Wyeth and Progenics Pharmaceuticals initiated three new clinical studies for their investigational drug, methylnaltrexone, a peripherally acting mu-opioid receptor antagonist. Two of these trials will study the use of subcutaneous methylnaltrexone for treating opioid-induced constipation (OIC) in patients outside of the palliative care population included in the first NDA submission. The third trial will investigate methylnaltrexone for managing post-operative ileus (POI). The companies are currently studying intravenous methylnaltrexone in Phase III trials to manage POI in patients undergoing segmental colectomy surgical procedures. All of the studies will investigate additional patient populations for the drug.

The first of the two subcutaneous methylnaltrexone trials, a Phase III study in OIC patients with chronic pain not related to cancer, is being conducted by Wyeth and is scheduled to enroll approximately 470 patients at approximately 100 centers worldwide. The primary efficacy endpoints are the proportion of methylnaltrexone injections resulting in bowel movements within four hours and the evaluation of the number of bowel movements per week, compared to placebo. The trial is expected to be complete by late 2008.

Progenics will conduct the second subcutaneous methylnaltrexone trial, a Phase II study in OIC patients rehabilitating from an orthopedic surgical procedure when opioids are used to control post-operative pain. This trial is scheduled to enroll approximately 260 patients at approximately 50 centers in the U.S. The clinical efficacy endpoints include relief of constipation as measured by laxation response. The trial is scheduled to begin in 4Q2007.

Wyeth will conduct the third Phase III intravenous methylnaltrexone study in patients with POI following a ventral hernia repair via laparotomy or laparoscopy. This trial is scheduled to enroll approximately 500 patients at 90 to 120 centers worldwide. The primary efficacy endpoint is measured by time to first bowel movement after the surgical repair. The trial is expected to be complete by the middle of 2008.