Which opioid antagonist is used to reverse opioid overdose?

• A. Naltrexone
• B. Naloxone
• C. Methadone
• D. Buprenorphine

Answer: (B)

When reversing an opioid overdose, you need a drug that can quickly block the opioid from its receptors. Naloxone fits this role because it is a competitive opioid antagonist with a high affinity for mu receptors, so it rapidly displaces opioids and reverses respiratory depression and sedation.

Naloxone works fast, especially when given by injection, but its effects may wear off relatively quickly, so patients must be monitored and sometimes re-dosed if long-acting opioids are involved to prevent re-narcotization.

Other options either act differently or are used in other contexts. Naltrexone is also an opioid antagonist but is long-acting and not suited for acute reversal. Methadone is an opioid agonist, not an antagonist, so it would worsen the overdose. Buprenorphine is a partial agonist with high receptor affinity, which can complicate reversal and precipitate withdrawal rather than immediately reversing overdose symptoms.

So, the best choice to reverse an opioid overdose is naloxone.