[Bjork]

Hello!

I posted this in another forum, but figured I would post it here as well so that I could get as many answers as I could get! Anyway, here it is:

I am on so many medications that I can hardly remember them all (seriously... I'm on 11 meds for depression, anxiety, ocd, you name it). Somewhere along the line I was told that I was not allowed to have Grapefruit or Grapefruit juice anymore because it interferes with my medications. This makes me cry!

I was wondering... what if I ate the grapefruit in the middle of the day, several hours *after* I have taken my medications? Can I have my grapefruit then? *crosses fingers* I have lived for a few years without grapefruits and I just can't take it anymore!

Bjork

[debi]

hiya

i'm only on four psych meds right now -- and i thought that was a lot. ever feel like you're just walking around in a cloud b/c of all the drugs in your system? i do sometimes.

anyway, regarding grapefruit. i don't remember which drugs interact with it (i've been on meds for 15 years now, can't remember which of them did not mix well with grapefruit, though i know there was at least one). but i do think, unfortunately, that if you can't have grapefruit, then you can't have it at any time that you're taking the drug b/c the drug builds up a level in your system, and it's always there. i would definitely ask your doctor/pharmacist though, 'cause i certainly am not an expert!

[Monty_girl]

I'm not on a psych med, but a med for cholesterol and I'm not aloud to have grapefruit either. Something about the grapefruit is suppose to increase the level of my medication in my system. All I can say is talk to your Doc, see what they say before you take a bite. Monty

[nothemama8]

Definatly ask Dr. hubby can't have grapefruit juice, the only time he can have orange juice is 2 hours after he takes his meds

[Larry_Hoover]

Grapefruit inhibits one specific enzyme, one that is found both in the lining of the gut, and in the liver. It is a detoxifying enzyme, designed to protect us from toxins in foods, most likely. But, that enzyme also can act to metabolize drugs.

The effect of inhibiting this enzyme really depends on what drugs you're taking. If you are taking 11 drugs, then chances are that grapefruit is affecting how those drugs work (well, probably one or a few of them).

If you have always been eating grapefruit (or the juice) while taking these drugs, then you have titrated your dosing taking into account the effect of the grapefruit, if you follow.

So, if you've always been a daily consumer of grapefruit, you don't have to change a thing.

If you listed the drugs you take, I could tell you more specifically what your risks are.

Lar

[Bjork]

Nah I haven't had grapefruit in years and really *crave* it for some reason. It seems to be th wonder-fruit! Hmm... I'll ask anyone I can find if I can eat a grapefruit again without the unwanted sideaffects. Thanks!

Claudia

[Lauren1214]

I was researching this topic last week and I found out that there's no way around it. Grapefruit is basically forbidden with certain medications, and that's 24 hours a day! The reason, apparently, is that the interaction of a certain enzyme in the stomach and grapefruit lets too much of the medication into the bloodstream and causes poisoning of the liver and other internal organs. Which, of course, leads me to question whether it's possible to have half the medication dose consistently taken with a glass of grapefruit juice... Any physicians out there who can give feedback on the matter?

Lauren

[Larry_Hoover]

I'm a toxicologist. This is an area I understand very well.

You've asked the important question. Yes, it is possible to take less of some drugs, if you take them with grapefruit juice. In fact, if you naively used grapefruit juice during the period when you were increasing the dose of a new drug up to the comfortable and effective dose (the dose titration period), you may have taken advantage of that effect from the beginning.

A friend of mine was using the mood-stabilizer Tegretol (carbamazapine), which is metabolized by this particular enzyme, 3A4. He was also in the habit of drinking about sixteen ounces of grapefruit juice every morning. When he found out about the grapefruit/carbamazapine interaction, he was going to suddenly stop the grapefruit juice, but I talked him out of it. If he had done so, he would have had to increase his carbamazapine dose to compensate, and, there was no way of predicting how much more drug he would have to take. He'd have to do a completely new dose titration under these new conditions. As it was, he had titrated his dose with grapefruit juice inhibition already accounted for (it was a daily ritual), so all he had to do was keep doing what he had always done, to maintain the proper therapeutic dose.

Grapefruit is not automatically a no-no. It certainly must be taken into account. But it depends on a number of factors, and the individual circumstances.

Lar

[CamW]

Lauren - Ten or so years ago I did study of the cytochrome-P450 system for the psychiatrists I was working with at the time. I spent weeks in the stacks at the University poring over studies, including some of the early studies involving inhibition of drug metabolism by grapefruit. This was the pre-internet days, so I really wore out my photocopy card (Hey Larry, remember the Index Medicus?).

The problem with trying to adjust (ie. lower) your medication dose and compensating by eating grapefruit is that every grapefruit will vary (at least, slightly; at most, significantly) in the amounts of enzyme inhibitors each on contains, due to differences in the size of each grapefruit and the genetic differences amongst different grapefruit trees. Granted, these differences may be small (then again they may not; I haven't seen any studies comparing enzyme inhibitor differences between different grapefruit trees), and as Larry said, you could titrate the dose, but you'd more than likely have to eat grapefruit from one tree only. That would be tough to do if you buy your grapefruit from Safeway.

The constiuents of grapefruit responsible for the inhibition of the cytochrome P-450 isoenzymes (esp. CYP1A2 and CYP3A4) are certain bioflavinoids (esp. naringen, which is converted by gut bacteria to the potent inhibitor, naringenin) and certain furanocoumarins (esp. 6,7-dihydroxybergamottin). There are several other compounds in grapefruit that inhibit CYP isoenzymes to varying degrees.

To further complicate matters, there is something in grapefruit that activates P-glycoprotein which reverses the absorption of certain drugs by actively pumping the drugs back into the intestine after they have been absorbed. This drug interaction mechanism is not thought to be clinically significant, especially when compared to the inhibition of the CYP isoenzymes by flavinoids and the furanocoumarins (et al), but the activity of P-glycoprotein pumps varies widely in individuals, due to differences in genetic make-up (ie. number of copies of the gene coding for P-glycoprotein). This could be one explanation why the extent of inhibition of drug metabolism by grapefruit is so widely variable and unpredictable in different people.

In short, I wouldn't bother trying to save on medication costs by eating grapefruit. There are just too many variables involved.

Larry (and others) - Here good website for Grapefruit-Drug Interactions . If you click on "Interactions & Clinical Significance" it lists drug categories whose metabolism is affected by grapefruit. Clicking on a category will give a detailed explanation of the significance of the interaction of individual drugs with grapefruit. To get a 2 page downloaded summary (.pdf) of drugs affected by grapefruit, and the extent to which they are affected, click on "Summary of GJDI's". I have a copy of this printed off for use at work.

I hope that all of this is of some use. - Cam

[Larry_Hoover]

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Larry (and others) - Here good website for Grapefruit-Drug Interactions . If you click on "Interactions & Clinical Significance" it lists drug categories whose metabolism is affected by grapefruit.

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Love the link, Cam. Thanks.

I've seen references to all the bits and pieces you've mentioned, but I didn't know anyone had taken the trouble to put it all together coherently. Good work.

Lar