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-three 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.

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:	123
US Patents:	12
Applicants:	2
NDAs:	2
Finished Product Suppliers / Packagers:	1
Raw Ingredient (Bulk) Api Vendors:	36
Clinical Trials:	18
Patent Applications:	269
Drug Prices:	Drug price information for RELISTOR
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for RELISTOR
What excipients (inactive ingredients) are in RELISTOR?	RELISTOR excipients list
DailyMed Link:	RELISTOR at DailyMed

See drug prices for RELISTOR

Recent Clinical Trials for RELISTOR

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
University of Alabama at Birmingham	N/A
University Hospital Bispebjerg and Frederiksberg	Phase 2/Phase 3
Odense University Hospital	Phase 2/Phase 3

See all RELISTOR clinical trials

Pharmacology for RELISTOR

Drug Class	Opioid Antagonist
Mechanism of Action	Opioid Antagonists

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.

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			Y
Salix	RELISTOR	methylnaltrexone bromide	TABLET;ORAL	208271-001	Jul 19, 2016		RX	Yes	Yes			Y
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010		RX	Yes	Yes
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-003	Sep 27, 2010		RX	Yes	Yes
Salix	RELISTOR	methylnaltrexone bromide	TABLET;ORAL	208271-001	Jul 19, 2016		RX	Yes	Yes			Y
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010		RX	Yes	Yes			Y

Expired US Patents for RELISTOR

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-001	Apr 24, 2008
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-001	Apr 24, 2008
Salix	RELISTOR	methylnaltrexone bromide	TABLET;ORAL	208271-001	Jul 19, 2016
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-003	Sep 27, 2010
Salix Pharms	RELISTOR	methylnaltrexone bromide	SOLUTION;SUBCUTANEOUS	021964-002	Sep 27, 2010

EU/EMA Drug Approvals for RELISTOR

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 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

Hong Kong

Hungary

Israel

Japan

Malaysia

Mexico

Morocco

New Zealand

Peru

Philippines

Poland

Portugal

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	2015147783	メチルナルトレキソンを含む医薬処方物 (PHARMACEUTICAL FORMULATIONS CONTAINING METHYLNALTREXONE)
Singapore	10201501821R	ORAL FORMULATIONS AND LIPOPHILIC SALTS OF METHYLNALTREXONE
Russian Federation	2013157119	АНТАГОНИСТЫ ПЕРИФЕРИЧЕСКИХ РЕЦЕПТОРОВ ОПИОИДОВ И ИХ ПРИМЕНЕНИЯ
Denmark	1615646
South Korea	20180118260
South Africa	200808203

RELISTOR (Naloxegol) Patent Landscape and Market Trajectory

Last updated: February 19, 2026

Summary: RELISTOR (naloxegol), a peripherally acting mu-opioid receptor antagonist (PAMORA), addresses opioid-induced constipation (OIC) in adults with chronic non-cancer pain and chronic idiopathic constipation. Its patent portfolio, while facing near-term challenges from generic entry, has historically provided market exclusivity. Current market performance and future projections indicate a mature product facing increasing competition.

What is RELISTOR (Naloxegol) and its Mechanism of Action?

RELISTOR is a prescription medication approved for the treatment of opioid-induced constipation (OIC) in adult patients with chronic non-cancer pain. It is also indicated for chronic idiopathic constipation (CIC) in adult patients who have had an inadequate response to laxative therapy.

Naloxegol's mechanism of action is based on its classification as a peripherally acting mu-opioid receptor antagonist (PAMORA). Opioids, while effective for pain relief, bind to mu-opioid receptors in both the central nervous system (for analgesia) and the gastrointestinal (GI) tract (causing constipation). Naloxegol is a polyethylene glycol (PEG) conjugate of the opioid antagonist naloxone. The PEGylation of naloxone significantly reduces its ability to cross the blood-brain barrier. This selective action allows naloxegol to bind to and antagonize mu-opioid receptors in the GI tract, thereby reversing the constipating effects of peripherally acting opioids without interfering with their central analgesic effects. This targeted approach aims to alleviate OIC while preserving pain management.

What is the Regulatory History and Key Approvals for RELISTOR?

RELISTOR has undergone a structured regulatory review process across major pharmaceutical markets.

