Grapefruit juice sales are gradually increasing since 1970s and reached an average of 24.9 million litres per annum between 2004 and 2007. The use of grapefruit juice on its own or in a mixture with other juices is gradually increasing in UK and grapefruit juice is now a regular part of breakfast consumption in most of Western Europe and America. Since the accidental discovery of its interaction with felodipine, more than 85 drugs have been identified to have the potential to cause serious adverse reactions. However there has been a lack of awareness of its effects on other medications in patients as well as physicians. It is necessary for all medical practitioners to be aware of the potential for enhanced serum levels of the affected drugs and the possibility of serious adverse effects. Grapefruit juice inhibits the CYP3A4 enzyme of the cytochrome P450 system in the intestinal mucosa, increasing the bioavailability of drugs with a high first pass metabolism. Therapeutic doses of the affected drugs may produce serious adverse reactions. More research is necessary to identify the mechanism of such interactions and to identify the active ingredients.
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