Grapefruit contains vitamin C and potassium, which helps the body work properly and can be part of a healthy diet. But when you have high blood pressure or arrhythmia, it can affect how your medication works.
Dr. Shiew Mei Huang of the US Food and Drug Administration said the FDA has asked for some prescription and over-the-counter drugs to be warned against eating with grapefruit.
The problems that grapefruit juice causes drug metabolism include:
Statins cholesterol-lowering drugs such as simvastatin and Lipitor.
Treatment of high blood pressure drugs, such as nifedipine equality.
A drug for rejection of an organ transplant, such as Mycoxins (Cyclosporine).
Anxiolytic drugs such as buspirone.
A glucocorticoid that treats Crohn’s disease or ulcerative colitis, such as budesonide.
A drug that treats abnormal heart rhythms, such as amiodarone.
Antihistamines, such as Ai Lai (fexofenadine).
Grapefruit juice does not necessarily affect all of the drugs in each of these categories, and the severity of this effect may vary, depending on the individual’s constitution, the amount of drug and the amount of grapefruit juice you drink.
Most drugs that interact with grapefruit juice will cause “juice to get more drugs into the bloodstream,” Shiew Mei Huang said. “When there is an excess of blood in your blood, you may have more side effects.”
For example, if you drink a lot of grapefruit juice while taking certain cholesterol-lowering statins, excess medication may stay in the body, increasing your risk of liver and muscle damage, leading to kidney failure.
Many drugs are broken down (metabolized) and are associated with an important enzyme in the small intestine, CYP3A4. Grapefruit juice blocks the action of CYP3A4, allowing more drugs to enter the bloodstream and stay in the body for longer periods of time. The result is that there are too many drugs in your body.
The amount of CYP3A4 enzyme in the intestine varies from person to person. Some people have a lot of enzymes, some have only one point. So even with the same medication, grapefruit juice may have different effects on people.
Although scientists have known for decades that grapefruit juice can cause some drug metabolism to slow down in the body, Shiew Mei Huang said recent research has found that grapefruit juice has the opposite effect on other drugs. “The grapefruit juice will reduce the amount of fexofenadine into the blood,” Shiew Mei Huang said. Fexofenadine can be used to relieve seasonal allergies and can not be taken with orange juice or apple juice, so the drug label says “Do not eat with juice.”
Why is there some effect on some drugs? Grapefruit juice affects the body’s drugs by changing the protein that helps the drug enter the cell, rather than changing the metabolism. As a result, the amount of drug entering the blood is less and the drug does not work.
How grapefruit juice affects certain drugs
When the drugs are swallowed, they may be broken down (metabolized) by the enzyme or absorbed by transport in the small intestine cells. Grapefruit juice causes changes in these enzymes and transporters, resulting in too much or too little drug in the body.
Some drugs, such as statins used to lower cholesterol, are degraded by enzymes. Grapefruit juice can block the action of these enzymes, thereby increasing the amount of drugs in the body and possibly producing more side effects.
Other drugs, such as fexofenadine, are transported into cells. Grapefruit juice can block the role of transporters, reduce the amount of drugs in the body, and may lead to drug failure.
Please communicate with your doctor or pharmacist before using the medication to read the information provided by your prescription or OTC medication to determine if the medication is used with grapefruit juice:
Whether your efficacy may be affected.
If so, how much grapefruit juice is used.
Whether there are other fruits or juices will also have an effect similar to grapefruit juice.