DCT
1:26-cv-00402
Azurity Pharma Inc v. Appco Pharma LLC
Key Events
Amended Complaint
Table of Contents
complaint Intelligence
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Azurity Pharmaceuticals, Inc. (Delaware)
- Defendant: Appco Pharma LLC (Delaware) and Somerset Therapeutics, LLC (Delaware)
- Plaintiff’s Counsel: Potter Anderson & Corroon LLP
- Case Identification: 1:26-cv-00402, D. Del., 09/09/2026
- Venue Allegations: Plaintiff asserts that venue is proper in the District of Delaware because Defendant Somerset is a Delaware corporation residing in the district. The complaint also alleges that the district is a likely destination for the accused product.
- Core Dispute: Plaintiff alleges that Defendants’ submission of an Abbreviated New Drug Application (ANDA) to the FDA for a generic version of Plaintiff’s ZONISADE® product constitutes an act of infringement of four patents covering oral liquid suspension formulations of the anticonvulsant drug zonisamide.
- Technical Context: The technology concerns stable, oral liquid suspension formulations of zonisamide, developed as an alternative to solid dosage forms to improve administration for patients who have difficulty swallowing pills, such as pediatric or geriatric patients.
- Key Procedural History: This is a Hatch-Waxman action triggered by Defendants’ notification to Azurity, via a letter dated February 24, 2026, of their ANDA filing. The complaint notes a dispute over the terms of Defendants' offer to provide confidential access to the ANDA, which Plaintiff deemed unreasonable.
Case Timeline
| Date | Event |
|---|---|
| 2017-08-19 | Patent Priority Date for all Patents-in-Suit |
| 2022-10-25 | U.S. Patent No. 11,478,456 ('’456 Patent) Issued |
| 2022-12-20 | U.S. Patent No. 11,529,333 ('’333 Patent) Issued |
| 2025-12-09 | U.S. Patent No. 12,491,179 ('’179 Patent) Issued |
| 2026-02-24 | Defendants send ANDA Notice Letter to Azurity |
| 2026-07-21 | U.S. Patent No. 12,685,723 ('’723 Patent) Issued |
| 2026-09-09 | Complaint Filing Date |
| 2038-08-18 | Expiration Date for the Patents-in-Suit per the complaint |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 11,478,456 - “Oral Pharmaceutical Composition Comprising Zonisamide and Process of Preparation Thereof”
The Invention Explained
- Problem Addressed: The patent background explains that the anticonvulsant drug zonisamide is available in solid dosage forms like capsules and tablets, which can be difficult for certain patients, such as children and the seriously ill, to swallow ʼ456 Patent, col. 3:1-4 ʼ456 Patent, col. 4:9-12
- The Patented Solution: The invention is a liquid oral pharmaceutical suspension of zonisamide designed for improved stability and palatability ʼ456 Patent, col. 3:24-27 It achieves this through a specific combination of excipients, including a suspending agent system, buffering agents to control pH, and preservatives, all formulated in an aqueous vehicle ʼ456 Patent, abstract ʼ456 Patent, col. 4:17-37
- Technical Importance: The development of a stable liquid formulation of an established drug like zonisamide makes the therapy accessible to patient populations with dysphagia (difficulty swallowing), expanding its clinical utility.
Key Claims at a Glance
- The complaint asserts infringement of "one or more claims" of the '456 patent Compl. ¶40 The patent contains one independent method claim.
- Independent Claim 1: A method of treating seizures by administering a liquid oral pharmaceutical suspension with the following key elements:
- Zonisamide in an amount of about 20 mg/mL.
- A specific suspending agent system comprising about 2 mg/mL to about 3.5 mg/mL xanthan gum and about 20 mg/mL of a combination of microcrystalline cellulose and sodium carboxymethylcellulose.
- One or more buffering agents.
- A preservative.
- The suspension has a pH of 3.5 to 5.0.
- The suspension is stable for at least 6 months when stored at 40° C. and 25% relative humidity.
