Grapefruit juice boosts drug’s anti-cancer effects

April 21st, 2009 - 1:20 pm ICT by IANS  

Washington, April 21 (IANS) A glass of grapefruit juice, combined with rapamycin, boosts the drug’s anti-cancer effects and enhances its potency in lower doses, according to a clinical study.
For decades, pharmacists have pasted ‘do-not-take-with-grapefruit-juice’ stickers on pill bottles because it can interfere with the enzymes that break down and eliminate certain drugs. This interference makes the drugs more potent.

University of Chicago Medical Centre (UCMC) researchers are examining ways to exploit this fruit’s medication-altering properties. “Grapefruit juice can increase blood levels of certain drugs three to five times,” said study director Ezra Cohen, cancer specialist at the UCMC.

“This has always been considered a hazard. We wanted to see if, and how much, it could amplify the availability, and perhaps the efficacy of rapamycin, a drug with promise for cancer treatment,” said Cohen.

The study followed 28 patients with advanced solid tumours, for which there is no effective treatment. The dose of the drug increased with each group of five patients, from 15 milligrams up to 35. Patients took the drug by mouth, as a liquid, once a week.

Beginning in week two, they washed it down with a glass of grapefruit juice (Citius paradisi), taken immediately after the rapamycin and then once a day for the rest of the week.

Twenty-five participants remained in the study long enough to be evaluated. Seven of those 25 (28 percent) had stable disease, with little or no tumour growth.

One patient (four percent) had a partial response, with the tumour shrinking by about 30 percent. That patient is still doing well more than a year after beginning the trial.

“My first cancer doctor gave me five years to live,” said that patient, Albina Duggan of Bourbonnais. “That time runs out next July.”

Duggan, mother of four, has a rare cancer, an epitheliod hemangioendothelioma that originated in the liver and subsequently spread to two vertebrae in the neck and to the lymph nodes.

She had surgery and radiation therapy and was evaluated for a liver transplant, but evidence of cancer beyond the liver made her ineligible for a transplant.

She “shopped around” for other therapies and was able to keep the disease in check for a year with sorafenib, a drug approved for kidney and liver cancers, said an UCMC release.

After a year of stable disease, however, her tumour began growing again and she had to look for an alternative therapy. Her doctors at the University of Chicago offered three clinical trials. The most appealing to her was the rapamycin plus grapefruit juice study. She took her first dose March 11 last year and is still on the drug-juice combination.

“My tumour is smaller and it’s no longer growing. I feel fine. I can do whatever I like and I have no real side effects,” she said. “What’s not to like?”

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