Cardiovascular: digoxin interactions: 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: digoxin interactions

Sample item

A patient with atrial fibrillation stable on digoxin starts quinidine. What happens to digoxin level and why?

AUnchanged, as they have different targetsBFalls, because quinidine induces its metabolismCRises, because quinidine reduces renal clearance and displaces tissue bindingDFalls, because quinidine increases excretion

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

The answer and the reasoning

C. Rises, because quinidine reduces renal clearance and displaces tissue binding

Quinidine, and also verapamil and amiodarone, raise digoxin concentration by reducing renal and non-renal clearance and displacing it from tissue sites. Doses of digoxin must be reduced by about half when combined.

Option by option

A. Unchanged, as they have different targets
A clinically important interaction exists.
B. Falls, because quinidine induces its metabolism
Quinidine is not an inducer.
C. Rises, because quinidine reduces renal clearance and displaces tissue binding (correct)
Correct. Digoxin levels rise, with toxicity risk.
D. Falls, because quinidine increases excretion
Excretion is reduced, not increased.

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.

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is C, Rises, because quinidine reduces renal clearance and displaces tissue binding. Quinidine, and also verapamil and amiodarone, raise digoxin concentration by reducing renal and non-renal clearance and displacing it from tissue sites.

Why is "Unchanged, as they have different targets" not the answer?

A clinically important interaction exists.

Why is "Falls, because quinidine induces its metabolism" not the answer?

Quinidine is not an inducer.

Why is "Falls, because quinidine increases excretion" not the answer?

Excretion is reduced, not increased.

What concept does this question test?

It tests Cardiovascular: digoxin interactions in Pharmacology. Doses of digoxin must be reduced by about half when combined.

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: digoxin interactions?

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.