Toxicology and antidotes: uridine triacetate for fluorouracil 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 · Toxicology and antidotes: uridine triacetate for fluorouracil toxicity

Sample item

A patient is accidentally given a large overdose of capecitabine and within hours develops severe mucositis, neutropenia and confusion. Which antidote reduces the toxicity of this fluoropyrimidine?

AGlucarpidaseBMesnaCLeucovorinDUridine triacetate

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

The answer and the reasoning

D. Uridine triacetate

Uridine triacetate is an oral prodrug of uridine that competes with the toxic fluorouracil metabolite for incorporation into RNA. It is given for overdose of fluorouracil or capecitabine and for early-onset severe toxicity. Leucovorin actually strengthens the binding of fluorouracil to thymidylate synthase.

Option by option

A. Glucarpidase
Glucarpidase breaks down methotrexate and is used for methotrexate toxicity.
B. Mesna
Mesna binds acrolein and protects the bladder from ifosfamide and cyclophosphamide.
C. Leucovorin
Leucovorin potentiates fluorouracil and is used to rescue methotrexate toxicity, not to reverse this.
D. Uridine triacetate (correct)
Correct. Uridine triacetate is the antidote for fluorouracil and capecitabine overdose.

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.

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is D, Uridine triacetate. Uridine triacetate is an oral prodrug of uridine that competes with the toxic fluorouracil metabolite for incorporation into RNA.

Why is "Glucarpidase" not the answer?

Glucarpidase breaks down methotrexate and is used for methotrexate toxicity.

Why is "Mesna" not the answer?

Mesna binds acrolein and protects the bladder from ifosfamide and cyclophosphamide.

Why is "Leucovorin" not the answer?

Leucovorin potentiates fluorouracil and is used to rescue methotrexate toxicity, not to reverse this.

What concept does this question test?

It tests Toxicology and antidotes: uridine triacetate for fluorouracil toxicity in Pharmacology. It is given for overdose of fluorouracil or capecitabine and for early-onset severe toxicity. Leucovorin actually strengthens the binding of fluorouracil to thymidylate synthase.

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 Toxicology and antidotes: uridine triacetate for fluorouracil 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.