Drug Absorption · Pharmacology

What effect does 'ion trapping' have on a basic drug in the stomach (pH 1.5)?

  1. The drug becomes unionized and is absorbed rapidly across the stomach lining
  2. The drug evaporates due to the acidity
  3. The drug binds to the stomach wall permanently
  4. The drug becomes highly ionized and remains 'trapped' in the stomach lumen
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Correct answer: The drug becomes highly ionized and remains 'trapped' in the stomach lumen

A basic drug in an acidic environment will accept protons and become positively charged (ionized). Because the ionized form cannot easily cross the lipid membrane back into the blood, it stays in the stomach.

Difficulty: Medium Question 17 of 20

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