I went the doctors today and discussed my fears with him about taking Imuran and he said he doesn't want to give it to me if I feel uncomfortable about taking it. He said he's worried that the Mestinon may not be as affective if I keep taking it, and he also gave me a list of other immuno-suppressants to look at to see if I'd be more willing to take them instead. They are as follows: Cyclosporine, Cellcept, and 6-Mercapto Purine. So right now, he's going to keep me on the Mestinon. Does Mestinon become less effective over time?