Tanabe Pharma Corp v. Azurity Pharma Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Tanabe Pharma Corporation (Japan)
  • Defendants: Azurity Pharmaceuticals, Inc. (Delaware); Azurity Pharmaceuticals India LLP (India); and Slayback Pharma LLC (Delaware)
  • Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP
• Case Identification: 1:26-cv-00069, D. Del., 01/21/2026
• Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendants Azurity and Slayback are incorporated in Delaware, and Azurity India is a foreign corporation that may be sued in any judicial district.
• Core Dispute: Plaintiff alleges that Defendants’ filing of a New Drug Application for a generic edaravone oral formulation constitutes an act of infringement of nine patents covering Plaintiff’s branded drug, RADICAVA ORS®, used for the treatment of Amyotrophic Lateral Sclerosis (ALS).
• Technical Context: The technology concerns stable, oral suspension formulations of the drug edaravone, developed to provide a less burdensome alternative to previous intravenous (IV) treatments for ALS, a fatal neurodegenerative disease.
• Key Procedural History: This is a Hatch-Waxman action filed within 45 days of Plaintiff's receipt of a Paragraph IV certification notice letter from Defendants, entitling Plaintiff to a 30-month statutory stay of FDA approval for the accused generic product. The complaint notes that an identical "protective suit" was filed five days prior in the District of New Jersey to preserve Plaintiff's rights in case of a jurisdictional dispute.

Case Timeline

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

U.S. Patent No. 10,987,341 - "Edaravone Suspension for Oral Administration"

The Invention Explained

• Problem Addressed: The patent describes Amyotrophic Lateral Sclerosis (ALS) as an "intractable disease that leads to respiratory failure" and notes the burden placed on patients and caregivers by existing intravenous injection therapies for the drug edaravone ’341 Patent, col. 4:38-67
• The Patented Solution: The invention is a suspension of solid edaravone particles in water, using a dispersant to keep the particles from agglomerating. This formulation allows for oral administration, which "reduces burden on ALS patients and caregivers, and achieves an ALS therapeutic effect equivalent to that of an injection." ’341 Patent, col. 4:62-67
• Technical Importance: This technology provided the first approved oral formulation of edaravone, offering a significant quality-of-life improvement for ALS patients by replacing burdensome, facility-based IV infusions with a treatment that can be self-administered at home Compl. ¶¶ 6, 8

Key Claims at a Glance

• The complaint asserts infringement of at least Independent Claim 1 of the '341 patent Compl. ¶62
• Independent Claim 1 requires:
  • An edaravone suspension for human oral administration, comprising: water;
  • edaravone particles comprising edaravone dispersed in the water; and
  • a dispersant dispersing the edaravone particles in water such that the dispersant maintains the edaravone particles in a solid particle state in the water,
  • wherein a blending amount of the edaravone particles is in a range of 0.5% (w/v) to 36% (w/v), and
  • the dispersant is at least one dispersant selected from the group consisting of polyvinyl alcohol, methylcellulose, hypromellose, sucrose fatty acid ester and polysorbate.
• The complaint does not explicitly reserve the right to assert dependent claims for this patent.

U.S. Patent No. 11,241,416 - "Edaravone Suspension for Oral Administration"

The Invention Explained

• Problem Addressed: The ’416 Patent addresses the same problem as the ’341 Patent: the need for a less burdensome, orally administered edaravone therapy for ALS patients that is therapeutically equivalent to an IV injection ’416 Patent, col. 4:1-5
• The Patented Solution: The ’416 Patent also discloses an oral edaravone suspension. The claims of this patent, however, define the invention partly by its pharmacokinetic (PK) properties, such as the mean maximum concentration (Cmax) and area under the curve (AUC) of the drug in a patient's plasma after administration ’416 Patent, col. 2:18-24 This approach claims the formulation based on its performance in the human body.
• Technical Importance: By claiming specific PK outcomes, the patent aims to protect formulations that achieve a bioequivalence profile similar to the successful IV therapy, ensuring the oral version delivers a comparable therapeutic effect ’416 Patent, col. 2:25-34

Key Claims at a Glance

• The complaint asserts infringement of at least Independent Claim 1 of the '416 patent Compl. ¶72
• Independent Claim 1 requires:
  • An edaravone suspension for human oral administration, comprising: water; edaravone particles dispersed in water; and a dispersant.
  • The dispersant exhibits a "transmission scattering light intensity of 1% or more."
  • The dispersant maintains the edaravone particles in a "solid particle state."
  • The blending amount of the dispersant is in a range of 0.001% (w/v) to 1.0% (w/v).
  • The blending amount of edaravone particles is in a range of 0.5% (w/v) to 36% (w/v).
  • When a 90 to 120 mg dose is orally administered, it exhibits a mean Cmax of 500 to 2500 ng/mL and a mean AUC of 1000 to 2500 h*ng/mL.
• The complaint does not explicitly reserve the right to assert dependent claims for this patent.

