Antimicrobials: metronidazole: 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: metronidazole

Sample item

A woman prescribed metronidazole for bacterial vaginosis drinks wine with dinner and experiences flushing, vomiting and palpitations. Which statement is correct about metronidazole?

AIt inhibits cell wall synthesisBIt can cause a disulfiram-like reaction and acts by forming DNA-damaging radicals in anaerobes and protozoaCIt causes the reaction by inducing alcohol dehydrogenaseDIt inhibits the 50S ribosome

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

The answer and the reasoning

B. It can cause a disulfiram-like reaction and acts by forming DNA-damaging radicals in anaerobes and protozoa

Metronidazole is reduced within anaerobic organisms to toxic radicals that fragment DNA. It is active against Entamoeba, Giardia, Trichomonas and anaerobes, and causes a metallic taste, neuropathy and a disulfiram-like reaction with alcohol.

Option by option

A. It inhibits cell wall synthesis
It does not target the cell wall.
B. It can cause a disulfiram-like reaction and acts by forming DNA-damaging radicals in anaerobes and protozoa (correct)
Correct. DNA damage in anaerobes and an alcohol reaction describe it.
C. It causes the reaction by inducing alcohol dehydrogenase
The reaction is explained by aldehyde dehydrogenase effects, not induction of ADH.
D. It inhibits the 50S ribosome
The 50S ribosome is the target of macrolides and chloramphenicol.

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 B, It can cause a disulfiram-like reaction and acts by forming DNA-damaging radicals in anaerobes and protozoa. Metronidazole is reduced within anaerobic organisms to toxic radicals that fragment DNA.

Why is "It inhibits cell wall synthesis" not the answer?

It does not target the cell wall.

Why is "It causes the reaction by inducing alcohol dehydrogenase" not the answer?

The reaction is explained by aldehyde dehydrogenase effects, not induction of ADH.

Why is "It inhibits the 50S ribosome" not the answer?

The 50S ribosome is the target of macrolides and chloramphenicol.

What concept does this question test?

It tests Antimicrobials: metronidazole in Pharmacology. It is active against Entamoeba, Giardia, Trichomonas and anaerobes, and causes a metallic taste, neuropathy and a disulfiram-like reaction with alcohol.

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: metronidazole?

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.