List of drugs affected by grapefruit
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This page has a list of drugs that are known to be affected by grapefruit. These interactions are generally caused by the fruit's naringin, bergamottin, and dihydroxybergamottin interfering with the enzyme cytochrome P450 isoform CYP3A4 in the intestine. However, bioactive compounds in grapefuit juice may also interfere with p-glycoprotein and organic anion transporting polypeptides (OATPs) either increasing or decreasing bioavailability of a number of drugs.
The list is ordered by its most common chemical name, followed by alternate chemical names and various trade names.
Caution: This is an incomplete list and should not be used to verify whether a drug is safe.
Contents |
[edit] Interacting
The following drugs definitely interact with CYP3A4:
- Bupropion, amfebutamone, Wellbutrin - rxlist.com
- Paroxetine, paroxetine hydrochloride, Paxil, Seroxat, Aropax, Pondera, Deroxat, Cebrilin - mentalhealth.com
- Valproate semisodium, divalproex sodium, Depakote, Epival - stanford.edu
- Benzodiazepines, including: alprazolam (Xanax), diazepam (Valium), midazolam (Versed), lorazepam (Ativan), oxazepam, and chlordiazepoxide (Librium). [1]
Additional drugs found to be affected by grapefruit juice include, but are not limited to:
- Statins such as atorvastatin, lovastatin, and simvastatin [2]
- Dihydropyridines including felodipine (Plendil), nicardipine (Cardene), difedipine, nisoldipine (Sular), nitrendipine (Bayotensin) [3]
- losartan (Cozaar) [4]
- repaglinide (Prandin) [5]
- verapamil (Calan SR, Covera HS, Isoptin SR, Verelan) [6]
- Antiarrhythmics including amiodarone (Cordarone), quinidine (Quinidex, Cardioquin, Quinora), disopyramine (Norpace), propafenone (Rhythmol), and carvediol [7]
- The male impotence drugs sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra) [8] [9]
- The anti-migraine drugs ergotamine (Cafergot, Ergomar) and nimodipine (Nimotop) [10]
[edit] Pharmacological effects
Grapefruit juice has been found to interact with many drugs taken orally. Compounds in the juice including bergamottin, dihydroxybergamottin, and some flavonoids such as naringin affect the activity of certain intestinal enzymes including CYP3A4 and CYP1A2.
These cytochrome P450 enzymes, which metabolize many drugs, are inhibited by grapefruit juice. As a result, serum drug concentrations increase, and may become toxic. This is particularly dangerous when the drug in question has a low therapeutic index, so that a small increase in blood concentration can be the difference between therapeutic success and toxicity. Grapefruit juice only inhibits the enzyme within the intestines, not elsewhere (the liver, for instance). Therefore, it does not affect injected drugs. The degree of the effect varies widely between individuals and between samples of juice, therefore it cannot be accounted for a priori.
Recently some researchers have shown that furanocoumarins, rather than flavonoids, may be the ingredients causing the various drug interactions. http://www.hon.ch/News/HSN/532584.html [1]
Drugs that may be affected include midazolam, cyclosporin, lovastatin, simvastatin, pravastatin, felodipine, sildenafil (Viagra) and caffeine, as well as a number of antihistamines including astemizole and terfenadine. [2]
An easy way to tell if a medication may be affected by grapefruit juice is by researching whether another known CYP3A4 inhibitor drug is already contraindicated with the drug in question. Examples of such known CYP3A4 inhibitors include cisapride (Propulsid), erythromycin, itraconazole (Sporanox), ketoconazole (Nizoral), and mibefradil (Posicor).
The flavonoid existing in highest concentration in grapefruit juice is naringin, which in humans is metabolized to naringenin. Other flavonoids exist in grapefruit juice in lower concentrations as well. Orange juice does not contain naringin in as high a concentration, instead containing hesperetin. It is sometimes recommended as a substitute. Juice of limes and Seville oranges can also inhibit drug metabolism, however, as can apple juice with some drugs. [1]
| Drug class | Major Interactions | Minor interactions |
|---|---|---|
| Calcium channel antagonists | Plendil Cardene (Nicardipine) Procardia (Nefedipine) Nimotop Sular DynaCirc |
|
| Statins (HMG-CoA reductatase inhibitors) | Mevacor (Lovastatin) | Lipitor Baycol |
| Immunosuppressants | Sandimmune (Cyclosporine) Prograf Rapamune |
|
| Sedatives, hypnotics, and anxiolytics | Buspar | Halcion Versed Valium (Diazepam) Sonata (Zaleplon) |
| Other psychotropics | Tegretol (Carbamazepine) Desyrel Serzone Seroquel |
|
| Antihistamines | Seldane Hismanal |
Claritin (Loratadine) |
| HIV protease inhibitors | Invirase Norvir Viracept Agenerase |
|
| Hormones | Ortho-Cept (Ethinyl estradiol) Depo-Medrol (Methylprednisolone) |
|
| Other drugs | Cordarone | Viagra Propulsid |
[edit] Alternatives
Orange juice does not contain naringin in as high a concentration, instead containing hesperetin, and may be recommended as a substitute.
[edit] See also
[edit] References
- ^ a b c Bakalar, Nicholas. "Experts Reveal the Secret Powers of Grapefruit Juice", The New York Times, 2006-03-21, p. F6. Retrieved on 2006-11-21. (in English)
- ^ http://abello.dic.uchile.cl/~hechavez/articulos/grapefru.htm.
[edit] External links
- USDA Database of Flavonoid content of food
- Arayne M, Sultana N, Bibi Z (2005). "Grape fruit juice-drug interactions.". Pak J Pharm Sci 18 (4): 45-57. PMID 16380358.
