I have tried all kinds of constipation pills, but so far the best is Figi fruit. You can eat the fruit if you like it but best are those compressed figi tablets. It takes about 12-24h to kick in, but it feels GREAT :D even when you are not constipated. what a release!
There are also other fruits that can help, like apricots, papayas, raisins, dates.
Prunes, in particular, are great because they not only are high in fiber, they also contain sorbitol, which is a natural laxative