Opioids: naloxone duration: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Opioids: naloxone duration

Sample item

A 24-year-old man receives naloxone 0.4 mg after a methadone overdose and wakes with normal breathing. Two hours later he is drowsy with a respiratory rate of 6 per minute. What explains this relapse?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Naloxone acts for a much shorter time than methadone, so a repeat dose or infusion is needed

Naloxone, a competitive mu-receptor antagonist, lasts about 30 to 90 minutes, whereas methadone acts for 24 hours or longer. Once naloxone is cleared the opioid effect returns, so patients need observation and repeat dosing or a naloxone infusion. Naloxone can also precipitate withdrawal in dependent patients.

Option by option

  • A. Naloxone caused a rebound release of endogenous opioids

    Naloxone does not cause rebound endogenous opioid release.

  • B. Methadone has induced tolerance to naloxone

    Tolerance to an antagonist does not develop in this way.

  • C. Naloxone has been converted into an agonist

    Naloxone is a pure antagonist and is not converted to an agonist.

  • D. Naloxone acts for a much shorter time than methadone, so a repeat dose or infusion is needed (correct)

    The duration mismatch lets methadone effects return, which needs repeat naloxone.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is D, Naloxone acts for a much shorter time than methadone, so a repeat dose or infusion is needed. Naloxone, a competitive mu-receptor antagonist, lasts about 30 to 90 minutes, whereas methadone acts for 24 hours or longer.

Why is "Naloxone caused a rebound release of endogenous opioids" not the answer?

Naloxone does not cause rebound endogenous opioid release.

Why is "Methadone has induced tolerance to naloxone" not the answer?

Tolerance to an antagonist does not develop in this way.

Why is "Naloxone has been converted into an agonist" not the answer?

Naloxone is a pure antagonist and is not converted to an agonist.

What concept does this question test?

It tests Opioids: naloxone duration in Pharmacology. Once naloxone is cleared the opioid effect returns, so patients need observation and repeat dosing or a naloxone infusion. Naloxone can also precipitate withdrawal in dependent patients.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Opioids: naloxone duration?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.