Naloxone vs Naltrexone
How to tell Naloxone and Naltrexone apart when a board question makes them look alike.
Naloxone: short-acting antagonist for acute overdose rescue; naltrexone: long-acting antagonist for maintenance after detox.
Side by side
Short-acting opioid antagonist for acute overdose with respiratory depression; can precipitate withdrawal.
Longer-acting opioid antagonist for relapse prevention after detoxification; must confirm opioid-free status.
Naloxone competitively antagonizes opioid receptors, especially mu receptors, rapidly reversing opioid effects.
Naltrexone blocks opioid receptors for sustained relapse prevention and also has alcohol-use-disorder utility.
Pinpoint pupils, respiratory depression, and immediate rescue context point naloxone.
Maintenance blockade, monthly injection/oral prevention, or precipitated withdrawal risk after detox points naltrexone.
The trap
Both precipitate withdrawal in an opioid-dependent patient, so the clinical setting and timing decide. Naloxone is the right answer for an unconscious patient with pinpoint pupils and respiratory depression: start with 0.4 to 2 mg IV/IM/intranasal and titrate to respiratory rate, NOT to full alertness, because full reversal can precipitate severe withdrawal and increase aspiration risk. Naltrexone is the right answer for a clean-and-sober patient seeking relapse prevention; the patient must be opioid-free for 7 to 10 days before starting or naltrexone will precipitate severe acute withdrawal.
Watch it explained
Test it nowThe repair move
For opioid antagonists, first decide emergency reversal versus long-term blockade.
Try a free question
CoreA patient with opioid overdose has respiratory depression and pinpoint pupils. A short-acting competitive opioid antagonist is given immediately and breathing improves. Which drug is this?
Show answer and explanation
Answer: A. Naloxone. Naloxone is the acute opioid overdose reversal drug; it competitively antagonizes opioid receptors and can precipitate withdrawal.
Why the other choices are tempting
- B. Naltrexone is longer acting and used for relapse prevention, not acute respiratory reversal.
- C. Flumazenil reverses benzodiazepine receptor effects and can trigger seizures.
- D. Buprenorphine is a partial opioid agonist.
- E. Methadone is a full opioid agonist used in opioid use disorder treatment and pain.
Flashcards
Tap a card to flip it.
What is the fastest separator for Naloxone vs Naltrexone?
Naloxone: short-acting antagonist for acute overdose rescue; naltrexone: long-acting antagonist for maintenance after detox.
What clue should make you choose Naloxone?
Short-acting opioid antagonist for acute overdose with respiratory depression; can precipitate withdrawal.
Quick answers
What is the fastest way to tell Naloxone from Naltrexone?
Naloxone: short-acting antagonist for acute overdose rescue; naltrexone: long-acting antagonist for maintenance after detox.
What is the key clue for Naloxone?
Short-acting opioid antagonist for acute overdose with respiratory depression; can precipitate withdrawal.
What is the key clue for Naltrexone?
Longer-acting opioid antagonist for relapse prevention after detoxification; must confirm opioid-free status.
What is the common trap with Naloxone vs Naltrexone?
Both precipitate withdrawal in an opioid-dependent patient, so the clinical setting and timing decide. Naloxone is the right answer for an unconscious patient with pinpoint pupils and respiratory depression: start with 0.4 to 2 mg IV/IM/intranasal and titrate to respiratory rate, NOT to full alertness, because full reversal can precipitate severe withdrawal and increase aspiration risk. Naltrexone is the right answer for a clean-and-sober patient seeking relapse prevention; the patient must be opioid-free for 7 to 10 days before starting or naltrexone will precipitate severe acute withdrawal.