Dementia drugs: cholinesterase inhibitors: 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 · Dementia drugs: cholinesterase inhibitors

Sample item

A 78-year-old woman with Alzheimer's disease on donepezil has two syncopal episodes, and her pulse is 42 per minute. What is the best explanation?

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

The answer and the reasoning

A. Enhanced vagal tone from acetylcholinesterase inhibition

Donepezil, rivastigmine and galantamine increase acetylcholine at muscarinic synapses, including the vagal supply of the sinoatrial and atrioventricular nodes. This can cause bradycardia, heart block and syncope, along with nausea and weight loss. Memantine, an NMDA antagonist, acts through a different mechanism.

Option by option

  • A. Enhanced vagal tone from acetylcholinesterase inhibition (correct)

    Raised acetylcholine increases vagal slowing of the heart.

  • B. Blockade of beta-1 receptors by donepezil

    Donepezil has no beta-blocking action.

  • C. NMDA receptor antagonism at the sinoatrial node

    NMDA antagonism is the mechanism of memantine and does not slow the sinoatrial node.

  • D. Histamine release by the drug

    Donepezil does not cause histamine release.

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.

More Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, Enhanced vagal tone from acetylcholinesterase inhibition. Donepezil, rivastigmine and galantamine increase acetylcholine at muscarinic synapses, including the vagal supply of the sinoatrial and atrioventricular nodes.

Why is "Blockade of beta-1 receptors by donepezil" not the answer?

Donepezil has no beta-blocking action.

Why is "NMDA receptor antagonism at the sinoatrial node" not the answer?

NMDA antagonism is the mechanism of memantine and does not slow the sinoatrial node.

Why is "Histamine release by the drug" not the answer?

Donepezil does not cause histamine release.

What concept does this question test?

It tests Dementia drugs: cholinesterase inhibitors in Pharmacology. This can cause bradycardia, heart block and syncope, along with nausea and weight loss. Memantine, an NMDA antagonist, acts through a different mechanism.

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 Dementia drugs: cholinesterase inhibitors?

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.