A 34-year old rickshaw puller has been using heroin for the past ten years. One evening his family members found him unconscious. He was brought to the casualty. On examination he had tachycardia, shallow breathing, constricted pupils. His blood pressure was 100/70 mm of Hg. He had brisk bilateral deep tendon reflexes. The planter reflexes were flexor on both sides. Which of the following is the best treatment for him?

**Core Concept**
The patient is presenting with signs of opioid overdose, characterized by respiratory depression, miosis, and altered level of consciousness. Opioid overdose is a medical emergency requiring prompt treatment to prevent respiratory failure and death.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with opioid-induced respiratory depression, which is caused by the activation of mu-opioid receptors in the brainstem, leading to decreased respiratory drive. The administration of naloxone, a specific opioid antagonist, rapidly reverses opioid-induced respiratory depression by competitively inhibiting the action of opioids at mu-opioid receptors. This is the first-line treatment for opioid overdose.

**Why Each Wrong Option is Incorrect**
**Option A:** Nalbuphine is a mixed agonist-antagonist opioid, which is not effective in reversing opioid-induced respiratory depression and may even worsen the situation.
**Option B:** Flumazenil is a benzodiazepine antagonist, which is not indicated for opioid overdose and may actually precipitate seizures in patients with a history of benzodiazepine use.
**Option C:** Physostigmine is a cholinesterase inhibitor, which is not indicated for opioid overdose and may actually worsen respiratory depression by increasing parasympathetic tone.

**Clinical Pearl / High-Yield Fact**
In patients with opioid overdose, always administer naloxone in a monitored setting and be prepared to repeat doses as the effects of naloxone may wear off.

**Correct Answer:** C. Naloxone

✓ Correct Answer: D. Naloxone