**Question:** A young man is with known heroin addiction is brought in the emergency in an unconscious state. On examination, the patient has decreased bowel sounds, depressed respiration and pinpoint pupil. The treatment of choice for this patient is

A. Naloxone
B. Morphine
C. Thiopentone
D. Propofol

**Correct Answer:** A. Naloxone

**Core Concept:**
Heroin is a potent opioid drug that acts as a competitive antagonist for the mu-opioid receptors. Mu-opioid receptors are widely distributed in the central nervous system and play a crucial role in modulating respiratory, cardiovascular, and autonomic functions. Heroin overdose results in respiratory depression, decreased bowel sounds, and fixed/pinpoint pupils due to mu-opioid receptor blockade.

**Why the Correct Answer is Right:**
Naloxone is a competitive antagonist of mu-opioid receptors. It works by binding to these receptors, displacing heroin and other opioids from the receptor site, and reversing the effects of opioid overdose. In this scenario, administering naloxone will antagonize the mu-opioid receptors, thereby reversing the respiratory depression and other adverse effects caused by heroin overdose.

**Why Each Wrong Option is Incorrect:**

A. Morphine (Option B): Morphine is another opioid drug that shares the same target receptor (mu-opioid receptors) as heroin. Administering more of the same type of medication would not counteract the effects of heroin overdose and might even worsen the situation.

B. Thiopentone (Option C): Thiopentone is an anesthetic and sedative drug that does not target opioid receptors and is not relevant in reversing heroin overdose.

D. Propofol (Option D): Propofol is an anesthetic drug that affects GABAergic neurons and is not associated with opioid receptors. It is also not the appropriate treatment for heroin overdose.

**Clinical Pearl:**
In cases of opioid overdose, timely administration of naloxone can potentially save a patient's life. However, it is crucial to have a high index of suspicion for drug overdose and seek immediate medical attention when treating patients with a history of substance abuse.