I drink one to 3 cans of Fresca a day, every day, I love the stuff and have for eons. It’s 1% Grapefruit. Ingredients says: Concentrated GFJ, and the can says: "contains less than 1% Grapefruit juice.
So, three cans = about 10ml GFJ…
Any thoughts?
I started w/ one tablet (Zydus) yesterday, my very first dose… No odd symptoms or anything…
I’m thinking now of doing a month at 1mg, then on the last day getting a “trough” level test, what’cha think?
My guess is that it’s not a substitute for grapefruit juice. It’s more like the ultra-processed version which probably had all the ‘good stuff’ removed. But this is just my WAG.
I agree with DeStrider on this - the effect of Fresca is likely extremely small, probably unmeasurable on your blood sirolimus levels. I wouldn’t spend much time thinking about it.
Ooh I used to be a steady drinker of Fresca, good stuff. I also like the soda called “Squirt” – another grapefruit-flavored drink. Ever try that? Maybe it’s a regional drink.
Thanks all. Yes Southhill, I do remember Squirt from days of Yore…
What happens if a person on sirolimus drinks one cup of real GFG every day?
I used to think that the Cytochrome P450 “system,” was only in the liver, I now see that somehow it’s active in the gut too.
Well, an hour or two after taking rapa, it’s out of the gut. I would think that removal would be entirely or mostly from the liver. So, if a person drinks GFJ every day, will the levels of rapa stay elevated perpetually? (OK, not perpetually… )
Grapefruit juice affects absorption of Rapamycin. So, if you take Grapefruit juice 1-4 hours before Rapamycin, you increase the amount your body absorbs by about 3X.
This I understand. Yet, if a person drinks GFJ every day, will the metabolism of the Rapamycin be much slower because you are tying up the 3A4 system?
It would seem that if that’s the case, GFJ could be used to one’s advantage to increase the level and/or resident time in the body, as you would be slowing its removal.
We need a randomized blinded controlled study of Fresca vs Coke.
There are many medications that can be affected by the inhibition of CYP3A4, if the Fresca had any effect on CYP3A4 we would probably already know.
I would be more concerned about the large amount of sugar involved in drinking a liter of fresca food every day.
It occurs to me to determine the effect of fresca on the inhibition of CYP3A4, with a medication such as sinedafil (25mg), given that the effects of this are relatively easier to identify.
“Fresca does not contain sugar, calories, or caffeine. Coca-Cola launched Fresca in 1967 as a zero-sugar, low-calorie alternative to soda, and as a mixer for alcoholic drinks. Fresca is flavored with natural fruit essences and is similar to Sprite, but with a grapefruit taste.”
It is “sweetish,” a bit, from aspartame…
I did see something which said gfj wirh rapamycin has a atrong effect as well as 1 hour in advance.
Today was my third time I’ve taken sirolimus (I’m up to 3mg Zydus Siromus). I took it at about 11AM. Around 4pm I drank a Fresca, without thinking about it…
Then, later, I noticed that I had an odd rash one the inside of both elbows. See photo:
Still wondering about Fresca, I found this…
Consumption of the carbonated soft drink Sun Drop® was recently reported to be temporally associated with clinically relevant doubling of serum ciclosporin trough levels in a lung transplant patient on Neoral® maintenance therapy on two occasions [8]. Moreover, intentional avoidance of this soft drink prevented the recurrence of this problem. Indeed, the makers confirmed that this citrus soda contained furanocoumarins. Our analysis of Sun Drop® and Fresca®, two of 15 citrus soda drinks screened for furanocoumarins, confirmed that both drinks potentially possessed concentrations of bergamottin capable of inhibiting CYP3A4 metabolism.
This study was conducted to investigate the effect of grapefruit juice and citrus sodas Sun Drop® and Fresca®, the latter soda containing 83-fold higher concentration of the proposed CYP3A4 inhibitor bergamottin than Sun Drop®, relative to water on oral ciclosporin pharmacokinetics.
Consider, it was the Sun Drop that caused the issue. Now that was chronic use and mine was a one-time, but now I wonder if my 3mg has acted as 21mg (considering a 7-fold increase).
I suppose it’s possible that the Fresca might have as much effect as whole GFJ.
Skin rashes seem fairly common with Sirolimus and it’s not angioedema, but now I’ll not drink Fresca the day before and perhaps not the day of taking my dose.
https://bpspubs.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2125.2005.02519.x
Here’s an interesting one with no GFJ but a person ate quite a lot of orange marmalade that was made for him—he loved the bitter taste. The person that made it could not get the right oranges so substituted grapefruit rind and had a severe OD of tacrolimus:
Tacrolimus severe overdosage after intake of masked grapefruit in orange marmalade
This fellow was taking 3 mg tacrolimus 2x daily. He was eating about 7 ounces of marmalade every day!
I’m wondering if the oil of the grapefruit is much more potent than the juice itself.
A reminder to be careful, we are, after all, in uncharted territory…
Once I get up to 6mg/dose for a few rounds, I’ll drop back to 1mg, drink a Fresca and then do a 2.5 hour max blood test. That’ll be interesting, maybe a Fresca + 1mg would get me to the sweet spot, sort of like a “cheap sirolimus fellow.”
