Intestinal luminal stool–water interface

The intestinal luminal stool–water interface is the physiological boundary between the aqueous phase of the intestinal contents (fecal water) and the solid fecal matter or the intestinal mucosa. This interface plays a vital role in the solubilization and transport of nutrients, electrolytes, and metabolic byproducts like bile acids (PMID: 10448775). It is not a discrete molecular target such as a protein or enzyme, but rather a microenvironment where various pharmacological interventions occur. For instance, bile acid sequestrants and phosphate binders operate at this interface by physically binding substances to prevent their systemic absorption (PMID: 2211458). Additionally, the composition of the stool-water phase is a key determinant of the local bioavailability of drugs intended for colonic action (PMID: 25613724). Alterations in the physicochemical properties of this interface are associated with gastrointestinal disorders, including chronic diarrhea and inflammatory bowel disease. Consequently, it serves as a critical site for monitoring biomarkers like fecal pH and electrolyte levels to assess gut health. Understanding the dynamics at this interface is essential for optimizing the delivery of drugs that act locally within the gastrointestinal tract.

Other names

Fecal water interfaceLuminal aqueous phaseStool-water phaseIntestinal stool-water interface

Drugs acting at this interface typically employ physical adsorption, ion exchange, or osmotic modulation to alter the chemical composition or volume of the luminal aqueous phase (PMID: 16258361).