Herceptin and grapefruit

[Patty D]

Awhile back I read a posting (Can't remember from who) saying that if you are on Herceptin you should not have grapefuit or the juice. I asked my chemo nurses about it and they said they had not heard this. Can someone enlighten me as I love grapefruit and hate to give it up. Thanks for your insight. Patty D

[RhondaH]

I've read on some drugs and cancer drug trials that grapefruit can affect the effectiveness of the drug. I asked my chemo nurse about this and she said that yes this is true (my dental assistant also, said this was true and if you look at some drugs and or trials, it tells you not to eat grapefruit w/ it). I don't know if Herceptin is one, but I am willing to give it up while I'm on it as I was MAXIMUM effectiveness. Take care.

Rhonda Hoffman

[RhondaH]

breastcancer.org Info
Grapefruit juice and medication
[list]
Certain components in grapefruit decrease the level of a particular enzyme that helps clear medications from the body
This interaction causes unpredictable changes in the amount of medication that your body can absorb
Medicine that accumulates in the body may cause an increase in side effects
Do not eat grapefruit or drink the juice while on tamoxifen, since grapefruit can interfere with absorption[/list}

Rhonda Hoffman

[al from Canada]

Patti,

This is one of the new posts I am working on.....coming soon
Al

[Rozebud]

They asked about grapefruit on breastcancer.org and was told it was a no-no while on tamoxifen....Here is the quote:

Sharilyn: Would supplements to cleanse/remove toxins in the body interfere with the activity of the tamoxifen I take?

Lisa Goldberg: For sure there are certain nutrients like grapefruit products that interfere with the absorption of tamoxifen and therefore, they can't be taken in combination. There is also a long list of herbs that can interfere with tamoxifen as well: Black Cohosh, Dong Quai, Red Clover, Licorice Root, and Wild Yam. Grapefruit is not a plant estrogen, but it contains an enzyme that gets metabolized in the liver, which can interfere with most medications.


Full text:

http://www.breastcancer.org/cmty_trans_2005_10.html

[al from Canada]

Grapefruit interferes with the cytochrome P450 group min enzymes used in 90% of all drug, hormone, steriod, and fatty acid metabolisms. Grapefruit is a P450 ANTAGONIST which means it reduces certain P450 enzymes. One of these just happens to be TAXOL. Which means: if you eat grapefruit (or drink its juice), you inhibit emzyme responsible for the breakdown of taxol which means increased drug load,

"Another factor in drug dosage is interfering substances from food. Grapefruit juice contains a CYP3A4 inhibitor that causes about a 12 fold increase in some drug concentrations. And the effect lasts for several days. It is advisable to discourage your patients from drinking grapefruit juice while on medication metabolized by CYP3A4."


Here is a further list of grapfruit affected CYP3A4 Substrates:



Acetominophen (Tylenol)
Codeine (narcotic)
Cyclosporin A (an immunosuppresant),
Diazepam (Valium)
Erythromycin (antibiotic)
Lidocaine (anaesthetic),
Lovastatin (HMGCoA reductase inhibitor, a cholesterol lowering drug),
Taxol (cancer drug),
Warfarin (anticoagulant).
Sooooo, my question is...how many of your oncs told you not to drink Grapefruit juice when taking taxol?? It could cause a 12 fold rise in potency and duration!

The long list and article is here: http://drnelson.utmem.edu/P450lect.html (http://drnelson.utmem.edu/P450lect.html)

Note the section on "inducers", where an increase in P450 enzymes can cause pro-carcinogens be metabolized into carcinogens.

Like wise xeloda is a P450 2C9 inhibitor which may cause you to bleed to death if you take warfarin:
Anticoagulants: Patients receiving concomitant capecitabine and oral coumarin-derivative anticoagulant

therapy should have their anticoagulant response (INR or prothrombin time) monitored closely with

great frequency and the anticoagulant dose should be adjusted accordingly (see Boxed WARNING

and CLINICAL PHARMACOLOGY). Altered coagulation parameters and/or bleeding have been

reported in patients taking XELODA concomitantly with coumarin-derivative anticoagulants such as

warfarin and phenprocoumon. These events occurred within several days and up to several months after

initiating XELODA therapy and, in a few cases, within one month after stopping XELODA. These

events occurred in patients with and without liver metastases. In a drug interaction study with single dose

warfarin administration, there was a significant increase in the mean AUC of S-warfarin. The maximum

observed INR value increased by 91%. This interaction is probably due to an inhibition of cytochrome

P450 2C9 by capecitabine and/or its metabolites (see CLINICAL PHARMACOLOGY).

http://www.fda.gov/medwatch/SAFETY/2001/xeloda_changes.PDF (http://www.fda.gov/medwatch/SAFETY/2001/xeloda_changes.PDF)


Know what you are taking and why you are taking it.

Regards,
Al

(sorry about the fonts, it's a copy and paste problem)

[Becky]

My onco told me nothing (I am not a grapefruit fan but my husband is - so when I first got diagnosed and started a "beat your cancer with nutrition" diet, I would have a glass of grapefruit juice every now and then figuring everything has a little something different in it that could be beneficial). However, being a biochemist, I know the grapefruit/drug problem and didn't drink any once I started treatment (or now because of supplements and Arimidex). I don't bug my husband because he is not on any medications.

Taxol - I wonder what would happen since it is so toxic to begin with?

Thanks for letting me know that (about Taxol) so I can warn others.

