The problem is not unknown: grapefruit juice can increase the bioavailability of some drugs. Because the medicines are not metabolized by the juice, the risk of overdoses increases. Scientists warn again.
Active substances from grapefruit can trigger dangerous interactions with some medicines. More than 85 drugs are known to interact with ingredients in grapefruit juice. Scientists warned of the phenomenon 20 years ago. Now they speak up again. Dr. David G. Bailey of the University of Western Ontario reports that 43 drugs can now cause serious side effects due to the interaction.
Ingredients in the juice inhibit the enzyme cytochrome P450 3A4 (CYP3A4), especially in the small intestine. Metabolites of furanocoumarins from grapefruit bind irreversibly to the enzyme and thus severely limit its activity. As a result, some drugs are no longer metabolized and the drug concentration becomes higher than intended. This applies to oral intake. Older people are particularly affected. Source: David G. Bailey et al. Grapefruit-medication interactions: Forbidden fruit or avoidable consequences? published ahead of print November 26, 2012, doi: 10.1503 / cmaj.120951 (pm)
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