grapefruit-danger-43-prescription-pills
More than 85 drugs in total can
interact with grapefruit, and of these 43 can have serious side effects, said
the researchers. Eating grapefruit can be deadly for some patients taking
certain prescription drugs, experts have warned. The fruit contains chemicals
that can interact with certain drugs, making them more potent. Adverse effects
can include acute kidney failure, respiratory failure, internal bleeding and
sudden death. While it is well known that some patients should avoid
grapefruit, or grapefruit juice, the list of drugs involved has risen sharply
in recent years. Between 2008 and 2012 the number of medications with the
potential to cause serious harm by interacting with grapefruit increased from
17 to 43, said scientists writing in the Canadian Medical Association Journal.
Each year, more than six of these
drugs on average were being made available to patients. Dr David Bailey, from
Lawson Health Research Institute in London, Ontario, and colleagues described
the trend as "disturbing". They wrote: "Unless healthcare
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. "In
addition, the patient may not volunteer this information.
"Thus, we contend that there
remains a lack of knowledge about this interaction in the general healthcare
community." More than 85 drugs in total can interact with grapefruit, and
of these 43 can have serious side effects, said the researchers. Other citrus
fruits such as Seville oranges, used to make marmalade, and limes contained the
same active ingredients that caused the drug interactions. The chemicals,
called furanocoumarins, act on an enzyme in the gut that normally reduces the
potency of medication. This can effectively boost the dose of some drugs many
times. The list of danger medicines includes treatments for anxiety,
depression, allergy, HIV infection, seizures, heart rhythm abnormalities and high
cholesterol. A modest single helping of grapefruit can have an effect even if
consumed hours before a drug is taken, said the scientists. Frequent exposure
to grapefruit could make matters worse. Combining the cholesterol-lowering drug
simvastatin with a 200 millilitre glass of grapefruit juice once a day for
three days more than tripled its concentration level. Older people with a
reduced ability to tolerate drug overdoses were at greatest risk. "The
current trend of increasing numbers of newly marketed grapefruit-affected drugs
possessing substantial adverse clinical effects necessitates an understanding
of this interaction and the application of this knowledge for the safe and
effective use of drugs in general practice," the experts concluded
The dangers of grapefruit juice
By Nicholas Bakalar
Published: Wednesday,
March 22, 2006
In 1989, a group of Canadian researchers studying a blood pressure
drug were astonished to discover that drinking a glass of grapefruit juice
dangerously increased the drug's potency. They were testing the effects of
drinking alcohol on a medicine called Plendil. The scientists needed something
that would hide the taste of alcohol so that subjects would know only that they
were taking the drug and not know whether they were drinking alcohol with it.
"One Saturday night, my wife and I tested everything in the
refrigerator," said Dr. David Bailey, a research scientist at the London
Health Sciences Center in London, Ontario, and the lead author on the study.
"The only thing that covered the taste was grapefruit juice." So they
used it in their experiment, expecting the grapefruit juice to be irrelevant to
their results. But blood levels of the drug went up significantly in the
control group that drank just grapefruit juice, without alcohol. "People
didn't believe us," Bailey said. "They thought it was a joke. We had
trouble getting it published in a major medical journal." Eventually the
paper was published by Lancet, in February 1991. Finding why juice had that
effect was the next question. The answer, it turned out, lay in a family of
enzymes called the cytochrome P-450 system, in particular one known as CYP 3A4.
This enzyme metabolizes many drugs, and toxins as well, into substances that
are less potent or more easily excreted or both. Grapefruit juice interferes
with the ability of CYP 3A4 to do that, increasing the potency of a drug by
letting more of it enter the bloodstream, in effect producing an excessive
dose. Grapefruit interacts with this enzyme only in the intestines, not in the
liver or other places where it is found. As a result, the effect is seen only
with medicines taken orally, not with injected drugs. Numerous studies now show
the interaction of grapefruit juice with many widely used medicines. Most
interactions have no serious consequences, but a few do. For example, drugs
used to lower cholesterol, like Lipitor, Mevacor and Zocor, have increased
potency when taken with grapefruit juice. Excessive levels of those drugs can
lead to a serious and sometimes fatal muscle disorder called rhabdomyolysis.
Does this mean a person could reduce the amount of medicine required simply by
drinking grapefruit juice? No, according to Bailey. "The problem is the
unpredictability of the effect," he said. "There's no uniformity from
one individual to another or from one bottle of grapefruit juice to the next.
