How to do P & B Shakes & Avoid Constipation?

Hello - I really want to cleanse all junk from my intestines and feel the p & b is necessary. But every single day that I use it I get constipated. If I go off of them, things go back to normal in a day or two.

I am trying to do a coffee enema daily, but with the p & b shakes this turns out to be highly time consuming because first I have to use low colonics to clear the way for the coffee.

Cascara works, but it seems to cause diarrhea (sp?) and they say you shouldn't use it ongoing anyway. I have tried drinking about 20 oz. of water with the p & b drink. That makes no difference, tho.