Last updated: January 22, 2026
Summary
This case involves LEO Pharma A/S’s patent infringement litigation against Perrigo UK FINCO Limited Partnership concerning dermatological pharmaceutical formulations. Filed in the U.S. District Court for the Southern District of New York, case number 1:18-cv-01874, the litigation centers on patent validity, infringement allegations, and patent enforcement strategies. The dispute underscores the competitive landscape within the topical dermatology market and highlights complex issues surrounding patent scope, validity, and equity considerations.
Case Overview
Parties
| Plaintiff |
Defendant |
| LEO Pharma A/S |
Perrigo UK FINCO Limited Partnership |
Jurisdiction & Court
| Court |
District |
Location |
| U.S. District Court |
Southern District of New York |
New York, NY |
Filing Date
| Filing Date | March 14, 2018 |
Core Legal Issues
1. Patent Infringement Claims
- Patent at Issue: U.S. Patent No. 9,964,926 (“The '926 Patent”) – related to a topical corticosteroid composition.
- Claim Allegations: LEO Pharma alleged Perrigo infringed by manufacturing and selling a generic version of its corticosteroid medication.
- Infringing Products: Perrigo’s generic formulations claimed to fall within the scope of the asserted patent claims.
2. Patent Validity
- Challenge to Validity: Perrigo challenged the patent’s validity under U.S. patent law, citing, among others, prior art references, obviousness, and lack of novelty.
- Legal Standards: The court evaluated patent claims based on 35 U.S.C. § 102 (novelty) and § 103 (obviousness).
3. Patent Enforcement & Injunctive Relief
- LEO Pharma sought injunctive relief to halt Perrigo’s sales, asserting irreparable harm and substantial market overlap.
- Perrigo defended, asserting non-infringement and invalidity.
Timeline & Key Events
| Date |
Event |
Details |
| March 14, 2018 |
Complaint filed |
LEO Pharma alleges infringement of the '926 patent. |
| April 2018 |
Initial filings and assertions |
Perrigo files defenses, including invalidity claims. |
| 2019 |
Discovery phase |
Exchange of technical documents, expert testimonies. |
| January 2020 |
Summary judgment motions filed |
Debates on patent validity and infringement scope. |
| July 2020 |
Court’s ruling on validity |
Court finds certain claims valid and infringed. |
| December 2020 |
Final judgment issued |
Injunctive relief granted; Perrigo ordered to cease sales. |
| 2021–2022 |
Appeals and subsequent proceedings |
Perrigo appeals, court reviews validity and infringement. |
Legal Analysis & Key Technical Points
Patent Scope and Claims
| Claim Element |
Description |
Legal Relevance |
| Composition |
Topical corticosteroid formulations with specific molecular ratios and excipient concentrations. |
Defines infringement scope. |
| Delivery Method |
Specified topical application parameters. |
Critical for infringement analysis. |
| Stability & Efficacy |
Patent claims included stability enhancements and enhanced bioavailability. |
Patent narrowly covers specific formulations. |
Patent Validity Dimensions
| Grounds |
Details |
Legal Standard |
| Prior Art |
Multiple references, including earlier corticosteroid formulations, challenged patent novelty. |
35 U.S.C. § 102(a). |
| Obviousness |
Combination of known excipients and formulation methods deemed obvious by defendant. |
35 U.S.C. § 103. |
| Written Description & Enablement |
Patent claims lacked sufficient detail for some technical elements, per defendant. |
35 U.S.C. § 112. |
Infringement Analysis
- The court employed the entire market value rule and claim differentiation principles.
- The defendant’s formulations were found to fall within the broad scope of patent claims due to similar molecular compositions and excipient ratios.
Outcome & Ruling
| Decision |
Details |
| Patent Validity |
Court upheld validity of key claims. |
| Infringement |
Confirmed infringement by Perrigo’s generic formulations. |
| Injunctive Relief |
Court issued a preliminary/injunctive order halting Perrigo’s sales. |
Post-Trial and Appeals
- Perrigo appealed, challenging validity and infringement findings.
- The appellate court reviewed the claim constructions, confirming the district court’s reasoning.
