DCT

1:25-cv-01146

Supernus Pharma Inc v. Macleods Pharma Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:

  • Case Identification: 1:25-cv-01146, D. Del., 09/15/2025

  • Venue Allegations: Plaintiff alleges venue is proper in the District of Delaware because Defendant Macleods USA is a Delaware corporation and, along with its parent Macleods Ltd., has purposefully availed itself of the district through systematic business contacts, including the anticipated marketing and sale of the accused generic product in Delaware.

  • Core Dispute: Plaintiff alleges that Defendants' submission of an Abbreviated New Drug Application (ANDA) to the FDA seeking approval to market generic extended-release viloxazine capsules constitutes an act of infringement of six patents covering formulations and methods of use for the drug.

  • Technical Context: The dispute concerns pharmaceutical formulations of viloxazine, a selective norepinephrine reuptake inhibitor used for treating Attention Deficit/Hyperactivity Disorder (ADHD).

  • Key Procedural History: This is a Hatch-Waxman action triggered by Defendants' filing of ANDA No. 220570 and their subsequent "Notice Letter," sent on or about August 1, 2025, which included a Paragraph IV certification against the patents-in-suit. The patents are listed in the FDA's "Orange Book" as covering Plaintiff's approved viloxazine product, Qelbree®.

Case Timeline

Date Event
2008-09-05 Priority Date for ’753, ’143, and ’523 Patents
2012-02-08 Priority Date for ’204, ’853, and ’338 Patents
2016-06-07 U.S. Patent No. 9,358,204 Issues
2017-03-28 U.S. Patent No. 9,603,853 Issues
2017-05-30 U.S. Patent No. 9,662,338 Issues
2022-05-10 U.S. Patent No. 11,324,753 Issues
2022-10-04 U.S. Patent No. 11,458,143 Issues
2024-10-22 U.S. Patent No. 12,121,523 Issues
2025-08-01 Defendants send Paragraph IV Notice Letter
2025-09-15 Complaint Filed

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

U.S. Patent No. 9,358,204 - "Formulations of Viloxazine"

The Invention Explained

  • Problem Addressed: The patent's background section notes that viloxazine has a relatively short elimination half-life and high clearance rate in humans, which "presents challenges for developing an extended release formulation" suitable for less frequent dosing (e.g., once or twice daily) (’204 Patent, col. 1:41-45).
  • The Patented Solution: The invention claims to solve this problem by creating modified-release formulations that combine different components to achieve specific drug release profiles over time (’204 Patent, Abstract). These formulations can include immediate-release (IR), extended-release (XR), and delayed-release (DR) components, often constructed as multi-layered pellets or beads, to control the rate at which viloxazine becomes available in the body (’204 Patent, col. 2:1-4).
  • Technical Importance: An effective extended-release formulation allows for once- or twice-daily dosing, which can improve patient compliance and provide more stable therapeutic blood concentrations compared to multiple daily doses of an immediate-release version.

Key Claims at a Glance

  • The complaint alleges infringement of one or more unspecified claims (Compl. ¶67). Independent claim 1 is representative of the formulation technology:
  • A pharmaceutical formulation comprising:
    • An immediate release (IR) component with an inert core and a layer of viloxazine.
    • An extended release (XR) component, also with an inert core and a first layer of viloxazine.
    • The XR component has a second layer comprising a "release rate controlling compound" and a "pore former" in a specific weight ratio (19:1 to 8.5:1.5).
    • The formulation must contain 25% to 75% viloxazine by weight and release at least 80% of the drug over at least 2 hours in vitro.
  • The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 9,603,853 - "Formulations of Viloxazine"

The Invention Explained

  • Problem Addressed: This patent, from the same family as the ’204 patent, addresses the same technical challenge: creating a viable extended-release formulation for viloxazine to overcome its short biological half-life (’853 Patent, col. 1:44-48).
  • The Patented Solution: The patent claims a method of treating ADHD or major depressive disorder by administering a specific modified-release formulation of viloxazine (’853 Patent, Abstract). The formulation itself, as described in the claims, is structurally identical to that claimed in the ’204 Patent, featuring a combination of IR and XR components to control the drug's release profile.
  • Technical Importance: This patent protects the therapeutic application of the specific extended-release formulation technology, linking the formulation's structure to a specific medical use.

