Abstract

DRUG INTERACTIONS WITH GRAPEFRUIT JUICE

Mr. Kiran C. Rodge*, Mrs. Sirgire K. S., Mr. Dharashive V. M., Mr. Sameer Shafi, Mr. Mugale V. S.

ABSTRACT

Concomitant intake with grapefruit juice increases the concentrations of many drugs in humans. The effect seems to be mediated mainly by suppression of the cytochrome P450 enzyme CYP3A4 in the small intestine wall. This results in a diminished first pass metabolism with higher bioavailability and increased maximal plasma concentrations of substrates of this enzyme. The effect was most pronounced in drugs with high first pass degradation. The components of grapefruit juice which are the most probable causes of the interaction are furanocoumarins derivatives, but the flavonoid naringenin may also contribute. Concomitant grapefruit juice intake does not generally decrease the variability of drug pharmacokinetic parameters. Therefore, it is recommended that patients abstain from drinking grapefruit juice when they are taking a drug that is extensively metabolised, unless a lack of interaction has already been demonstrated for that drug. It is also recommended that drugs possibly interacting with grapefruit juice should be appropriately labelled.

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