{"entity":{"id":"methylnaltrexone","kind":"drug","name":"Methylnaltrexone","aka":[],"tldr":"Methylnaltrexone (Relistor) is an injection or tablet that relieves the severe constipation caused by strong painkillers in people with advanced cancer, without blocking the pain relief itself.","summary":"Methylnaltrexone was approved by the FDA in April 2008 for opioid-induced constipation in adults with advanced illness receiving palliative care when laxatives have failed, on two randomised placebo-controlled trials in hospice and palliative populations in which about half of patients had a bowel movement within four hours of the first subcutaneous dose versus around 15% on placebo; indications for chronic non-cancer pain and oral tablets followed in 2014 to 2016. The EU authorised Relistor in 2008. It is a standard second-line option in palliative care guidelines after conventional laxatives; naloxegol and naldemedine are oral alternatives. Abdominal pain, flatulence and nausea are common, and gastrointestinal perforation has been reported in patients with structural bowel disease. Marketed by Salix (Bausch Health).","status":"approved","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Methylnaltrexone","links":[{"label":"MNTX 302 (NEJM 2008)","url":"https://doi.org/10.1056/NEJMoa0707377"},{"label":"US label (DailyMed)","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c488fb7c-0a5b-487c-b452-996809d1cb99"},{"label":"NCI drug page","url":"https://www.cancer.gov/about-cancer/treatment/drugs/methylnaltrexonebromide"},{"label":"EPAR","url":"https://www.ema.europa.eu/en/medicines/human/EPAR/relistor"}],"tags":["nci-list","supportive"],"related":[],"cancers":[],"sections":[],"technologies":["palliative-care","pain-management"],"targets":["oprm1"],"drugs":[],"companies":["bausch-health"],"institutions":[],"pathways":[],"terms":[],"trials":["mntx-302"],"people":[],"bottlenecks":[],"keyPapers":["paper-mntx-302-thomas-nejm-2008"],"journals":[],"dependsOn":[],"notes":[],"brand":"Relistor","modality":"Peripherally acting mu-opioid receptor antagonist","supportive":true,"mechanism":"Quaternary derivative of naltrexone that does not cross the blood-brain barrier; blocks mu-opioid receptors in the gut to reverse opioid-induced constipation without reducing analgesia or precipitating withdrawal.","approvals":[{"region":"US","year":2008,"indication":"Opioid-induced constipation in advanced illness receiving palliative care (chronic non-cancer pain and oral tablets added 2014 to 2016)"},{"region":"EU","year":2008,"indication":"Opioid-induced constipation in advanced illness receiving palliative care when laxatives are insufficient (Relistor)"}],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/methylnaltrexone/","neighbours":{"technology":[{"id":"pain-management","kind":"technology","name":"Cancer pain management","route":"/technologies/pain-management/"},{"id":"palliative-care","kind":"technology","name":"Early integrated palliative care","route":"/technologies/palliative-care/"}],"target":[{"id":"oprm1","kind":"target","name":"Mu-opioid receptor","route":"/targets/oprm1/"}],"company":[{"id":"bausch-health","kind":"company","name":"Bausch Health","route":"/companies/bausch-health/"}],"trial":[{"id":"mntx-302","kind":"trial","name":"MNTX 302","route":"/trials/mntx-302/"}],"paper":[{"id":"paper-mntx-302-thomas-nejm-2008","kind":"paper","name":"Methylnaltrexone for opioid-induced constipation in advanced illness (MNTX 302)","route":"/key-papers/paper-mntx-302-thomas-nejm-2008/"}],"drug":[{"id":"fentanyl","kind":"drug","name":"Fentanyl (transmucosal, for breakthrough cancer pain)","route":"/drugs/fentanyl/"}]}}