Toxicology: lead: 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: lead

Sample item

A 4-year-old child with pica has anaemia with basophilic stippling, constipation and a blood lead level of 52 mcg/dL. He is alert and has no encephalopathy. Which chelator is most appropriate?

AOral succimerBFomepizoleCDeferoxamineDPrussian blue

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

The answer and the reasoning

A. Oral succimer

Succimer (DMSA) is an oral, water-soluble analogue of dimercaprol with good efficacy and safety for children with symptomatic or moderately raised blood lead levels. Severe poisoning or encephalopathy needs parenteral therapy, with dimercaprol and then calcium disodium EDTA. The source of exposure must also be removed.

Option by option

A. Oral succimer (correct)
Succimer is the oral chelator used for moderate lead poisoning in children.
B. Fomepizole
Fomepizole inhibits alcohol dehydrogenase in methanol and ethylene glycol poisoning.
C. Deferoxamine
Deferoxamine chelates iron and aluminium, not lead.
D. Prussian blue
Prussian blue is used for thallium and radioactive caesium.

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 A, Oral succimer. Succimer (DMSA) is an oral, water-soluble analogue of dimercaprol with good efficacy and safety for children with symptomatic or moderately raised blood lead levels.

Why is "Fomepizole" not the answer?

Fomepizole inhibits alcohol dehydrogenase in methanol and ethylene glycol poisoning.

Why is "Deferoxamine" not the answer?

Deferoxamine chelates iron and aluminium, not lead.

Why is "Prussian blue" not the answer?

Prussian blue is used for thallium and radioactive caesium.

What concept does this question test?

It tests Toxicology: lead in Pharmacology. Severe poisoning or encephalopathy needs parenteral therapy, with dimercaprol and then calcium disodium EDTA. The source of exposure must also be removed.

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: lead?

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.