U.S. Patent No. 11,529,333 - “Oral Pharmaceutical Composition Comprising Zonisamide and Process of Preparation Thereof”
The Invention Explained
- Problem Addressed: The '333 patent addresses the same problem as the '456 patent: the lack of a suitable liquid dosage form for zonisamide, which limits its use in patients who cannot swallow solid pills ʼ333 Patent, col. 3:1-6
- The Patented Solution: The patent discloses a stable liquid oral pharmaceutical suspension of zonisamide. The composition is defined by its components, including a specific concentration of zonisamide, a dual-component suspending agent, buffering agents, a preservative, and functional properties including a specific pH range and demonstrated long-term stability under accelerated conditions ʼ333 Patent, abstract ʼ333 Patent, claim 1
- Technical Importance: This invention provides a specific, stable, and ready-to-use liquid formulation of zonisamide, potentially improving patient compliance and broadening therapeutic access.
Key Claims at a Glance
- The complaint asserts infringement of "one or more claims" of the '333 patent Compl. ¶45 The patent contains one independent composition claim.
- Independent Claim 1: A liquid oral pharmaceutical suspension comprising:
- Zonisamide in an amount of about 20 mg/mL.
- A suspending agent comprising about 2 mg/mL to about 3.5 mg/mL xanthan gum and about 20 mg/mL of a combination of microcrystalline cellulose and sodium carboxymethylcellulose.
- One or more buffering agents.
- A preservative.
- A pH of 3.5 to 5.0.
- The composition is stable for at least 6 months when stored at 40° C. and 25% relative humidity.
U.S. Patent No. 12,491,179 - “Oral Pharmaceutical Composition Comprising Zonisamide and Process of Preparation Thereof”
- Patent Identification: U.S. Patent No. 12491179, “Oral Pharmaceutical Composition Comprising Zonisamide and Process of Preparation Thereof,” issued December 9, 2025 Compl. ¶24
- Technology Synopsis: The patent claims a stable liquid oral pharmaceutical suspension of zonisamide, which is identified as the sole active ingredient ʼ179 Patent, claim 1 The formulation includes a specific suspending agent, buffering agents (citric acid monohydrate and trisodium citrate dihydrate), a sodium benzoate preservative, and flavorings, all within a defined pH range and stability profile ʼ179 Patent, claim 1
- Asserted Claims: The complaint alleges infringement of "one or more claims" Compl. ¶50 Claim 1 is the sole independent claim.
- Accused Features: The accused instrumentality is the Defendants' ANDA product, which is alleged on information and belief to be a zonisamide oral suspension that meets the compositional and functional limitations of the asserted claims Compl. ¶37 Compl. ¶50
U.S. Patent No. 12,685,723 - “Oral Pharmaceutical Composition Comprising Zonisamide and Process of Preparation Thereof”
- Patent Identification: U.S. Patent No. 12685723, “Oral Pharmaceutical Composition Comprising Zonisamide and Process of Preparation Thereof,” issued July 21, 2026 Compl. ¶28
- Technology Synopsis: This patent claims a liquid oral pharmaceutical suspension where zonisamide is the only active ingredient ʼ723 Patent, claim 1 The claimed composition includes zonisamide, a specific suspending system, particular buffering agents, sucralose, strawberry flavor, and a sodium benzoate preservative, and is further defined by its pH and a specific impurity profile after one month of storage at accelerated conditions ʼ723 Patent, claim 1
- Asserted Claims: The complaint alleges infringement of "one or more claims" Compl. ¶55 Claim 1 is the sole independent claim.
