Grapefruit and pills mix warning
1 December BBC
Doctors have warned of a "lack of knowledge" about the dangers of
mixing some medications with grapefruit.
The fruit can cause overdoses of some drugs by stopping the medicines
being broken down in the intestines and the liver.
The researchers who first identified the link said the number of
drugs that became dangerous with grapefruit was increasing rapidly.
They were writing in the Canadian Medical Association Journal.The
team at the Lawson Health Research Institute in Canada said the number
of drugs which had serious side effects with grapefruit had gone from 17
in 2008 to 43 in 2012.
They include some drugs for a range of conditions including blood
pressure, cancer and cholesterol-lowering statins and those taken to
suppress the immune system after an organ transplant.
Chemicals in grapefruit, furanocoumarins, wipe out an enzyme which
breaks the drugs down. It means much more of the drug escapes the
digestive system than the body can handle.Three times the levels of one
blood pressure drug, felodipine, was reported after patients had a glass
of grapefruit juice compared with a glass of water.The side effects are
varied depending on the drug, but include stomach bleeds, altered heart
beat, kidney damage and sudden death.Dr David Bailey, one of the
researchers, told the BBC: "One tablet with a glass of grapefruit juice
can be like taking five or 10 tablets with a glass of water and people
say I don't believe it, but I can show you that scientifically it is
sound.
"So you can unintentionally go from a therapeutic level to a toxic
level just by consuming grapefruit juice."The report said: "We contend
that there remains a lack of knowledge about this interaction in the
general health care community."They added: "Unless health care
professionals are aware of the possibility that the adverse event they
are seeing might have an origin in the recent addition of grapefruit to
the patient's diet, it is very unlikely that they will investigate
it."Other citrus fruits such as Seville oranges, often used in
marmalade, and limes have the same effect.
Neal Patel, from the Royal Pharmaceutical Society said: "Grapefruit
isn't the only food that can cause issues, for example milk can stop the
absorption of some antibiotics if taken at the same time."Although some
of these interactions may not be clinically significant, some may lead
to more serious outcomes."Pharmacists are the best port of call for
anyone concerned about how their diet may affect their medication.
Information about any interactions would always be included in the
patient information leaflet that comes with the medicine."
A spokesman from the Medicines and Healthcare products Regulatory
Agency said: "We encourage patients and healthcare professionals to
report any suspected adverse drug reactions to our Yellow Card Scheme.
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