Grapefruit and Medicine Interaction

Grapefruit and Medicine Interaction

Many chemical formulations have changed in recent years that affected how prescription drugs interact with grapefruit. The lack of awareness among some doctors regarding this drugs-grapefruit interaction resulted in the increased incidence of life-threatening cases.

More drugs are available now in the market that can cause adverse and serious life-threatening cases when combined with grapefruit. Since 2008, there were 43 drugs identified that can cause severe side effects.
Health care professionals need to be up-to-date with information regarding the drugs and their potential harmful interaction with grapefruit, so that they can prescribe drugs that are safe for patients to use.

Serious Health Threat When Combining Grapefruit With Some Drugs

There were reports of sudden death of patients and serious illnesses like respiratory failure, kidney failure and gastrointestinal bleeding as a result of the intake of even little amounts of grapefruit or its juice which reacted with the prescribed medication. Some drugs intended for treating high cholesterol, high blood pressure, cancer and some antibiotics like erythromycin have been identified as culprits in such cases.

It’s not just grapefruit that the drugs interact with. Citrus fruits that have the active ingredient furanocoumarin, including Seville oranges and limes, have been found to react with the drugs and cause dangerous reactions. It seems that grapefruit interferes with the function of an enzyme in deactivating the potency of the medication by half.

When a person takes the medication orally, it is not metabolized very well. Most of the drug component simply passes through the stomach and does not enter the bloodstream.

But when eating grapefruit, even if just a small amount several hours before taking the medication, the percentage of the metabolized drug increases. In effect, it would seem that the person is taking many doses of the drug at once.

The toxicity can build up quickly with repeated intake of the drug. For example, a person is taking Zocor, a cholesterol-lowering drug, once a day for 3 days. When taken together with 7 ounces of grapefruit juice, there will be a 330 percent increase of the drug flowing in the person’s bloodstream.

List of drugs that adversely react with grapefruit

The following drugs have been reported to interact with grapefruit:

1. Drugs for lowering cholesterol levels – Zocor (simvastatin), Pravachol (pravastatin) and Lipitor (atorvastatin)
2. Drugs for lowering blood pressure – Nifediac and Afeditab (nifedipine)
3. Drugs for organ transplant rejection – Neoral and Sandimmune (cyclosporine)
4. Cardiovascular medications – Nexterone and Cordarone (amiodarone), apixaban and clopidogrel

The researchers identified those who are 45 years old and above as the most likely buyers of grapefruit. They are also the most likely users of the above-mentioned medications. They must be warned against the dangerous grapefruit-drug interaction.

In reality, there are no hard facts regarding the occurrence of the adverse effects being talked about on patients. A future study is warranted to find more information.
When doctors prescribe medications that can adversely interact with grapefruit, they should advise the patients to avoid eating grapefruit. Another option is to prescribe alternative drugs that do not interact with grapefruit or its juice.

Photo credit: By FDA graphic by Michael J. Ermarth (Grapefruit Juice and Medicine May Not Mix) [Public domain]

Categories: Health