The generics produced by Zydus, Biocon, etc. have not been well evaluated (to the best of my knowledge) by anyone here, to do a good comparison from a technological standpoint. It would take some digging into possible patents by the companies, etc., and the information may not be available.
The information we have gotten, from people doing blood tests after taking the generics, is that the generics all seem to work pretty well in terms of bioavailability (you can search here in our forums for people reporting on their blood test results).
But, nobody has, I believe, done a head to head comparison (via blood work) of the branded Pfizer Rapamune vs. the generics. It would be interesting, but whatever the case they are not too far off from each other.
Thanks and I do understand this. But also keep in mind the bioavailability, unlike most people think, is not just an AUC in serum of a certain compound. Its also about how it can enter into different tissue like brain (BBB) or the affinity it has with cells membranes. For instance, we could speculate that higher blood serum of the molecule means less distributed in tissue. See its a complicated topic and we want Rapamycin to act in our entire system. If I could sell it, I would have made liposomal structure of it