Methylnaltrexone is a μ-opioid antagonist used for the treatment of opioid-induced constipation in palliative patients that are inadequately responding to laxative therapy. Methylnaltrexone is a pheriphally-acting μ-opioid antagonist that acts on the gastrointestinal tract to decrease opioid-induced constipation without producing analgesic effects or withdrawal symptoms.
- Mechanism
- Curator reviewed
Methylnaltrexone is a pheriphally-acting μ-opioid antagonists that acts on the gastrointestinal tract inhibit opioid-induced decrease in gastric motility and transit time. Because methylnaltrexone is a quaternary derivative of naltrexone, it produces its gastrointestinal effects without producing analgesic effects or withdrawal symptoms as it does not cross the blood-brain-barrier.
- Primary indication
- Treatment of opioids induced constipation in palliative patients that are inadequately responding to laxative therapy.Curator reviewed · 2 structured indications
- Formula / weight
- C21H26NO4 · 356.441 g/mol (avg)
- First approval
- Canada, 2012 · United States, 2008 · European Union, 2016
- Also known as
- MNTX
- Code names
- MRZ-2663 · MRZ 2663BR
- Brand names
Resolves to
JVLBPIPGETUEET-WIXLDOGYSA-OSMILESC[N@+]1(CC2CC2)CC[C@]23[C@H]4OC5=C(O)C=CC(C[C@@H]1[C@]2(O)CCC4=O)=C35What you can answer from here — as of August 30, 2026
Which drugs share a target with Methylnaltrexone, and which of those have an active Phase 3 trial?
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