What types of grapefruit juice increase Rapamycin levels the most?

There are a few types of grapefruits: white, pink and red grapefruits.
Which one of them increase the concentration of Sirolimus the most?

Are there any drugs that could increase Sirolimus blood levels? (to save $ on Rapamycin)
Ketoconazole isn’t available in my country

There have been lots of discussions on this… I think people have pulled out the information you seek:

here is one study suggesting similar outcomes with both:

and another article/paper:

But here is a study suggesting pink grapefruit is better:

There is also a lot of discussions on this here: Improve Bioavailability of Rapamycin (2)

I seem to remember another drug that someone here researched that has a large multiplier effect - can anyone remember what it was?


I think you mean ritonavir?
Alternative to ketoconazole is also itraconazole (but I haven’t deeply researched that, effect on rapamycin should be similar to ketoconazole).


If it’s between grapefruit or a potentially harmful drug to boost absorption, I’ll go with the grapefruit.


White Grapefruit have higher levels of the CYP3A4 inhibitor but they are hard to find. I’m referring to Duncan.


Sure, but ritonavir and itraconazole both seem to have a good record. Ritonavir is daily medicine for HIV suppression, so thousands take it daily for years (available sine 1996) and itraconazole is probably one of the most widely used antimycotic medicines on the market from late seventies, still similarly to ketoconazole might be liver toxic (safer though) and with longer half life that would probably affect rapamycin metabolism more in terms of expanding the AUC, but it is available in Europe and quite reasonably priced. Ritonavir is a very potent irreversible inhibitor of CYP3A4 and would probably extend AUC even longer. In any case I would not take this two regularly without testing my rapamycin serum levels and effect on my body. Rapamycin absorption and metabolism depends so much on individual organism that adding variables in form of CYP3A4 inhibitors makes things even less predictable.
With GFJ which is the simplest of all since it inhibits CYP3A4 mostly in intestine and thus increases mostly absorption but not AUC is probably the safest but again it might be too variable in CYP3A4 inhibition? IDK.


I think you just answered your own question. I agree with your assessment.

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I did not A-B test forms of GF, just a binary experiment and blood tested post several times.

  • Blended into water 6mg, took in the afternoon, blood tested 8am next morning. = zero in my blood
    some have said blood test 2 hr post taking rapa.

  • I tested 12-20mg and best I saw was 0.5-2ish. Yes some say I should test 2 hr post rapa. But given 62 hr half life I figured next day 8am I should see most of the peak… ???

  • Caned frozen pink GFJ from Kroger + kitchen sink of other suppressers; 1g berberine, 20mg of peperine, quercetin (may not be needed), Fisetin(not sure this either), I’m Kitchen type. Blended and took in the AM and set a 2 hr timer.

  • noonish took 15mg rapa 2 hr after GF mix.

  • 2 -3 hr after rapa had Labcorp sirulimus test blood draw.

  • Eureka; 20-30 (?? some units) of sirulimus reported in my blood.

A few other scenarios and a few other blood tests and blood levels between 0.2 up to highest seen 40…

Given N=1 variable blood levels, I’ll guess that folks here (etc) are seeing a wide range of absorbtion!!! Some here I’ll guess are getting zero benefit due to low absorption.

I would suggest that any study that blood testing be done on all participants and then participants use that protocol every time. IE I have compliance and consistent timing variances. ;(

And what blood levels should we be targeting? :> :> :>

best to all, curt

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Did you use powder form or pills? Matt Kaeberlein (leading Rapamycin researcher) said that Rapamycin in powder has almost no bioavailability


That’s probably why all rapamycin tablets have some form of enteric coating. Which allows it to bypass stomach acid and dissolve in higher pH intestines.


Rapamycin powders from compounding pharmacists are pretty much a waste of time and money. They don’t make it into the blood stream. You need the enteric coating from the pills that a compounding pharmacist just can’t replicate.