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Grapefruit drug interactions - A Healthy Breakfast May Have Dangerous Consequences - drugdiscovery.com

Grapefruit drug interactions - A Healthy Breakfast May Have Dangerous Consequences - drugdiscovery.com
Grapefruit or its juice is a popular choice for breakfast or a refreshing snack. While the fruit has many health benefits, it is also true that when combined with some commonly used medicines it can produce dangerous drug interactions.

This fruit that was originally created by crossing the orange and the pomelo is a powerhouse of healthy compounds. It is packed with vitamin C and vitamin A and minerals such as potassium and calcium. The antioxidant effects of vitamins C and A, as well as lycopene and beta-carotene, help combat the free radicals that may promote the formation of cancer. There is evidence that citrus may lower the risk of ischemic stroke in women, and lower the triglyceride levels in the blood of people subject to atherosclerosis.

A serving of this pulpy yellow fruit has another benefit that is a bit less complicated: it provides fiber and water. Fiber is important to keep the products of digestion moving through the intestine, and water helps to keep the body hydrated. People often may not be aware that they are dehydrated unless the condition becomes severe, but even subtle dehydration can have negative effects on the body. Fatigue, headaches, constipation and skin that has lost its freshness are all signs of a need for liquids; at a water content of over 90 percent, this fruit is an excellent source of those liquids.

Despite all the positive qualities of the fruit, it can also have negative, even fatal effects if combined with certain drugs. These effects are due to the way in which a component of the fruit interacts with an enzyme in the small intestine.

There is an enzyme in the body called cytochrome P450. One particular form of this enzyme is called CYP3A4, and that is the one of interest in this discussion. Many drugs that are taken orally are metabolized, or broken down, by CYP3A4 when they pass through the small intestine. Any amount of the drug that is not broken down at this point can pass from the intestine into the blood stream, where it has its desired effect. Unfortunately, compounds in grapefruit called furanocoumarins interact with CYP3A4 and may have a profound effect on the way that enzyme works.

Specifically, furanocoumarins inhibit the action of CYP3A4. This means that the enzyme breaks down less of the drug, or breaks it down more slowly, leaving more of the drug to enter the bloodstream. The effect on the body is as if a much higher dose of the medicine has been taken. This is particularly dangerous when there is a very small difference between the amount of the drug that is medically necessary and the amount that is toxic. Taking the prescribed dose with the fruit in this case could be fatal, and they do not have to be taken at the same time. The danger zone ranges from four hours before the drug is taken to 72 hours after. Because different people have different amounts of CYP3A4 in their bodies, and different samples of fruit have varying concentrations of furanocoumarins, there are no concrete guidelines about how pronounced the interaction between them may be.

It is not possible to give a full list here of all the 85 drugs that are subject to interactions with furanocoumarins, but a partial list includes such popular cholesterol-lowering drugs as Zocor and Lipitor. Medicines taken to reduce heart arrhythmia, such as Cordarone, and anti-anxiety drugs like BuSpar are of concern, as well as drugs like Nifediac to lower blood pressure, and some drugs taken by organ transplant recipients to combat rejection. Even Allegra, a common antihistamine, is on the list. Forty-three of the 85 drugs can produce a fatal outcome. Life-threatening circumstances can result from dropping blood pressure, disruptions in normal heart rhythm, depressed respiration and muscle breakdown leading to kidney failure.

One example of the dangerous drug and food interaction was reported in the journal “Neurology.” A middle-aged woman who had been taking simvastatin (Zocor) to manage her cholesterol arrived at the hospital complaining of weakness in her legs. Tests showed the presence of the muscle breakdown that can result from too-high levels of the statin. With immediate treatment and discontinuation of the drug, the woman made a full recovery. Upon being questioned by her doctors, she revealed that in the two weeks before she came to the hospital she had eaten one grapefruit per day.

In summary, the combination of a favorite breakfast fruit and a doctor-prescribed medicine has the potential for risky or even fatal drug interactions. When beginning a new drug regimen, always remember to discuss with the doctor any possible combinations of the drug and other substances in your diet that could prove dangerous.

By Eszter Hazai, PhD Google+

Tags: grapefruit, drug interactions - September 24, 2014

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