Becker, G., Galandi, D., & Blum, H.E. (2007). Peripherally acting opioid antagonists in the treatment of opiate-related constipation: A systematic review. Journal of Pain and Symptom Management, 34, 547-565.doi: 10.1016/j.jpainsymman.2006.12.018
To evaluate evidence on the effectiveness of the peripherally acting mu-receptor antagonists alvimopan and methylnaltrexone in the management of opioid-induced constipation.
Ten studies were appropriate for this review. However, four of the 10 had two or three parts performed in different populations or using different dosing regimens. The differing parts were treated as different studies and assessed individually, yielding 15 studies (10 randomized controlled trials and five phase II studies addressing dose and toxicity).
This systematic review looked mainly at the efficacy of using the peripherally acting opioid antagonists methylnaltrexone (nine studies) and alvimopan (six studies) in managing opioid-induced constipation. Internal validity of the studies was high, indicating methylnaltrexone and alvimopan may be effective in relieving opioid-induced constipation. However, most study participants were healthy volunteers or members of methadone programs.