Grapefruit Juice Boosts Anti-Cancer Drug Effect

CHICAGOResearchers at the University of Chicago Medical Center have found that combining eight ounces of grapefruit juice with the anti-cancer drug rapamycin can increase drug levels, allowing lower doses of the drug to be given. They also showed that the combination can be effective in treating various types of cancer.

Grapefruit juice can increase blood levels of certain drugs three to five times, said study director Ezra Cohen, MD, a cancer specialist at the University of Chicago Medical Center.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.

Rapamycin, also known as sirolimus, was originally developed to suppress the immune system, preventing rejection in patients receiving a transplanted kidney. Cancer specialists became interested in the drug when they learned that it disrupted a biochemical pathway involved in the development of the new blood vessels that tumors need to grow; however, the drug is expensive and less than 15 percent is absorbed when taken by mouth.

This study showed that substances known a furanocoumarins, plentiful in some forms of grapefruit juice, can decrease the breakdown of rapamycin. This makes the drug reach higher levels in the bloodstream, two to four times the levels seen without a juice boost, and thus increases the amount of the drug that reaches its targets.

Many of the newer cancer medications, precisely focused on specific targets, are now taken as pills rather than intravenously. Some of these drugs, including rapamycin, can cost thousands of dollars a month. Hence, this is an opportunity for real savings, Cohen said. A daily glass of juice could lower the cost by 50 percent.