DMARDs: leflunomide: 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 · DMARDs: leflunomide

Sample item

Leflunomide is used in rheumatoid arthritis. What is the enzyme target of its active metabolite teriflunomide?

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

The answer and the reasoning

C. Dihydroorotate dehydrogenase

Teriflunomide inhibits dihydroorotate dehydrogenase, blocking de novo pyrimidine synthesis and thereby proliferation of activated lymphocytes. Its long half-life means that a washout with cholestyramine is needed in toxicity or pregnancy.

Option by option

  • A. Janus kinase

    JAK is the target of tofacitinib.

  • B. Dihydrofolate reductase

    DHFR is the target of methotrexate.

  • C. Dihydroorotate dehydrogenase (correct)

    Correct. DHODH inhibition blocks pyrimidine synthesis in lymphocytes.

  • D. Inosine monophosphate dehydrogenase

    IMPDH is the target of mycophenolate.

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 C, Dihydroorotate dehydrogenase. Teriflunomide inhibits dihydroorotate dehydrogenase, blocking de novo pyrimidine synthesis and thereby proliferation of activated lymphocytes.

Why is "Janus kinase" not the answer?

JAK is the target of tofacitinib.

Why is "Dihydrofolate reductase" not the answer?

DHFR is the target of methotrexate.

Why is "Inosine monophosphate dehydrogenase" not the answer?

IMPDH is the target of mycophenolate.

What concept does this question test?

It tests DMARDs: leflunomide in Pharmacology. Its long half-life means that a washout with cholestyramine is needed in toxicity or pregnancy.

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 DMARDs: leflunomide?

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.