Pharmacology: physostigmine: 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 · Pharmacology: physostigmine

Sample item

Which anticholinesterase crosses the blood-brain barrier and reverses central anticholinergic syndrome?

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

The answer and the reasoning

D. Physostigmine

Physostigmine is a tertiary amine that penetrates the central nervous system and reverses central effects of anticholinergic drugs such as atropine and scopolamine, including delirium and agitation. Neostigmine, pyridostigmine and edrophonium are quaternary compounds that do not cross the blood-brain barrier. Physostigmine can cause bradycardia and seizures.

Option by option

  • A. Neostigmine

    Neostigmine is a quaternary amine and has no central effect.

  • B. Pyridostigmine

    Pyridostigmine is quaternary and does not enter the CNS.

  • C. Edrophonium

    Edrophonium is quaternary and does not enter the CNS.

  • D. Physostigmine (correct)

    Correct. As a tertiary amine it reaches the brain.

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 D, Physostigmine. Physostigmine is a tertiary amine that penetrates the central nervous system and reverses central effects of anticholinergic drugs such as atropine and scopolamine, including delirium and agitation.

Why is "Neostigmine" not the answer?

Neostigmine is a quaternary amine and has no central effect.

Why is "Pyridostigmine" not the answer?

Pyridostigmine is quaternary and does not enter the CNS.

Why is "Edrophonium" not the answer?

Edrophonium is quaternary and does not enter the CNS.

What concept does this question test?

It tests Pharmacology: physostigmine in Anaesthesia. Neostigmine, pyridostigmine and edrophonium are quaternary compounds that do not cross the blood-brain barrier. Physostigmine can cause bradycardia and seizures.

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 Pharmacology: physostigmine?

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.