Autonomic: atropine toxicity: 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 · Autonomic: atropine toxicity

Sample item

A child who ate Datura seeds is flushed with dry skin, dilated pupils, fever and delirium. Which phrase best summarises the mechanism of these effects?

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

The answer and the reasoning

C. Competitive blockade of muscarinic receptors

Atropine-like alkaloids competitively block muscarinic receptors, producing dry mouth, anhidrosis with hyperthermia, mydriasis, tachycardia and delirium. Sweat glands are sympathetic but cholinergic, so their blockade causes the characteristic dry, hot skin.

Option by option

  • A. Inhibition of acetylcholinesterase

    Cholinesterase inhibition causes the opposite cholinergic picture.

  • B. Blockade of nicotinic receptors at the ganglion only

    Ganglionic blockade would not account for the CNS delirium and mydriasis pattern as a primary mechanism.

  • C. Competitive blockade of muscarinic receptors (correct)

    Correct. Muscarinic blockade explains the anticholinergic syndrome.

  • D. Stimulation of alpha-1 adrenoceptors

    Alpha-1 stimulation does not cause this syndrome.

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 C, Competitive blockade of muscarinic receptors. Atropine-like alkaloids competitively block muscarinic receptors, producing dry mouth, anhidrosis with hyperthermia, mydriasis, tachycardia and delirium.

Why is "Inhibition of acetylcholinesterase" not the answer?

Cholinesterase inhibition causes the opposite cholinergic picture.

Why is "Blockade of nicotinic receptors at the ganglion only" not the answer?

Ganglionic blockade would not account for the CNS delirium and mydriasis pattern as a primary mechanism.

Why is "Stimulation of alpha-1 adrenoceptors" not the answer?

Alpha-1 stimulation does not cause this syndrome.

What concept does this question test?

It tests Autonomic: atropine toxicity in Pharmacology. Sweat glands are sympathetic but cholinergic, so their blockade causes the characteristic dry, hot skin.

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 Autonomic: atropine toxicity?

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.