Study of Methylnaltrexone in Opioid-Induced Constipation Patients

Inclusion Criteria: * A life expectancy of 3 month or more * Qualifying patients received opioids for analgesia for 1 week or more and a stable regimen of opioids and laxatives for 3 or more days before study entry * Patients had opioid-induced constipation with either fewer than three laxation during the preceding week and no clinically meaningful laxation (as determined by the in investigator ) within 24h before the first study dose or no clinically meaningful laxation within 48h before the first study dose * During the two-week trail , patients would keep their life habits (dietary fiber , fluid intake and physical activity) * Patients volunteered for the trail * Women of childbearing potential had negative pregnancy tests. Both male and female patients need to take effective contraceptives to avoid pregnancy. Exclusion Criteria: * Constipation that was not primarily caused by opioids ( as determined by the investigator) * Mechanical gastrointestinal obstruction, an indwelling peritoneal catheter, clinically active diverticular disease , fecal impaction , acute surgical abdomen , and fecal ostomy * Patients had the surgery plan which would effect the results of pain assessment * Patients had hypersensitivity to methylnaltrexone , naltrexone or naloxone or if any investigational drug or experimental product