Antiepileptics: topiramate adverse effects: 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 · Antiepileptics: topiramate adverse effects

Sample item

A 28-year-old woman on an antiepileptic for focal seizures has lost weight and presents with colicky flank pain and haematuria. Serum bicarbonate is low and a stone is seen on imaging. Which drug is most likely responsible?

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

The answer and the reasoning

D. Topiramate

Topiramate weakly inhibits carbonic anhydrase, causing a non-anion gap metabolic acidosis, alkaline urine, hypocitraturia and calcium phosphate nephrolithiasis. It also causes anorexia and weight loss, paraesthesia and cognitive slowing. Unlike valproate, it is not associated with weight gain.

Option by option

  • A. Sodium valproate

    Valproate typically causes weight gain, tremor and hepatotoxicity rather than stones.

  • B. Phenytoin

    Phenytoin typically causes gingival hyperplasia, ataxia and hirsutism.

  • C. Levetiracetam

    Levetiracetam typically causes somnolence and irritability, not acidosis or stones.

  • D. Topiramate (correct)

    Carbonic anhydrase inhibition explains the acidosis, renal stones and weight loss.

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 D, Topiramate. Topiramate weakly inhibits carbonic anhydrase, causing a non-anion gap metabolic acidosis, alkaline urine, hypocitraturia and calcium phosphate nephrolithiasis.

Why is "Sodium valproate" not the answer?

Valproate typically causes weight gain, tremor and hepatotoxicity rather than stones.

Why is "Phenytoin" not the answer?

Phenytoin typically causes gingival hyperplasia, ataxia and hirsutism.

Why is "Levetiracetam" not the answer?

Levetiracetam typically causes somnolence and irritability, not acidosis or stones.

What concept does this question test?

It tests Antiepileptics: topiramate adverse effects in Pharmacology. It also causes anorexia and weight loss, paraesthesia and cognitive slowing. Unlike valproate, it is not associated with weight gain.

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 Antiepileptics: topiramate adverse effects?

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.