Is Methylnaltrexone approved by the US FDA?

Drugs@FDA lists 4 application product lines for Methylnaltrexone, including RELISTOR (Prescription); RELISTOR (Prescription); METHYLNALTREXONE BROMIDE (Discontinued); METHYLNALTREXONE BROMIDE (Discontinued).

Is Methylnaltrexone authorised in the European Union?

EMA lists 1 centrally authorised medicine containing Methylnaltrexone: Relistor.

Are there safety signals or safety updates for Methylnaltrexone?

US FDA: 1 entry (latest 2017-05-16).

Active substance

Methylnaltrexone

US FDA 4
EMA 1
Health Canada 1
NHS prices 1
Safety 1

Open in the medicines table

US FDA United States — FDA approvals (Drugs@FDA)

Product	Strength	Form · route	Applicant	Status	First approved
RELISTOR	12MG/0.6ML (12MG/0.6ML); 8MG/0.4ML (8MG/0.4ML)	solution · subcutaneous	SALIX PHARMS	Prescription	24 Apr 2008
RELISTOR	150MG	tablet · oral	SALIX	Prescription	19 Jul 2016
METHYLNALTREXONE BROMIDE	8MG/0.4ML (8MG/0.4ML); 12MG/0.6ML (12MG/0.6ML)	solution · subcutaneous	ACTAVIS LLC	Discontinued	26 Aug 2024
METHYLNALTREXONE BROMIDE	12MG/0.6ML (12MG/0.6ML)	solution · subcutaneous	MYLAN LABS LTD	Discontinued	28 May 2025

EMA European Union — centrally authorised medicines

Relistor Bausch Health Ireland Limited · Authorised · authorised 1 Jul 2008 · ATC A06AH01

Therapeutic indication (EMA)

Treatment of opioid-induced constipation in advanced-illness patients who are receiving palliative care when response to usual laxative therapy has not been sufficient.

Canada Canada — marketed products (Health Canada)

Brand	DIN	Strength	Form · route	Company
RELISTOR	02308215	20 MG / ML	SOLUTION · SUBCUTANEOUS	SALIX PHARMACEUTICALS INC

Prices — United States and England

Source	Product as listed	Price	Unit / pack	Date
NHS Drug Tariff	Methylnaltrexone bromide 12mg/0.6ml solution for injection vials	£147.35	7 vial	1 Oct 2026

NADAC: average price US retail pharmacies pay to buy the medicine. NHS Drug Tariff Part VIIIA: basic price reimbursed to pharmacies in England and Wales.

Safety signals and safety-related labeling changes

US FDA 16 May 2017 RELISTOR — safety-related labeling change
Labeling sections changed: Adverse Reactions; Drug Interactions; Use in Specific Populations

All safety entries for methylnaltrexone →

Values as published by each source: SFDA human drug list (4-2026, as published by the Council of Health Insurance; indications from the CHI Daman Drug Formulary), Drugs@FDA, EMA medicines data, Health Canada Drug Product Database (Open Government Licence – Canada), CMS NADAC, NHS Drug Tariff Part VIIIA (NHSBSA Copyright, Open Government Licence v3.0), WHO Model List of Essential Medicines (CC BY 3.0 IGO; regrouped by active substance, not created by WHO), EMA PRAC, US FDA safety-related labeling changes and MHRA Drug Safety Update (Open Government Licence v3.0). Sources and reuse. Not a substitute for the official registers or the product information.