Cardiology: clopidogrel activation: practice question

A General Medicine 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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General Medicine · Cardiology: clopidogrel activation

Sample item

A patient with a drug-eluting stent develops recurrent stent thrombosis although taking clopidogrel regularly. Genotyping shows two loss-of-function alleles in the gene for the hepatic enzyme that converts the drug to its active form. Which gene is this?

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

The answer and the reasoning

B. CYP2C19

Clopidogrel is a prodrug that needs hepatic activation, mainly by CYP2C19. Loss-of-function variants reduce active metabolite formation and platelet inhibition, and omeprazole competes for the same enzyme. Ticagrelor and prasugrel do not need this step.

Option by option

  • A. CYP2D6

    CYP2D6 is mainly involved in activating codeine and tamoxifen.

  • B. CYP2C19 (correct)

    Correct. CYP2C19 variants cause poor activation and clopidogrel resistance.

  • C. CYP3A4

    CYP3A4 metabolises many drugs such as statins but is not the main step for clopidogrel.

  • D. CYP2C9

    CYP2C9 metabolises warfarin and phenytoin.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is B, CYP2C19. Clopidogrel is a prodrug that needs hepatic activation, mainly by CYP2C19.

Why is "CYP2D6" not the answer?

CYP2D6 is mainly involved in activating codeine and tamoxifen.

Why is "CYP3A4" not the answer?

CYP3A4 metabolises many drugs such as statins but is not the main step for clopidogrel.

Why is "CYP2C9" not the answer?

CYP2C9 metabolises warfarin and phenytoin.

What concept does this question test?

It tests Cardiology: clopidogrel activation in General Medicine. Loss-of-function variants reduce active metabolite formation and platelet inhibition, and omeprazole competes for the same enzyme. Ticagrelor and prasugrel do not need this step.

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 Cardiology: clopidogrel activation?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.