I've wondered the same thing Cate. I've been using the generic version for about a month and a half and it has helped tremendously. Around 3 weeks after I started I noticed that I really didn't feel well (general weakness) until my second dose so I tried the time release 180mg name brand mestinon overnight. My neuro had written a script for both and told me to fill the time release if needed.

The two (three?) times I tried it, my stomach was so upset I couldn't sleep for most of the night. Aren't the two bio identical? The only think I can think of is that maybe there is something in the coating of the mestinon that doesn't agree with me.

I'll be interested in the responses of those with more experience.