This study is a prospective, randomized, open-label crossover study consisting of a 1-week washout period, a 2-week treatment period, another 1-week washout and a final 2-week treatment period. The study will assess the overall patient preference Movantik versus Polyethylene Glycol 3350 for the treatment of their opioid-induced constipation. This study will also evaluate the reasons for patient preference (only among subjects who indicate a preference), patient global impression of change, and change in bowel function over the treatment periods measured by Bowel Function Index. Patient's bowel movement diary will also be collected during the study.