"There's huge variation in the amount of enzyme people have in their guts.
Fooling around with grapefruit juice is not a good idea." Grapefruit juice
can also interfere with the metabolism of selective serotonin reuptake
inhibitors, or SSRIs, like Prozac, used to treat depression. Dr. Marshall Forstein,
an associate professor of psychiatry at Harvard, said he told patients to
switch from grapefruit juice to something else because most oranges and other
citrus fruits do not have the same effect. Among fruit juices, grapefruit has
the strongest effect, but lime juice and orange juice made from Seville oranges
similarly inhibit the CYP 3A4 enzyme. With some drugs, apple juice may interact
in the same way. While Bailey suggests avoiding grapefruit juice entirely when
taking medicine, some experts say the effect of the juice should not be
exaggerated. "The circumstances under which an interaction will occur are
relatively unusual," said David Greenblatt, a professor of pharmacology at
Tufts University School of Medicine in Boston. First, he said, the drug has to
be metabolized significantly by intestinal CYP 3A4, and relatively few are.
"When you look at the actual data for each drug, the scientific
conclusions are that the interactions are unusual, sometimes quite small and
not of clinical importance. But there are some cases in which it's
significant." Greenblatt and his co-investigators at Tufts have conducted
research sponsored by the National Institutes of Health in this field for
years, and he has been a paid consultant to the Florida Citrus Commission. Dr.
Richard Kim, a professor of medicine and pharmacology at Vanderbilt University
in Nashville, Tennesseeagreed that the interaction was a serious health concern
in some patients. "Grapefruit consumption is a clinically relevant issue,
especially for the elderly, who are most likely to be taking the drugs affected
by it," Kim said. "If you're taking multiple medications, or have
recently switched to a different type of medication, you should be particularly
careful. The easiest thing to do under those circumstances is to take the
medicine with water and avoid the juice completely." More Articles in Health »
Grapefruit Juice:
The Hidden Dangers Of Drug Interaction
Grapefruit juice is one of the healthiest foods around, right?
A cup of unsweetened white
grapefruit juice has only 100 calories, no fat, more than 100% of the
recommended daily amount of vitamin C, and it's got a zingy taste that can
really get you moving in the morning. However, grapefruit juice (including the
juice found in your morning grapefruit half) can interact with certain
medications, leading to potentially serious consequences.
Which medications does grapefruit juice interact with?
Grapefruit juice can interact with many different drugs that people take
to maintain their health. If you eat grapefruit or drink grapefruit juice, you
should ask your prescribing health care provider and pharmacist about any drugs
that you're currently taking and ask again whether new drugs interact with
grapefruit juice. The list below contains some of the drugs that interact with
grapefruit juice. This is not a complete list, so if you're a grapefruit fan,
check with your doctor before starting any medication.
* Valium (diazepam): This drug is used to treat certain seizure
disorders and anxiety.
* Norvasc (amlodipine): This is one of the drugs called a "calcium
channel blocker." It is used to treat angina (chest pain related to
malfunctioning arteries around the heart). Grapefruit juice interacts with many
of the calcium channel blockers
* Pravachol (pravastatin): Like several of the "statin" drugs
used to lower cholesterol, grapefruit juice can change the effectiveness of
this product
* Cordarone (Amiodarone): This drug is used to treat
"arrhythmias" - to correct irregular heart beat patterns.
What Are The Symptoms of These Interactions?
Use of any of these drugs while taking grapefruit juice can lead to
serious complications. For example, the following have been observed in the
interaction of each of the drugs above with grapefruit juice:
* Valium (diazepam): Grapefruit juice can cause you to feel sedated and
might make it harder for you to control your muscular movements; driving can be
dangerous
* Norvasc (amlodipine): Grapefruit interacts with several of the calcium
channel blockers to provide a very fast heartrate ("tachycardia")
and/or a drop in blood pressure to below safe levels ("hypotension."
* Pravachol (pravastatin): The statin drugs can interact with grapefruit
juice to cause muscle toxicities, symptoms of which include muscle weakness,
aches and shaking
* Cordarone (Amiodarone): Ironically, mixing this drug with grapefruit
juice can cause an increase in the very condition it is intended to treat -
arrhythmias
What Causes These Potentially Dangerous Interactions?
