Toxicology: carbamate poisoning: practice question

A Forensic Medicine 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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Forensic Medicine · Toxicology: carbamate poisoning

Sample item

A farmer develops sweating, salivation and miosis after spraying carbaryl and recovers within 24 hours with atropine alone. Why are oximes generally not needed?

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

The answer and the reasoning

C. The carbamylated cholinesterase hydrolyses spontaneously within hours, so the inhibition is short-lived and reversible

Carbamates carbamylate the enzyme, and the complex dissociates spontaneously far more quickly than a phosphorylated one, so toxicity is brief and milder. Atropine and supportive care are enough. Oximes offer little benefit and are avoided with carbaryl, but they are essential in organophosphate poisoning.

Option by option

  • A. Carbamates form an aged complex that oximes cannot reverse

    Ageing of the enzyme complex is a feature of organophosphates, not carbamates.

  • B. Oximes are contraindicated in every cholinesterase inhibitor poisoning

    Oximes are the key antidote in organophosphate poisoning, so the statement is wrong.

  • C. The carbamylated cholinesterase hydrolyses spontaneously within hours, so the inhibition is short-lived and reversible (correct)

    Correct. Spontaneous hydrolysis of the carbamylated enzyme explains the short, reversible course.

  • D. Carbamates do not inhibit cholinesterase and act directly on muscarinic receptors

    Carbamates do inhibit acetylcholinesterase; the effect is simply reversible.

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 Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, The carbamylated cholinesterase hydrolyses spontaneously within hours, so the inhibition is short-lived and reversible. Carbamates carbamylate the enzyme, and the complex dissociates spontaneously far more quickly than a phosphorylated one, so toxicity is brief and milder.

Why is "Carbamates form an aged complex that oximes cannot reverse" not the answer?

Ageing of the enzyme complex is a feature of organophosphates, not carbamates.

Why is "Oximes are contraindicated in every cholinesterase inhibitor poisoning" not the answer?

Oximes are the key antidote in organophosphate poisoning, so the statement is wrong.

Why is "Carbamates do not inhibit cholinesterase and act directly on muscarin…" not the answer?

Carbamates do inhibit acetylcholinesterase; the effect is simply reversible.

What concept does this question test?

It tests Toxicology: carbamate poisoning in Forensic Medicine. Atropine and supportive care are enough. Oximes offer little benefit and are avoided with carbaryl, but they are essential in organophosphate poisoning.

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 Toxicology: carbamate poisoning?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine 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.