Approximately 40 sites will participate in each of these two studies, which are being conducted by Wyeth. Each trial is expected to enroll approximately 120 patients who are receiving opioids to help manage their chronic pain and have opioid-induced constipation (OIC). Both studies are expected to take approximately six months to complete.
Each study will separately evaluate a different oral formulation of methylnaltrexone, including the formulation that exhibited positive preliminary results in a Phase I study. The companies plan to assess the safety and dose-response of oral methylnaltrexone as measured by the occurrence of spontaneous bowel movements during the treatment period. The studies are expected to assist in determining the formulation and doses to be advanced into Phase III studies.