How does GI motility relate to absorption?

How does GI motility relate to absorption?

• A. Increased motility decreases contact with mucosa and reduces absorption
• B. Increased motility has no effect on absorption
• C. Increased motility increases contact with mucosa and increases absorption
• D. Motility only affects distribution, not absorption

Answer: (C)

GI absorption depends on how long and how well the drug is in contact with the absorptive mucosa. When motility increases, segmentation and mixing motions churn the luminal contents against the mucosal surface, increasing contact area and time at the absorptive sites. This enhanced contact improves dissolution for poorly soluble drugs and provides more opportunities for diffusion or carrier-mediated uptake into the intestinal cells. In the small intestine, where most absorption occurs, that extra mucosal contact generally translates to more drug crossing into the bloodstream. Of course, if transit becomes extremely fast, contact time can drop and absorption may fall, but under the scenario of increased motility with more mixing, the result is greater mucosal contact and greater absorption.

GI absorption depends on how long and how well the drug is in contact with the absorptive mucosa. When motility increases, segmentation and mixing motions churn the luminal contents against the mucosal surface, increasing contact area and time at the absorptive sites. This enhanced contact improves dissolution for poorly soluble drugs and provides more opportunities for diffusion or carrier-mediated uptake into the intestinal cells. In the small intestine, where most absorption occurs, that extra mucosal contact generally translates to more drug crossing into the bloodstream. Of course, if transit becomes extremely fast, contact time can drop and absorption may fall, but under the scenario of increased motility with more mixing, the result is greater mucosal contact and greater absorption.