Tuesday, June 29, 2010

A little grapefruit juice to wash down that medicine? You might want to think twice.

I love eating grapefruit and drinking grapefruit juice. That's why it's so annoying when I'm taking a new medication and I find out that grapefruit is temporarily off the menu. That's because grapefruit doesn't always "play well" with some medicines. Of course, doctors and pharmacists don't always remember to tell you about grapefruit/drug interactions in advance... and who actually reads ALL of the small type on the drug inserts or handouts anyway?

So what can happen if you mix grapefruit juice or slices with some medications? Well, that depends on the drug. In some cases, it can make your doses stronger than they should be; in other cases, it could make your medicine worthless by canceling out the drug's action in your body.

That's why I was thrilled to find an online resource that lists grapefruit-drug interactions. Your best option, of course, is always to ask your doctor or pharmacist if grapefruit interacts with your medicine. Find out if you'll need to avoid grapefruit juice and slices within a certain time frame of taking your medicine, or if you'll have to stay away from them altogether. If you forget to ask your doctor or pharmacist, though, another good option is to keep this list handy.

The following information is posted with the permission of Dr. Dean Elbe of Food-Medication Interactions. This information is from 2007; an updated listing will be available soon.

1 - Manufacturer recommends avoidance.
2 - Use with grapefruit/related citrus only on advice of a physician.
3 - Serum/Plasma level monitoring required/recommended.
4 - Minor interaction, not clinically significant.
5 - Interaction suspected, but no formal studies.
6 - No formal studies, but lacks a cardiotoxic metabolite.
7 - Not metabolized by 3A4, no interaction suspected.
8 - No interaction when drug administered parenterally [by injection, IV, or means other than eating/ingesting]
9 - Withdrawn from market.
10 - Blood levels/bioavailability decreased.
11 – Risk higher in CYP 2D6 poor metabolizers.

Medications that should be avoided with grapefruit:
amiodarone (Cordarone) 8
astemizole (Hismanal) 5, 9
atorvastatin (Lipitor)
budesonide (Entocort) 8
buspirone (BuSpar)
cerivastatin (Baycol) 5, 9
cilostazol (Pletal) 5
cisapride (Propulsid, Prepulsid) 9
colchicine 5
eletriptan (Relpax) 5
etoposide (Vepesid) 8, 10
halofantrine (Halfan)
lovastatin (Mevacor)
mifepristone (Mifeprex) 5
pimozide (Orap) 5
quinidine (Quinaglute, Quinidex) 8, 10
sildenafil (Viagra)
simvastatin (Zocor) 8
sirolimus (Rapamune) 1, 5
terfenadine (Seldane) 9
ziprasidone (Geodon) 5

Use with grapefruit with caution:
albendazole (Albenza)
alfentanil (Alfenta) 8
alfuzosin (Uroxatral) 5
almotriptan (Axert) 5
aprepitant (Emend) 5
aripiprazole (Abilify) 5
bupropion (Wellbutrin, Zyban) 5
carbamazepine (Tegretol) 3
cinacalcet (Sensipar) 5
clomipramine (Anafranil)
cyclosporine (Neoral) 2, 3, 8
darifenacin (Enablex) 5
delavirdine (Rescriptor) 5
diazepam (Valium) 8
dofetilide (Tikosyn) 5
efavirenz (Sustiva) 5
erlotinib (Tarceva) 5
erythromycin (Eryc, E-mycin, Erythromid, Erybid) 8
eszopiclone (Lunesta) 5
felodipine (Renedil, Plendil)
fexofenadine (Allegra) 10
fluvoxamine (Luvox)
gefitinib (Iressa) 5
imatinib mesylate (Gleevec/Glivec) 5
indinavir (Crixivan) 10
itraconazole (Sporanox) 10
losartan (Cozaar)
methadone (Dolophine) 5
methylprednisolone (Medrol) 8
midazolam (Versed) 8
montelukast (Singulair) 5
nicardipine (Cardene) 8
nifedipine (Procardia)
nimodipine (Nimotop)
nisoldipine (Sular)
oxybutynin (Ditropan) 5
propafenone (Rythmol) 5, 11
quetiapine fumarate (Seroquel) 5
ramelteon (Rozerem) 5
saquinavir (Invirase) 2
sertraline (Zoloft)
solifenacin (Vesicare) 5
tacrolimus (Prograf) 2, 3, 8
tamoxifen (Nolvadex) 5
tamsulosin (Flomax) 5
tolterodine (Detrol) 5
triazolam (Halcion)
trazodone (Desyrel) 5

