Why Can Grapefruit Interfere With Some Medications?

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Why Can Grapefruit Interfere With Some Medications?

http://www.medicalnewstoday.com/articles/101013.php

s Hopkins Health Alerts' recent Prescription Drug Health Alert

reported on new research regarding the reason why grapefruit juice

can potentially cause a dangerous interaction with certain of the

medications you take.

FOOD AND DRUG INTERACTIONS

Certain foods and drinks don't mix well with certain medications. For

example, grapefruits or grapefruit juice may interact badly with a

number of medications, because natural grapefruit contains a

substance that affects the activity of an enzyme in the intestines

and liver that processes these medications. This could result in a

dangerous increase in the level of the drug in your blood.

Another potentially dangerous interaction is between the blood

thinner warfarin (Coumadin and generic brands) and vitamin K. The

vitamin, present in many multivitamins and supplements, neutralizes

or reduces the effect of the medication warfarin. This raises the

risk of a blood clot, which the warfarin is intended to prevent.

GRAPEFRUIT AND DRUG INTERACTIONS

Now scientists have identified the specific chemical in grapefruit

juice responsible for many drug-food interactions, according to an

article in the American Journal of Clinical Nutrition (Volume 83,

page 1097).

Previous research implicated a family of chemical compounds called

furanocoumarins (FCs) as the culprit in grapefruit juice. To confirm

this suspicion, the scientists created FC-free grapefruit juice and

compared its effects with those of whole grapefruit juice or orange

juice (the control group in the study).

GRAPEFRUIT AND DRUG INTERACTION STUDY

Eighteen study volunteers drank 8 oz of whole or FC-free juice along

with a dose of felodipine (Plendil), a blood pressure medication.

The blood concentration of Plendil was nearly THREE times higher when

people took it with 8 ounces of whole grapefruit juice, compared with

blood levels after subjects took it with the FC-free grapefruit juice

or orange juice (the control group in the study).

This means that the blood level of Plendil was higher when taken with

whole grapefruit juice, potentially causing dangerously low blood

pressure.

The researchers said their finding could assist in the study of other

drug-food interactions.

Grapefruit has also been known to diminish the absorption of some

drugs in the body. So always follow the guidelines given on your

medications with regard to food and drug interactions.

One further note: In reference to the control group in the study,

regular orange juice was found to be safe to drink with Plendil.

However, you may want to avoid Seville oranges in juice or marmalade,

as they are the only type of oranges to contain furanocoumarins.