Sorry to hear that. I've been taking it for less than a year now and I had to up the dosage from 1.5mgs/day to 2 because it wasn't working as well. At this dose it's as effective as the first time I took it. I have asked others about the possibility of tolerance build-up and one fellow sufferer did experience loss of effectiveness but after a while decided to try it again and it worked. I take it almost everyday as I interact with people often. I do find however, that if I take it and then sleep; it loses all effectiveness..very weird and will ask the pharmacist about that.
Could the Paxil be counteracting the glycopyrrolate you're taking?
btw if you take Paxil for generalized anxiety disorder there's a very interesting medication I just recently read about that is not addiction forming and the side effects are a lot less severe:
Buspar (Buspirone):
http://en.wikipedia.org/wiki/Buspar==
*I have also read St.John't Wort and b-complexes work very well for depression/anxiety..thought I'd share.