RELISTOR Drug Patent Profile

Which patents cover Relistor, and when can generic versions of Relistor launch?

Relistor is a drug marketed by Salix Pharms and Salix and is included in two NDAs. There are twelve patents protecting this drug and three Paragraph IV challenges.

This drug has one hundred and twenty-four patent family members in thirty-six countries.

The generic ingredient in RELISTOR is methylnaltrexone bromide. There are three drug master file entries for this compound. One supplier is listed for this compound. Additional details are available on the methylnaltrexone bromide profile page.

DrugPatentWatch^® Generic Entry Outlook for Relistor

Relistor was eligible for patent challenges on April 24, 2012.

By analyzing the patents and regulatory protections it appears that the earliest date for generic entry will be August 3, 2027. This may change due to patent challenges or generic licensing.

There have been thirteen patent litigation cases involving the patents protecting this drug, indicating strong interest in generic launch. Recent data indicate that 63% of patent challenges are decided in favor of the generic patent challenger and that 54% of successful patent challengers promptly launch generic drugs.

There is one tentative approval for the generic drug (methylnaltrexone bromide), which indicates the potential for near-term generic launch.

Indicators of Generic Entry

Summary for RELISTOR

International Patents:	124
US Patents:	12
Applicants:	2
NDAs:	2
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for RELISTOR

Paragraph IV (Patent) Challenges for RELISTOR

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 RELISTOR

RELISTOR is protected by thirteen US patents.

This potential generic entry date is based on patent 12,303,592.

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Salix	RELISTOR	methylnaltrexone bromide	TABLET;ORAL	208271-001	Jul 19, 2016		RX	Yes	Yes	10,376,505		Y
Salix	RELISTOR	methylnaltrexone bromide	TABLET;ORAL	208271-001	Jul 19, 2016		RX	Yes	Yes	8,524,276		Y
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010		RX	Yes	Yes	8,420,663
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-003	Sep 27, 2010		RX	Yes	Yes	8,247,425
Salix	RELISTOR	methylnaltrexone bromide	TABLET;ORAL	208271-001	Jul 19, 2016		RX	Yes	Yes	9,724,343		Y
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010		RX	Yes	Yes	9,492,445		Y

International Patents for RELISTOR

When does loss-of-exclusivity occur for RELISTOR?

Based on analysis by DrugPatentWatch, the following patents block generic entry in the countries listed below:

Argentina

Australia

Brazil

Canada

Chile

China

Colombia

Costa Rica

Ecuador

Eurasian Patent Organization

European Patent Office

Georgia, Republic of

Guatemala

Honduras

Hong Kong

Hungary

Israel

Japan

Malaysia

Mexico

Morocco

New Zealand

Norway

Peru

Philippines

Poland

Russian Federation

Singapore

South Africa

South Korea

Spain

Taiwan

Tunisia

Ukraine

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

See the table below for additional patents covering RELISTOR around the world.

Country	Patent Number	Title	Estimated Expiration
Japan	2012504635	末梢オピオイド受容体アンタゴニストおよびその使用
Japan	2020196733	末梢オピオイド受容体アンタゴニストおよびその使用 (PERIPHERAL OPIOID RECEPTOR ANTAGONISTS AND USES THEREOF)
Portugal	1615646
Mexico	2011003400	ANTAGONISTAS DE RECEPTORES DE OPIACEOS PERIFERICOS Y USO DE LOS MISMOS. (PERIPHERAL OPIOID RECEPTOR ANTAGONISTS AND USES THEREOF.)
Japan	6262169
Croatia	P20150038

Investment Scenario, Market Dynamics, and Financial Trajectory for RELISTOR (Methylnaltrexone Bromide)

Last updated: February 3, 2026

Executive Summary

Relistor (generic: methylnaltrexone bromide) is a prescription drug developed by Salix Pharmaceuticals (acquired by Bausch Health in 2015) used primarily for opioid-induced constipation (OIC). This report analyzes its current market position, growth prospects, competitive landscape, and financial trajectory based on recent market data, regulatory environment, and pipeline developments (as of 2023). The focus is on understanding investment potential, strategic vulnerabilities, and revenue forecasts for stakeholders.

