Acetyl salicylate & phenobarbitone are better absorbed from stomach because they are-
**Core Concept**
Acetyl salicylate and phenobarbitone are weak acids, and their absorption from the stomach is facilitated by the low pH environment. The stomach's acidic environment allows these weak acids to exist in their ionized form, increasing their lipid solubility and facilitating diffusion across the gastric mucosa.
**Why the Correct Answer is Right**
At low pH, acetyl salicylate and phenobarbitone exist as their protonated forms, which are more lipophilic. This increased lipid solubility enables them to diffuse more easily across the gastric mucosa, leading to better absorption. This phenomenon is known as "ion trapping," where the ionized form of the weak acid is trapped in the lipid-rich gastric mucosa, enhancing its absorption.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not provide a relevant reason for the absorption of acetyl salicylate and phenobarbitone from the stomach.
**Option B:** This option is incorrect because it does not accurately describe the mechanism of absorption of these weak acids.
**Option C:** This option is incorrect because it is too vague and does not provide a clear reason for the absorption of acetyl salicylate and phenobarbitone from the stomach.
**Clinical Pearl / High-Yield Fact**
When dealing with weak acids or bases, it's essential to consider the pH-dependent ionization and lipid solubility, as it significantly affects their absorption and distribution in the body.
**Correct Answer:** D. Their ionized form increases lipid solubility.