Grapefruit juice can interfere with a lot of prescription and nonprescription drugs, but cancer researchers found that the tart juice helps the body absorb more of a promising medication, reducing side effects and saving patients money because they need smaller doses.
Cancer researchers at the University of Chicago found that a glass of grapefruit juice increased the body's uptake of a powerful drug called sirolimus, which allowed doctors to cut the drug dosage by a third to get the same desired effect as a full dose, reports Scientific American.com.
Sirolimus, a kidney transplant drug, is being tested for its tumor-fighting effects on patients with incurable cancer, according to HealthDay.com.
Unfortunately, the body is only able to absorb about 14 percent of a dose of the drug, said lead researcher Ezra Cohen, M.D., of the University of Chicago Medical Center. The problem is, a larger dose of sirolimus -- anything above 45 mg -- causes serious gastrointestinal problems, such as severe nausea and diarrhea.
But Cohen remembered that grapefruit juice can increase the blood levels of certain drugs. In fact, the Food and Drug Administration warns against taking medicines like statins or antihistamines with grapefruit because it can an cause overdoses.
But that was a plus when it came to sirolimus.
Cohen and his team gave patients sirolimus along with grapefruit juice. The juice increased the drug's levels in the blood by 350 percent and lowered the necessary dose from 90 mg per week to between 25 and 35 mg. weekly.
"We're talking about cutting..costs by a half to a third," Cohen told ABC News.
One interesting twist: The patients were first given grapefruit juice purchased from the non-refrigerated section of the grocery store. Non-refrigerated juice has to be heated for food safety reasons, which kills the enzyme that increases drug absorption, so the juice had no effect.
But when the Florida Department of Citrus heard about the study and sent fresh, refrigerated juice, it had a dramatic effect, Cohen said.
Cohen cautioned that people shouldn't experiment with grapefruit juice to increase the potency of their drugs.
The effect will vary with each drug and with the type of juice used. Determining the exact amount of grapefruit juice needed will have to be researched much more, he said.
The study was published Tuesday in the journal Clinical Cancer Research.
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Photo: Courtesy dullhunk via flickr.com