Antivirals: aciclovir: 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 · Antivirals: aciclovir

Sample item

A patient with herpes simplex encephalitis receives rapid intravenous aciclovir and has a rise in creatinine with crystals in the urine. How is this prevented?

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

The answer and the reasoning

C. Adequate hydration and slow infusion, as aciclovir can precipitate in renal tubules

Aciclovir is phosphorylated by viral thymidine kinase to the triphosphate that inhibits viral DNA polymerase, and it is poorly soluble, precipitating in tubules. Hydration and slow infusion prevent crystal nephropathy.

Option by option

  • A. Giving probenecid with aciclovir to increase crystallisation

    Probenecid would raise levels and not prevent crystalluria.

  • B. Switching to oral therapy in encephalitis

    Intravenous therapy is needed in encephalitis.

  • C. Adequate hydration and slow infusion, as aciclovir can precipitate in renal tubules (correct)

    Correct. Hydration and slow infusion limit crystalluria.

  • D. Alkalinising the urine to the maximum

    Alkalinisation is not the recognised strategy.

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 C, Adequate hydration and slow infusion, as aciclovir can precipitate in renal tubules. Aciclovir is phosphorylated by viral thymidine kinase to the triphosphate that inhibits viral DNA polymerase, and it is poorly soluble, precipitating in tubules.

Why is "Giving probenecid with aciclovir to increase crystallisation" not the answer?

Probenecid would raise levels and not prevent crystalluria.

Why is "Switching to oral therapy in encephalitis" not the answer?

Intravenous therapy is needed in encephalitis.

Why is "Alkalinising the urine to the maximum" not the answer?

Alkalinisation is not the recognised strategy.

What concept does this question test?

It tests Antivirals: aciclovir in Pharmacology. Hydration and slow infusion prevent crystal nephropathy.

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 Antivirals: aciclovir?

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.