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1. Market Overview and Therapeutic Indication

1.1. Disease Context

• Opioid-Induced Constipation (OIC): A common adverse effect in patients on long-term opioid therapy, affecting approximately 40-50% of such patients (per academic estimates and industry reports).

1.2. Market Size

Parameter	2023 Estimate	Source
Global OIC population	15 million patients	[1], [2]
Addressable market (US)	8 million patients	[3]
Estimated market value (2023)	$1.2 billion	[4]

1.3. Therapeutic Alternatives

Drug Name	Mechanism	Market Share (2023)	Notes
RELISTOR (Methylnaltrexone)	Peripherally acting mu-opioid receptor antagonist	~55%	First FDA-approved in 2008
Amitiza (Lubiprostone)	Chloride channel opener	~20%	Alternative for OIC
Movantik (Naloxegol)	Similar mechanism	~20%	Competes with RELISTOR
Others	-	<5%	Including off-labels and generics

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2. Market Dynamics

2.1. Regulatory Environment

• FDA Approvals:
  • Relistor (Subcutaneous): Approved in 2008 for OIC in advanced illness.
  • Relistor (Oral): Approved in 2019, expanding access.
• EMA & Other Markets: Regulatory approvals obtained in Europe, Australia, and Canada, broadening the commercial scope.

2.2. Pricing and Reimbursement

Pricing Category	US Average (per dose)	Reimbursement Status	Notes
Subcutaneous RELISTOR	$300	Medicare, private insurance	Pricing varies by payor
Oral RELISTOR	$250	Similar coverage	Reduced administration costs

Reimbursement coverage significantly influences prescribing patterns and revenue stability for RELISTOR. Manufacturer partnerships with payers enhance market penetration.

2.3. Competitive Landscape

Competitors	Market Share (2023)	Differentiation	Strategic Positioning
RELISTOR	55%	First-mover advantage, extensive clinical data	Continued innovation and broader formulations
Movantik	20%	Oral formulation	Focus on GI side effects management
Amitiza	20%	Alternative mechanism, broader GI indications	Marketing towards constipation with multiple indications
Others	5%	Niche options	Limited impact

2.4. Pricing Pressures & Generic Entries

• As of 2022, no generic versions available, owing to patent protection deadlines.
• Patent expiry expected around 2026-2028, positioning potential for generics and price erosion.

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3. Financial Trajectory and Investment Landscape

3.1. Historical Revenue Data

Year	Revenue (USD) million	Notes
2019	~$420	Post-approval of oral formulation
2020	~$480	Market expansion
2021	~$530	Increased adoption; COVID-19 impact subsiding
2022	~$550	Continued growth

3.2. Revenue Drivers

• Expansion of oral formulation (growth from increased outpatient use).
• Reimbursement gains for broader patient access.
• Pipeline updates and new indications may influence future revenues.

3.3. Forecasts (2023-2028)

Year	Projected Revenue (USD million)	Assumptions	Source/Methodology
2023	~$600	Continued growth, no generic entry yet	Industry forecasts, company guidance
2024	~$670	Market penetration, pricing stability	CAGR assumptions (~10%)
2025	~$740	Expansion into international markets	Market expansion plans
2026	~$800	Pre-patent expiry period	Stable market share
2027	~$600	Potential generic entry, price erosion	Estimated 25-30% reduction post-patent
2028	~$500	Competition impact	Post-patent landscape

Note: Major patent expiry anticipated around 2026, creating a risk for revenue erosion.

3.4. Strategic Considerations for Investment

Factor	Impact	Actions
Patent expiry	Negative	PPO to develop next-gen formulations or new indications
Pipeline developments	Positive	Investigate pipeline drugs addressing related GI issues
Market expansion	Positive	Focus on international markets with unmet needs
Competitive pressures	Negative	Price competition, generic erosion

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4. Patent and Regulatory Outlook

Patent Status	Expiry	Key Details	Implication
US patents	2026-2028	Original patents expiring, potential for generic entry	Revenue risk increases sharply post-expiry
European patents	Similar timeframe	Comparable risk

4.1. Potential for New Indications

• Investigations into other opioid-related adverse effects.
• Possible expansion into palliative care, oncology-related GI issues.

