Adrenergic drugs: beta2 agonist in hyperkalaemia: 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 · Adrenergic drugs: beta2 agonist in hyperkalaemia

Sample item

A 55-year-old man on dialysis has serum potassium 6.9 mmol/L with peaked T waves and has received intravenous calcium gluconate. Which additional drug lowers serum potassium by a beta2-mediated shift of potassium into cells?

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

The answer and the reasoning

C. Nebulised salbutamol

Beta2 stimulation activates the sodium-potassium ATPase in skeletal muscle and drives potassium into cells, so nebulised salbutamol is a recognised temporising measure for hyperkalaemia alongside insulin with glucose. A non-selective beta-blocker does the reverse and impairs potassium uptake.

Option by option

  • A. Intravenous propranolol

    Propranolol blocks beta2 receptors and can raise serum potassium.

  • B. Nebulised ipratropium

    Ipratropium is an antimuscarinic bronchodilator with no effect on cellular potassium uptake.

  • C. Nebulised salbutamol (correct)

    Correct. Beta2 stimulation of Na-K ATPase moves potassium intracellularly.

  • D. Intravenous phenylephrine

    Phenylephrine is an alpha1 agonist and does not act on the beta2 pump mechanism.

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, Nebulised salbutamol. Beta2 stimulation activates the sodium-potassium ATPase in skeletal muscle and drives potassium into cells, so nebulised salbutamol is a recognised temporising measure for hyperkalaemia alongside insulin with glucose.

Why is "Intravenous propranolol" not the answer?

Propranolol blocks beta2 receptors and can raise serum potassium.

Why is "Nebulised ipratropium" not the answer?

Ipratropium is an antimuscarinic bronchodilator with no effect on cellular potassium uptake.

Why is "Intravenous phenylephrine" not the answer?

Phenylephrine is an alpha1 agonist and does not act on the beta2 pump mechanism.

What concept does this question test?

It tests Adrenergic drugs: beta2 agonist in hyperkalaemia in Pharmacology. A non-selective beta-blocker does the reverse and impairs potassium uptake.

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 Adrenergic drugs: beta2 agonist in hyperkalaemia?

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.