Grapefruit juice and medications:

For many people, downing a glass of grapefruit juice — especially brands
fortified with calcium — is part of a healthy routine. The juice carries the
American Heart Association's healthy "heart-check" food mark and contains
compounds that may reduce the risks for cardiovascular disease and cancer.

But a new review of existing research indicates that taking prescription medicine
with a glass of grapefruit juice may lead to higher than normal blood levels of
many drugs and could lead to problems.

Unlike other juices of citrus fruits, grapefruit juice interacts with a variety of
prescription medications by inhibiting one of the intestinal enzyme systems,
according to researchers at Mayo Clinic, Rochester, Minn.

Garvan C. Kane, M.D., and James J. Lipsky, M.D., the authors of the study, say
that drug-grapefruit juice interactions are of special concern because medications
often are taken at breakfast along with juice.

In addition, the people most likely to increase their consumption because of the
added calcium — middle-age and older people — also are most likely to be taking
prescription drugs, according to the study published in the September issue of
Mayo Clinic Proceedings.

Nearly a decade has passed since investigators first discovered an interaction
 between grapefruit juice and felodipine, a drug used to treat heart failure and
angina and to lower blood pressure. The researchers say their review of existing
clinical findings of drug-grapefruit juice interactions suggests that grapefruit juice
affects many other drugs, as well.

Physicians should consider an individual's consumption of grapefruit juice when
prescribing drugs, the study concludes.

"Certainly grapefruit juice is safe in itself but we know that it does interact with
certain prescription medications," says Dr. Kane.
 

FDA Reccommendation:

Never drink grapefruit juice less than two hours before or five hours after
taking heart drugs called calcium channel blockers, like Procardia. The mix
sometimes kills.

Grapefruit juice taken with cyclosporin, which fights organ rejection in
transplant recipients, can cause confusion and trembling