Toxicology: nicotine 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: nicotine poisoning

Sample item

A farmer sprays a nicotine-based insecticide without protection. He develops salivation, vomiting, sweating, tachycardia and hypertension, followed by muscle fasciculations and then weakness with respiratory paralysis. What explains the biphasic course?

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

The answer and the reasoning

B. Initial stimulation followed by blockade of nicotinic receptors

Nicotine first stimulates nicotinic receptors at autonomic ganglia and the neuromuscular junction, causing the early excitatory features. With larger doses it causes persistent depolarisation, which blocks transmission and leads to paralysis. Treatment is supportive, with atropine for the muscarinic features.

Option by option

  • A. Blockade of muscarinic receptors

    Muscarinic blockade, as in atropine poisoning, causes dry skin and dilated pupils.

  • B. Initial stimulation followed by blockade of nicotinic receptors (correct)

    Correct. Stimulation then depolarising blockade explains the two phases.

  • C. Inhibition of the mitochondrial respiratory chain

    Cyanide inhibits the respiratory chain and gives rapid collapse without fasciculations.

  • D. Irreversible inhibition of acetylcholinesterase

    Organophosphates inhibit acetylcholinesterase, which gives a different pattern of muscarinic excess.

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 B, Initial stimulation followed by blockade of nicotinic receptors. Nicotine first stimulates nicotinic receptors at autonomic ganglia and the neuromuscular junction, causing the early excitatory features.

Why is "Blockade of muscarinic receptors" not the answer?

Muscarinic blockade, as in atropine poisoning, causes dry skin and dilated pupils.

Why is "Inhibition of the mitochondrial respiratory chain" not the answer?

Cyanide inhibits the respiratory chain and gives rapid collapse without fasciculations.

Why is "Irreversible inhibition of acetylcholinesterase" not the answer?

Organophosphates inhibit acetylcholinesterase, which gives a different pattern of muscarinic excess.

What concept does this question test?

It tests Toxicology: nicotine poisoning in Forensic Medicine. With larger doses it causes persistent depolarisation, which blocks transmission and leads to paralysis. Treatment is supportive, with atropine for the muscarinic features.

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 Toxicology: nicotine 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.