My son's CD is in his TI but the GI said due to severity he would need to go straight to remicade. It has worked out really well he has imroved greatly with the first dose. So sorry I can't help you out with the pentasa but I'm sure someone will be along soon with experience and advise! Hope your son improves!
My children have never been on Pentasa. It is a mild drug and if your son's disease is very mild and superficial he may have success with it but I'm not sure that how likely that will be.