Hi. Are there any serum levels and half-life studies and comparisons between the different brands? Pfizer vs. Indian labels?
You can so a search on the forum (Search bar in the upper right corner of the screen, when on a laptop computer (vs. phone) on “blood test” or “sirolimus blood test” or “rapamycin blood test” to see people’s reporting of their blood sirolimus levels based on different brands of rapamycin.
The problem is that its really hard (if not impossible) to do an apples to apples comparison. The key issue is that the blood level of rapamycin spikes really quickly after dosing, with a peak around 2 hours after dosing. Then it falls extremely rapidly there-after. When you’re getting a blood test, a 20 minute variation in terms of the timing could make a huge difference in the blood sirolimus level reading. When you go to the blood test centers (Labcorp or Quest) you can easily be put on a wait list for 20 minutes to an hour (I have been many times). Add to that the many other variables like food in your stomach, types of nutrients you’ve consumed in the past day, etc. that could influence the test results.
There is also a large individual variation in 1/2 life for sirolimus if you look at the scientific research, with a range from around 60 hours to 80 hours for 1/2 life. So one person’s test with a given generic or brand (rapamune) version of sirolimus is not going to be directly comparable to another person’s blood test, even if they were timed exactly to the minute.
The net of all this that only a well-funded lab could do the type of testing with a large enough number of people, and with strictly controlled variables, to get a meaningful result. The cost of such an experiment would be high (think hundreds of thousands of dollars) and little incentive to do such a test as all the drugs are generic.
So - no, this test hasn’t been done, and likely won’t be.
See the blood level curve of typical blood sirolimus levels here: How to get a Rapamycin (sirolimus) Blood Level Test
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