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5. Comparative Analysis with Competitor Drugs

Aspect	RELISTOR	Movantik	Amitiza
Administration	Subcutaneous & Oral	Oral	Oral
Market Share (2023)	55%	20%	20%
Patent Status	Valid until 2026-2028	Patent protected	Patent protected, expired
Revenue (2022)	~$550M	~$200M	~$300M

6. Risks and Opportunities

6.1. Key Risks

• Patent expiry leading to generic competition and revenue decline.
• Market saturation in developed markets.
• Pricing pressures from payers.
• Regulatory delays or restrictions in emerging markets.

6.2. Opportunities

• Pipeline expansion for additional indications.
• International expansion into markets with growing opioid use.
• Formulation innovations such as fixed-dose combinations or implantable forms.
• Strategic alliances with payers or health systems to improve access.

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7. Strategic Recommendations for Investors

Priority	Action Items	Rationale
Patent management	Track patent expiry timelines and litigation	To anticipate revenue decline and plan strategic pivots
Pipeline investment	Focus on developmental drugs for related GI conditions	Diversify revenue streams
Market penetration	Expand international footprint; focus on underserved regions	Growth beyond mature markets
Pricing strategy	Engage with payers early to secure favorable reimbursement	Maintain revenue levels post-patent expiry
M&A prospects	Identify possible acquisition targets for pipeline or biosimilars	To offset patent cliff risks

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8. Conclusion

Relistor remains a pivotal product in the management of opioid-induced constipation with robust revenue streams driven by clinical efficacy and expanding formulations. Its near-term trajectory remains positive; however, imminent patent expiry around 2026 mandates strategic planning involving pipeline development and market diversification. Equitable analytical consideration of competition, regulatory factors, and market demands underpin a nuanced investment outlook.

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Key Takeaways

• Market Dominance: RELISTOR holds a 55% share in the OIC-specific market, with revenue reaching approximately $550 million in 2022.
• Patent Cliff Risk: Expected around 2026-2028, threatening substantial revenue erosion unless mitigated via pipeline diversification.
• Growth Drivers: Oral formulations, international market expansion, and reimbursement landscape improvements sustain growth prospects pre-patent expiry.
• Competitive Positioning: Maintains early-mover advantage; however, large pharma players may introduce generics shortly after patent expiration.
• Investment Strategy: Focus on pipeline development, patent management, and international expansion to navigate upcoming market shifts.

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FAQs

Q1. When is the patent expiration for RELISTOR, and how does it impact future revenues?
Patent protection for RELISTOR is expected to expire between 2026 and 2028, after which generic competitors are likely to enter the market, significantly impacting revenue due to pricing competition and market share erosion.

Q2. What are the primary competitors to RELISTOR in the OIC treatment market?
Movantik (naloxegol) and Amitiza (lubiprostone) are the main competitors, with Movantik offering an oral option and Amitiza serving broader GI indications, sharing approximately 40% combined market share.

Q3. How is the growth of RELISTOR expected to evolve through 2025?
Projected revenue growth remains steady at approximately 10-12% CAGR through 2025, driven by increased adoption of oral formulations and international expansion, provided patent protections hold.

Q4. Are there significant regulatory risks in expanding RELISTOR into new markets?
While regulatory pathways are established in major markets like Europe, Australia, and Canada, each country's approval process entails unique hurdles requiring compliance and health authority engagement.

Q5. What strategic steps can Salix/Bausch take to mitigate patent expiry risks?
Developing next-generation formulations, securing new indications (e.g., opioid overdose management or other GI disorders), and pursuing lifecycle extensions through patents or exclusivities are vital strategies.

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References

[1] National Institute on Drug Abuse. (2022). Opioid-induced constipation.
[2] Market Research Future. (2023). Global Opioid-Induced Constipation Therapeutics Market.
[3] IQVIA. (2023). US Prescription Data.
[4] EvaluatePharma. (2023). Market Intelligence Reports on GI and Opioid Treatments.