I am pretty sure I notice a significant variation in the 'potency' of effect on pregnyl from vial to vial. If I understand correctly, it's purified from pregnant women's urine? I have no idea what standards are in place for their manufacturing practices, but it would seem plausible that there is actually a difference in potency from one batch to the next. I also can't help but wonder if there are other 'impurities' or chemical differences in it. I've recently come across this idea that pharma or generic hgh can have varying amount of dimer levels, resulting in potentially different side effect profiles. I wonder if something similar could be happening with pregnyl. I don't have the expertise to know if any of this is possible/plausible, and ultimately the variation I feel is tolerable so it doesn't matter a whole lot.
I have been on Pregnyl since September 2022, so have gone through over 15 vials in that 27 month period. My hypothesis (only from subjective feeling on it for >2 years) is it's often overly-potent after first mixing, giving more than 10,000 iu per vial. Then fades and depending on how the vial is used and stored, by the 6 or 7 week mark is quite weak and the effects are subjectively quite different than when started. It seems not just "weaker effects". More like "still disrupting sleep about the same, but not boosting mood the same at all".
It seems pregnyl felt more powerful than the empower hcg I was on prior, though that may have been related to it getting degraded in shipping from empower or poor manufacturing practices or something. By ordering Pregnyl from optum, with next day delivery, I think it's much less likely to degrade from heat.
