Definitely worked better than generic in this case
My cat was on the generic of Methimazole for a few years, and it was fine, but then his thyroid began to get worse, and the doctor wanted me to try a different brand before increasing his dose, as he found that sometimes other generics work better than others. We tried another generic from his office, and it still didn't help, so I took it upon myself to try Tapazole instead, and his numbers went from 7 something to 2 something in just a few days of use. I don't know what these numbers mean, but I do know that he is now in normal range, and it was a big difference. the downside is that this one is extremely expensive, however I happen to have pet insurance so most of my cost is covered, and I always take advantage of any points or coupons I have for PetCareRx. If you do not have insurance and cannot afford the difference in cost, make sure you are getting your pet tested periodically and you may need to use a higher dose.