title: Methylnaltrexone for opioid-induced constipation in pediatric oncology patients.
abstract: BACKGROUND
  Pediatric oncology patients can experience opioid-induced constipation, which may not respond to laxative treatment. Methylnaltrexone is an opioid receptor antagonist that can reverse opioid-induced constipation without affecting analgesia. Published literature on the use of methylnaltrexone in children is very limited. This retrospective review describes the effectiveness and safety of methylnaltrexone for opioid-induced constipation in pediatric oncology patients.
  
  
  METHODS
  A retrospective review of health records was conducted for pediatric oncology in-patients who were prescribed methylnaltrexone between May 2008 and September 2012 at The Hospital for Sick Children. Demographic, clinical, efficacy, and safety data were collected, including; opioid, laxative, and methylnatrexone dosing and frequency.
  
  
  RESULTS
  Fifteen patients (median age: 14 years, range: 4-17 years) received methylnaltrexone; 12 received a single dose while three received multiple doses. At the time of methylnaltrexone administration, patients were receiving a median oral morphine dose equivalent of 5.7 mg/kg/day (range: 1.5-29.2 mg/kg/day) and had not had any bowel movements for several days despite treatment with multiple laxatives. Methylnaltrexone was given at a mean dose of 0.15 ± 0.02 mg/kg/dose (range: 3-12 mg/dose) as a subcutaneous injection. After 14 of 19 doses administered, patients had a bowel movement within 4 hours. Three patients had documented mild gastrointestinal upset following methylnaltrexone administration. None reported a reduction of pain control or opioid withdrawal symptoms.
  
  
  CONCLUSIONS
  This case series suggests that methylnaltrexone is safe and may be effective when given subcutaneously as a 0.15 mg/kg single dose to pediatric oncology patients with opioid-induced constipation.
authors.affiliation: Department of Pharmacy, The Hospital for Sick Children, Toronto, Canada. amelia.mascarenhas@sickkids.ca
authors.forename: Amelia
authors.initials: A
authors.lastname: Rodrigues
authors.forename: Cherie
authors.initials: C
authors.lastname: Wong
authors.forename: Andrea
authors.initials: A
authors.lastname: Mattiussi
authors.forename: Sarah
authors.initials: S
authors.lastname: Alexander
authors.forename: Elaine
authors.initials: E
authors.lastname: Lau
authors.forename: L Lee
authors.initials: LL
authors.lastname: Dupuis
mesh_terms: D000293:Adolescent; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D003248:Constipation / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D009271:Naltrexone / Q000008:administration & dosage / Q000031:analogs & derivatives*; D009292:Narcotic Antagonists / Q000008:administration & dosage*; D009369:Neoplasms; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage; D012189:Retrospective Studies
chemical_list: D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D000644:Quaternary Ammonium Compounds; C032257:methylnaltrexone; D009271:Naltrexone
keywords: pain medicine; pediatric oncology; quality of life