Naltrexone is used for which of the following poisoning ?
**Core Concept**
Naltrexone is an opioid receptor antagonist that reverses opioid effects by blocking the mu-opioid receptor. It has a specific role in treating opioid overdose and poisoning by counteracting the effects of opioids on the central nervous system.
**Why the Correct Answer is Right**
Naltrexone works by competitively inhibiting the binding of opioids to the mu-opioid receptor, thereby blocking the release of endogenous opioids and reducing their analgesic and euphoric effects. In the context of poisoning, naltrexone is used to reverse the life-threatening effects of opioids, such as respiratory depression and sedation. By blocking the opioid receptors, naltrexone helps to restore normal respiratory function and prevent further complications.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because naltrexone is not used to treat poisoning caused by benzodiazepines. Benzodiazepine overdose is typically managed with flumazenil, a benzodiazepine receptor antagonist.
* **Option B:** This option is incorrect because naltrexone is not used to treat poisoning caused by barbiturates. Barbiturate overdose is typically managed with supportive care and, in severe cases, activated charcoal and hemodialysis.
* **Option C:** This option is incorrect because naltrexone is not used to treat poisoning caused by local anesthetics. Local anesthetic overdose is typically managed with supportive care and, in severe cases, administration of intravenous lipid emulsion.
**Clinical Pearl / High-Yield Fact**
It is essential to note that naltrexone should only be used in the context of opioid overdose, as it can precipitate opioid withdrawal in individuals who are physically dependent on opioids.
**Correct Answer:** D