- Accused Features: The allegations target the formulation of the Defendants' generic zonisamide suspension, which Plaintiff alleges will infringe the specific compositional and stability requirements of the patent's claims Compl. ¶37 Compl. ¶55
III. The Accused Instrumentality
Product Identification
The accused instrumentality is the "Defendants' ANDA Product," a proposed generic version of Azurity's ZONISADE® (zonisamide oral suspension) for which Defendants have sought FDA approval under ANDA No. 220833 Compl. ¶1 Compl. ¶32
Functionality and Market Context
The act of infringement alleged is the submission of the ANDA itself, which seeks approval to market a generic drug before the expiration of the patents-in-suit Compl. ¶40 By filing the ANDA, Defendants have represented to the FDA that their product has the same active ingredient (zonisamide), dosage form (oral suspension), strength, and route of administration as the branded ZONISADE® product, and is bioequivalent to it Compl. ¶37 The complaint does not provide specific details on the formulation of the Defendants' ANDA Product, noting that Defendants' offer of confidential access to the ANDA was subject to what Plaintiff considered "unreasonable restrictions" Compl. ¶38
No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
The complaint does not contain detailed infringement contentions or claim charts, as is common in initial ANDA complaints filed before full discovery. The infringement theory is based on Defendants’ submission of ANDA No. 220833, which, on information and belief, describes a product that will meet the limitations of the asserted claims (Compl. ¶¶40-41; Compl. ¶¶45-46).
11,478,456 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A method of treating seizures in a subject in need thereof, comprising administering to the subject a liquid oral pharmaceutical suspension comprising: zonisamide in an amount of about 20 mg/mL; | The Defendants' ANDA Product is a liquid oral suspension of zonisamide at the same strength as the reference listed drug. The proposed label will direct its administration for treating seizures. | ¶37; ¶41 | col. 11:40-42 |
| a suspending agent comprising about 2 mg/mL to about 3.5 mg/mL xanthan gum and about 20 mg/mL of a combination of microcrystalline cellulose and sodium carboxymethylcellulose; | On information and belief, the ANDA Product's formulation contains this specific suspending agent system within the claimed concentration ranges. | ¶37; ¶41 | col. 11:43-48 |
| one or more buffering agents; | On information and belief, the ANDA Product contains one or more buffering agents as claimed. | ¶37; ¶41 | col. 11:49 |
| a preservative; | On information and belief, the ANDA Product contains a preservative as claimed. | ¶37; ¶41 | col. 11:51 |
| wherein the liquid oral pharmaceutical suspension has a pH of 3.5 to 5.0; | On information and belief, the ANDA Product is formulated to have a pH within the claimed range. | ¶37; ¶41 | col. 12:1-2 |
| wherein the liquid oral pharmaceutical suspension is stable for at least 6 months when stored at 40° C. and 25% relative humidity. | On information and belief, stability data submitted in the ANDA will demonstrate that the product meets this functional limitation. | ¶37; ¶41 | col. 12:4-7 |
11,529,333 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A liquid oral pharmaceutical suspension, comprising: zonisamide in an amount of about 20 mg/mL; | The Defendants' ANDA Product is a liquid oral suspension alleged to contain zonisamide at the claimed concentration. | ¶37; ¶46 | col. 11:36-37 |
| a suspending agent comprising about 2 mg/mL to about 3.5 mg/mL xanthan gum and about 20 mg/mL of a combination of microcrystalline cellulose and sodium carboxymethylcellulose; | On information and belief, the ANDA Product's formulation includes this specific combination of suspending agents at the claimed concentrations. | ¶37; ¶46 | col. 11:38-43 |
| one or more buffering agents; | On information and belief, the ANDA Product's formulation includes one or more buffering agents. | ¶37; ¶46 | col. 11:44 |
| wherein the composition is stable for at least 6 months when stored at 40° C. and 25% relative humidity. | On information and belief, stability data within the ANDA filing demonstrates the product meets this stability requirement. | ¶37; ¶46 | col. 11:50-53 |
Identified Points of Contention
- Compositional Questions: The central issue will be a factual one discoverable from the confidential ANDA: does the Defendants' proposed generic formulation contain the exact combination of excipients (e.g., xanthan gum, microcrystalline cellulose, sodium carboxymethylcellulose), in the specific concentration ranges, required by the independent claims?
