Chamberlain, B.H., Cross, K., Winston, J.L., Thomas, J., Wang, W., Su, C., & Israel, R.J. (2009). Methylnaltrexone treatment of opioid-induced constipation in patients with advanced illness. Journal of Pain and Symptom Management, 38, 683-690.doi:10.1016/j.jpainsymman.2009.02.234
To describe laxative response to subcutaneous methylnaltrexone in patients with advanced illness and opioid-induced constipation.
Patients were randomly assigned to receive either methylnaltrexone 0.15 mg/kg or placebo subcutaneously every other day for two weeks. Patients were permitted to continue their baseline laxatives. By day 8, the study drug dose (methylnaltrexone or placebo) could be doubled if patients had fewer than three rescue-free bowel movements (BMs).
The study has clinical applicability for the end-of-life and palliative phases of care.
This was a post-hoc analysis of a two-week double-blind, randomized, placebo-controlled study.
Methylnaltrexone 0.15 mg/kg administered subcutaneously every other day was effective in relieving opioid-induced constipation.
Sixteen percent of patients (10 of 62) in the methylnaltrexone group and 24% (17 of 71) in the placebo group did not complete the study.
Subcutaneous methylnaltrexone 0.15 mg/kg appears to be effective in relieving opioid-induced constipation in a timely and predictable manner without reducing pain control or producing symptoms of opioid withdrawal. If an individual does not respond to the first dose, they may still receive some benefit with additional doses. However, the response rate decreased to 25% for individuals receiving a third dose in this study. Reasons for constipation other than opioid use may need to be looked for in nonresponders.