Methylnaltrexone for Opioid-Induced Constipation in Pediatric Oncology Patients

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. Procedure 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. Conclusion 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. Pediatr Blood Cancer 2013;60:1667–1670. © 2013 Wiley Periodicals, Inc.