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Tamoxifen and fluoxetine — GPhC CRA MCQ

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HardDrug InteractionsTamoxifen and fluoxetineGPhC CRA

A woman taking tamoxifen after breast cancer treatment is started on fluoxetine for depression. She asks whether the antidepressant choice matters. What is the most appropriate alternative?

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Correct answer: D — Citalopram after prescriber review

Tamoxifen activation involves CYP2D6, and fluoxetine is a strong CYP2D6 inhibitor. This may reduce active metabolite formation and potentially reduce tamoxifen effectiveness. An antidepressant with less CYP2D6 inhibition should be discussed with the prescriber.

Reference: BNF