Grapefruit juice could boost cancer drug
Wednesday August 8th, 2012
The effectiveness of a transplant drug with potential anti-cancer properties is dramatically increased if taken alongside grapefruit juice, researchers say.
A
team of researchers from the University of Chicago, USA, are looking at
the effect of food and drink on the uptake and elimination of medicines.
For this study, they focused on a drug called sirolimus, which is approved
for transplant patients but may also help many people with cancer.
A total of 138 patients with incurable cancer were recruited and given either sirolimus alone, sirolimus plus grapefruit juice, or sirolimus plus a drug called ketoconazole which slows drug metabolism.
Participants who were taking sirolimus and also drinking eight ounces (235ml) a day of grapefruit juice increased their sirolimus levels by 350 per cent. Findings also showed that ketoconazole increased sirolimus levels by 500 per cent.
Full details are published in the August issue of Clinical Cancer Research. The authors say that that grapefruit juice could help prevent the side-effects of high doses of the drug, as well as reducing costs.
Dr Ezra Cohen says: "Grapefruit juice, and drugs with a similar mechanism, can significantly increase blood levels of many drugs, but this has long been considered an overdose hazard. Instead, we wanted to see if grapefruit juice can be used in a controlled fashion to increase the availability and efficacy of sirolimus."
He explains that grapefruit juice can inhibit enzymes in the intestine that break down sirolimus and many other drugs, starting within a few hours of consumption and lasting a few days.
The best dose of sirolimus for anti-cancer action while avoiding side-effects appeared to be 45mg twice a week. But when taken with ketoconazole, a dose of just 16mg per maintained the same blood levels of sirolimus. When taken with grapefruit juice, patients only needed 25 to 35mg of sirolimus per week.
Cohen, E. et al. Clinical Cancer Research August 2012 (in press).
Tags: Cancer | Diet & Food | Internal Medicine | North America | Transplant | Pharmaceuticals
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