Stereo,
Good question.
But you have your doc's ok, which is good.
In the beginning, when I was first diagnosed, I was put on various different mesalamines - they didn't help, and within a few weeks I developed an intolerance to them. So I quit them cold turkey. I did stay on canasa for a bit, but it really didn't help me.
What helped me the most was: the combination of diet modification, supplements - especially VSL, slippery elm, l-glutamine, Paleo diet, and LDN of course.
IMHO, I still believe that slippery elm powder is pretty good substitute for mesalamines - as this has been my experience.
So, I would say, it very much depends on your gut.