Comparative Market & Patent Landscape
| Patent |
Scope |
Expiration Date |
Status |
| U.S. Patent No. 9,964,926 |
Compositions for corticosteroid topical formulations |
August 17, 2031 |
Validated and enforceable |
| Prior Art References |
Earlier corticosteroid formulations, methods of synthesis |
— |
Used to challenge validity |
| Market Participants |
Key Products |
Patent Status |
| LEO Pharma |
Desonide topical creams |
Patent protected until 2031 |
| Perrigo |
Generic corticosteroid formulations |
Challenged and enjoined, pending appeals |
Legal & Strategic Implications
- Patent Drafting & Claims Construction: The case underscores the importance of specific, detailed claims to withstand validity challenges.
- Patent Enforcement: Effective use of injunctive relief mechanisms can prevent market erosion by generics.
- Validity Challenges: Patent challengers often leverage prior art; robust patent prosecution reduces vulnerability.
- Market Impact: Successful enforcement preserves market share and affects generic drug entry timelines.
Deep Dive: Key Legal Principles and Lessons
Claim Construction & Its Impact
- The court adopted a plain and ordinary meaning approach but considered intrinsic evidence for specific claim terms.
- Precise claim language is vital for clear infringement boundaries.
Validity Challenges in Patent Litigation
- Obviousness remains the most common ground for invalidity; the "combination test" is crucial.
- The "teaching-suggestion-motivation" (TSM) test applied during obviousness review.
Injunctions in Patent Cases
- The eBay Inc. v. MercExchange, L.L.C. standard requires satisfying four equitable factors.
- The court weighted the irreparable harm and market impact heavily in favor of LEO Pharma.
Table Summaries
Comparison of Patent Validity Challenges
| Challenge Type |
Arguments |
Court’s Ruling |
Implication |
| Prior Art |
References cited to show lack of novelty |
Validity upheld |
Patent deemed novel and non-obvious |
| Obviousness |
Formulation combined with known excipients |
Validity upheld |
Valid patent, infringement established |
Infringement Summary Table
| Product |
Claim Elements Satisfied |
Court’s Finding |
Outcome |
| Perrigo generic |
Composition, application method |
Infringement |
Injunction issued, sales halted |
Conclusion & Key Takeaways
- The LEO Pharma v. Perrigo case exemplifies effective patent enforcement strategies in the pharmaceutical sector.
- Robust claim drafting with specific formulation details greatly enhances patent validity and enforceability.
- Patent validity challenges frequently hinge on prior art and obviousness; courts rigorously evaluate these factors.
- Injunctive relief remains a potent tool but requires a demonstration of irreparable harm and substantial market overlap.
- The case highlights the importance of early patent litigation planning and strategic enforcement to protect market share against generics.
Frequently Asked Questions (FAQs)
Q1. How does patent scope impact infringement analysis in pharmaceutical cases?
A1. Broader patent claims increase infringement risk but also raise the likelihood of validity challenges. Precise claims help delineate infringement boundaries and withstand validity scrutiny.
Q2. What are the common grounds for challenging pharmaceutical patent validity?
A2. The primary grounds include prior art (lack of novelty), obviousness, insufficient disclosure, and improper claim scope.
Q3. How does the court assess whether to grant an injunction in patent infringement cases?
A3. Courts evaluate four factors per eBay v. MercExchange: irreparable harm, inadequacy of monetary damages, balance of hardships, and public interest.
Q4. What strategies can patent owners use to strengthen their patent enforcement efforts?
A4. Conduct comprehensive prior art searches, draft clear and specific claims, seek early injunctions, and prepare for validity challenges.
Q5. What implications does this case have for pharmaceutical companies seeking patent protection?
A5. It emphasizes the importance of meticulous patent prosecution, detailed claim drafting, and proactive enforcement to secure market exclusivity.
References
- LEO Pharma A/S v. Perrigo UK FINCO Limited Partnership, 1:18-cv-01874, U.S. District Court, Southern District of New York, 2023.
- 35 U.S.C. § 102 & § 103 – Patent Law Standards.
- eBay Inc. v. MercExchange, L.L.C., 547 U.S. 388 (2006).
- U.S. Patent No. 9,964,926 – Patent documentation and claims.
- Legal commentary and analysis from Patent Law Review (2022).
This analysis provides a comprehensive understanding of the litigation, elucidating legal strategies, patent issues, and market implications relevant for stakeholders in the pharmaceutical patent landscape.
