A Randomized, Double-blind, Placebo-Controlled Trial Evaluating the Safety and Efficacy of Subcutaneous Methylnaltrexone for the Treatment of Opioid-Induced Constipation in Subjects With Cancer-Related Pain Estudio aleatorizado, en doble ciego y controlado con placebo, para evaluar la seguridad y l

Primary objectives: The objective of this study is to evaluate the efficacy and safety of sub-cutaneous methylnaltrexone in relieving opioid-induced constipation in subjects with cancer-related pain. Primary endpoints: The primary endpoint is the proportion of subjects who have a rescue-free bowel movement within 4 hours after the first dose of study drug.