Medications with no significant interaction with grapefruit
Drugs in this section have all been studied with grapefruit,
and found to have either a minimal/negligible interaction:

acebutolol (Monitan, Sectral) 4
alprazolam (Xanax) 4
amlodipine (Norvasc) 4
amprenavir (Agenerase) 4, 10
caffeine 4, 8
carvedilol (Coreg) 4
clarithromycin (Biaxin)
clozapine (Clozaril) 4
digoxin (Lanoxin) 8
diltiazem (Cardizem) 4, 8
eplerenone (Inspra) 4
ethinyl estradiol 4, 8
fentanyl (Actiq) 4, 8
haloperidol (Haldol) 8
lansoprazole (Prevacid) 4, 8
levothyroxine (Eltroxin, Synthroid) 4, 8
omeprazole (Losec, Prilosec) 4
phenytoin (Dilantin) 8
pravastatin (Pravachol)
prednisone (Deltasone)
scopolamine (Hyoscine) 4, 8
17-β estradiol 4, 8
telithromycin (Ketek) 4
theophylline (Theo-Dur, Uniphyl)
verapamil (Calan, Isoptin, Verelan) 8
warfarin (Coumadin) 8

Medications considered safe for use with grapefruit:
cetirizine (Zyrtec, Reactine) 6
desloratadine (Aerius, Clarinex) 7
fluvastatin (Lescol) 7
loratadine (Claritin) 6
praziquantel (Biltricide)
rosuvastatin (Crestor) 7


  1. What a great resource! Thank you. I love grapefruit, but it does not like me. I have only anecdotal evidence, but it appears to exacerbate/contribute to mouth ulcers. I find if I avoid citrus except for as a rare 'treat' it reduces the ulcer outbreaks. Anyone else?

  2. Thanks! Joanne
    I'm printing this off as well as saving on my computer.

    Jeanne' in TX

  3. In the AERIUS product monograph there is no interaction between grape fruit juice and AERIUS. Therefore there are no contradictions of using both together.

    Please consult the article below for more information on the product.
    BACKGROUND: Certain foods, such as grapefruit juice, are known to substantially alter the bioavailability of some drugs. These effects may be mediated by interactions with enzyme systems, such as cytochrome P450, or with active transporter systems, such as P-glycoprotein and organic anion transporting polypeptides. OBJECTIVE: To assess the effect of consumption of grapefruit juice on the oral bioavailability of two nonsedating antihistamines, fexofenadine and desloratadine. DESIGN: Non-blinded, randomised, single-dose, four-way crossover study. PARTICIPANTS: Twenty-four healthy adult volunteers. INTERVENTIONS: Single oral doses of desloratadine 5mg and fexofenadine 60mg taken without and with grapefruit juice (pretreatment with 240ml of double-strength juice three times daily for 2 days prior to administration of study drug, plus the same amount simultaneously with, and 2 hours after, the drug dose). Each treatment was separated by at least 10 days. MAIN OUTCOME MEASURES: Log-transformed pharmacokinetic parameters [peak plasma concentration (C(max)) and area under the curve (AUC)], time to maximum concentration, elimination half-life and electrocardiographic (ECG) parameters. RESULTS: Comparing the ratio of the pharmacokinetic parameter means (C(max) and AUC) with and without grapefruit juice (expressed as a percentage), the rate (C(max)) and extent (AUC) of absorption of fexofenadine were reduced by 30% by consumption of grapefruit juice. In contrast, the bioavailability of desloratadine was unaffected by grapefruit juice. No clinically significant changes in ECG parameters were observed following coadministration of grapefruit juice with desloratadine or fexofenadine compared with either antihistamine given alone. CONCLUSION: The bioavailability of drugs that do not undergo significant intestinal or hepatic metabolism, such as fexofenadine, may be altered when administered with agents that influence drug transport mechanisms.

    This information is intended to provide pertinent scientific data that will assist you in forming your own conclusions. It is not intended to recommend new usage of our products.

    The dosage, indications and directions for products referred to in these articles are not necessarily those appearing in the product monograph.

    The opinions expressed in the abstracts mentioned are those of the authors and not attributable to Schering-Plough Canada Inc.

    Please refer to the AERIUS Product Monograph for further information.

    We thank you for your interest in Merck Canada. If you have any further questions, please feel free to contact our Medical Services Department at 1-800-463-5442.

  4. Totally agree Frederique - that is exactly why its listed under "medications considered safe for use with grapefruit"... the abstract referenced in the Merck comment/post refers to fexofenadine (Allegra)... a completely different product.

    Dr Dean Elbe (author of the GJ interaction table)