But just because you have a gym membership that you actually use doesnât mean you canât also have a few things at home for doing other types of workouts that you donât have time for at the gym, or for those days that you just canât make it out the front door.
The inside wall of the small intestine needs to be thin, with a really big surface area. This allows absorption to happen quickly and efficiently. If the small intestine had a thick wall and a small surface area, a lot of digested food might pass out of the body before it had a chance to be absorbed.
Absorption rate is slowed by coating drug particles with wax or other water-insoluble material, by embedding the drug in a matrix that releases it slowly during transit through the GI tract, or by complexing the drug with ion-exchange resins. Most absorption of these forms occurs in the large intestine.