# MNTX 302

Source: https://onco.cc/trials/mntx-302/  
OnCo record `mntx-302` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

MNTX 302 showed that a gut-only opioid blocker injected under the skin produced a bowel movement within four hours in about half of people with advanced illness on strong painkillers, against about one in seven on placebo, without weakening pain relief; it was one of the two trials behind the US approval of Relistor.

## Summary

MNTX 302 was a randomised, double-blind, placebo-controlled phase 3 trial of subcutaneous methylnaltrexone in adults with advanced illness and opioid-induced constipation who had not responded to stable laxatives. Patients received methylnaltrexone 0.15 mg per kilogram or placebo every other day for two weeks. The coprimary endpoints were laxation within four hours of the first dose and laxation within four hours after two or more of the first four doses.

In the NEJM 2008 report, 48 percent of patients on methylnaltrexone had laxation within four hours of the first dose versus 15 percent on placebo, and 52 percent versus 8 percent had laxation without a rescue laxative within four hours after two or more of the first four doses (P less than 0.001 for both). Median time to laxation was significantly shorter on methylnaltrexone. Abdominal pain and flatulence were the most common adverse events, and the paper reported no evidence of central opioid withdrawal or change in pain scores.

The US Relistor label names the same study Study 5 and analyses the same 133 patients (62 Relistor, 71 placebo); across its two advanced-illness studies most patients had a primary diagnosis of incurable cancer. The registry lists organisation id MNTX 302 as a completed phase 3 with an actual enrolment of 134. The programme treats opioid-induced constipation in advanced illness rather than a named cancer, so the record carries no cancer ids.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-24
- Also known as: Study 5; MNTX302
- Registry id: NCT00402038
- Phase: 3
- Setting: Advanced illness with opioid-induced constipation despite stable opioids and laxatives: subcutaneous methylnaltrexone 0.15 mg per kilogram every other day for two weeks versus placebo
- Sponsor: Bausch Health Americas (originally Progenics and Wyeth)
- Enrolled: 133
- Result: Laxation within four hours of the first dose 48% vs 15% on placebo; laxation after two or more of the first four doses 52% vs 8% (P<0.001 for both).
- Outcomes: Laxation within 4 hours of the first dose: Methylnaltrexone 0.15 mg/kg 48% vs Placebo 15%; Laxation without rescue laxative within 4 hours after two or more of the first four doses: Methylnaltrexone 0.15 mg/kg 52% vs Placebo 8%
- Replication: The single-dose companion pivotal MNTX 301 (NCT00401362, Slatkin 2009; Relistor label Study 4) reported the same direction of effect and is not yet recorded here.

## Sources

- ClinicalTrials.gov NCT00402038: https://clinicaltrials.gov/study/NCT00402038
- NEJM 2008: https://doi.org/10.1056/NEJMoa0707377
- Relistor label (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c488fb7c-0a5b-487c-b452-996809d1cb99

## Connected records

- fronts: [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- drugs: [Methylnaltrexone](https://onco.cc/drugs/methylnaltrexone/)
- companies: [Bausch Health](https://onco.cc/companies/bausch-health/)
- key papers: [Methylnaltrexone for opioid-induced constipation in advanced illness (MNTX 302)](https://onco.cc/key-papers/paper-mntx-302-thomas-nejm-2008/)

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