Antiarrhythmics: adenosine: 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 · Antiarrhythmics: adenosine

Sample item

A regular narrow-complex supraventricular tachycardia terminates immediately after intravenous adenosine. What is adenosine's principal action?

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

The answer and the reasoning

C. Transiently blocks conduction through the AV node

Adenosine activates A1 receptors, increasing potassium conductance and reducing cAMP in the AV node. Its very short action can interrupt AV-node-dependent re-entry tachycardias.

Option by option

  • A. Inhibits platelet P2Y12 receptors

    P2Y12 blockade is the action of drugs such as clopidogrel.

  • B. Increases calcium entry into nodal tissue

    It reduces, rather than increases, nodal calcium current.

  • C. Transiently blocks conduction through the AV node (correct)

    Correct. Brief AV nodal block terminates many re-entry SVTs.

  • D. Permanently blocks sodium channels in ventricular muscle

    Class I drugs block sodium channels; adenosine is not one.

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 C, Transiently blocks conduction through the AV node. Adenosine activates A1 receptors, increasing potassium conductance and reducing cAMP in the AV node.

Why is "Inhibits platelet P2Y12 receptors" not the answer?

P2Y12 blockade is the action of drugs such as clopidogrel.

Why is "Increases calcium entry into nodal tissue" not the answer?

It reduces, rather than increases, nodal calcium current.

Why is "Permanently blocks sodium channels in ventricular muscle" not the answer?

Class I drugs block sodium channels; adenosine is not one.

What concept does this question test?

It tests Antiarrhythmics: adenosine in Pharmacology. Its very short action can interrupt AV-node-dependent re-entry tachycardias.

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 Antiarrhythmics: adenosine?

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.