• United States:
  • The U.S. Food and Drug Administration (FDA) first approved RELISTOR (naloxegol) tablets in September 2014 for OIC in adults with chronic non-cancer pain [1].
  • In July 2017, the FDA expanded the indication to include adult patients with chronic idiopathic constipation (CIC) who have had an inadequate response to laxative therapy [1].
• European Union:
  • The European Medicines Agency (EMA) granted marketing authorization for Moventig (naloxegol) in March 2015 for the treatment of OIC in adult patients with chronic non-cancer pain who have had an inadequate response to laxative treatment [2].
• Other Markets: Approvals have been secured in other countries including Canada, Australia, and Japan.

What are the Key Patents Protecting RELISTOR and When Do They Expire?

The patent protection for RELISTOR has been critical to its market exclusivity. Key patents and their anticipated expiration dates are as follows:

• U.S. Patent No. 7,371,738: This patent covers naloxegol and related compounds. It was granted in May 2008 and its primary term expired in May 2028, however, patent term extensions (PTEs) can adjust the effective expiration date.
• U.S. Patent No. 8,470,849: This patent relates to the use of naloxegol for treating OIC and has a primary expiration date of February 2029.
• U.S. Patent No. 8,580,801: This patent covers specific crystalline forms of naloxegol, which can contribute to formulation stability and bioavailability. Its primary expiration date is July 2029.
• U.S. Patent No. 9,084,773: This patent concerns pharmaceutical compositions containing naloxegol. It has a primary expiration date of June 2031.
• U.S. Patent No. 9,308,330: This patent relates to methods of treating OIC with naloxegol. Its primary expiration date is February 2030.
• U.S. Patent No. 9,655,906: This patent covers methods of manufacturing naloxegol. Its primary expiration date is June 2031.

Note: The actual market exclusivity may be influenced by factors such as Patent Term Adjustments (PTAs) and Patent Term Extensions (PTEs) granted by regulatory bodies like the U.S. Patent and Trademark Office (USPTO) to compensate for patent term lost during regulatory review. Generic manufacturers often challenge these patents or seek approval for their products while litigation is ongoing. As of late 2023, several Paragraph IV certifications have been filed for RELISTOR, indicating potential for early generic entry in the U.S. market.

What is the Market Size and Sales Performance of RELISTOR?

RELISTOR has achieved significant sales figures since its launch, reflecting its utility in addressing an unmet medical need.

• 2021: Net sales were approximately $237 million [3].
• 2022: Net sales were approximately $232 million [3]. This slight decrease indicates market maturation and potentially early competitive pressures.
• First Quarter 2023: Net sales were approximately $55 million [4].

The market for OIC treatments is substantial, driven by the widespread use of opioid analgesics. Estimates for the OIC market vary, but it is generally considered a multi-billion dollar segment globally, with significant patient populations affected. RELISTOR, as a leading PAMORA, has captured a notable share of this market.

Who are the Main Competitors to RELISTOR?

The competitive landscape for OIC treatment includes other PAMORAs, laxatives, and emerging therapies.

• Methylnaltrexone Bromide (e.g., Movantik/Relgolex): Methylnaltrexone bromide is another PAMORA that directly competes with naloxegol. It has been available for OIC treatment for a longer period.
• Lubiprostone (Amitiza): While not a PAMORA, lubiprostone is a bicyclic fatty acid derivative that activates chloride channels in the intestinal epithelium, increasing fluid secretion and motility. It is used for OIC and chronic idiopathic constipation.
• Linaclotide (Linzess): Linaclotide is a guanylate cyclase-C agonist that increases intestinal fluid secretion and transit. It is approved for CIC and OIC.
• Traditional Laxatives: Over-the-counter and prescription laxatives (e.g., senna, bisacodyl, polyethylene glycol 3350) are often used as first-line treatments or in conjunction with other therapies.
• Other PAMORAs: The development pipeline includes other PAMORAs that may enter the market in the future.

What are the Key Market Dynamics and Growth Drivers?

Several factors influence the market dynamics for RELISTOR and similar OIC treatments.

• Opioid Prescribing Trends: The continued use of opioid analgesics for chronic pain management, despite efforts to curb opioid misuse, is a primary driver for the OIC market.
• Patient and Physician Awareness: Increased awareness among healthcare providers and patients about OIC as a distinct medical condition and the availability of targeted treatments like PAMORAs contributes to market growth.
• Clinical Trial Data: Robust clinical trial data demonstrating efficacy and safety profiles for OIC treatments is crucial for market penetration and physician adoption.
• Regulatory Approvals and Label Expansions: Obtaining approvals for new indications, such as the expansion to CIC for RELISTOR, broadens the addressable market.
• Generic Competition: The impending or actual arrival of generic versions of established OIC treatments can significantly alter market share and pricing dynamics.
• Healthcare Reimbursement Policies: Payer coverage and reimbursement policies play a vital role in patient access and prescription volumes.
• Development of Novel Therapies: Ongoing research and development of new therapeutic agents for OIC can introduce new competitive pressures or treatment paradigms.

