Interactions of Grapefruit Juice with Drugs

Interactions between grapefruit juice and oral drugs have been reported in the literature. The constituents of the juice that give rise to pharmacokinetic interactions have not been identified with certainty. It has been suggested that the mechanisms may involve inhibition of intestinal cytochrome P450 CYP3A4 isozyme and of drug efflux transporters. There are several variables that may influence the clinical significance of the drug-food interactions. In the pharmacy practice setting, the major concern is the increased bioavailability of drugs having a narrow therapeutic index.