Progenics Pharmaceuticals and Wyeth achieved positive results from a three-month open-label extension study of subcutaneous methylnaltrexone for the treatment of opioid-induced constipation (OIC) in patients with advanced illness.
Eighty-two OIC patients completed a placebo-controlled Phase III study (MNTX 302) and participated in the three-month open-label extension study of subcutaneous methylnaltrexone. The goal of the extension study was to obtain efficacy and safety data on subcutaneous methylnaltrexone, administered as needed, for as long as three months.
Forty-two OIC patients received subcutaneous methylnaltrexone previously in MNTX 302, and then entered the open-label extension study. The mean laxation response rates were 45.5% during the first month, 57.7% in the second month, and 57.3% in the third and final month. For the remaining 40 patients who had first received placebo in the MNTX 302 study prior to this open-label extension study, laxation response rates were 48.3% during the first month, 47.6% in the second month, and 52.1% in the third and final month. Consistent with previous studies, subcutaneous methylnaltrexone was generally well-tolerated in the three-month open-label study, and the most common adverse event reported was abdominal pain which was typically mild-to-moderate in severity.