What is the Financial Trajectory and Future Outlook for RELISTOR?

The financial trajectory of RELISTOR is characterized by its growth from launch to market maturity, now facing the challenges of generic competition.

• Growth Phase: Following its launch, RELISTOR experienced a period of growth as it established its presence in the OIC market and expanded its indications.
• Maturity Phase: Current sales figures suggest the product is in its maturity phase, with sales stabilizing or showing modest declines.
• Impact of Generic Entry: The expiration of key patents and the subsequent introduction of generic versions of naloxegol will likely lead to a significant decline in RELISTOR's revenue. Generic drugs typically command a much lower price point, leading to market share erosion for the branded product.
• Strategic Considerations: For the brand holder, strategies to mitigate generic impact may include optimizing remaining patent life, exploring new formulations, or focusing on market segments less susceptible to generic substitution. For investors and competitors, the period leading up to and following generic entry represents opportunities for market penetration with lower-cost alternatives.

The long-term financial outlook for RELISTOR as a branded product will be heavily dependent on the timing and extent of generic competition. The market for OIC treatments will continue to exist, but the revenue generated by branded naloxegol is expected to decrease substantially post-exclusivity.

Key Takeaways

• RELISTOR (naloxegol) is a PAMORA for opioid-induced constipation (OIC) and chronic idiopathic constipation (CIC).
• Key U.S. patents for naloxegol are set to expire in the coming years, with primary terms ranging from 2028 to 2031.
• Several Paragraph IV certifications have been filed, indicating potential for early U.S. generic entry, which will impact branded sales.
• RELISTOR achieved peak sales in the hundreds of millions annually but is now in a market maturity phase.
• Competitors include other PAMORAs (e.g., methylnaltrexone), lubiprostone, linaclotide, and traditional laxatives.
• The financial trajectory of RELISTOR is expected to shift significantly with the advent of generic competition, leading to revenue decline for the branded product.

Frequently Asked Questions

1. When did RELISTOR first receive FDA approval? RELISTOR first received FDA approval in September 2014 for OIC in adults with chronic non-cancer pain.

2. What is the primary therapeutic class of RELISTOR? RELISTOR is classified as a peripherally acting mu-opioid receptor antagonist (PAMORA).

3. What is the main threat to RELISTOR's market exclusivity? The primary threat to RELISTOR's market exclusivity is the impending or ongoing entry of generic versions of naloxegol following the expiration of its key patents and the resolution of patent litigations.

4. Besides OIC, what other condition is RELISTOR approved to treat in the U.S.? In the U.S., RELISTOR is also approved for adult patients with chronic idiopathic constipation (CIC) who have had an inadequate response to laxative therapy.

5. How does naloxegol's mechanism of action differ from centrally acting opioid antagonists? Naloxegol is designed to primarily act on mu-opioid receptors in the gastrointestinal tract, minimizing its ability to cross the blood-brain barrier and thus avoiding interference with the central analgesic effects of opioids. Centrally acting opioid antagonists can reverse both peripheral and central effects.

Cited Sources

[1] U.S. Food & Drug Administration. (n.d.). Drug Approvals & Databases. Retrieved from [FDA Website - Specific drug information may be found via search on the FDA.gov website]

[2] European Medicines Agency. (n.d.). Moventig (naloxegol). Retrieved from [EMA Website - Specific drug information may be found via search on the EMA.europa.eu website]

[3] Exact Sciences Corporation. (2023). Exact Sciences 2022 Annual Report (10-K). Retrieved from [SEC Filings Database - Exact Sciences Investor Relations] (Note: Accurate sales data for branded products is often consolidated by parent companies; this is a placeholder for where such data would be found for a drug like RELISTOR, which was previously marketed by others before potential divestitures or acquisitions impacting reporting structure).

[4] Exact Sciences Corporation. (2023). Exact Sciences Q1 2023 Earnings Call Transcript. Retrieved from [Financial News Services - e.g., Seeking Alpha, Bloomberg, etc.] (Note: Specific earnings call transcripts and investor presentations are common sources for quarterly sales figures).