methylnaltrexone bromide - Profile

What are the generic sources for methylnaltrexone bromide and what is the scope of patent protection?

Methylnaltrexone bromide is the generic ingredient in two branded drugs marketed by Actavis Llc, Mylan Labs Ltd, Salix Pharms, and Salix, and is included in four NDAs. There are twelve patents protecting this compound and three Paragraph IV challenges. Additional information is available in the individual branded drug profile pages.

Methylnaltrexone bromide has one hundred and twenty-four patent family members in thirty-six countries.

There is one tentative approval for this compound.

Summary for methylnaltrexone bromide

International Patents:	124
US Patents:	12
Tradenames:	2
Applicants:	4
NDAs:	4
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for methylnaltrexone bromide

DrugPatentWatch^® Estimated Loss of Exclusivity (LOE) Date for methylnaltrexone bromide

Dosage:

SOLUTION;SUBCUTANEOUS

Dosage:

TABLET;ORAL

^*The generic entry opportunity date is the latter of the last compound-claiming patent and the last regulatory exclusivity protection. Many factors can influence early or later generic entry. This date is provided as a rough estimate of generic entry potential and should not be used as an independent source.

Generic filers with tentative approvals for METHYLNALTREXONE BROMIDE

Applicant	Application No.	Strength	Dosage Form
		12MG/0.6ML	SOLUTION;SUBCUTANEOUS

The 'tentative' approval signifies that the product meets all FDA standards for marketing, and, but for the patents / regulatory protections, it would approved.

Paragraph IV (Patent) Challenges for METHYLNALTREXONE BROMIDE

Tradename	Dosage	Ingredient	Strength	NDA	ANDAs Submitted	Submissiondate
RELISTOR	Tablets	methylnaltrexone bromide	150 mg	208271	1	2016-09-06
RELISTOR	Injection	methylnaltrexone bromide	8 mg/0.4 mL, Single Dose Prefilled Syringe	021964	1	2015-09-08
RELISTOR	Injection	methylnaltrexone bromide	12 mg/0.6 mL, Single Dose Vial	021964	1	2015-07-22

US Patents and Regulatory Information for methylnaltrexone bromide

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Actavis Llc	METHYLNALTREXONE BROMIDE	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	208112-001	Aug 26, 2024		DISCN	No	No
Actavis Llc	METHYLNALTREXONE BROMIDE	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	208112-002	Aug 26, 2024		DISCN	No	No
Mylan Labs Ltd	METHYLNALTREXONE BROMIDE	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	208592-001	May 28, 2025		DISCN	No	No
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010		RX	Yes	Yes
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010		RX	Yes	Yes			Y
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010		RX	Yes	Yes			Y

Expired US Patents for methylnaltrexone bromide

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-001	Apr 24, 2008
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-003	Sep 27, 2010
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-001	Apr 24, 2008
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-001	Apr 24, 2008

EU/EMA Drug Approvals for methylnaltrexone bromide

Company	Drugname	Inn	Product Number / Indication	Status	Generic	Biosimilar	Orphan	Marketing Authorisation	Marketing Refusal
Bausch Health Ireland Limited	Relistor	methylnaltrexone bromide	EMEA/H/C/000870Treatment of opioid-induced constipation in advanced-illness patients who are receiving palliative care when response to usual laxative therapy has not been sufficient.	Authorised	no	no	no	2008-07-01

International Patents for methylnaltrexone bromide

Country	Patent Number	Title	Estimated Expiration
Argentina	080491
Australia	2011224275
Brazil	112012022873
Canada	2789798
Chile	2012002192
China	102918039

Investment Scenario & Fundamentals Analysis for Methyl naltrexone bromide (Relistor) Patents, Exclusivity, Litigation, and Generic/Biosimilar Risk

Last updated: July 10, 2026

Methyl naltrexone bromide is an oral peripherally acting mu-opioid receptor antagonist used for opioid-induced constipation (OIC). The U.S. exclusivity and generic-entry risk depend on Orange Book patent coverage and any later-filed formulation or method-of-use patents. On the available basis in this dataset, no complete, citation-backed Orange Book and litigation record can be produced for methyl naltrexone bromide, so a complete investment thesis with patent dates, Paragraph IV exposure, and FDA pathway timing cannot be finalized without that record.

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What is methyl naltrexone bromide’s current market position and revenue exposure?

No Orange Book, FDA approval history, or U.S. commercial timeline data is available in the provided context to quantify (1) current brand usage, (2) revenue trajectory, (3) payer mix, (4) dispensing share, or (5) contract/wholesale dynamics that drive investment case viability.

Key commercial drivers to anchor an investment model

• OIC prevalence and opioid prescribing trends.
• Formulary behavior for second-line OIC agents (access, prior authorization, step therapy).
• Competing product category mix and price erosion from generics.

Competitive set that typically pressures value

• Other peripherally acting mu-opioid receptor antagonists for OIC:
  • naldemedine
  • naloxegol
  • methylnaltrexone subcutaneous (the same active ingredient portfolio typically has differentiated dosing routes)

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What patents protect methyl naltrexone bromide in the U.S., and how many are enforceable?

A complete patent estate analysis requires a current Orange Book listing for each U.S. NDA and each listed patent (including application/patent numbers, claim coverage type, and expiration). That dataset is not present here, so the number of enforceable patents, their expiration dates, and claim scope cannot be stated.

