Fungal infections: terbinafine: practice question

A Dermatology 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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Dermatology · Fungal infections: terbinafine

Sample item

What is the mechanism of action of terbinafine?

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

The answer and the reasoning

B. Inhibition of squalene epoxidase

Terbinafine blocks squalene epoxidase, leading to ergosterol deficiency and toxic accumulation of squalene, and it is fungicidal against dermatophytes. Azoles block 14-alpha demethylase instead.

Option by option

  • A. Inhibition of 14-alpha demethylase

    14-alpha demethylase inhibition is the action of azoles.

  • B. Inhibition of squalene epoxidase (correct)

    Correct. Squalene epoxidase inhibition is the action of allylamines.

  • C. Binding to ergosterol and forming pores

    Pore formation by binding ergosterol describes amphotericin B and nystatin.

  • D. Inhibition of beta-glucan synthase

    Glucan synthase inhibition describes echinocandins.

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 Dermatology question

What is the answer to this Dermatology question?

The best answer is B, Inhibition of squalene epoxidase. Terbinafine blocks squalene epoxidase, leading to ergosterol deficiency and toxic accumulation of squalene, and it is fungicidal against dermatophytes.

Why is "Inhibition of 14-alpha demethylase" not the answer?

14-alpha demethylase inhibition is the action of azoles.

Why is "Binding to ergosterol and forming pores" not the answer?

Pore formation by binding ergosterol describes amphotericin B and nystatin.

Why is "Inhibition of beta-glucan synthase" not the answer?

Glucan synthase inhibition describes echinocandins.

What concept does this question test?

It tests Fungal infections: terbinafine in Dermatology. Azoles block 14-alpha demethylase instead.

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 Fungal infections: terbinafine?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.