Antivirals: antiretroviral toxicity: 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: antiretroviral toxicity

Sample item

A man on tenofovir-lamivudine-dolutegravir who also takes co-trimoxazole prophylaxis develops glycosuria with normal blood glucose, hypophosphataemia and a normal anion-gap acidosis. Which component is responsible?

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

The answer and the reasoning

C. Tenofovir

Tenofovir accumulates in proximal tubular cells and causes Fanconi-type syndrome with glycosuria, phosphaturia and proximal renal tubular acidosis, plus a fall in GFR. Dolutegravir raises serum creatinine by blocking tubular creatinine secretion without a true GFR fall, but does not cause Fanconi syndrome. Lamivudine is well tolerated.

Option by option

  • A. Dolutegravir

    Dolutegravir only raises serum creatinine by inhibiting OCT2, with no tubular damage.

  • B. Co-trimoxazole

    Co-trimoxazole can raise creatinine and potassium, but it does not cause glycosuria with phosphate wasting.

  • C. Tenofovir (correct)

    Correct. Proximal tubular toxicity with Fanconi syndrome is characteristic of tenofovir.

  • D. Lamivudine

    Lamivudine is renally excreted but is not tubulotoxic and does not cause Fanconi syndrome.

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, Tenofovir. Tenofovir accumulates in proximal tubular cells and causes Fanconi-type syndrome with glycosuria, phosphaturia and proximal renal tubular acidosis, plus a fall in GFR.

Why is "Dolutegravir" not the answer?

Dolutegravir only raises serum creatinine by inhibiting OCT2, with no tubular damage.

Why is "Co-trimoxazole" not the answer?

Co-trimoxazole can raise creatinine and potassium, but it does not cause glycosuria with phosphate wasting.

Why is "Lamivudine" not the answer?

Lamivudine is renally excreted but is not tubulotoxic and does not cause Fanconi syndrome.

What concept does this question test?

It tests Antivirals: antiretroviral toxicity in Pharmacology. Dolutegravir raises serum creatinine by blocking tubular creatinine secretion without a true GFR fall, but does not cause Fanconi syndrome. Lamivudine is well tolerated.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: antiretroviral toxicity?

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.