Autonomic nervous system: ivacaftor: 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: ivacaftor

Sample item

A teenager with cystic fibrosis carries the G551D gating mutation. His CFTR protein reaches the cell surface but the channel stays closed. Which drug type is most appropriate?

AAn epithelial sodium channel blockerBA CFTR potentiator that increases channel open probabilityCAn inhaled recombinant DNaseDA CFTR corrector that improves protein folding and trafficking

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

The answer and the reasoning

B. A CFTR potentiator that increases channel open probability

Ivacaftor is a CFTR potentiator that increases the open probability of CFTR channels already present at the cell surface, as in gating mutations such as G551D. Correctors like lumacaftor and tezacaftor help misfolded protein, as in the F508del mutation, reach the membrane. Dornase alfa only thins sputum.

Option by option

A. An epithelial sodium channel blocker
Blocking the sodium channel is not a defined treatment of the underlying CFTR defect.
B. A CFTR potentiator that increases channel open probability (correct)
Correct. A potentiator opens channels that reach the membrane but remain closed.
C. An inhaled recombinant DNase
Dornase alfa thins sputum but does not correct the channel defect.
D. A CFTR corrector that improves protein folding and trafficking
Correctors help misfolded protein reach the membrane, which is not the defect in a gating mutation.

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 B, A CFTR potentiator that increases channel open probability. Ivacaftor is a CFTR potentiator that increases the open probability of CFTR channels already present at the cell surface, as in gating mutations such as G551D.

Why is "An epithelial sodium channel blocker" not the answer?

Blocking the sodium channel is not a defined treatment of the underlying CFTR defect.

Why is "An inhaled recombinant DNase" not the answer?

Dornase alfa thins sputum but does not correct the channel defect.

Why is "A CFTR corrector that improves protein folding and trafficking" not the answer?

Correctors help misfolded protein reach the membrane, which is not the defect in a gating mutation.

What concept does this question test?

It tests Autonomic nervous system: ivacaftor in Pharmacology. Correctors like lumacaftor and tezacaftor help misfolded protein, as in the F508del mutation, reach the membrane. Dornase alfa only thins sputum.

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 Autonomic nervous system: ivacaftor?

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.