Study finds juices can cut absorption of some medicines

The medical world was stunned, and initially quite skeptical, when a Canadian pharmacologist in the early 1990s announced the discovery of the so-called grapefruit-juice effect.

The University of Western Ontario researcher, David Bailey, said a glass of grapefruit juice could boost, two- to threefold, the potency of a wide variety of commonly prescribed medicines, including the cholesterol fighter Lipitor, the world's biggest-selling drug.

Today, 48 drugs ranging from cholesterol-lowering statins to cancer therapies such as Gleevec carry a warning that grapefruit juice may turn a safe dose into an overdose, according to the American Academy of Family Physicians.

Soon, there could be even more.

Apple, orange juice too

This summer, Bailey announced his latest findings: Grapefruit juice, as well as apple and orange juice, also can have the opposite effect.

A series of studies, he said, found these juices dramatically cut the absorption of certain cancer, blood-pressure and cholesterol drugs, as well as antihistamines such as Allegra.

Healthy volunteers who took Allegra with grapefruit, apple or orange juice, for example, absorbed only half the amount of the drug, compared with volunteers who took it with water.

"Most people have not thought of this," Bailey said last week from his office in London, Ontario. "We talk about drug interactions, but food-drug interactions is kind of passé, not a big concern."

Bailey's findings, the experts said, have the potential to change medical practices, such as altering the way millions of patients are instructed to take medication.

What's more, pharmaceutical companies and drug researchers already are studying grapefruit as a way to cut medicine costs by boosting the effectiveness of smaller doses of expensive cancer drugs.

The studies suggest drinking fruit juices to wash down pills at breakfast may not be a good idea, Bailey said. Juice drinkers probably should wait a minimum two hours after taking their medications, he said.

Although Bailey's findings have been documented in four studies published in scholarly journals since 2002, they have had little effect in the medical community.

With grapefruit juice, organic chemicals called furanocoumarins cause more prescription medicine to enter the bloodstream faster, according to Bailey's studies. It has a particularly powerful effect on anti-cholesterol statins and beta-blockers taken daily by millions of sufferers of hypertension and irregular heartbeats.

As a result, taking one tablet of cholesterol medicine with a glass of grapefruit juice, Bailey says, could have the same potency as a dozen tablets taken with water.

Bailey presented a summary of his latest research on apple and orange juice at the American Chemical Society conference last month in Philadelphia. It found the juices block proteins in the intestine, known as transporters, that shuttle pharmaceuticals through the gastrointestinal tract and into the bloodstream.

Medical acceptance

The grapefruit-juice effect didn't gain traction until it was published in the Lancet, a respected medical journal.

Marc Cohen, chief cardiologist at Newark Beth Israel Medical Center in New Jersey, said the latest research into grapefruit, apple and orange juice will not be widely accepted by doctors until it is verified in a large-scale clinical trial.

"There might be measurements we can do in a test tube, but at the end of the day, does that translate into more heart or fewer heart attacks, more hospital stays or fewer hospital stays?" Cohen said.

Since the grapefruit-juice effect became widely publicized, sales of grapefruit juice have fallen nearly 40 percent since 2003, according to the Florida Department of Citrus.