- Functional Questions: A key point of dispute may be whether the Defendants' product meets the functional limitations of the claims, specifically the required pH range (3.5 to 5.0) and the stability profile (stable for at least 6 months at 40° C. and 25% RH). The definition of "stable" itself, including acceptable impurity levels, may become a focus of the dispute.
V. Key Claim Terms for Construction
The Term: "about" (e.g., "about 20 mg/mL")
- Context and Importance: This term is used to qualify nearly all concentration values in the independent claims of the patents-in-suit. The construction of "about" will be critical in determining the literal scope of the claims. If the Defendants' ANDA product uses concentrations that are close but not identical to the recited values, the definition of this term could be dispositive of infringement.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The repeated use of "about" throughout the claims suggests the inventors contemplated and intended to cover some variation from the stated numerical values. The specification's description of a specific formulation in Table 1 could be argued as merely an exemplary embodiment, not a limitation on the scope of "about" ʼ456 Patent, col. 8:5-20
- Evidence for a Narrower Interpretation: Parties may argue that the meaning of "about" should be informed by the context of the invention and the significance of the numerical values to achieving the desired stability and performance. The specific, non-approximated values in the patent's working examples (e.g., "20.00" mg/ml for Zonisamide in Table 1) may be cited to support a narrower range of equivalents ʼ456 Patent, col. 8:5-20
The Term: "stable for at least 6 months when stored at 40° C. and 25% relative humidity"
- Context and Importance: This functional limitation appears in the independent claims of both the '456 and '333 patents and is a requirement for infringement. The dispute will center on what evidence is required to prove a product is "stable."
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A patentee might argue the term should be given its plain and ordinary meaning in the context of FDA regulatory standards for pharmaceutical stability. The stability data presented in the patent's examples (e.g., '456 Patent, Table 2) could be positioned as one way, but not the only way, to demonstrate the claimed stability.
- Evidence for a Narrower Interpretation: A defendant could point to dependent claims that add specific impurity limits to the stability requirement (e.g., '456 Patent, claim 15, limiting single max impurity to 0.06% or less). They may argue that the absence of such limits in the independent claim means "stable" is a broader term, but could also use these dependent claims to argue that the inventors knew how to define stability with precision, potentially limiting the scope of the term in the independent claim through claim differentiation principles.
VI. Other Allegations
Indirect Infringement
The complaint alleges induced infringement for all four patents. The basis for this allegation is that the Defendants' proposed product labeling will instruct physicians and patients to administer the generic drug for the treatment of seizures, thereby directing them to perform the steps of the asserted method claims and use the composition in an infringing manner Compl. ¶46 The complaint also states there are "no substantial non-infringing uses" for the ANDA product, which supports both induced and contributory infringement Compl. ¶47
Willful Infringement
The complaint alleges that Defendants had "actual and constructive knowledge" of the patents prior to filing their ANDA and that they possessed "specific intent to infringe" Compl. ¶42 Compl. ¶47 This allegation is based on the patents being listed in the FDA's Orange Book for ZONISADE® and the statutory framework of the Hatch-Waxman Act, which requires an ANDA filer to certify its position regarding listed patents.
VII. Analyst’s Conclusion: Key Questions for the Case
- A central question will be one of compositional identity: does the precise formulation detailed in the Defendants' confidential ANDA filing fall within the literal scope of the claims, particularly with respect to the specific combination and concentration ranges of the claimed suspending agents?
- A second key issue will be one of functional performance: does the Defendants' ANDA product meet the claimed functional limitations regarding pH and long-term stability under accelerated conditions, and how will the term "stable" be construed by the court, especially in relation to impurity profiles?
- The case may also turn on a question of definitional scope during claim construction: how broadly will the court interpret the term "about" when applied to the claimed concentrations, a determination that could directly impact the infringement analysis if the accused product's formulation deviates even slightly from the numbers recited in the claims.
Analysis metadata