Small intestine absorption (HIA)

Small intestine absorption is the physiological process by which nutrients, electrolytes, water, and xenobiotics (including drugs) are transported from the intestinal lumen across the epithelial lining into the systemic circulation. This process occurs primarily in the duodenum, jejunum, and ileum via mechanisms such as passive diffusion, paracellular transport, and active carrier-mediated transport. Key molecular players in this process include transporters like Solute Carrier (SLC) family members (e.g., SGLT1 for glucose, PepT1 for peptides) and ATP-binding cassette (ABC) efflux pumps like P-glycoprotein. While essential for life and a fundamental pharmacokinetic parameter in drug development (the 'A' in ADME), "Small intestine absorption" is a complex biological pathway rather than a single molecular target. Impairment of this process leads to malabsorption syndromes, while therapeutic modulation often involves targeting specific constituent enzymes or transporters to treat conditions like obesity, diabetes, or hypercholesterolemia.

Other names

Intestinal absorptionGastrointestinal absorptionEnteral absorptionHuman intestinal absorption (HIA)Small bowel absorption

Modulation of intestinal absorption typically involves the inhibition of specific digestive enzymes (e.g., alpha-glucosidase) or membrane transporters (e.g., NPC1L1) to reduce the uptake of dietary components or the use of pro-absorptive agents to enhance nutrient retention.