Allergan v. MSN Laboratories: Eluxadoline ANDA Consent Injunction
Allergan Holdings sued MSN Laboratories in Delaware over ANDA No. 213576 for generic 75 mg and 100 mg eluxadoline tablets — the active ingredient in Viberzi®. The case closed after 766 days with a stipulated order establishing infringement of two patents and permanently enjoining MSN from commercialising the generic product for the life of both patents.
Consent injunction ends Allergan’s Viberzi® ANDA battle with MSN
Allergan Holdings Unlimited Co. filed this Hatch-Waxman infringement action in the District of Delaware on 21 July 2023 before Judge Maryellen Noreika. The complaint targeted MSN Laboratories Private Limited’s ANDA No. 213576, which sought FDA approval to market generic eluxadoline oral tablets in 75 mg and 100 mg strengths — the formulations sold under the Viberzi® brand for irritable bowel syndrome with diarrhoea. Two patents were asserted: US11484527B2 and companion patent US11284187, both directed to eluxadoline compositions and formulations.
The case resolved on 25 August 2025 through a stipulated consent order signed by both parties and entered by the court. The order formally adjudges that the filing of ANDA No. 213576 constituted an act of infringement under 35 U.S.C. § 271(e)(2)(A) — the Hatch-Waxman constructive infringement provision. MSN is permanently enjoined from manufacturing, selling, offering for sale, importing, or using the ANDA products in the United States for the full remaining life of both patents, including any extensions and paediatric exclusivities. All remaining claims, counterclaims, and defences were dismissed without prejudice.
The 766-day duration is consistent with a negotiated resolution rather than a contested trial, but the timeline suggests substantive pre-trial activity before parties reached agreement. Notably, the order expressly preserves MSN’s rights under 35 U.S.C. § 271(e)(1) — the safe harbour for research use — and leaves open the possibility of future litigation between the same parties over the same patents if a different product is involved. The absence of any disclosed licence suggests Allergan secured a pure blocking injunction rather than a royalty-bearing settlement.
Filing to Dismissed without Prejudice in 766 days
766 days — above the median for ANDA Hatch-Waxman cases resolved by consent order in Delaware
Stipulated consent order: what the injunction means for both parties
§ 271(e)(2)(A) infringement by ANDA filing — what it means
Under the Hatch-Waxman Act, the act of filing an ANDA referencing a patented drug is itself a statutory act of infringement under 35 U.S.C. § 271(e)(2)(A). No commercial product needs to have reached the market. Here, MSN stipulated that ANDA No. 213576 constituted infringement of both asserted patents. The remaining claims — including any invalidity or non-infringement defences — were dismissed without prejudice, meaning they were never adjudicated on the merits.
Constructive infringement — ANDAWithout prejudice: what remains open and what does not
The dismissal without prejudice of all remaining claims means MSN’s invalidity and non-infringement defences were not decided and could theoretically be raised again. However, the order is carefully scoped: it binds MSN specifically to ANDA No. 213576 and the 75 mg/100 mg eluxadoline tablet products. A separate ANDA or a different eluxadoline product formulation could, in principle, give rise to new litigation — a carve-out Allergan accepted in exchange for MSN’s waiver of appeal rights.
No merits adjudication on invalidityAllergan secures patent-life injunction without trial risk
Allergan obtained a consent injunction covering the full remaining life of both patents, including extensions and paediatric exclusivities — a commercially significant result that blocks MSN’s generic entry into the US market without the litigation risk of an invalidity trial. The order also retains court jurisdiction for enforcement, strengthening Allergan’s position if MSN breaches the injunction. No licence was disclosed, suggesting Allergan prioritised market exclusivity over royalty income.
Full patent-life market protectionMSN blocked from US generic eluxadoline market under ANDA 213576
MSN is enjoined from all commercialisation activity in the US for the listed ANDA products for the life of both patents. Critically, MSN retains § 271(e)(1) safe-harbour rights — preserving its ability to conduct research and regulatory activities. MSN also waived appeal rights expressly under the stipulation, foreclosing any immediate route to challenge the injunction. The without-prejudice dismissal of its invalidity defences leaves a narrow theoretical pathway, but a new challenge would require a distinct litigation trigger.
