Why does Grapefruit Interact with Drugs?

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Why does Grapefruit Interact with Drugs? – The Chemistry of a Grapefruit

You may have heard of ‘the grapefruit juice effect’ – a range of medications recommend avoiding grapefruits or grapefruit juice whilst you are taking them, due the unfavourable interactions with the medication and the unwanted side effects this can cause. So, what chemical compounds cause these interactions?

The principal culprits are a family of chemical compounds called furanocoumarins, and particularly the compounds bergamottin & dihydroxybergamottin. Both of these compounds interfere with the activity of an enzyme that plays an important part in breaking down some drugs in the body, and prevent it from doing so. This, in turn, can lead to increased levels of concentration of the drug in the bloodstream. This is a problem, because prescriptions for drugs take into account the rate at which your body breaks down the drug in their dosage recommendations. Since these compounds in grapefruits greatly decrease the rate of breakdown, repeated doses can lead to much higher doses of the drug in the bloodstream, in turn potentially leading to harmful side effects.