My daughter went the prednisone/pentasa route after first being diagnosed. The prednisone will get things under control, but there is a large school of thought amongst GI's, that Pentasa is a useless medication.
After two years, my daughter developed severe Crohn's issues, and was then transitioned to Imuran,(6mp).
There'll be differing opinions on Pentasa, but i don't believe it's a viable treatment option at all.