December 10, 2012

Like Grapefruit? Watch for Drug Interactions

Ever had a jaw dropping moment? I did and now I know why I am not eating grapefruit or drinking grapefruit juice any longer. I did not realize this and was having some problems with a statin. My wife found something in her drug guide saying not to drink grapefruit juice if taking this drug. Now it is in WebMD (Medscape reprint), and I thank them for that. This topic was also a MedicalNews Today article in May 2006, and even then doctors were saying it was not news. I wish this would get more publicity, but the media does not think it is important enough or will generate enough interest. For anyone taking statins, this is important!

The article clearly states the problem with grapefruit, which contains furanocoumarins, (furanocoumarins are a class of organic chemical compounds produced by a variety of plants) is creating potentially fatal side effects in many drugs. The number of drugs being affected has in the last four years has risen from 17 drugs, and now stands at more than 85 drugs that may be affected by grapefruit. Seville oranges (often used in marmalade), limes, and pomelos also contain the active ingredients (furanocoumarins), but have not been as widely studied.

The list includes some statins that lower cholesterol (such as atorvastatin, lovastatin, and simvastatin), some antibiotics, cancer drugs, and heart drugs. Most at risk are older people who use more prescriptions and buy more grapefruit.” The gist of the situation is the grapefruit, which contains furanocoumarins, blocks an enzyme that normally breaks down certain medications in the body. When this happens, medication levels in the body can become toxic. This is not presently on the FDA's list of things to watch for, but should be.

Grapefruit interacts with drugs taken orally and one 7-ounce glass of grapefruit juice used once a day for three days can affect simvastatin and makes it a 330% concentration greater than taking simvastatin with water. It does not matter if the grapefruit is taken with simvastatin or hours before you take it. This may cause muscle damage called rhabdomyolysis, which can be life threatening. Rhabdomyolysis is an acute, fulminant, potentially fatal disease that destroys skeletal muscle and is often accompanied by the excretion of myoglobin in the urine.

In addition to statins, grapefruit may interact with some antibiotics, cancer drugs, heart drugs and hormonal drugs. Many can interact and have more of a potential deadly effect if taken in close proximity to drinking grapefruit juice. Therefore, if you are taking any of the above types of drugs, remember to talk with your physician or your pharmacist to know if you need to avoid eating grapefruit or drinking grapefruit juice. Remember that the other fruits mentioned above may also need to be avoided.

This is a reminder that not all of an entire drug class may interact with grapefruit products, so be sure for your health, that you talk to your physician to possibly substitute a related drug that will not interact with your favorite fruit. Never stop taking a prescription drug unless you have talked to your doctor first. He/she may feel it is better for you not to use grapefruit than switch you to a grapefruit-friendly drug.

Grapefruit is a great aid to most diets, but always double check with you doctor or pharmacist to avoid problems of grapefruit having a dangerous interaction with the drug you are taking. A good rule is “better safe than sorry.”

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