ENTEREG Drug Patent Profile

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

Entereg is a drug marketed by Cubist Pharms and is included in one NDA. There is one patent protecting this drug and one Paragraph IV challenge.

This drug has one patent family member in one country.

The generic ingredient in ENTEREG is alvimopan. There are four drug master file entries for this compound. Four suppliers are listed for this compound. Additional details are available on the alvimopan profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Entereg

A generic version of ENTEREG was approved as alvimopan by WATSON LABS TEVA on December 19^th, 2019.

Summary for ENTEREG

International Patents:	1
US Patents:	1
Applicants:	1
NDAs:	1
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for ENTEREG

Paragraph IV (Patent) Challenges for ENTEREG

Tradename	Dosage	Ingredient	Strength	NDA	ANDAs Submitted	Submissiondate
ENTEREG	Capsules	alvimopan	12 mg	021775	1	2017-06-16

US Patents and Regulatory Information for ENTEREG

ENTEREG is protected by one US patents.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Cubist Pharms	ENTEREG	alvimopan	CAPSULE;ORAL	021775-001	May 20, 2008		DISCN	Yes	No

International Patents for ENTEREG

See the table below for patents covering ENTEREG around the world.

Country	Patent Number	Title	Estimated Expiration
European Patent Office	0657428	Préparation de pipéridinyl-n-alkylcarboxylates 3,4,4-trisubstituées et intermédiaires, utile comme opioide antagonistes (Preparation of 3,4,4-trisubstitutedpiperidinyl-n-alkylcarboxylates and intermediates, useful as opioid antagonists)
Israel	149650	PIPERIDINE N-ALKYLCARBOXYLATE COMPOUNDS FOR USE AS MEDICAMENTS FOR THE TREATMENT AND PREVENTION OF ILEUS
Hungary	221316	PROCESS FOR PREPARING PIPERIDINE DERIVATIVES
Norway	944644
European Patent Office	0506478	Dérivés de la pipéridine (Piperidine derivatives)
Finland	106860

ENTEREG Market Analysis and Financial Projection

Last updated: February 3, 2026

What Is ENTEREG and Its Market Position?

Entereg (alvimopan) is an opioid antagonist developed by GlaxoSmithKline (GSK) for reducing gastrointestinal (GI) complications after bowel surgery. Approved by the U.S. Food and Drug Administration (FDA) in 2008, it targets post-operative ileus (POI), a common complication delaying gastrointestinal recovery. The drug is marketed solely in the United States and is available by prescription.

The drug's market presence remains limited by its restricted use case, primarily in hospital settings for specific surgeries. Its breakthrough therapy designation and patent status are crucial to understanding its competitive position and intellectual property landscape.

What Are the Core Market Drivers and Barriers?

Market Drivers

• Unmet Medical Need: POI affects up to 30% of bowel surgery patients, creating substantial healthcare costs estimated at over $1.5 billion annually in the US.
• Regulatory Support: FDA approval and labeling for specific indications incentivize hospital adoption.
• Hospital Bundled Payments: Focus on reducing postoperative complications encourages drugs that facilitate faster recovery.

Barriers

• Limited Indication: Use restricted to inpatient surgery, limiting market size.
• Safety Concerns: Rare but serious adverse events, such as myocardial infarction, have prompted caution and restricted use.
• Market Penetration: Competition with existing analgesics and non-pharmacological protocols.

What Does the Patent and Intellectual Property Landscape Look Like?

Entereg's patent protection primarily stems from its chemical composition and manufacturing process. Key patents have had lapsing dates between 2018 and 2020, exposing potential expiry in 2023-2025.

GSK has sought additional patents on methods of use and formulations, but many are close to expiry, risking generic entry. The exclusivity period limited the opportunity for broad market capture beyond initial indications.

How Do Financial and Clinical Data Stakeholders View ENTEREG?

Finances

• In 2022, sales of Entereg in the US comprised approximately $100 million, a decline from $150 million in 2018, pressured by generic competition and restricted use.
• The drug's pricing historically was around $400 per dose, with typical treatment involving multiple doses per patient.

Clinical Data

• Randomized trials demonstrated that Entereg significantly reduces time to GI recovery post-surgery.
• Post-approval studies highlighted safety concerns, leading to restricted usage recommendations.

What Opportunities Exist for Investment or R&D?

• New Indications: Exploring broader postoperative GI recovery, including other surgeries or outpatient settings.
• Combination Therapies: Developing combinations with analgesics or other mitigating agents.
• Geographic Expansion: GSK has not pursued outside the US, indicating potential for regulatory approval in other countries.
• Formulation Innovation: Sustained-release versions or delivery methods might improve compliance and outcomes.

What Risks Are Associated With ENTEREG Investment?

• Patent Expiry: The nearing expiration of key patents opens lucrative windows for generic manufacturers.
• Market Saturation: Hospitals' reluctance due to safety concerns or reimbursement issues may hinder expansion.
• Regulatory Risks: Post-marketing safety concerns could lead to restrictions.
• Competitive Landscape: New drugs or protocols that replace pharmacological approaches may reduce demand.

What Does Competitive and Strategic Outlook Suggest?

GSK's focus appears to be on maintaining current indications, with limited pipeline movement. The competitive landscape includes drugs like methylnaltrexone and naloxegol for opioid-induced constipation, but none directly targeting POI.

Emerging biotechnolog brands are developing GI motility modulators, yet none have gained significant market share for POI.

Key Metrics Summary

Metric	Data
2022 US Sales	~$100 million
Patent Expiry	2023–2025 (main patents)
US Market Size	$1.5 billion (postoperative GI complication costs)
Pricing per Dose	~$400
Estimated Patients per Year	250,000 (post-bowel surgery in US hospitals)

Key Takeaways

• Entereg has a focused use case with limited growth potential due to patent expiry and restricted indications.
• Market adoption is limited by safety signals, reimbursement concerns, and competition.
• Opportunities exist in expanding indications via clinical research, geographic expansion, and formulation development.
• The impending patent expirations create risks of generic competition severely impacting sales.
• GSK's current strategy lacks aggressive pipeline expansion, which may influence long-term valuation.

FAQs

1. What are the primary clinical benefits of ENTEREG?
Entereg accelerates gastrointestinal recovery after bowel surgery, reducing hospital stays and post-operative complications related to POI.

2. When do key patents for ENTEREG expire?
Main patents are set to expire between 2023 and 2025, opening the market to generics.

3. Can ENTEREG be prescribed outside the US?
Currently, no; GSK has not secured regulatory approvals outside the US, limiting international market potential.

4. What are the main safety concerns associated with ENTEREG?
In rare cases, Entereg has been linked to myocardial infarction, which led to restricted usage recommendations.

5. Are there any ongoing R&D efforts to expand ENTEREG's indications?
GSK has shown limited recent activity; however, academic and industry studies are exploring broader GI recovery applications, though not yet translating into commercial strategies.

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Sources:

1. FDA Label for ENTEREG.
2. GSK Annual Reports (2018–2022).
3. IQVIA Sales Data.
4. Patent databases (USPTO, EPO).
5. ClinicalTrials.gov.