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St John's wort with SSRI and DOAC — GPhC CRA MCQ

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HardDrug InteractionsSt John's wort with SSRI and DOACGPhC CRA

A 67-year-old woman takes fluoxetine 20mg daily and asks to buy St John's wort because her mood is still low. She also takes apixaban for AF. What is the most important interaction to flag?

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Correct answer: B — St John's wort may reduce apixaban exposure and increase serotonergic adverse-effect risk with fluoxetine.

St John's wort induces drug metabolism and transport pathways, which can reduce exposure to medicines such as some anticoagulants. It can also contribute to serotonergic adverse effects when combined with SSRIs. The patient should be advised not to self-start it and to seek prescriber review.

Reference: https://www.pharmacyregulation.org/students-and-trainees/pharmacist-education-and-training/registration-assessment