Sex hormone modulators: tamoxifen: 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 · Sex hormone modulators: tamoxifen

Sample item

A 58-year-old woman on tamoxifen for ER-positive breast cancer reports postmenopausal bleeding, and ultrasound shows endometrial thickness of 14 mm. Which property of the drug explains this?

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

The answer and the reasoning

C. Partial oestrogen agonist action on the endometrium

Tamoxifen is a selective oestrogen receptor modulator: antagonist in breast but partial agonist in endometrium, bone and liver. This increases the risks of endometrial hyperplasia and carcinoma, and of venous thromboembolism, while preserving bone density. Raloxifene lacks endometrial stimulation.

Option by option

  • A. Induction of hepatic metabolism of oestrogen

    Tamoxifen does not act by inducing oestrogen metabolism.

  • B. Inhibition of aromatase in adipose tissue

    Aromatase inhibition is the mechanism of anastrozole and would lower oestrogen.

  • C. Partial oestrogen agonist action on the endometrium (correct)

    Correct. Tissue-specific agonism stimulates the endometrium.

  • D. Antagonism of progesterone receptors

    Tamoxifen is not a progesterone antagonist.

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, Partial oestrogen agonist action on the endometrium. Tamoxifen is a selective oestrogen receptor modulator: antagonist in breast but partial agonist in endometrium, bone and liver.

Why is "Induction of hepatic metabolism of oestrogen" not the answer?

Tamoxifen does not act by inducing oestrogen metabolism.

Why is "Inhibition of aromatase in adipose tissue" not the answer?

Aromatase inhibition is the mechanism of anastrozole and would lower oestrogen.

Why is "Antagonism of progesterone receptors" not the answer?

Tamoxifen is not a progesterone antagonist.

What concept does this question test?

It tests Sex hormone modulators: tamoxifen in Pharmacology. This increases the risks of endometrial hyperplasia and carcinoma, and of venous thromboembolism, while preserving bone density. Raloxifene lacks endometrial stimulation.

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 Sex hormone modulators: tamoxifen?

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.