Autonomic nervous system: alosetron adverse effect: 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: alosetron adverse effect

Sample item

The use of the 5-HT3 antagonist alosetron in women with severe diarrhoea-predominant irritable bowel syndrome is tightly restricted. Which serious adverse effect is the reason?

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

The answer and the reasoning

A. Ischaemic colitis and serious constipation

Alosetron blocks 5-HT3 receptors on enteric neurons, slowing colonic transit. It was withdrawn and later reintroduced under restrictions because of ischaemic colitis and serious complications of constipation. Ondansetron has constipation and QT effects but is not restricted for this reason.

Option by option

  • A. Ischaemic colitis and serious constipation (correct)

    Correct. Ischaemic colitis and severe constipation led to the restrictions on alosetron.

  • B. Torsades de pointes with QT prolongation

    QT prolongation is a recognised effect of ondansetron and not the restriction on alosetron.

  • C. Fulminant hepatitis with liver failure

    Fulminant hepatitis is not the characteristic adverse effect of alosetron.

  • D. Extrapyramidal reactions with dystonia

    Extrapyramidal reactions are typical of dopamine blockers such as metoclopramide.

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 A, Ischaemic colitis and serious constipation. Alosetron blocks 5-HT3 receptors on enteric neurons, slowing colonic transit.

Why is "Torsades de pointes with QT prolongation" not the answer?

QT prolongation is a recognised effect of ondansetron and not the restriction on alosetron.

Why is "Fulminant hepatitis with liver failure" not the answer?

Fulminant hepatitis is not the characteristic adverse effect of alosetron.

Why is "Extrapyramidal reactions with dystonia" not the answer?

Extrapyramidal reactions are typical of dopamine blockers such as metoclopramide.

What concept does this question test?

It tests Autonomic nervous system: alosetron adverse effect in Pharmacology. It was withdrawn and later reintroduced under restrictions because of ischaemic colitis and serious complications of constipation. Ondansetron has constipation and QT effects but is not restricted for this reason.

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: alosetron adverse effect?

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.