Pharmacology: ondansetron: practice question

A Anaesthesia 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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Anaesthesia · Pharmacology: ondansetron

Sample item

Which statement about ondansetron is correct?

AIt is a 5-HT3 antagonist that can prolong the QT interval and cause headache and constipationBIt has no cardiac effects at any doseCIt is a dopamine D2 agonistDIt is an H2 receptor blocker

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

The answer and the reasoning

A. It is a 5-HT3 antagonist that can prolong the QT interval and cause headache and constipation

Ondansetron blocks 5-HT3 receptors in the chemoreceptor trigger zone and gut, making it effective for PONV and chemotherapy-induced vomiting. Common effects are headache and constipation, and it can prolong the QT interval in a dose-related fashion. It has no sedative effect.

Option by option

A. It is a 5-HT3 antagonist that can prolong the QT interval and cause headache and constipation (correct)
Correct. Its profile includes headache, constipation and QT prolongation.
B. It has no cardiac effects at any dose
Cardiac effects, including QT prolongation, can occur.
C. It is a dopamine D2 agonist
Dopamine antagonism characterises drugs such as metoclopramide and droperidol.
D. It is an H2 receptor blocker
H2 blockers such as ranitidine act on histamine receptors.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is A, It is a 5-HT3 antagonist that can prolong the QT interval and cause headache and constipation. Ondansetron blocks 5-HT3 receptors in the chemoreceptor trigger zone and gut, making it effective for PONV and chemotherapy-induced vomiting.

Why is "It has no cardiac effects at any dose" not the answer?

Cardiac effects, including QT prolongation, can occur.

Why is "It is a dopamine D2 agonist" not the answer?

Dopamine antagonism characterises drugs such as metoclopramide and droperidol.

Why is "It is an H2 receptor blocker" not the answer?

H2 blockers such as ranitidine act on histamine receptors.

What concept does this question test?

It tests Pharmacology: ondansetron in Anaesthesia. Common effects are headache and constipation, and it can prolong the QT interval in a dose-related fashion. It has no sedative effect.

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 Pharmacology: ondansetron?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.