Because your affected area is right-sided, where Pentas dissolve is more likely to target the area better than if it were lower. It still is dispersed throughout th colon, but a high amount would be in the ileum and ascending colon.
Even though I had diarrhea 20 times a day, the Asacol helped quickly...and I was only on 4 a day to start..then upped to 6. But, I didn't have whole colon involvement....so, some of it was dispursed above the affected area obviously. I've never seen whole pills in the bowl...even at the worst of flares. Asacol dissolves depending on the intestinal ph level.....others dissolved depending on the bacteria. Good thing there are different 5ASA meds available with different delivery systems.
Keep us posted as to how you're getting along with Pentasa....what's the dosage the doc's putting you on?
This link seems very helpful.