Question

Given below are two statements:
Statement I : Antimotility opioid drugs afford only symptomatic relief in diarrhoea.
Statement II : The major action of those drugs appears to be mediated through $\alpha$-adrenoceptors located on enteric neuronal network.
In light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

To remember this mechanism: Antimotility *opioids* naturally act through *opioid* receptors ($\mu$ and $\delta$) in the gut wall, not through adrenergic pathways.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Antidiarrheal therapy is designed to reduce the frequency and fluid volume of stools.
Antimotility agents, primarily opioids, act directly on the gastrointestinal tract to slow down motility and increase fluid absorption.
However, these drugs do not treat the underlying infectious or toxic cause of the diarrhea.

Step 2: Detailed Explanation:
Let us analyze both statements:
1. Statement I: Antimotility opioid drugs afford only symptomatic relief in diarrhoea.
This statement is correct.
Antimotility opioid drugs (such as loperamide and diphenoxylate) work by slowing intestinal transit time, allowing more water to be absorbed from the feces.
This reduces the frequency of defecation and firms the stool.
However, they do not address the primary cause of the diarrhea, such as bacterial toxins, viral infections, or mucosal inflammation.
Therefore, they provide only symptomatic relief.
Thus, Statement I is true.
2. Statement II: The major action of those drugs appears to be mediated through $\alpha$-adrenoceptors located on enteric neuronal network.
This statement is incorrect.
The major action of antimotility opioid drugs is mediated through specific opioid receptors, primarily $\mu$-opioid receptors and to a lesser extent $\delta$-opioid receptors, located on the enteric nerves in the myenteric plexus.
Binding to these receptors inhibits the release of acetylcholine and prostaglandins, which reduces propulsive peristaltic activity and increases segmenting contractions.
While $\alpha_2$-adrenergic agonists (like clonidine) can also reduce intestinal secretion, the primary mechanism of action for antimotility *opioid* drugs is not mediated through $\alpha$-adrenoceptors.
Therefore, Statement II is false.

Step 3: Final Answer:
Statement I is true because opioid antidiarrheals provide only symptomatic relief, but Statement II is false because they act through opioid receptors rather than $\alpha$-adrenoceptors.
Therefore, the correct option is (C).