title: Subcutaneous methylnaltrexone for the treatment of opioid-induced constipation in patients with advanced illness: a double-blind, randomized, parallel group, dose-ranging study.
abstract: Methylnaltrexone, a peripherally-acting quaternary opioid antagonist, is an investigational treatment for opioid-induced constipation in patients with advanced illness. This randomized, parallel-group, repeated dose, dose-ranging trial included a double-blind phase for one week followed by an open-label phase for a maximum of three weeks. Opioid-treated patients with advanced illness who met criteria for opioid-induced constipation despite laxative therapy were potentially eligible. Double-blind treatment occurred on Days 1, 3, and 5; open-label therapy could be administered as often as every other day. The initial dose range of 1mg, 5mg, or 12.5mg was extended by adding a 20mg group during the study while still maintaining the double blind; the initial open-label dose of 5mg could be titrated. The primary outcome was a laxation response within four hours after the first dose. Thirty-three patients received at least one dose of methylnaltrexone. Only one of 10 patients (10%) who received the 1mg dose experienced laxation within four hours of dosing. The median time to laxation was >48 hours for the 1mg dose group, compared to 1.26 hours for all patients receiving >or=5mg (P=0.0003). There was no apparent dose-response above 5mg. Most adverse events were related to the gastrointestinal system, were mild, and did not lead to discontinuation. In conclusion, methylnaltrexone relieved opioid-induced constipation at doses >or=5mg in patients with advanced illness, and did not reduce analgesia or cause opioid withdrawal symptoms.
authors.affiliation: Department of Pain Medicine and Palliative Care, Beth Israel Medical Center, New York, New York 10003, USA. rporteno@chpnet.org
authors.forename: Russell K
authors.initials: RK
authors.lastname: Portenoy
authors.forename: Jay
authors.initials: J
authors.lastname: Thomas
authors.forename: Michele L
authors.initials: ML
authors.lastname: Moehl Boatwright
authors.forename: Diep
authors.initials: D
authors.lastname: Tran
authors.forename: Frank L
authors.initials: FL
authors.lastname: Galasso
authors.forename: Nancy
authors.initials: N
authors.lastname: Stambler
authors.forename: Charles F
authors.initials: CF
authors.lastname: Von Gunten
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Israel
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000701:Analgesics, Opioid / Q000009:adverse effects*; D003967:Diarrhea / Q000139:chemically induced* / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D009271:Naltrexone / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D009369:Neoplasms / Q000150:complications; D010146:Pain / Q000188:drug therapy / Q000209:etiology; D010147:Pain Measurement; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D013727:Terminal Care
chemical_list: D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D000644:Quaternary Ammonium Compounds; C032257:methylnaltrexone; D009271:Naltrexone