Interaction Between Grapefruit Juice and Drugs

Abstract

Clinically significant grapefruit juice-drug interactions are an interesting development in the last ten years of research process in the scope of drug interactions. In 1989 a group of Canadian researchers found incidentally that grapefruit juice, used as a carrier system, interacts with some calcium channel blockers, while applying alcohol during a study on alcohol-drug interactions, and presented it in Lancet as a "short report". In this report it is stated that this effect of grapefruit juice is specific and there is no similar interaction with orange juice. The grapefruit juice interactions with drugs and changes in drug pharmacokinetics, individual responses to grapefruit juice in the relationship between the drug concentration and the effect began to gain a larger clinical significance. Drugs interacting with grapefruit juice are metabolized by cytochrome P450 enzyme system in liver or intestinal section. Flavonoids contained in grapefruit juice inhibit the enzyme, bind as a substrate to the enzyme system and disrupt its bioavailability. Naringin is an essential bioflavonoid in the grapefruit juice. Naringin is not a potent inhibitor of cytochrome P450, but it is partly metabolised to "Naringenin" by intestinal bacteria. This substance is a powerful inhibitor of cytochrome P450 and it is believed by some researchers, that these are components responsible for the effect of grapefruit juice. In 2008 the number of drugs that can cause danger when taken together with grapefruit was 17. It has been reported that this number has risen to 43 in 2012. However, while the research of the possible effects of other not yet identified components of the grapefruit juice is still in progress, FDA has begun to put cautionary statement to many drug prescriptions.