Grapefruit Juice Boost Cancer Drug’s Potential
While doctors have long warned patients that eating grapefruit could cause dangerous interactions with some prescription medications, a new study found that grapefruit juice may help boost an anti-cancer drug's potential.
The drug in question, sirolimus, is not yet used to treat cancer. It's a drug commonly used by transplant patients to prevent rejections, but has been shown to have cancer fighting processes in several studies.
"It's a drug that was discovered in the 70s," Dr. Ezra Cohen, study author and a cancer specialist at the University of Chicago, told Fox News. "It was clearly shown to have anti-cancer effects and anti-neoplastic effects, but it hadn't been developed for cancer extensively because the patent ran out. There wasn't a lot of commercial interest to develop sirolimus, so it sort of was pushed aside for a while. Eventually, sirolimus was indeed approved, but for people who got organ transplants to prevent rejection."
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Grapefruits and grapefruit juice is known to boost the efficacy of drugs, which is why doctors warn patients against the fruit when taking certain medication, such as cholesterol medication or antihistamines.
"Investigators were doing a study on alcohol's effect on a certain heart drug," Cohen told Fox News. "And to mask the taste of alcohol, they used grapefruit juice. What they ended up finding out was that the grapefruit juice increased the blood levels of the drug."
However, Cohen decided to use that to his advantage.
"We saw that not as a problem but as an opportunity to enhance the pharmacology to not only sirolimus but to a wide range of drugs," Cohen told ABC News. "We're talking about cutting those costs by a half to a third."
Researchers looked at 138 patients with incurable cancer, and found that patients who drank the grapefruit juice saw three times the benefit as people who just used the drug.
"One of the issues with sirolimus is that it has very poor bioavailability, meaning only 14 percent gets absorbed when you take the pill," Cohen told Fox News. "That's why the company that manufacturers sirolimus actually created an intravenous analog of the drug, because of the availability issue. So we thought, 'Why don't we try to modify the metabolism of sirolimus by using a ketoconazole or using grapefruit juice. If we can reduce even some of the side effects associated with the drug and develop a combination, that could be effective."
While it could be years, if ever, before sirolimus is used to treat cancer, Dr. Jerry Avorn, chief of the Division of Pharmacoepidemiology and Pharmacoeconomics at Brigham and Women's Hospital in Boston, who was not involved in the study, told ABC News that the study's findings are interesting nevertheless.
"It's important not to see this as a new cure for cancer," he said. "But rather, it's a very interesting way of using a known food-drug interaction as a means of getting better drug levels into cancer patients."
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