Market entry blocked; appeal waivedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Allergan Holdings Unlimited Co. | Company | Pharmaceutical IP holding entity — holder of US11484527B2 covering eluxadoline formulationsSearch in Eureka ↗ |
| Defendant | MSN Laboratories Private Limited | Individual | MSN Laboratories Private Limited — Indian generic pharmaceutical manufacturer, ANDA filerSearch in Eureka ↗ |
| Plaintiff counsel | Connie P. Lee | Attorney | Counsel for Allergan Holdings Unlimited Co.Search in Eureka ↗ |
| Plaintiff counsel | Gyuhyun (joanne) Bae | Attorney | Counsel for Allergan Holdings Unlimited Co.Search in Eureka ↗ |
| Plaintiff counsel | Hassen Sayeed | Attorney | Counsel for Allergan Holdings Unlimited Co.Search in Eureka ↗ |
| Plaintiff counsel | Jack B. Blumenfeld | Attorney | Counsel for Allergan Holdings Unlimited Co.Search in Eureka ↗ |
| Plaintiff counsel | Jeremy A. Tigan | Attorney | Counsel for Allergan Holdings Unlimited Co.Search in Eureka ↗ |
| Plaintiff counsel | Jonathan T. Clark | Attorney | Counsel for Allergan Holdings Unlimited Co.Search in Eureka ↗ |
| Plaintiff law firm | Morris, Nichols, Arsht & Tunnell LLP | Law Firm | Representing Allergan Holdings Unlimited Co.Search in Eureka ↗ |
| Defendant counsel | Richard C. Weinblatt | Attorney | Counsel for MSN Laboratories Private LimitedSearch in Eureka ↗ |
| Defendant law firm | Stamoulis & Weinblatt LLC | Law Firm | Representing MSN Laboratories Private LimitedSearch in Eureka ↗ |
| Presiding judge | Judge Maryellen Noreika | Judge | Delaware District CourtSearch in Eureka ↗ |
Official order — verbatim text
The stipulated order is notable for its surgical precision: it adjudges ANDA-based infringement under § 271(e)(2)(A) as an agreed fact, while leaving all other claims — including MSN’s invalidity and non-infringement defences — unresolved and dismissed without prejudice. This structure is commercially rational for both sides: Allergan secures a judicially enforceable market-exclusivity injunction without assuming trial risk, while MSN avoids a binding merits ruling on patent validity that could prejudice future ANDA activity on related products. The express appeal waiver by both parties under paragraph 4 is unusual and effectively renders the consent order final and non-reviewable in this action.
US11484527B2 — eluxadoline oral tablet formulation patent
US11484527B2 is a US utility patent directed to pharmaceutical compositions and formulations of eluxadoline — a mixed opioid receptor agonist-antagonist indicated for irritable bowel syndrome with diarrhoea (IBS-D). The patent covers the formulated oral tablet products sold under the Viberzi® brand in 75 mg and 100 mg dosage strengths. Eluxadoline’s mechanism of action and formulation complexity — including its physicochemical properties and manufacturing challenges — make formulation patents particularly important for maintaining market exclusivity beyond the compound patent.
For the branded pharmaceutical sector, formulation patents like US11484527B2 represent a critical second line of exclusivity after primary compound protection. In the Hatch-Waxman context, each formulation patent listed in the FDA Orange Book forces a generic ANDA filer to either certify non-infringement (Paragraph III) or file a Paragraph IV challenge — triggering automatic 30-month stay rights. The consent injunction in this case confirms that Allergan successfully defended this formulation coverage against at least one generic challenger, signalling meaningful claim strength. Competitors in the IBS-D therapeutic space or generic manufacturers targeting eluxadoline should monitor the patent’s term and any supplemental protection certificates closely.
Should you run an FTO analysis against US11484527B2?