U.S. Patent No. 11,478,450 - "Edaravone Suspension for Oral Administration"

• Technology Synopsis: Continuing the same technological theme, this patent claims a method of treating ALS by orally administering an edaravone formulation with specific components and administration schedules, including claims directed at specific dosages like 105 mg/day ’450 Patent, Abstract; Claim 6
• Asserted Claims: At least Independent Claim 1 Compl. ¶82
• Accused Features: The accused instrumentality is Defendants' proposed generic edaravone oral formulation and its intended use for treating ALS Compl. ¶81

U.S. Patent No. 11,826,352 - "Edaravone Suspension for Oral Administration"

• Technology Synopsis: This patent claims an edaravone suspension containing a specific type of thickening agent, such as xanthan gum or tragacanth powder, and defines the formulation by its IDDSI (International Dysphagia Diet Standardisation Initiative) level, which relates to its viscosity and suitability for patients with swallowing difficulties ’352 Patent, Claim 1
• Asserted Claims: At least Independent Claim 1 Compl. ¶92
• Accused Features: Defendants' proposed generic edaravone oral suspension, which Plaintiff alleges is a partial suspension that infringes the claims Compl. ¶¶ 91-92

U.S. Patent No. 11,957,660 - "Edaravone Suspension for Oral Administration"

• Technology Synopsis: This patent claims an edaravone suspension that notably lacks a preservative but still resists bacterial growth for at least 28 days, a key feature for multi-dose liquid formulations. The claims recite specific thickening agents and a lack of common preservatives like parabens or benzoic acid ’660 Patent, Claim 1
• Asserted Claims: At least Independent Claim 1 Compl. ¶102
• Accused Features: Defendants' proposed generic edaravone oral suspension Compl. ¶101

U.S. Patent No. 12,194,025 - "Pharmaceutical composition for oral administration of edaravone and method of administering same"

• Technology Synopsis: This patent claims a method of administering edaravone based on the timing relative to meal consumption. It specifies different time intervals for administration after consuming high-fat, standard, or light meals to avoid food effects on the drug's pharmacokinetics ’025 Patent, Abstract; Claim 1
• Asserted Claims: At least Independent Claim 1 Compl. ¶112
• Accused Features: The intended use and administration instructions for Defendants' proposed product, which would be outlined in its product labeling Compl. ¶111

U.S. Patent No. 12,285,409 - "Edaravone Suspension for Oral Administration"

• Technology Synopsis: This patent is similar to others in the family, claiming an edaravone suspension with specific particle size limitations (D50 and D90) and pharmacokinetic outcomes (Cmax and AUC) when administered to a human ’409 Patent, Claim 1
• Asserted Claims: At least Independent Claim 1 Compl. ¶122
• Accused Features: The physical and performance characteristics of Defendants' proposed generic edaravone oral suspension Compl. ¶121

U.S. Patent No. 12,310,946 - "Pharmaceutical composition for oral administration of edaravone and method of administering same"

• Technology Synopsis: This patent claims a method of treating ALS by administering a liquid edaravone formulation according to a specific intermittent dosing schedule (e.g., an administration period followed by an interruption period), mirroring the clinical regimen for RADICAVA ORS® ’946 Patent, Claim 1
• Asserted Claims: At least Independent Claim 1 Compl. ¶132
• Accused Features: The intended therapeutic use and dosing regimen for Defendants' proposed generic product Compl. ¶131

U.S. Patent No. 12,478,611 - "Pharmaceutical composition for oral administration of edaravone and method of administering same"

• Technology Synopsis: This patent also claims a method of treating an oxidative stress disease by administering edaravone with a specific time interval relative to meal consumption, similar to the '025 patent, to avoid food effects on drug absorption ’611 Patent, Abstract
• Asserted Claims: At least Independent Claim 1 Compl. ¶142
• Accused Features: The intended use and administration instructions for Defendants' proposed product Compl. ¶141

III. The Accused Instrumentality

Product Identification

• The accused instrumentality is Defendants' proposed "edaravone oral formulation '105 mg / 5 mL'," which is the subject of New Drug Application (NDA) No. 221059 filed with the FDA Compl. ¶¶ 2, 23

Functionality and Market Context

• The product is an oral formulation of the drug edaravone intended for the treatment of ALS Compl. ¶23 It is a proposed generic version of Plaintiff's RADICAVA ORS® product, and this lawsuit was triggered by Defendants' filing of a 505(b)(2) NDA seeking FDA approval to market this product prior to the expiration of the patents-in-suit Compl. ¶¶ 2, 23-24 The complaint alleges, based on Defendants' own patents (U.S. Patent Nos. 12,343,330 and 12,491,178), that the proposed product is "at a minimum, a partial suspension requiring a crystallization inhibitor" Compl. ¶¶ 62, 72 No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

