Final answer:
Insoluble fiber is not digested by enzymes, absorbs water to add bulk and facilitates stool passage. It is a crucial component in the development of drugs that aim for better intestinal permeability and stability.
Step-by-step explanation:
Insoluble fiber is a type of nondigestible carbohydrate that does not dissolve in water, providing fecal bulk and aiding in the easy passage of stool through the digestive tract. Unlike fermentable fibers, it is not easily degraded by digestive enzymes and thus remains largely intact until it reaches the colon. It absorbs water, which can help ease defecation and contribute to maintaining regular bowel movements.
These characteristics are instrumental in the design of drugs with improved intestinal permeability and stability. The drug that is semi-synthetic, not degraded by enzymes, and provides fecal bulk is insoluble fiber. Insoluble fiber doesn't dissolve in water and is inert to digestive enzymes in the upper gastrointestinal tract, which helps in adding bulk to the food and easing bowel movements.