What the investment-grade patent estate must include

• Drug substance patents (active ingredient)
• Drug product/formulation patents (dosage form, composition, release profile)
• Method-of-use patents (OIC endpoints, patient populations, dosing regimens)
• Manufacturing method patents (if listed)

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When does methyl naltrexone bromide lose exclusivity in the U.S.?

An exclusivity timeline requires:

• NDA/ANDA-level regulatory exclusivities (marketing exclusivity, 5-year drug exclusivity, 3-year novelty, pediatric exclusivity)
• Orange Book patent expiration dates
• Any recent FDA approvals that extend the reference product timeline (including lifecycle management)

No FDA exclusivity or Orange Book timeline data is provided here, so an exclusivity-loss date cannot be produced.

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Which companies can launch generics of methyl naltrexone bromide, and what Paragraph IV risks exist?

A generics risk assessment requires:

• Identifying ANDA filers
• Determining whether any Paragraph IV certifications exist
• Mapping any court filings, stays, and settlements

No ANDA Paragraph IV, court docket entries, or settlement terms are available in the provided context, so generic entry risk cannot be quantified.

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What patent litigation affects methyl naltrexone bromide, and what are the settlement outcomes?

A litigation-focused investment section depends on:

• Filed suits under 35 U.S.C. § 271(e)(2)
• Claim construction rulings
• Enforceability findings
• Settlement dates and “enter-at” designations (where applicable)

No litigation record is available here, so settlement outcomes and launch timing cannot be stated.

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What is the Orange Book status of methyl naltrexone bromide?

Orange Book status requires the NDA number(s) for the methyl naltrexone bromide product and the exact patent list with:

• Patent numbers
• Claim types (drug substance vs drug product vs method)
• Expiration dates
• Listing status (active vs expired)

This Orange Book table cannot be produced from the provided information.

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How does methyl naltrexone bromide compare with naloxegol and naldemedine on lifecycle and IP durability?

A durability comparison requires patent-by-patent analysis across competitors and their Orange Book estates. Without the methyl naltrexone bromide Orange Book and the competitors’ listing records in the dataset, a quantified durability ranking cannot be created.

Typical comparison metrics for an investment screen

• Remaining patent runway in the U.S.
• Formulation lifecycle extensions
• Method-of-use expansion attempts
• Litigation frequency and claim-level strength

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What formulations of methyl naltrexone bromide are protected, and what changes could enable a “non-infringing” generic?

Formulation IP barriers require:

• Composition claims
• Pharmaceutical form constraints (tablet vs solution, strength-specific claims)
• Excipients and manufacturing parameters

No formulation patent claim text or Orange Book formulation listing is included here, so the ability for a generic to design around cannot be assessed.

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What generic entry risks exist for methyl naltrexone bromide by dosage form and route?

For route-specific risk:

• Oral vs subcutaneous methyl naltrexone products must be handled separately.
• Each has distinct patent listings and generic pathways.

No route/dosage form-specific Orange Book coverage is available here, so a dosage-form risk map cannot be created.

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How strong is the patent estate for methyl naltrexone bromide based on enforceability signals?

Enforceability signals require:

• Court outcomes
• Inventorship validity patterns
• Whether patents are maintained through claim amendments and survive typical novelty/obviousness scrutiny

No litigation or claim-interpretation record is present here, so patent-strength scoring cannot be produced.

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FDA pathway fundamentals: what NDA/label scope governs methyl naltrexone bromide’s exclusivity and labeling protections?

An FDA fundamentals section needs:

• Approval date(s)
• Label indications and limitations
• Changes to dosing, patient populations, and contraindications over time
• Pediatric exclusivity triggers (if any)

No approval record is provided here.

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Investment scenario: does methyl naltrexone bromide offer a defensible long-run cash flow profile?

A defensible cash-flow profile for an older small molecule depends on:

• Remaining enforceable U.S. patent life
• Presence of “hard” litigation or settlements controlling generic entry
• Continued market access advantages (payer preference, administration convenience)

No remaining enforceable patent runway, generic-control terms, or current market position data are available in the provided context. As a result, an investment scenario with cash-flow timing and risk-adjusted entry probability cannot be constructed.

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Key Takeaways

• Methyl naltrexone bromide’s investment fundamentals hinge on U.S. Orange Book patent runway, exclusivity periods, and any Paragraph IV litigation or settlements.
• The provided context does not include the necessary Orange Book listings, FDA exclusivity dates, ANDA Paragraph IV records, or litigation outcomes to produce an investment-grade timeline or generic-entry risk model.
• A complete patent-by-patent and FDA-by-FDA investment assessment cannot be generated from the available information.

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FAQs

1. What determines whether methyl naltrexone bromide generics face an FDA stay?
2. How do method-of-use patents on opioid-induced constipation affect generic design-around?
3. Does formulation IP (excipients, release control, tablet characteristics) block simple ANDA workarounds for methyl naltrexone bromide?
4. What role do settlements play in setting the generic launch date for OIC products?
5. How does labeling scope change the economic value of an older OIC brand like methyl naltrexone bromide?

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References (APA)

1. (No cited sources were provided in the prompt.)