Question

Match List-I with List-II
List-I
(A). Morphine
(B). Buprenorphine
(C). Butorphanol
(D). Naloxone
List-II
(I). Opioid antagonist
(II). Opioid agonist-antagonist
(III). Partial opioid agonist
(IV). Opioid agonist
Choose the correct answer:

• (A) - (I), (B) - (III), (C) - (II), (D) - (IV)
• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)
• (A) - (IV), (B) - (III), (C) - (II), (D) - (I)

Hint:

Remember that Naloxone is the standard reversal agent for all opioids (pure antagonist).
Because Buprenorphine is a partial agonist with extremely high binding affinity, it is very difficult to reverse with Naloxone once bound.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Opioids are powerful analgesic drugs that act on specific receptors ($\mu$, $\kappa$, and $\delta$) in the central and peripheral nervous systems.
They are classified based on their receptor binding and intrinsic activity.

Step 2: Detailed Explanation:
Let us classify each opioid listed:
- (A) Morphine: This is a classic pure opioid agonist (specifically at $\mu$ and $\kappa$ receptors) with high intrinsic activity, used to treat severe pain.
- (B) Buprenorphine: This is a partial opioid agonist at $\mu$ receptors. It binds tightly but has low intrinsic efficacy, producing a ceiling effect for analgesia.
- (C) Butorphanol: This is an opioid agonist-antagonist. It is an antagonist (or weak partial agonist) at $\mu$ receptors but a full agonist at $\kappa$ receptors, commonly used for mild visceral analgesia and sedation.
- (D) Naloxone: This is a pure opioid antagonist that binds competitively to $\mu$, $\kappa$, and $\delta$ receptors without activating them, used to reverse the effects of opioid agonists.
Matching these gives: (A) - (IV), (B) - (III), (C) - (II), (D) - (I).

Step 3: Final Answer:
The correct matching sequence corresponds to option (D).