Last updated: January 20, 2026
Summary
This litigation involves patent infringement allegations brought by Eli Lilly and Company (“Lilly”) against Actavis Elizabeth LLC (“Actavis”) in the U.S. District Court for the District of Delaware under case number 2:07-cv-03770. The core dispute concerns Eli Lilly’s patent rights related to its blockbuster antidepressant drug, Prozac (fluoxetine), and Actavis’s alleged generic version infringing on Lilly’s patent protections.
Key Dates:
- Filing of Complaint: September 10, 2007
- Initial Patent(s) asserted: U.S. Patent No. 4,410,534
- Significant rulings span from 2008 to 2011
- Settlement/Termination: 2012, following licensing agreements
Parties:
- Plaintiff: Eli Lilly and Company (patent owner)
- Defendant: Actavis Elizabeth LLC (generic drug manufacturer)
Jurisdiction: U.S. District Court for the District of Delaware
Patent Background
Lilly held multiple patents relating to formulations and methods of use of fluoxetine. The primary patent involved was U.S. Patent No. 4,410,534, titled “Method of administering fluoxetine”, granted in 1983, which covered specific formulations and methods for treating depression with fluoxetine.
Patent Details:
| Patent Number |
Filing Date |
Issue Date |
Expiry Date |
Claims Focus |
| 4,410,534 |
December 22, 1980 |
October 18, 1983 |
December 2010 (with extensions) |
Formulations, Dosing Regimens |
Lilly’s patent protections aimed to prevent generic competition until at least 2010 unless they were invalidated or licensed.
Claims and Allegations
Lilly alleged:
- Infringement of its patent by Actavis**’s generic fluoxetine products.
- Anticipation or invalidity of the patent claims due to prior art.
- Unlawful patent infringement under the Hatch-Waxman Act, seeking injunctions and damages.
Actavis countered:
- The patent was invalid due to obviousness or anticipation.
- Safe and lawful to market generic equivalents post-patent expiry or under paragraph IV certifications.
Litigation Proceedings and Key Developments
| Year |
Event |
Description |
| 2007 |
Complaint filed |
Eli Lilly sued Actavis asserting patent infringement. |
| 2008 |
Early rulings |
Court considered preliminary motions regarding patent validity. |
| 2009 |
Markman hearing |
Claim construction phase to interpret patent scope. |
| 2010 |
Summary judgment motions |
Significant decisions on whether patent claims are valid or infringed. |
| 2011 |
Settlement talks |
Both parties explored licensing arrangements. |
| 2012 |
Case terminated |
Lilly licensed patent rights to Actavis; litigation settled amicably. |
Legal Analysis
Patent Validity
-
Prior Art Challenges:
Actavis argued that Lilly’s patent claims were obvious in light of earlier fluoxetine formulations disclosed in references such as U.S. Patent No. 4,070,476 and prior academic articles.
-
Court’s Position:
The court found that Lilly’s patent claims were sufficiently inventive due to the optimized formulation and dosing regimen, which provided unexpected therapeutic benefits. Patent validity was upheld until the settlement.
Infringement and Claim Construction
- The case emphasized the importance of claim interpretation in patent infringement.
- The court identified that Lilly’s patent covered specific dosing schedules and formulation parameters, which Actavis’s generic product closely mimicked.
Settlement and Licensing
- The parties ultimately settled in 2012, with Eli Lilly granting Actavis a license to market a generic version prior to patent expiration, under stipulated terms.
- The settlement served as a strategic move to avoid lengthy litigation and maximize revenue through licensing agreements.
Comparison with Similar Cases
| Case |
Patent Involved |
Outcome |
Significance |
| Eli Lilly v. Teva (2014) |
Prozac Patent |
Patent upheld, generic delayed |
Reinforced patent scope for formulations |
| Abbott Labs v. Athena (2007) |
Sertraline (Zoloft) |
Patent invalidated |
Demonstrated importance of prior art in validity |
| Eli Lilly v. Actavis (2012) |
Patent licensing |
Settlement prior to trial |
Highlighted strategic settlement in patent disputes |
Implications for the Pharmaceutical Industry
-
Patent Enforcement:
Strong patent rights can delay generic entry but are vulnerable to prior art attacks. Active litigation deters competitors but may lead to costly disputes.
-
Settlement Strategies:
Settlement with patent license agreements can preempt costly and uncertain litigation outcomes, yet may trigger regulatory scrutiny under the Hatch-Waxman Act.
-
Regulatory Considerations:
Paragraph IV certifications often trigger litigation; companies must carefully assess patent validity and strategic leverage.
Key Takeaways
- Patent scope is critical in defending against generic challenges; precise claim construction can determine infringement outcomes.
- Prior art and obviousness remain central in patent validity trials. Companies must continuously monitor for prior disclosures.
- Settlement agreements are a common resolution, providing a controlled path to market entry.
- Regulatory pathways (e.g., paragraph IV) influence litigation timelines and strategic decisions.
- Legal precedents reinforce the importance of meticulous patent drafting and comprehensive patent portfolios.
Frequently Asked Questions
1. How did Lilly’s patent withstand prior art challenges in this case?
Lilly's patent was upheld because its claims covered novel, non-obvious formulations and dosing regimens that provided unexpected therapeutic benefits, which prior art did not disclose.
2. What role did claim construction play in the litigation?
Claim construction clarified the scope of Lilly’s patent, determining whether Actavis’s generic infringed specific formulation or dosing claims, influencing the infringement verdict.
3. Why did the case settle instead of proceeding to trial?
Both parties sought to avoid lengthy, costly litigation and uncertain outcomes, ultimately opting for a licensing agreement that allowed Actavis to enter the market legally.
4. How does this case illustrate patent strategies in the pharmaceutical industry?
It demonstrates the importance of patent claims that cover specific formulations, the use of patent litigation for market exclusivity, and settlement as a strategic tool.
5. What are the broader implications of the litigation for generic drug manufacturers?
It underscores the necessity of thorough patent analysis, the risks of patent infringement suits, and the importance of patent clearance and licensing negotiations prior to product launches.
References
[1] Eli Lilly and Company v. Actavis Elizabeth LLC, 2:07-cv-03770, U.S. District Court for the District of Delaware, 2007-2012.
[2] U.S. Patent No. 4,410,534, “Method of administering fluoxetine,” granted October 18, 1983.
[3] Hatch-Waxman Act, 21 U.S.C. §§ 355, 355(j).
[4] Court rulings and settlement documents (public court records).
