I have tested the generic (Pyridostigmine) vs brand Mestinon by taking the generic for a month then switching to the brand and I can tell a distinct difference. I have done this trial twice and one time I had to stop the generic and pay much more for the brand earlier than insurance allowed. After running out of brand several days ago before insurance would buy the brand today I was getting very weak with some breathing difficulty and an hour after I took my first 60 mg of brand Mestinon I am much better. I am an organic chemist and professor and I don't think that a drug synthesized and "purified" in a lab only God knows where would not have the purity of an American made drug that is more quality controlled. There was a independent quality control lab in India or run by an Indian doctor on 20/20 last week testing supplements and their results were ludicrous and dangerous as they missed arsenic and other toxins at high levels..
The extreme hygroscopic property, the tendency to absorb water, would decrease it's viabilty right off the shelf and if it is crumbling I would think it is not usable and most likely partly decomposed. My neurologist, a major researcher at a med school, complained to Global to no avail. I am convinced based on two personal trials the brand Mestinon is the much better safer choice, especially if you have mainly bulbar symptoms- breathing, speech, eating or vision issues.