Cardiovascular drugs: adenosine in PSVT: 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 · Cardiovascular drugs: adenosine in PSVT

Sample item

A haemodynamically stable 24-year-old woman has narrow-complex tachycardia at 190 per minute that does not respond to vagal manoeuvres. Which drug is most appropriate?

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

The answer and the reasoning

B. Intravenous adenosine as a rapid bolus

Adenosine activates A1 receptors, opening potassium channels and transiently blocking the AV node, which breaks AV nodal re-entry. Its half-life is under 10 seconds, so it must be given as a rapid bolus followed by a flush. Brief flushing, chest tightness and a pause are expected; theophylline antagonises it and dipyridamole potentiates it.

Option by option

  • A. Intravenous lignocaine

    Lignocaine acts on ventricular tissue and does not affect AV nodal re-entry.

  • B. Intravenous adenosine as a rapid bolus (correct)

    Correct. A brief AV nodal block terminates the re-entry circuit.

  • C. Intravenous digoxin loading

    Digoxin acts slowly and is not suitable for acute termination.

  • D. Intravenous atropine

    Atropine would accelerate nodal conduction and the rate.

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 B, Intravenous adenosine as a rapid bolus. Adenosine activates A1 receptors, opening potassium channels and transiently blocking the AV node, which breaks AV nodal re-entry.

Why is "Intravenous lignocaine" not the answer?

Lignocaine acts on ventricular tissue and does not affect AV nodal re-entry.

Why is "Intravenous digoxin loading" not the answer?

Digoxin acts slowly and is not suitable for acute termination.

Why is "Intravenous atropine" not the answer?

Atropine would accelerate nodal conduction and the rate.

What concept does this question test?

It tests Cardiovascular drugs: adenosine in PSVT in Pharmacology. Its half-life is under 10 seconds, so it must be given as a rapid bolus followed by a flush. Brief flushing, chest tightness and a pause are expected; theophylline antagonises it and dipyridamole potentiates it.

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 Cardiovascular drugs: adenosine in PSVT?

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.