Personally, I would not use bac water. I've heard mix info on the internet, just like everyone else, that it'll hold in bac water from 24 to 48 hours. If I were to do large doses of 100mcg, then sure, I wouidn't have issue with mixing and using right away, but I believe that large doses make igf stop working, quickly. Instead, I opt for 25mcg to 40mcg. Often, I start lower, around 25mcg and add more a few wks later. If I need my IGF to last 4 days, I don't want to take the risk of it breaking down in Bac water. If you are concerned with the sting of acetic acid, you can always add bac water or sterile water to your dose, each time you draw it up. This will cut the sting. If you do, I would suggest back loading the insulin pin. Maybe I'm a pussy, but after all the shots I've done, I hate sticking myself with a super dull needle!