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Grapefruit and calcium-channel blockers — GPhC CRA MCQ

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ModerateDrug InteractionsGrapefruit and calcium-channel blockersGPhC CRA

A patient taking felodipine asks whether a daily glass of grapefruit juice is acceptable with breakfast. What is the most important interaction to flag?

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Correct answer: A — Increased felodipine exposure and risk of hypotension or flushing

Grapefruit juice can inhibit intestinal metabolism of some calcium-channel blockers, including felodipine. This may increase drug exposure and adverse effects such as flushing, dizziness and hypotension. The patient should be advised to avoid grapefruit products unless the prescriber advises otherwise. The direction of effect is increased, not reduced, exposure.

Reference: BNF