Question

Choose the correct match of laxative and its Mechanism of Action (MOA):

• A. (1)-(Q), (2)-(P), (3)-(R), (4)-(S)
• B. (1)-(Q), (2)-(R), (3)-(S), (4)-(P)
• C. (1)-(R), (2)-(Q), (3)-(P), (4)-(S)
• D. (1)-(Q), (2)-(R), (3)-(P), (4)-(S)

Hint:

Understanding laxative mechanisms helps in selecting appropriate therapy based on constipation etiology and patient condition.

Answer 1

The Correct Option is A

- Senna is a stimulant laxative (Q). It acts by stimulating the enteric nerves to increase peristalsis, promoting bowel movements.
- Lactulose is an osmotic purgative (P). It draws water into the colon, softening stools and increasing bowel movement frequency.
- Lubiprostone causes fecal softening (R) by activating chloride channels in the intestinal epithelium, increasing fluid secretion into the bowel.
- Prucalopride is a selective 5-HT₄ receptor agonist (S) that enhances colonic motility by stimulating serotonin receptors.
This classification aligns with the pharmacological mechanisms of these laxatives used in clinical practice.

Answer 2

This question matches four laxatives with their mechanism of action. Fix each drug's true mechanism first: Senna is a stimulant laxative (Q), Lactulose is an osmotic laxative (P), Lubiprostone acts by opening intestinal chloride channels to soften stool (R), and Prucalopride is a 5-HT4 receptor agonist that boosts colonic motility (S). Now check which option lines these up correctly.

1. (1)-(Q), (2)-(P), (3)-(R), (4)-(S): This pairs Senna with the stimulant mechanism, Lactulose with the osmotic mechanism, Lubiprostone with the chloride channel mechanism, and Prucalopride with the 5-HT4 agonist mechanism. Every drug sits with its real mechanism, so this combination is correct.
2. (1)-(Q), (2)-(R), (3)-(S), (4)-(P): This pairs Lactulose with the chloride channel mechanism and Lubiprostone with the 5-HT4 agonist mechanism, neither of which is how those two drugs actually work, so this combination is wrong.
3. (1)-(R), (2)-(Q), (3)-(P), (4)-(S): This pairs Senna with the chloride channel mechanism and Lactulose with the stimulant mechanism, again swapping mechanisms between drugs that do not share them, so this combination is wrong.
4. (1)-(Q), (2)-(R), (3)-(P), (4)-(S): This keeps Senna correctly on the stimulant mechanism and Prucalopride correctly on the 5-HT4 agonist mechanism, but it pairs Lactulose with the chloride channel mechanism and Lubiprostone with the osmotic mechanism, reversing their real modes of action, so this combination is wrong.

Only the first combination assigns every laxative to the mechanism it actually works through.

Therefore, the correct answer is (1)-(Q), (2)-(P), (3)-(R), (4)-(S).