Best regards

Becky

[RhondaH]

which was prompted by the increase in my liver enzymes (which incidentally are back to normal) and what may have caused this. I take 60 mg daily of phenobarbital (which I found to be an INDUCER) and then other articles regarding grapefruit (which being the diet freak that I am consisted of 1/2 grapefruit each day...no longer doing that while on Herceptin) and its absorption. I only did it the 1st week of chemo as the dose dense TEC (Taxotere, Epirubicin and Cytoxan) gave me BAD diahrea (sp) and the Breast Cancer diet I do only magnified it, but NOW I'm back on it full force.

Rhonda Hoffman

[al from Canada]

an easy way to do this is list the drugs you are taking, go to the article http://drnelson.utmem.edu/P450lect.html find out the P450 metabolic pathway and stay away from both antagonists and inducers of that pathway as the first will increase serum levels of the drug and the second will decrease serum levels, ie the difference between grapfruit juice and phenobarbitol.
Al

[evebarry]

I read that grapefruit juice is a good liver cleanser. Herceptin is not like the other drugs mentioned here so I'm not sure if it's to avoided. I am a little confused. Does grapefruit juice cause the drugs you take to be more potent or less effective?
And, is grapefruit juice from a grocery store the same as eating a fresh grapefruit?

[Becky]

Grapefruit causes drugs to not be broken down as quickly therefore, you have a higher dose in your body for a longer period of time. Drugs are formulated to have an effective dose so manufacturers figure what that is so the dose would be too high.

Herceptin is different but could be affected.

[hutchibk]

I don't eat or drink anything grapefruit. My oncs, docs, nurses, etc and even clin trial coordinator asked me not to starting about 8 years ago. I would probably end up on many different kinds of drugs (on and off over the years) and grapefruit may or may not affect some of them, so it was smarter to have me stop grapefruit all together. I liked it, but I look at it like 'those days are over'.

And also, I don't use Splenda either. It's sugar or stevia only. My reasoning on Splenda stems from this... "a new report from scientists at Duke University... "This report makes it clear that the artificial sweetener Splenda and its key component sucralose pose a threat to the people who consume the product. Consumers have complained about side effects from using Splenda in this study, published in the Journal of Toxicology and Environmental Health Part A.

Among the results in the study by Drs. Mohamed B. Abou-Donia, Eman M. El-Masry, Ali A. Abdel-Rahman, Roger E. McLendon and Susan S. Schiffman is evidence that, in the animals studied, Splenda reduces the amount of good bacteria in the intestines by 50%, increases the pH level in the intestines, contributes to increases in body weight and affects the P-glycoprotein (P-gp) in the body in such a way that crucial health-related drugs could be rejected. It has been noted that the P-gp effect "could result in crucial medications used in chemotherapy for cancer patients, AIDS treatment and drugs for heart conditions being shunted back into the intestines rather than being absorbed by the body as intended."

[evebarry]

I agree about splenda. I stay away from all artificial sugars. I love raw honey and maple surup.
I've read yesterday several studies that grapefruit juice prevents cancer recurrence. I'm not taking tamoxifen or did I do chemo...only Herceptin so from what I read there aren't studies done on it to say grapefruit juice will interfer with Herceptin treatments. If so, let me know the studies that show it interfers with Herceptin. thanks

[hutchibk]

That's great Evebarry! Just be sure you aren't taking other meds besides cancer meds... grapefruit is thought to interfere with lots of things. Just talk to your onc... be sure they know.

[Mtngrl]

I was told to avoid grapefruit while I was on Taxol, and again now that I'm on Tykerb/Lapatinib. I think I'll just avoid it from now on.

[Jackie07]

Maybe somebody can find the English translation of the article below. Perhaps we might be able to enjoy the food we like by eating/drinking it many hours apart from the time we take the drug in question?

Praxis (Bern 1994). (http://www.ncbi.nlm.nih.gov/pubmed/22715076#) 2012 Jun 20;101(13):849-55.
[Clinically important food-drug interactions: what the practitioner needs to know].

[Article in German]
Corti N (http://www.ncbi.nlm.nih.gov/pubmed?term=Corti%20N%5BAuthor%5D&cauthor=true&cauthor_uid=22715076), Taegtmeyer AB (http://www.ncbi.nlm.nih.gov/pubmed?term=Taegtmeyer%20AB%5BAuthor%5D&cauthor=true&cauthor_uid=22715076).
Source

Klinik für Klinische Pharmakologie, Universitätsspital Zürich.

Abstract

Most medicines are taken with breakfast which is usually unproblematic and has the advantage of improving adherence through establishment of a daily routine. However, due to alterations in absorption from the gastrointestinal tract, there are a number of medicines that either lose (such as bisphosphonates) or gain (such as albendazole) efficacy if taken together with food.

Food components can also affect drug-metabolising enzymes and even cause drug toxicity (alcohol and grapefruit juice are notable examples). Conversely, drugs such as monoamine oxidase inhibitors can inhibit the metabolism of tyramine in tyramine-rich foods and lead to adverse circulatory reactions.

These and other examples of when the ingestion of medication together with food can cause clinically relevant problems are discussed in this article.

[Ceesun]

I have been on tykerb now with herceptin since 2008--my onc says no grapefruit especially with the tykerb. Ceesun

[Jackie07]

More drugs added to the 'no grapefruit' list:

http://www.webmd.com/news/20121127/grapefruit-some-medications-risky?ecd=soc_fb_112812-am_news_grapefruitmedicationrisk

Ask your doctor about your medication:

http://www.voanews.com/content/report-indicates-more-drugs-found-to-interact-adversely-with-grapefruit/1555996.html