Antimicrobials: rifamycins and protease inhibitors: 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 · Antimicrobials: rifamycins and protease inhibitors

Sample item

A man with HIV on a protease-inhibitor-based regimen develops pulmonary tuberculosis. Which rifamycin is a weaker inducer of CYP3A4 and is preferred over rifampicin in this setting?

ARifampicin at a higher doseBRifaximinCRifabutinDRifapentine

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

The answer and the reasoning

C. Rifabutin

Rifampicin strongly induces CYP3A4 and lowers protease inhibitor levels to subtherapeutic concentrations. Rifabutin is a much weaker inducer and is used with dose adjustment instead. Rifapentine is a strong inducer, and rifaximin is not absorbed and not used for tuberculosis.

Option by option

A. Rifampicin at a higher dose
A higher rifampicin dose would induce still more and lower protease inhibitor levels further.
B. Rifaximin
Rifaximin is poorly absorbed and is not used for tuberculosis.
C. Rifabutin (correct)
Correct. It is a weak CYP3A4 inducer and can be used with protease inhibitors.
D. Rifapentine
Rifapentine is a strong inducer, similar to rifampicin.

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, Rifabutin. Rifampicin strongly induces CYP3A4 and lowers protease inhibitor levels to subtherapeutic concentrations.

Why is "Rifampicin at a higher dose" not the answer?

A higher rifampicin dose would induce still more and lower protease inhibitor levels further.

Why is "Rifaximin" not the answer?

Rifaximin is poorly absorbed and is not used for tuberculosis.

Why is "Rifapentine" not the answer?

Rifapentine is a strong inducer, similar to rifampicin.

What concept does this question test?

It tests Antimicrobials: rifamycins and protease inhibitors in Pharmacology. Rifabutin is a much weaker inducer and is used with dose adjustment instead. Rifapentine is a strong inducer, and rifaximin is not absorbed and not used for tuberculosis.

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 Antimicrobials: rifamycins and protease inhibitors?

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.