Methylnaltrexone bromide
Relistor · ATC code A06AH01
Also known as: Methylnaltrexoniumbromid, Metilnaltrekson bromür
- Key facts
- Active substance
- Methylnaltrexone bromide
- ATC code
- A06AH01
- Authorisation
- centrally authorised across the EU (EMA)
- Dosage forms
- Relistor 12 mg/0.6 mL solution for injection · Relistor 8 mg solution for injection in pre-filled syringe · Relistor 12 mg solution for injection in pre-filled syringe
- Marketing authorisation holder
- Bausch Health Ireland Limited
- Information as of
- 2026-10-28
Key facts
Methylnaltrexone bromide (Relistor) is a peripherally acting opioid receptor antagonist given by subcutaneous injection for opioid-induced constipation.
What it is used for
- Treatment of opioid-induced constipation in adults aged 18 years and older when response to laxative therapy has not been sufficient.
Dosing
- Adults with chronic pain (except palliative care patients): 12 mg (0.6 mL) subcutaneously as needed, at least 4 doses weekly up to once daily (7 doses weekly); usual laxatives are stopped when starting.
- Palliative care patients with advanced illness: 8 mg (0.4 mL) for 38-61 kg or 12 mg (0.6 mL) for 62-114 kg, usually one dose every other day, added to usual laxatives; outside these weight ranges 0.15 mg/kg (using vials).
- Two consecutive doses 24 hours apart only if there was no bowel movement after the previous day's dose.
- Severe renal impairment (creatinine clearance less than 30 mL/min): reduce from 12 mg to 8 mg for 62 to 114 kg; outside this range reduce the mg/kg dose by 50 %. Not recommended on dialysis or in severe hepatic impairment.
- Inject into upper legs, abdomen or upper arms, rotating sites; can be given without regard to food.
Contraindications
- Hypersensitivity to the active substance or any excipient.
- Known or suspected mechanical gastrointestinal obstruction, increased risk of recurrent obstruction, or acute surgical abdomen (risk of perforation).
Important warnings
- Severe, persistent or worsening symptoms should be reported promptly; with severe or persistent diarrhoea, therapy should not be continued.
- Not for constipation unrelated to opioid use.
- Bowel movements may start rapidly (within 30 to 60 minutes on average).
- Caution with known or suspected lesions of the gastrointestinal tract; GI perforation has been reported.
- Not studied beyond 4 months in patients with advanced illness; use only for a limited period.
Side effects
- Very common: abdominal pain, nausea, diarrhoea and flatulence, generally mild or moderate.
- Common: dizziness, vomiting, opioid-withdrawal-like symptoms (e.g. chills, tremor, hyperhidrosis), injection site reactions.
- Not known: gastrointestinal perforation.
Interactions
- Does not affect the pharmacokinetics of medicines metabolised by CYP450 and is minimally metabolised by CYP enzymes.
Pregnancy and breastfeeding
- Should not be used during pregnancy unless clearly necessary.
- During breast-feeding, a benefit-risk decision between breast-feeding and therapy is required.
Summary of the official product information, written with AI on 2026-10-29. Every number was checked automatically against the original text. Not reviewed by a physician – the full official text is authoritative.
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For patients
Package leaflet, verbatim
This product has no separate US patient information.
Authorisation and brand names by country
Medicines with exactly this active-substance composition, as listed in the national registers – alphabetical and without ranking. Whether a product is currently available is not shown here.
EU – centrally authorised (all member states)
- RelistorBausch Health Ireland Limited · EMEA/H/C/000870
Source: European Medicines Agency (EMA), product information
Brand names in 3 more European countries
- Iceland
- Relistor
- Liechtenstein
- Relistor
- Norway
- Relistor
EMA – Article 57 product data (EU/EEA), 2026-10-29
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Other substances in the same group
Another question about this substance?
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Sources
- European Medicines Agency. Relistor – EPAR, Product Information. 2026-10-28. https://www.ema.europa.eu/en/documents/product-information/relistor-epar-product-information_en.pdf
Editorial: Medelix editorial team · last updated 2026-10-28 · How these pages are made · Report an error
Source: European Medicines Agency (EMA), product information. Not advertising, not a treatment recommendation. For questions about your own treatment, ask your doctor or pharmacist.