If gastric emptying is increased by cholinergic stimulation, what is the expected impact on absorption?

• A. Decreases absorption
• B. Increases absorption
• C. No effect
• D. Variable depending on pH

Answer: (B)

When gastric emptying speeds up, the dose leaves the stomach and arrives at the small intestine sooner. Absorption for most orally administered drugs occurs primarily in the small intestine, which has a large surface area and favorable conditions for uptake. By delivering the drug to this absorptive site more quickly, the rate of absorption increases (and, for drugs where dissolution in the stomach was the limiting step, the extent of absorption can also rise). So, cholinergic stimulation that enhances gastric emptying tends to enhance absorption. Note that for drugs absorbed mainly in the stomach or where other factors limit absorption, the effect could differ, but the typical outcome for most drugs is increased absorption.