'341 Patent Infringement Allegations

• Identified Points of Contention:
  • Scope Questions: A central question will be whether any excipient in Defendants' formulation falls within the scope of the term "dispersant" as defined by the Markush group in Claim 1. The characterization of the accused product as a "partial suspension" also raises the question of whether it meets the claim limitation requiring the dispersant to maintain particles in a "solid particle state."
  • Technical Questions: What evidence does the complaint provide, beyond general allegations and reference to Defendants' other patents, that the accused product actually contains a dispersant from the claimed chemical class? The infringement analysis will depend heavily on the specific excipients disclosed in the confidential NDA filing.

'416 Patent Infringement Allegations

• Identified Points of Contention:
  • Scope Questions: Will the "transmission scattering light intensity" be a disputed limitation? Its measurement is defined by a specific protocol in the patent, raising questions about how that test applies to Defendants' product.
  • Technical Questions: Does the bioequivalence data submitted in NDA No. 221059, intended to link the generic product to RADICAVA ORS®, also conclusively demonstrate that the product meets the specific Cmax and AUC ranges required by Claim 1? This will be a key question of fact, comparing the NDA data directly to the claim limitations.

V. Key Claim Terms for Construction

The Term: "dispersant" (’341 Patent, Claim 1)

• Context and Importance: This term is central to infringement, as it defines a required ingredient by its chemical class. Whether an excipient in the accused product qualifies as a claimed "dispersant" will be a primary point of dispute. Practitioners may focus on this term because the complaint's infringement theory appears to rely on characterizing an ingredient, potentially labeled as a "crystallization inhibitor," as a claimed "dispersant."
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification provides a functional definition, stating a dispersant is what "allows the edaravone particles to be well dispersed in water without causing the edaravone particles to form secondary agglomerates" ’341 Patent, col. 5:63-67 This could support including any compound that performs this function, if it also belongs to the specified Markush group.
  • Evidence for a Narrower Interpretation: The patent lists specific examples, such as polyvinyl alcohol and methylcellulose, and describes their properties in detail ’341 Patent, col. 5:55-62; col. 6:1-4 A defendant may argue that the term should be construed in light of these specific embodiments and not cover compounds with different primary functions, such as crystallization inhibition.

The Term: "maintains the edaravone particles in a solid particle state" (’341 Patent, Claim 1)

• Context and Importance: This limitation distinguishes the claimed invention as a suspension from a solution. The complaint alleges the accused product is a "partial suspension," making the scope of this term critical. The dispute will likely involve how much of the edaravone must remain in a solid state to meet this limitation.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language does not quantify the amount that must be maintained as solid. This may support an interpretation where the presence of any solid edaravone particles, as in a "partial suspension," is sufficient to meet the limitation.
  • Evidence for a Narrower Interpretation: The patent background distinguishes from prior art solutions, and the summary of the invention emphasizes the formulation is a "suspension" containing "edaravone particles" ’341 Patent, Abstract; col. 4:62-64 A defendant could argue this context implies that a substantial, stable fraction of the drug must be in solid form, not a transient or minor amount that might be found in a formulation primarily designed as a solution.

VI. Other Allegations

• Indirect Infringement: The complaint alleges that upon FDA approval, Defendants will induce and contribute to infringement by commercially manufacturing, marketing, and selling the accused product for use in treating ALS Compl. ¶¶ 65, 68 The allegations are prospective, based on the future commercialization of the product described in the NDA.
• Willful Infringement: The complaint does not use the word "willful" but alleges that Defendants had "actual and constructive notice" of the patents-in-suit prior to filing their NDA Compl. ¶66 This allegation of pre-suit knowledge forms the basis for a potential claim for enhanced damages under 35 U.S.C. § 284.

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

• A core issue will be one of evidentiary proof: can Plaintiff substantiate its infringement allegations, which rely on inferring the composition of the accused product from Defendants' unrelated patents, with concrete evidence from the confidential NDA submission? The case will likely transition from notice pleading to a technical, evidence-based dispute over the specific ingredients and properties of the proposed generic.
• A second key issue will be one of claim scope and function: can the term "dispersant," defined by a specific list of chemical classes, be construed to cover an ingredient that Defendants may characterize as a "crystallization inhibitor" in their formulation? This raises a fundamental question of whether infringement can be found based on an ingredient's alleged function, even if its primary purpose and chemical identity are described differently by the defendant.
• Finally, for patents with pharmacokinetic limitations, a central question will be one of bioequivalence versus infringement: does the data submitted in the 505(b)(2) NDA to prove bioequivalence to RADICAVA ORS® also, as a matter of fact, demonstrate that the accused product meets the specific Cmax and AUC ranges recited in the asserted claims?