How can something as seemingly
harmless as grapefruit juice affect the medications you take? It has to do with
a special enzyme in your intestines and liver that help you absorb many oral
drugs and then excrete them when you're done with the drug. When a physician
prescribes a specific dose of drug (for example, one pill of 50 mg), she works
on the assumption that given the size of your body, you will absorb the drug
into your body at a certain rate and excrete it at a certain rate. Enzymes in
your gastrointestinal (or GI) tract bring food and oral medications into your
body. Grapefruit juice seems to affect both the rate of the drug coming into
your body and how quickly it is removed. The end result can be an overdose of
the drug) even if you're taking the correct dosage for your size.
What Can I Do To Avoid Dangerous Drug Interactions?
If you are on medications that interact with grapefruit juices, avoid
eating grapefruit or drinking grapefruit juice. Spacing out the drugs and the
juice (for example, taking your medication at night and having grapefruit for
breakfast) will NOT solve the problem; the grapefruit juice effect remains even
after you've stopped having it. If you like the health benefits of grapefruit,
or just miss that morning zing, think about moving to other fruits such as
tomatoes (a single can has just 41 calories and more than 70% of the vitamin C
for the day) or oranges.
Kharasch, E. "Influence of hepatic and intestinal cytochrome P4503A
activity on the acute disposition and effects of oral transmucosal fentanyl
citrate," Anesthesiology, Volume 101, issue 3, pages 729-737, 2004
Maskalyk, J., "Grapefruit juice: potential drug interactions,"
Canadian Medical Association Journal, Volume 167 issue 3, p 279-80, 2002
Shapiro, L, "Drug interactions: Proteins, pumps, and P-450s,"
Journal of the American Academy of Dermatology, Volume 47, issue 4, pages
467-84, 2002
Copyright (C) Shoppe.MD and Ian Mason, 2004-2005
Ian Mason, owner of Shoppe.MD, your source for Online Prescription Medications,
drug information and support forums. Ian is a fat-to-fit student of health,
weight loss, exercise, and several martial arts; maintaining several websites
in an effort to help provide up-to-date and helpful information for other who
share his interests in health of body and mind.
Article Source: http://EzineArticles.com/?expert=Ian_Mason
Article Source: http://EzineArticles.com/18991
http://www.mayoclinic.com/health/food-and-nutrition/AN00413
Question
Grapefruit juice: Beware of dangerous medication
interactions
I like to drink grapefruit juice but hear that it can
interfere with some of my prescription medications. Is that true?
Answer from Katherine Zeratsky, R.D., L.D.
Yes, grapefruit
juice, other grapefruit products and certain other citrus fruits can interfere
with several kinds of prescription medications. Don't take these interactions
lightly, as some can cause potentially dangerous health problems. Check with
your doctor or pharmacist before consuming any grapefruit products or citrus
fruits if you take prescription medications. You may need to eliminate
grapefruit products from your diet. Simply taking your medication and
grapefruit product at different times doesn't stop the interaction. Certain
chemicals that grapefruit products and citrus fruits contain can interfere with
the enzymes that break down (metabolize) various medications in your digestive
system. As a result, more medication stays in your body. This can increase the
potency of your medication to potentially dangerous levels, causing serious
side effects.
Pomelos and
Seville oranges, a type of bitter orange often used to make marmalades and
compotes, may have a similar effect. Researchers are identifying other foods
that also may interact with medications, so check with your doctor or
pharmacist if you have any concerns. Here are a few examples of prescription
medications that can have serious interactions with grapefruit products. This
is not a complete list of grapefruit-medication interactions, so check with
your doctor or pharmacist to see if your medication is affected.
|
Examples of
grapefruit-medication interactions
|
|
|
Type of
medication
|
Medication name
|
|
Anti-anxiety
|
Buspirone
|
|
Anti-arrhythmia
|
Amiodarone
(Cordarone)
|
|
Antidepressant
|
Sertraline
(Zoloft)
|
|
Antihistamine
|
Fexofenadine
(Allegra)
|
|
Anti-retroviral
|
Saquinavir
(Invirase), indinavir (Crixivan)
|
|
Anti-seizure
|
Carbamazepine
(Carbatrol, Tegretol)
|
|
Calcium channel
blocker
|
Nifedipine
(Procardia), nimodipine (Nimotop), nisoldipine (Sular)
|
|
Immunosuppressant
|
Cyclosporine
(Neoral, Sandimmune), tacrolimus (Prograf), sirolimus (Rapamune)
|
|
Statin
|
Simvastatin
(Zocor), lovastatin (Mevacor), atorvastatin (Lipitor)
|
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