Fresenius Kabi USA LLC v. Meitheal Pharma Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:

  • Plaintiff: Fresenius Kabi USA, LLC (Delaware)
  • Defendant: Meitheal Pharmaceuticals, Inc. (Delaware)
  • Plaintiff’s Counsel: Farnan LLP

• Case Identification: 1:23-cv-01050, D. Del., 09/26/2023

• Venue Allegations: Plaintiff alleges venue is proper in the District of Delaware based on statutory requirements and Defendant's alleged history of not contesting venue in the district in prior litigation.

• Core Dispute: Plaintiff alleges that Defendant’s filing of an Abbreviated New Drug Application (ANDA) to market a generic version of the anesthetic Diprivan® constitutes an act of infringement of a patent related to stable propofol formulations.

• Technical Context: The patent concerns pharmaceutical formulations for propofol, a widely used intravenous anesthetic, focusing on ensuring the drug's chemical stability when stored in containers with specific types of closures.

• Key Procedural History: The complaint notes that on January 16, 2020, following an inter partes review, the U.S. Patent and Trademark Office cancelled several claims of the patent-in-suit, including independent claim 1. Plaintiff explicitly states it is not asserting the cancelled claims but is asserting claim 21, which originally depended from the cancelled claim 1. This history raises a threshold question regarding the legal status and enforceability of the asserted dependent claim.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 8,476,010 - Propofol Formulations with Non-Reactive Container Closures

• Patent Identification: U.S. Patent No. 8,476,010, “Propofol Formulations with Non-Reactive Container Closures,” issued July 2, 2013 (’010 Patent).

The Invention Explained

• Problem Addressed: The patent's background describes issues with prior art propofol formulations, including the risk of microbial contamination and hyperlipidemia in patients due to high fat content (’010 Patent, col. 3:5-21). It further identifies an unexpected problem: when the protective oil content in the formulation is reduced, the propofol becomes susceptible to degradation and potency loss when stored in containers sealed with common closures like rubber stoppers (’010 Patent, col. 4:46-64).
• The Patented Solution: The invention claims to solve this problem by pairing a propofol composition with a container that has a specific "inert or non-reactive closure" (’010 Patent, col. 4:51-52). This specific combination of formulation and closure material is described as preventing the degradation of propofol, particularly in formulations containing less than 10% solvent (’010 Patent, col. 8:50-59). The patent describes an accelerated testing method, involving agitation, to demonstrate the stability of compositions stored with compatible closures versus the significant potency loss observed with incompatible closures (’010 Patent, col. 23:22-38, Example 31).
• Technical Importance: This approach addresses the need for safer propofol formulations (with lower lipid content) while ensuring the drug remains stable and potent through its shelf life by controlling its interaction with packaging components.

Key Claims at a Glance

• The complaint asserts "at least claim 21" of the ’010 Patent (Compl. ¶37).
• Claim 21 is a dependent claim. The complaint states that its original parent, independent claim 1, was cancelled by the USPTO (Compl. ¶26). As recited in the complaint, the essential elements of claim 21 are:
  • A sterile pharmaceutical composition of propofol in a container.
  • The container includes a closure and a composition.
  • The composition comprises from 0.5% to 10% by weight propofol and from about 0 to about 10% by weight solvent for propofol.
  • When the composition in the sealed container is agitated at 300-400 cycles/minute for 16 hours at room temperature, it maintains a propofol concentration of at least 93% of the starting concentration.
  • The closure is selected from the group consisting of siliconized bromobutyl rubber, metal, and siliconized chlorobutyl rubber.
  • The closure also comprises metal.

III. The Accused Instrumentality

Product Identification

• Defendant’s generic Diprivan® products, identified as Propofol Injectable Emulsion USP, 500 mg/50mL and 1000 mg/100 mL (Compl. ¶30).

Functionality and Market Context

• The accused products are described as generic versions of the Diprivan® injectable emulsion, intended for use as an intravenously administered sedative and anesthetic (Compl. ¶¶1, 28). The complaint alleges that Defendant has filed an ANDA with the FDA seeking approval to manufacture, use, and sell these products in the United States prior to the expiration of the ’010 Patent (Compl. ¶30). The act of filing the ANDA for a product that allegedly meets the limitations of the patent's claims is the basis for the infringement action (Compl. ¶35).

IV. Analysis of Infringement Allegations

The complaint alleges, upon information and belief, that Defendant's generic propofol products meet all limitations of at least claim 21 (Compl. ¶39).

’010 Patent Infringement Allegations

• Identified Points of Contention:
  • Legal Question: A primary issue is whether dependent claim 21 remains valid and enforceable after its independent base claim, claim 1, was cancelled during inter partes review (Compl. ¶26). The defendant may argue that the dependent claim cannot stand on its own.
  • Factual Question: The complaint alleges on "information and belief" that the accused product meets the functional agitation test (maintaining ≥93% potency) and uses a closure from the claimed material group (Compl. ¶39). A key factual dispute will likely be whether testing of Defendant's product confirms these properties. The specifics of the agitation test itself, as outlined in the patent's examples, may be a focus of discovery and expert testimony (’010 Patent, col. 23:22-38).

No probative visual evidence provided in complaint.

V. Key Claim Terms for Construction

• The Term: "closure is selected from the group consisting of siliconized bromobutyl rubber, metal, and siliconized chlorobutyl rubber"
• Context and Importance: This Markush group defines the specific materials required for the container closure. The infringement analysis will depend entirely on whether the material of the Defendant’s closure falls within this narrowly defined list. Practitioners may focus on this term because any ambiguity in the definitions of "siliconized bromobutyl rubber" or "siliconized chlorobutyl rubber," or the physical structure of a closure that "comprises metal," could be outcome-determinative.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language uses the open-ended term "comprises metal," which could be argued to cover closures where metal is a minor component or is present in a form other than a solid cap.
  • Evidence for a Narrower Interpretation: The specification provides specific examples of commercial stoppers, including "Stelmi 6720/6722... bromobutyl rubber" and "West 4400 series" closures (’010 Patent, col. 9:49-65). A party could argue that the claim scope should be interpreted in light of these specific commercial examples identified as suitable.

VI. Other Allegations

• Indirect Infringement: The complaint makes a general allegation that Defendant's future actions would constitute induced infringement, based on the intent to market and sell the product upon FDA approval (Compl. ¶¶42-43).
• Willful Infringement: The complaint alleges that Defendant had pre-suit knowledge of the ’010 Patent and was aware that filing its ANDA constituted an act of infringement (Compl. ¶41). This allegation forms the basis for a potential claim of willfulness.

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of legal validity: can asserted claim 21, a dependent claim, be legally enforced after its independent base claim, claim 1, was cancelled by the USPTO? The resolution of this threshold question could determine the viability of the entire case.
• A key evidentiary question will be one of factual compliance: does the Defendant's generic product, particularly its container closure, actually meet the specific material and functional performance requirements of claim 21? This will likely require technical evidence and expert testimony comparing the accused product against the claim's stability test and its narrowly defined list of approved closure materials.