Grapefruit Is One of the Weirdest Fruits on the Planet {Drug interactions ! } (Atlas Obscura)

[eppur_se_muova]

by Dan Nosowitz October 6, 2020

In 1989, David Bailey, a researcher in the field of clinical pharmacology (the study of how drugs affect humans), accidentally stumbled on perhaps the biggest discovery of his career, in his lab in London, Ontario. Follow-up testing confirmed his findings, and today there is not really any doubt that he was correct. “The hard part about it was that most people didn’t believe our data, because it was so unexpected,” he says. “A food had never been shown to produce a drug interaction like this, as large as this, ever.”
***
Eventually, with Bailey leading the effort, the mechanism became clear. The human body has mechanisms to break down stuff that ends up in the stomach. The one involved here is cytochrome P450, a group of enzymes that are tremendously important for converting various substances to inactive forms. Drugmakers factor this into their dosage formulation as they try to figure out what’s called the bioavailability of a drug, which is how much of a medication gets to your bloodstream after running the gauntlet of enzymes in your stomach. For most drugs, it is surprisingly little—sometimes as little as 10 percent.

Grapefruit has a high volume of compounds called furanocoumarins, which are designed to protect the fruit from fungal infections. When you ingest grapefruit, those furanocoumarins permanently take your cytochrome P450 enzymes offline. There’s no coming back. Grapefruit is powerful, and those cytochromes are donezo. So the body, when it encounters grapefruit, basically sighs, throws up its hands, and starts producing entirely new sets of cytochrome P450s. This can take over 12 hours.

This rather suddenly takes away one of the body’s main defense mechanisms. If you have a drug with 10 percent bioavailability, for example, the drugmakers, assuming you have intact cytochrome P450s, will prescribe you 10 times the amount of the drug you actually need, because so little will actually make it to your bloodstream. But in the presence of grapefruit, without those cytochrome P450s, you’re not getting 10 percent of that drug. You’re getting 100 percent. You’re overdosing.
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Despite this, the Food and Drug Administration does not place warnings on many of the drugs known to have adverse interactions with grapefruit. Lipitor and Xanax have warnings about this in the official FDA recommendations, which you can find online and are generally provided with every prescription. But Zoloft, Viagra, Adderall, and others do not. “Currently, there is not enough clinical evidence to require Zoloft, Viagra, or Adderall to have a grapefruit juice interaction listed on the drug label,” wrote an FDA representative in an email.
***
more: https://www.atlasobscura.com/articles/grapefruit-history-and-drug-interactions

[No Vested Interest]

1. Yes, I miss grapefruit. Haven't had any for many years; taking Lipitor...

[CozyMystery]

14. Same here. I love grapefruit. nt

[Onyrleft]

2. I have definitely noticed,

that people who enjoy psychedelics enjoy grapefruit.

[Duppers]

3. MOST interesting.

Thank you. Passing this on.

[NJCher]

4. Murder mystery plot

If the victim was taking certain medication, the murderer could feed them grapefruit instead of using poison.

[kiri]

5. does Trump like grapefruit?

[samnsara]

17. it did say they have no idea how many ppl died because of this interaction..YIKES!!!

...and 1984 wasnt that long ago. This is relatively a recent discovery..and hubby was already out of Pharmacy school by then.

[MFM008]

6. I hate it

Always have.

[DFW]

7. I had stent implants in 2004

I have had to take a statin every day since. I was warned at the time about grapefruit and haven’t touched it since.

[pansypoo53219]

8. i LOVE grapefruit, so when i was given prescriptions. i asked if they were grapefruit safe.

YES! whew.

[soothsayer]

9. At last, the explanation I've longed for!

Why not just put grapefruit in with the drug (or prescribe it alongside) and give people 1/10th of the drug?

[bluedye33139]

10. In HIV medication, they actually use this mechanism on purpose

Most HIV medications are administered with a booster, another drug that depletes the cytochrome p450 so that the medication is not broken down by the liver as quickly. You're not crazy, exploiting this mechanism really is something that doctors and researchers are looking into.

The danger of course with most medications is that you'll end up with too much in the bloodstream, and with some medications this is very dangerous. With other medications, it's not so dangerous.

[soothsayer]

11. Right. Fascinating! Thank you

[eppur_se_muova]

15. Thanks, that was very informative. nt

[druidity33]

12. That's a real good question...

i didn't see it answered in the article. Has anyone tried this?

[soothsayer]

13. The comment right above yours says yes! Check it out

[samnsara]

18. cuz ppl would still eat grapefruit then they would have twice the GF probs...

.. I asked hubby why there werent stickers on meds in the US and he said he puts them on whenever he sells a med that will interact. There should be a giant GF Mr. Yuck Sticker

[soothsayer]

19. Hmm. But if the meds are 1/10 as strong....

Idk.

Contact, with little tiny timepills?

[samnsara]

16. this article was fascinating! Hubby is a Pharmacist and knew about the interactions and he always..

...told me about it.. but I never i knew WHY or the history of grapefruit. I love my tequila and grapefruit (dbl tall plz) but now I may just have a dbl short

[wishstar]

20. Article states that lime has same effect as grapefruit

but since quantiy of lime juice consumed is so much less than grapefruit, lime consumption would not have as strong an impact as grapefruit