Grapefruit juice @ drug interractions-caution

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Grapefruit Juice: Is it Affecting Your Medication?

A nutraceutical is a food or part of a food that allegedly provides

medicinal or health benefits, including the prevention and treatment

of disease. Grapefruit juice has been touted as containing many

compounds that can reduce hardening of the arteries (atherosclerosis)

and even the risk of cancer. Grapefruit juice can, therefore, be

justifiably referred to as a classic nutraceutical. However, for many

persons taking certain medications, grapefruit juice might actually

better be termed a " nutrapollutical! "

It turns out that grapefruit juice can directly or indirectly interact

in important ways with a number of medications. This is especially

important since grapefruit juice is consumed by approximately one

fifth of Americans for breakfast - a time of the day when medications

also are commonly taken.

Grapefruit juice blocks special enzymes in the wall of the small

intestine that actually destroys many medications and prevents their

absorption into the body. Thus, smaller amounts of the drugs get into

the body than are ingested. When the action of this enzyme is blocked,

more of the drugs get into the body and the blood levels of these

medications increase. This can lead to toxic side effects from the

medications.

Amazingly, this remarkable food-drug interaction was discovered

completely by accident over a decade ago! Researchers were

investigating whether alcohol could interact with felodipine (Plendil)

and used a solution of alcohol with grapefruit juice to mask the taste

of alcohol for the study. Researchers discovered that blood levels of

felodipine were increased several fold more than in previous studies.

This increased blood level caused an increase in the effect and side

effects of felodipine. Further research revealed that the grapefruit

juice itself was actually increasing the amount of the study drug in

the body.

Research about the interaction of grapefruit juice with drugs suggests

that compounds in grapefruit juice, called furanocoumarins (e.g.

bergamottin), may be responsible for the effects of grapefruit juice.

Researchers believe that furanocoumarins block the enzymes in the

intestines that normally break down many drugs. One glass of

grapefruit juice could elicit the maximum blocking effect, and the

effect may persist for longer than 24 hours. Since the effects can

last for such a prolonged period of time, grapefruit juice does not

have to be taken at the same time as the medication in order for the

interaction to occur. Therefore, unlike similar interactions, where

the interaction can be avoided by separating the administration of the

two interacting agents by a couple of hours, administration of

grapefruit juice with susceptible drugs should be separated by 24 or

more hours to avoid the interaction. Since this is not practical for

individuals who are taking a medication daily, they should not consume

grapefruit juice when taking medications that are affected by

grapefruit juice.