Grapefruit
Juice and Medications May Not Mix
Grapefruit
juice can cause serious consequences for people on certain medications,
according to a report in the American
Journal of Nursing.
"The
Grapefruit Challenge: The juice inhibits a crucial enzyme, with
possibly fatal consequences," focuses on interactions between
grapefruit juice and medications, which have long been recognized.
The
US Food and Drug Administration
requires all prospective new medications to be tested for interactions
with grapefruit juice. And a warning about grapefruit juice
is included in the "food-drug interactions" that come with dozens
of medications.
Nevertheless,
Amy Karch, R.N., M.S., of the School of Nursing at the University
of Rochester Medical Center, says many healthcare professionals
and patients do not know about the risk.
"The
potential of drug interactions with grapefruit juice has been
out there a long time, but most people just aren't aware of
it," says Karch.
"There
is so much information bombarding people all the time, that
a lot of people may have heard this but forgotten it," she says.
"But the problems can be life-threatening."
Karch
reported on a man from a northern climate who moved to Florida
for the winter - one of tens of thousands of "snowbirds" who
head south each winter - and began drinking two to three glasses
of grapefruit juice each day.
The
patient profiled in Karch's article had high cholesterol and
other risk factors for cardiac disease. The physician put the
patient on atorvastatin (Lipitor®), and the patient began
dieting and exercising.
Two
months after the patient went to Florida for the winter, he
suddenly had muscle pain, fatigue, and fever, and went to the
emergency room.
The
only major change in the person's lifestyle had been that, upon
arriving in Florida, he began picking grapefruit off a tree
on the patio and drinking two or three glasses of fresh grapefruit
juice every day.
Karch,
an expert on medication interactions, explains that grapefruit
juice is one of the foods most likely to cause problems with
drugs, because it is metabolized by the same enzyme in the liver
that breaks down many medications.
The
cytochrome P-450 3A4 enzyme breaks down grapefruit juice into
useful components for the body, just like it breaks down dozens
of medications. Karch says when the system is overloaded, the
grapefruit juice can "swamp" the system, keeping the liver busy
and blocking it from breaking down drugs and other substances.
Medications
that use the same pathway and interact with grapefruit juice
target some of the most common health problems physicians see
today. The list consists of more than 50 medications, including
some used to treat high cholesterol, depression, high blood
pressure, cancer, depression, pain, impotence, and allergies.
Karch
notes that interactions with grapefruit juice are well known
and documented among drug researchers, and that an appropriate
warning label is included with each prescription.
However,
she says that many patients fail to read the warning labels
about medication-food interactions.
The consequences
of an interaction depend on the medication involved. A
person on an antidepressant might have too much or too little energy,
depending on the specific medication. Someone on antibiotics might end
up with diarrhea or could be ill longer than usual because the drug
will not work as well as it should.
A
heart patient might not get the lowered blood pressure that
a medication should deliver, or the heart's rhythm might become
irregular if an antiarrhythmia medication cannot do its job.
The
most severe effects are likely with some cholesterol-lowering
medications, Karch says. While the liver devotes its resources
to grapefruit juice, the medication can build up to dangerous
levels, causing a breakdown of the body's muscles and even kidney
failure.
To
prevent such problems, Karch repeats what physicians and nurses
tell their patients every day: Read a medication's warning label
carefully. If an interaction with grapefruit juice is possible,
the patient should stop drinking the juice until speaking with
his or her physician.
In
some cases it might be possible to switch an individual to a
different medication without the risk; in other cases the person
might simply have to give up grapefruit juice.
She
says that more people than usual are vulnerable at this time
of year, because losing weight is among the most popular New
Year's resolutions, and some diets are built around drinking
lots of grapefruit juice.
Always
consult your physician for more information. |
