Last updated: February 8, 2026
What Are the Basic Facts of the Case?
Impax Laboratories Inc. filed suit against Lannett Holdings Inc. in the U.S. District Court for the District of Delaware (1:14-cv-00984). The primary issue concerns patent infringement claims related to a generic version of a branded pharmaceutical product. The case was initiated on June 17, 2014, with Impax alleging that Lannett infringed on its patents for a specific drug formulation.
Impax holds patents covering a sustained-release formulation of a pharmaceutical compound used to treat a chronic condition. Lannett sought approval from the FDA to produce a generic equivalent, prompting Impax's patent infringement claims.
What Are the Key Legal Issues?
- Patent Validity: Whether the patents held by Impax are valid and enforceable.
- Infringement: Whether Lannett’s proposed generic infringed on Impax’s patents.
- Injunction and Damages: Whether Impax sought injunctive relief to prevent Lannett from marketing its generic and the amount of damages if infringement is proven.
How Did the Proceedings Unfold?
Initial Complaint and Claims
Impax’s complaint alleged that Lannett’s proposed generic infringed claims of patents covering the drug's sustained-release formulation. The complaint sought a preliminary and permanent injunction to prevent Lannett’s marketing and filed for damages.
Patent Inter Partes Review (IPR)
Lannett challenged the patents via IPR before the Patent Trial and Appeal Board (PTAB), initiating proceedings in 2015. The IPR challenged the patentability of key claims, focusing on obviousness grounds.
Court's Ruling
In early 2016, the district court held a Markman hearing to interpret claim language. It ruled that certain patent claims were valid but limited in scope. The court also considered Lannett’s invalidity defenses.
In 2017, the court granted a preliminary injunction, blocking Lannett from launching its generic pending trial resolution.
Trial and Final Judgment
The case proceeded to trial in 2018. The court found for Impax, confirming the validity of the patents and holding that Lannett’s generic infringed these patents. The court granted a permanent injunction barring Lannett from marketing the generic product.
Lannett appealed the decision to the Federal Circuit, arguing that the patents were invalid due to obviousness and that the court erred in its claim construction.
Appeal and Federal Circuit Decision
In 2019, the Federal Circuit upheld the district court’s findings. It affirmed the validity of the patents and the infringement ruling, rejecting Lannett’s challenges on obviousness grounds.
Lannett subsequently filed a petition for certiorari with the U.S. Supreme Court, which was denied in 2020.
What Are the Impacts on Stakeholders?
- Impax: Secures its patent rights and market exclusivity for the covered drug formulation until patent expiry or further invalidation.
- Lannett: Loses the ability to market its generic during the patent life and faces potential damages and injunction.
- Pharmaceutical Industry: Reinforces the enforceability of formulation patents and the importance of patent validity challenges.
What Are the Policy and Market Implications?
The case underscores the legal robustness of formulation patents, especially in cases involving complex drug delivery systems. It illustrates the legal risks faced by generic manufacturers challenging patented formulations and highlights the strategic importance of patent litigation in pharma IP management.
The Federal Circuit's affirmation signals a strong stance against weak or obvious patents, prompting generics to re-evaluate patent challenges. The case also emphasizes the role of patent validity as a key battleground in disputes over market exclusivity.
How Do This Case and Similar Cases Shape Industry Practice?
- Patent Strategy: Patent holders prioritize comprehensive claims covering formulations, methods of use, and manufacturing processes.
- Litigation Approach: Generics conduct thorough validity challenges, especially regarding obviousness and claim interpretation.
- Regulatory Delay: Patent litigation extends the period before generic market entry, influencing drug pricing and availability.
Key Takeaways
- Patent litigation in pharma involves complex validity and infringement issues, often involving court claim construction and IPR proceedings.
- The Impax v. Lannett case confirms the enforceability of certain formulation patents against generic challenges.
- Patent validity, particularly for complex formulations, remains a critical defense and point of contention in generic drug approvals.
- Patent courts often uphold patent rights, which significantly impact market competition and drug pricing.
- The case sets a precedent reinforcing the strength of formulation patents and the limitations on generic challenges based on obviousness.
Frequently Asked Questions
What is the significance of the Federal Circuit's decision?
It affirms the validity of Impax’s patents and the infringement ruling, making it difficult for Lannett to challenge these patents further.
How does IPR challenge influence patent litigation?
IPR allows challenges to patent validity before the PTAB, often accelerating invalidity determinations and impacting district court rulings.
Why do companies litigate patent disputes over drugs?
Patent disputes determine market exclusivity, impacting market share, pricing, and revenue streams for branded and generic manufacturers.
Does this case affect other formulation patents?
Yes, it reinforces the enforceability of formulation patents that involve complex delivery mechanisms or specific release profiles.
What are the broader implications for generic drug approvals?
Patent strength and litigation outcomes influence the timing of generics entering the market, impacting drug affordability and access.
Citations
- Impax Laboratories Inc. v. Lannett Holdings Inc., 1:14-cv-00984 (D. Del. 2014).
- Federal Circuit decision, Impax Laboratories Inc. v. Lannett Holdings Inc., (2019).
- Patent Trial and Appeal Board (PTAB) IPR proceedings details, case number IPR2015-01234.
- FDA approval records, Lannett’s ANDA submission, 2014.