Any pharmaceutical company developing, reformulating, or seeking generic approval for eluxadoline-containing oral tablet products in the United States should treat US11484527B2 as a primary FTO priority. The consent order in this case confirms the patent’s enforceability and Allergan’s willingness to litigate — and win injunctive relief — against ANDA challengers. Companies working on alternative strengths, combination tablets, or novel delivery systems incorporating eluxadoline should assess whether their specific formulation falls within the patent’s claim scope before committing to regulatory filings.
PatSnap Eureka’s FTO Search Agent can map the full claim landscape of US11484527B2, identify related family members and continuations, surface prior art relevant to any invalidity strategy, and benchmark the patent against Orange Book listings and competing ANDA filings. For in-house IP and R&D teams, Eureka’s automated monitoring can flag new continuation filings by Allergan in the eluxadoline space — providing early warning before a product development programme reaches a regulatory decision point.
Run a freedom-to-operate analysis on US11484527B2 to assess your product’s exposure
Run FTO in Eureka →Similar ANDA eluxadoline and IBS-D formulation patent cases
Hatch-Waxman ANDA infringement cases in the Delaware District Court involving IBS-D formulation patents and generic oral tablet challenges similar to Allergan v. MSN.
What this case signals for the generic pharma IP landscape
This consent injunction reflects a well-established Hatch-Waxman dynamic: patent holders trading certainty for speed, and generic challengers trading market access for litigation exit.
Consent orders with infringement stipulations are potent blocking tools
By securing a stipulated infringement finding under § 271(e)(2)(A), Allergan achieved a judicially enforceable injunction without proving infringement at trial. For patent holders in pharmaceutical ANDA litigation, this outcome — blocking a specific ANDA for patent life — is often more commercially valuable than a damages award, particularly for high-revenue branded formulations like Viberzi®.
Generic challengers: the § 271(e)(1) safe harbour carve-out matters
The explicit preservation of MSN’s § 271(e)(1) research safe-harbour rights in the consent order is a standard but strategically important clause. It signals that MSN may continue FDA-related and research activities on eluxadoline formulations, potentially positioning it to file a new or amended ANDA for a different product configuration in the future — a risk Allergan accepted by agreeing to a without-prejudice dismissal of invalidity claims.
Allergan v MSN — key questions answered
The Delaware District Court entered a consent order on 25 August 2025 adjudging that MSN’s ANDA No. 213576 filing constituted infringement of US11484527B2 and a companion patent under 35 U.S.C. § 271(e)(2)(A). MSN was permanently enjoined from commercialising generic eluxadoline 75 mg and 100 mg tablets in the US for the life of both patents. Remaining claims were dismissed without prejudice.
US11484527B2 is a US utility patent covering eluxadoline oral tablet formulations in 75 mg and 100 mg strengths — the dosage forms marketed as Viberzi® for IBS-D. Its Orange Book listing triggers the Hatch-Waxman 30-month stay mechanism against generic ANDA filers. The consent injunction in this case confirms its enforceability and provides Allergan with market exclusivity for the patent’s remaining life including any extensions.
The without-prejudice dismissal of MSN’s invalidity and non-infringement defences means those arguments were never adjudicated on the merits. MSN — or any other party — could theoretically raise similar arguments in future litigation. However, MSN expressly waived its appeal rights under this order, and the injunction specifically covers ANDA No. 213576 and the 75 mg/100 mg tablet products, not alternative eluxadoline formulations.
Yes. Paragraph 9 of the consent order expressly preserves MSN’s rights under 35 U.S.C. § 271(e)(1) — the Hatch-Waxman safe harbour for research, development, and regulatory submission activities. The order also specifies it is without prejudice to any future action regarding the patents and a product other than the ANDA 213576 eluxadoline tablets, leaving a narrow pathway for future activity.
The case was filed on 21 July 2023 and closed on 25 August 2025, a duration of 766 days. This timeline is consistent with a negotiated resolution following substantive pre-trial proceedings rather than a summary dismissal or early settlement, suggesting the parties engaged in discovery and potentially claim construction proceedings before reaching the stipulated consent order.
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