Opioids: pethidine: practice question

A Anaesthesia 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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Anaesthesia · Opioids: pethidine

Sample item

Pethidine is used to treat postoperative shivering, but it is avoided with repeated dosing in renal failure. What is the reason?

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

The answer and the reasoning

C. Accumulation of norpethidine, which causes seizures

Norpethidine is an active metabolite with a long half-life that lowers the seizure threshold and accumulates in renal failure. Pethidine also has an atropine-like effect and can cause tachycardia.

Option by option

  • A. Accumulation of morphine-6-glucuronide

    M6G is the metabolite of morphine.

  • B. Histamine release

    Histamine release is not the main concern.

  • C. Accumulation of norpethidine, which causes seizures (correct)

    Correct. Norpethidine is neurotoxic.

  • D. Cumulative cholinesterase inhibition

    Pethidine does not inhibit cholinesterase.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, Accumulation of norpethidine, which causes seizures. Norpethidine is an active metabolite with a long half-life that lowers the seizure threshold and accumulates in renal failure.

Why is "Accumulation of morphine-6-glucuronide" not the answer?

M6G is the metabolite of morphine.

Why is "Histamine release" not the answer?

Histamine release is not the main concern.

Why is "Cumulative cholinesterase inhibition" not the answer?

Pethidine does not inhibit cholinesterase.

What concept does this question test?

It tests Opioids: pethidine in Anaesthesia. Pethidine also has an atropine-like effect and can cause tachycardia.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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: pethidine?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.