Grapefruit Juice Helps Anti-Cancer Drug Work Better

Editor's Choice Main Category: Cancer / Oncology Article Date: 08 Aug 2012 - 12:00 PDT

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Scientists from Chicago's University of Medicine have researched the potential impact of foods on the uptake and elimination of drugs used for cancer treatment and discovered that eight ounces a day of grapefruit juice can slow the body's metabolism of a drug called sirolimus, an approved drug for transplant patients, which may also be of benefit to many suffering from cancer.

They observed that sirolimus levels were raised by 350% in patients who drank eight ounces of grapefruit juice per day, and by 500% in those taking ketoconazole, a drug that slows down the metabolism.

Director of the study Ezra Cohen, MD, a cancer specialist at the University of Chicago Medicine said:

Grapefruit juice can inhibit enzymes in the intestine, which break down sirolimus and several other drugs. The effect starts within a few hours of what the researchers refer to as "grapefruit juice administration," and gradually subsides over a few days.

Cohen and his team conducted three simultaneous phase-1 trials of sirolimus in which 138 patients with incurable cancer and no known effective therapy either received only sirolimus or sirolimus plus ketoconazole, or sirolimus plus grapefruit juice. To maximize the greatest anti-cancer effect with the least side effects, the team started the first patients on very low doses of sirolimus, which they increased as the study progressed in order to assess the required amount of drug in each setting to reach targeted levels.

They noted that the best cancer-fighting dose in the sirolimus alone group consisted of around 90 mg per week, although they observed that doses above 45 mg caused serious gastrointestinal problems like diarrhea and nausea, and therefore switched this group of patients back to 45 mg twice a week. In contrast, the optimal doses to maintain the same levels of drug in the blood for the sirolimus plus ketoconazole group was 16 mg per week and that of the sirolimus plus grapefruit juice group between 25 and 35 mg per week, which is considerably lower.

The team comments: "This is the first cancer study to harness this drug-food interaction."

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Grapefruit Juice Helps Anti-Cancer Drug Work Better