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Methylnaltrexone (MNTX)
Methylnaltrexone is a peripheral mu-opioid receptor antagonist that blocks opioid receptors in the gastrointestinal tract without crossing the blood-brain barrier, thereby reversing opioid-induced constipation.
Methylnaltrexone is a peripheral mu-opioid receptor antagonist that blocks opioid receptors in the gastrointestinal tract without crossing the blood-brain barrier, thereby reversing opioid-induced constipation. Used for Opioid-induced constipation in patients with chronic non-cancer pain, Opioid-induced constipation in patients with advanced illness receiving palliative care.
At a glance
| Generic name | Methylnaltrexone (MNTX) |
|---|---|
| Also known as | Relistor®, Relistor |
| Sponsor | Bausch Health Americas, Inc. |
| Drug class | Peripheral mu-opioid receptor antagonist |
| Target | Mu-opioid receptor (peripheral) |
| Modality | Small molecule |
| Therapeutic area | Gastroenterology / Pain Management |
| Phase | FDA-approved |
Mechanism of action
Methylnaltrexone is a quaternary amine derivative of naltrexone that selectively antagonizes mu-opioid receptors located in the peripheral nervous system of the gastrointestinal tract. Because it is highly polar and does not cross the blood-brain barrier, it blocks the constipating effects of opioids on the gut while preserving the analgesic and other central nervous system effects of opioid therapy. This mechanism allows patients on chronic opioid therapy to maintain pain relief while restoring normal bowel function.
Approved indications
- Opioid-induced constipation in patients with chronic non-cancer pain
- Opioid-induced constipation in patients with advanced illness receiving palliative care
Common side effects
- Abdominal pain
- Diarrhea
- Nausea
- Flatulence
- Dizziness
Key clinical trials
- RELISTOR's Effects on Opioid-Induced Constipation
- Chronic Widespread Pain in HIV: Novel Mechanisms and Therapeutics (NA)
- Methylnatrexone In Resectable Head and Neck Squamous Cell Carcinoma (MINK). A "Window of Opportunity" Pilot Study. (PHASE4)
- Methylnaltrexone vs Naloxegol in the Treatment of Opioid-Induced Constipation (PHASE4)
- Effects of Peripherally Acting µ-opioid Receptor Antagonists on Acute Pancreatitis (PHASE2, PHASE3)
- Naloxone and Intravenous Methylnaltrexone Effects on Bladder Function (PHASE1)
- Naloxegol to Prevent Lower Gastrointestinal Paralysis in Critically Ill Adults Administered Opioids (PHASE4)
- Dasatinib, Bevacizumab, Paclitaxel in Patients With Advanced Malignancies (PHASE1)
Primary sources
Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.
| Source | Used for |
|---|---|
| ClinicalTrials.gov | Trial enrolment, design, endpoints, results |
Competitive intelligence
For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:
- Methylnaltrexone (MNTX) CI brief — competitive landscape report
- Methylnaltrexone (MNTX) updates RSS · CI watch RSS
- Bausch Health Americas, Inc. portfolio CI