Methylnaltrexone or laxatives for the Management of Opioid-induced Constipation among Palliative Patients on Opioid Therapy: Evidencebased Review

Abstract

Constipation is a common symptom in advanced cancer patients. Studies have demonstrated that 40 to 80% of patients on a palliative care service have constipation, this proportion increases to ≥ 90% when patients are treated with opioids. Opioids are very effective analgesics, frequently prescribed in cancer pain, despite proven analgesic efficacy; the use of opioids is commonly associated with frequently dose-limiting constipation that seriously impacts on patients’ quality of life, almost all patients on opioids report constipation as the major side-effect. The aim of this article is to determine the effectiveness of methylnaltrexone and laxatives in the management of opioidinduced constipation among cancer patients in palliative care setting, with focus on randomized clinical trials. A comprehensive and extensive online database search of Science Direct Database, PubMed, Springer Online Database, and HINARI/WHO Database was conducted; also reference lists of related studies were searched, six studies fulfilling the inclusion criteria from 1991 to 2009 were selected and formed the basis for this paper. In three studies the laxatives lactulose, senna, co danthramer, misrakasneham, and magnesium hydroxide with liquid paraffin were evaluated, in three methylnaltrexone. In studies comparing the different laxatives evidence was inconclusive. Evidence on subcutaneous methylnaltrexone was clearer; evidence on laxatives for management of constipation remains limited due to insufficient RCTs. Ultimately it can be suggested from the data presented here that subcutaneous methylnaltrexone is effective in inducing laxation in palliative care patients with opioid-induced constipation and where conventional laxatives have failed.