Amitiza
"I am 71 and have had constipation all of my life. I've tried OTC products (all of them) and even some prescription products. I take 4 of this per week with plenty of water. More give me some cramps.  However, my constipation is finally under control.  It isn't easy, but I do get results about 4 times a week.  That beats 1 or 2 with a lot of bleeding from strain.  I may increase to 7 times per week and see if the cramping stops.  I have a superlong colon which has caused the chronic constipation."