Prepopik
"I used Prepopik one day prior to my colonoscopy.  First, it is expensive when not covered by insurance.  If I had not had a coupon it would have cost over $100.  Second, it took a while to start working. Lastly, when they did the colonoscopy I was not sufficiently cleaned out and the procedure had to be rescheduled.  I will use other more effective methods the next time around."