which drug? I've been doing the same with brand Lipitor. It appears perhaps they will pay in 2024 according to, now on, Medicare. I will find out if Part D shows the drug and price then I can buy it at that price.
Generics are permitted to use any fillers/buffers/additives they wish. Most ingredients come from China and India. Zero regulation or testing. Plenty are articles on the subject in BusinessWeek/Bloomberg and WaPro.