. However, the stomach's low surface area and high acidity limit drug absorption.

Gastric emptying transfers drugs from the stomach to the small intestine, rate-limiting the absorption process. Factors like high-fat meals or cold beverages delay the emptying process, lengthening drug absorption time.

The small intestine's duodenum neutralizes incoming acidic content from the stomach. Its unique anatomy— folds, villi, and microvilli make it an important site for drug absorption.

These structures provide a large surface for absorption, aided by a rich capillary network in the villi for rapid drug movement along the concentration gradient.

Intestinal peristalsis allows drugs to contact intestinal mucosal cells, taking 1-4 hours for optimal absorption, depending on the drug's formulation and properties. Rapid motility in diarrhea causes insufficient absorption, while longer intestinal transit times allow complete drug absorption.