Safety of Subcutaneous Methylnaltrexone for Opioid-Induced Constipation in Patients With Advanced Illness

Inclusion Criteria: * Has completed study 3200K1-4000-WW, including 2 weeks of therapy and completion of all post baseline efficacy, safety, and health outcomes assessments. * Is receiving opioids on a regular schedule, not just as needed to control pain. * Likely to continue to need treatment of OIC for the duration of participation in the study. Exclusion Criteria: * Has a suspected mechanical gastrointestinal obstruction, fecal impaction, or clinically important active diverticular disease as determined by the investigator. * Currently using an opioid antagonist or partial antagonist. * Has any other clinically important abnormalities such that risk to patient of participation outweighs the potential benefit of therapy as determined by the investigator