List of Drugs Affected by Grapefruit

         Grapefruit and grapefruit juice have the potential to interact with numerous drugs. A number of organic compounds, identified as furanocoumarin derivatives, interfere with the hepatic and intestinal enzyme cytochrome P450 isoform CYP3A4 and are therefore primarily responsible for the interaction. However, bioactive compounds in grapefruit juice may also interfere with P-glycoprotein and organic anion transporting polypeptides (OATPs) either increasing or decreasing bio-availability of a number of drugs. Pomelo (the Asian fruit which was crossed with an orange to produce grapefruit) also contains high amounts of furanocoumarin derivatives.

Certain chemicals that grapefruit products and citrus fruits contain can interfere with the enzymes that break down (metabolize) various medications in your digestive system. As a result, more medication stays in your body. This can increase the potency of your medication to potentially dangerous levels, causing serious side effects.
Pomelos and Seville oranges, a type of bitter orange often used to make marmalades and compotes, may have a similar effect. Researchers are identifying other foods that also may interact with medications, so check with your doctor or pharmacist if you have any concerns.


In 1989 a pharmacological study evaluated the possibility of an interaction between ethanol ingestion and medication with the dihydropyridine calcium channel blocker - felodipine. Grapefruit juice was used as a flavouring additive during the test. The results of study showed several-fold increase of felodipine concentrations compared to results obtained in other investigations of the drug. Additionally, there were lower blood pressure readings and more adverse effects compared to the group of subjects on felodipine alone. Further investigations revealed that grapefruit juice strikingly elevated felodipine bioavailability and could influence its other pharmacokinetic and pharmacodynamic properties.

Drugs affected by grapefruit juice

Drug class	Major Interactions	Minor interactions
Calcium channel antagonists		Plendil Cardene (Nicardipine) Procardia (Nifedipine) Nimotop Sular DynaCirc
Antiarrhythmics	Cordarone Multaq
Statins (HMG-CoA reductase inhibitors)	Mevacor (Lovastatin)	Lipitor Baycol (off the market)
Immunosuppressants		Sandimmune (Cyclosporine) Prograf Rapamune Mercaptopurine
Dissociatives	Dextromethorphan
Sedatives, hypnotics, and anxiolytics	Buspar	Halcion Versed Valium (Diazepam) Sonata (Zaleplon) Alprazolam
Other psychotropics		Tegretol (Carbamazepine) Desyrel Serzone Seroquel Fluvoxamine
Antihistamines	Seldane (off the market) Diphenhydramine (partially) Hismanal (off the market)	Claritin (Loratadine)
HIV protease inhibitors		Invirase Norvir Viracept Agenerase
Hormones		Ortho-Cept (Ethinyl estradiol) Depo-Medrol (Methylprednisolone)
Other drugs		Viagra Propulsid

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