Grapefruit juice shows strong interaction

The problem is not unknown: Grapefruit juice can increase the bioavailability of some medications. Because the medicines are not metabolised by the juice, the risk of overdoses increases. Scientists warn again.

12/12/2012

Grapefruit ingredients, along with some medicines, can cause dangerous interactions. More than 85 medicines are known to interact with constituents in grapefruit juice. Already 20 years ago scientists warned about the phenomenon. Now sign up again. Dr. David G. Bailey of the University of Western Ontario reports that in the meantime 43 compounds can interact with severe side effects.

Ingredients of 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. Some drugs will no longer be metabolized and the drug concentration will be higher than intended. This applies to oral intake. Particularly affected are older people. 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)

Picture: Rainer Sturm