Autonomic nervous system: dornase alfa in cystic fibrosis: 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 · Autonomic nervous system: dornase alfa in cystic fibrosis

Sample item

A 9-year-old with cystic fibrosis has recurrent plugging by thick, purulent sputum. A nebulised recombinant enzyme is added to thin the secretions. On which component of the sputum does it act?

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

The answer and the reasoning

B. Extracellular DNA released from degenerating neutrophils

Dornase alfa is recombinant human DNase I. It cleaves the extracellular DNA from dead neutrophils that makes cystic fibrosis sputum viscous, and so improves lung function and reduces exacerbations. Acetylcysteine acts on mucin disulfide bonds instead.

Option by option

  • A. Epithelial sodium channel activity

    Sodium channel block is the action of amiloride and has no part in dornase alfa.

  • B. Extracellular DNA released from degenerating neutrophils (correct)

    Correct. Dornase alfa digests neutrophil-derived DNA in the sputum.

  • C. Bacterial cell wall peptidoglycan

    Peptidoglycan is the target of beta-lactams and lysozyme, not of a nebulised DNase.

  • D. Disulfide bonds of mucin glycoproteins

    Cleaving mucin disulfide bonds is the action of acetylcysteine, not dornase alfa.

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.

More Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is B, Extracellular DNA released from degenerating neutrophils. Dornase alfa is recombinant human DNase I.

Why is "Epithelial sodium channel activity" not the answer?

Sodium channel block is the action of amiloride and has no part in dornase alfa.

Why is "Bacterial cell wall peptidoglycan" not the answer?

Peptidoglycan is the target of beta-lactams and lysozyme, not of a nebulised DNase.

Why is "Disulfide bonds of mucin glycoproteins" not the answer?

Cleaving mucin disulfide bonds is the action of acetylcysteine, not dornase alfa.

What concept does this question test?

It tests Autonomic nervous system: dornase alfa in cystic fibrosis in Pharmacology. It cleaves the extracellular DNA from dead neutrophils that makes cystic fibrosis sputum viscous, and so improves lung function and reduces exacerbations. Acetylcysteine acts on mucin disulfide bonds instead.

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 Autonomic nervous system: dornase alfa in cystic fibrosis?

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.