Drug reactions: cross-reactivity of antiepileptics: 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 · Drug reactions: cross-reactivity of antiepileptics

Sample item

A patient had DRESS syndrome on carbamazepine. Which antiepileptic is most likely to cross-react and should be avoided?

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

The answer and the reasoning

B. Phenytoin

Aromatic antiepileptics (carbamazepine, phenytoin, phenobarbital) share arene oxide metabolites and show high cross-reactivity in hypersensitivity reactions. Non-aromatic agents such as valproate, levetiracetam and gabapentin are safer substitutes.

Option by option

  • A. Levetiracetam

    Levetiracetam is non-aromatic and is a commonly used alternative.

  • B. Phenytoin (correct)

    Correct. Phenytoin is an aromatic antiepileptic with substantial cross-reactivity.

  • C. Sodium valproate

    Sodium valproate is non-aromatic and cross-reactivity is not expected.

  • D. Gabapentin

    Gabapentin is non-aromatic and is not expected to cross-react.

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, Phenytoin. Aromatic antiepileptics (carbamazepine, phenytoin, phenobarbital) share arene oxide metabolites and show high cross-reactivity in hypersensitivity reactions.

Why is "Levetiracetam" not the answer?

Levetiracetam is non-aromatic and is a commonly used alternative.

Why is "Sodium valproate" not the answer?

Sodium valproate is non-aromatic and cross-reactivity is not expected.

Why is "Gabapentin" not the answer?

Gabapentin is non-aromatic and is not expected to cross-react.

What concept does this question test?

It tests Drug reactions: cross-reactivity of antiepileptics in Dermatology. Non-aromatic agents such as valproate, levetiracetam and gabapentin are safer substitutes.

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 Drug reactions: cross-reactivity of antiepileptics?

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.