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St John's wort interactions — GPhC CRA MCQ

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HardDrug InteractionsSt John's wort interactionsGPhC CRA

A 66-year-old man taking sertraline and rivaroxaban buys St John's wort for low mood after seeing it advertised as natural. He has a history of TIA and takes atorvastatin. What is the most important interaction to flag?

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Correct answer: B — St John's wort can reduce rivaroxaban exposure and increase serotonergic adverse effects

St John's wort induces drug-metabolising enzymes and transporters and can reduce exposure to medicines such as some anticoagulants. It also has serotonergic activity, creating concern with SSRIs. In a patient anticoagulated after TIA, reduced rivaroxaban exposure could be clinically serious. The product should be avoided unless the prescriber has reviewed the full regimen.

Reference: BNF