By John M. Weigand, M.D.

Director of Geriatric Services

Central Ohio Geriatrics

I was giving a talk over the holidays and asked audience members if they had any general medical questions. One intrepid questioner asked me about drug interactions with grapefruit juice. I thought it was a great question, especially since many people love grapefruit.

A number of medications are broken down or metabolized by enzymes that are present in the liver and gastrointestinal tract. Grapefruit juice has been shown to inhibit these enzymes and therefore increase the drug levels in patients who take these prescription medications. In some cases, grapefruit juice ingested within 24 hours of oral administration of these prescription medications can result in this interaction. Orange juice has not been shown to have this effect on medication metabolism. Not everyone has the same degree of effect of grapefruit juice on these medications, but you should be aware of the potential interaction. If you love grapefruit juice but you are on one or more of these medications listed below, talk to your doctor or pharmacist about alternative medications that may not have an interaction.

If you take any of the medications listed, it is recommended that you avoid consumption of grapefruit juice or talk to your physician about this interaction.

Name of Medication (Brand name)

Acetaminophen (Tylenol, Panadol, Tempra, Darvocet, Anexsia, Fioricet, Lorcet, Lortab, Percocet, Roxicet, Talacen, Tylox, Vicoden, Wygesic, Esgic, Midrin)

Alprazolam (Xanax)

Atorvastatin (Lipitor)

Azithromycin (Zithromax)

Buspirone (BuSpar)

Caffeine (NoDoz, Vivarin, Darvon Compound, Fioricet, Fiorinal, Norgesic, Esgic)*

Carbamazepine (Tegretol)

Cisapride (Propulsid)

Clarithromycin (Biaxin)

Clozapine (Clozaril)

Corticosteroids (Multiple brand names)

Cyclosporine (Sandimmune)

Diazapam (Valium)

Diltiazem (Cardiazem, Dilacor, Tiazac)

Erythromycin (Eryc, E-mycin, EES, Ilosone, PCE)

Estrogens (Multiple products)

Felodipine (Plendil)

Imipramine (Tofranil)

Isradipine (DynaCirc)

Ketoconazole (Nizoral)

Lidocaine (Xylocaine)

Loratidine (Claritin)

Lovastatin (Mevacor)

Miconazole (Monistat, Micatin)

Midazolam (Versed)

Nifedipine (Procardia, Adalat)

Nicardipine (Cardene)

Quinidine (Quinaglute, Quinalan, Quinidex, Quinora)

Simvastatin (Zocor)

Tacrine (Cognex)*

Tacrolimus (Prograf)

Terfenadine (Seldane)

Theophylline (Theo-dur, Slo-Phyllin, Elixophyllin, Slo-bid)*

Trazodone (Desyrel)

Verapamil (Isoptin, Calan, Verelan, Covera)

Warfarin (Coumadin)*

Zaleplon (Sonata)

*Weak interaction

COMPILED BY JOHN M. WEIGAND, M.D., Director of Geriatric Services; Central Ohio Geriatrics, Granville, Ohio

SOURCES: Pharmacist’s Letter (209) 472-2248

Turner RE and Rampersaud GC. Using Medications Safely: Interactions between Grapefruit Juice and Prescription Drugs. http://edis.ifas.ufl.edu

Photo by Hedwig Storch