By Robin Varela, RN, BSN, contributor
When you talk with patients about their diet, and specifically
when you talk with patients about making healthy diet choices, you may include
grapefruit and grapefruit juices as healthy options. It is high in vitamin C,
relatively low in calories, has no fat and very low sodium. But did you know
that grapefruit and grapefruit juice can potentially cause serious drug-food
interactions with some of the most commonly given drugs?
In very simple terms, as the grapefruit is broken down, it
binds to enzymes that are part of the Cytochrome P450 system (CYP 450). CYP 450
is responsible for the breakdown and metabolism of many drugs. Since the enzymes
that are bound to the grapefruit are not available to metabolize the drugs, a
potentially toxic amount of the drug can accumulate.
Unfortunately, it can take up to 48 to 72 hours for the
grapefruit interaction with the CYP 450 system to dissipate, so giving the drug
at a different time of day is not an option.
Common drugs that interact with grapefruit juice are:
- Statins: Lipitor (atorvastatin), Mevacor (lovastatin),
Zocor (simvastatin)
- Antiarrhythmics: Cordorone (amiodorone), Quinaglute and
Quinidex (quinidine)
- Immunosuppressants and corticosteroids: Sandimmune
(cyclosporine) and Entocort (budesonide)
- Non-nuceloside analogues (NNTI): Crixivan (indinavir)
- Antihistamines: Seldane (terfenadine)
- Viagra
This is only a partial list of drugs that may interact. Keep
in mind that drugs metabolized in the stomach and liver are more likely to have
this interaction. Teach patients on these drugs to avoid grapefruit in their
diet. If they cannot, they should discuss the issue with their physician and
find alternative medications.
Bottom line: Encourage a healthy diet in your patients; don’t
exclude grapefruit juice, but be aware of and teach your patients about possible
food-drug interactions.
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