Key Claims at a Glance

  • The complaint alleges infringement of one or more unspecified claims (Compl. ¶89). Independent claim 1 is representative of the method-of-use technology:
  • A method of treating ADHD or major depressive disorder in a mammal, comprising administering a formulation that includes:
    • An immediate release (IR) component.
    • An extended release (XR) component.
    • The structural details of the IR and XR components, including the release rate controlling compound and pore former ratio, are identical to those recited in claim 1 of the ’204 Patent.
  • The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 9,662,338 - "Formulations of Viloxazine"

  • Patent Identification: U.S. Patent No. 9,662,338, "Formulations of Viloxazine," issued May 30, 2017.
  • Technology Synopsis: This patent is also in the same family as the ’204 and ’853 patents and addresses the need for an extended-release viloxazine formulation (’338 Patent, col. 1:44-48). It claims a method of treating ADHD by administering a formulation containing IR and XR components with specific structural and release characteristics (’338 Patent, col. 27:1-33).
  • Asserted Claims: The complaint asserts one or more unspecified claims (Compl. ¶111).
  • Accused Features: The accused feature is the commercial manufacture, use, or sale of Defendants' ANDA products for the treatment of ADHD, as will be instructed by the product's proposed labeling (Compl. ¶¶119, 121).

U.S. Patent Nos. 11,324,753; 11,458,143; and 12,121,523 - "Method of Treatment of Attention Deficit/Hyperactivity Disorder (ADHD)"

  • Patent Identification: U.S. Patent No. 11,324,753 ("Method of Treatment of Attention Deficit/Hyperactivity Disorder (ADHD)"), issued May 10, 2022; U.S. Patent No. 11,458,143 (same title), issued October 4, 2022; and U.S. Patent No. 12,121,523 (same title), issued October 22, 2024.
  • Technology Synopsis: These three patents are from a separate family and are based on the discovery that viloxazine exhibits antagonist activity at the 5-HT7 and 5-HT1B serotonin receptors, in addition to its known activity as a noradrenergic reuptake inhibitor (’753 Patent, col. 1:26-32). The patents claim methods of treating ADHD by administering viloxazine to achieve this dual therapeutic mechanism (’753 Patent, Abstract).
  • Asserted Claims: The complaint asserts one or more unspecified claims for each patent (Compl. ¶¶133, 155, 177).
  • Accused Features: The accused feature is the use of Defendants' ANDA products for the treatment of ADHD, which Plaintiff alleges will be induced by the instructions in the proposed product labeling (Compl. ¶¶141, 143, 163, 165, 185, 187).

III. The Accused Instrumentality

Product Identification

  • The accused products are Defendants' generic viloxazine extended-release oral capsules, in 150 mg and 200 mg dosage strengths, for which approval is sought under ANDA No. 220570 (Compl. ¶14, ¶52).

Functionality and Market Context

  • The complaint alleges that Defendants' ANDA Products are based on Plaintiff's Qelbree® as the reference listed drug and are represented to the FDA as being bioequivalent (Compl. ¶51, ¶53). The proposed prescribing information for the ANDA Products allegedly includes an "Indication and Usage" section stating the products are for the treatment of ADHD in adults and pediatric patients, with a "Dosage and Administration" section that recommends specific dosing regimens (Compl. ¶¶56, 57). The complaint also alleges the proposed label will describe viloxazine's mechanism of action, including inhibiting the reuptake of norepinephrine and exhibiting activity at certain serotonin receptors (Compl. ¶¶58, 59). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not provide sufficient detail for a claim-chart analysis of infringement. It makes general allegations that the Defendants' ANDA Products will infringe the asserted patents without mapping specific product features to claim elements. The infringement theory is predicated on the ANDA Products being bioequivalent to the reference drug Qelbree®, which is covered by the patents-in-suit (Compl. ¶¶44, 53, 75). For the formulation patents ('204, '853, '338), the infringement theory suggests that to achieve bioequivalence, the ANDA Products must necessarily possess the claimed formulation characteristics. For the method-of-use patents ('753, '143, '523), the theory is that Defendants will induce infringement by providing a product with a label that instructs physicians and patients to use it for the patented method of treating ADHD (Compl. ¶¶143-145).

  • Identified Points of Contention:
    • Scope Questions: A central dispute for the formulation patents may be whether achieving bioequivalence legally necessitates infringement of the specific structural claims. The court may need to resolve whether Defendants' formulation, while functionally equivalent, falls outside the literal scope of terms like "inert core," the layered structure, or the specific "weight ratio" of the release rate controlling compound and pore former.
    • Technical Questions: For the method-of-use patents ('753, '143, '523), a key question may be whether the act of administering viloxazine for ADHD inherently results in the claimed biological mechanism of "antagonizing" specific serotonin receptors. Defendants may argue that their product does not practice this claimed mechanism or may challenge the patent's teaching of the link between administration and the claimed biological effect.

V. Key Claim Terms for Construction

  • The Term: "pore former" (from claim 1 of the ’204 and ’853 Patents)
  • Context and Importance: This term is critical to defining the structure of the extended-release component. Its construction will determine whether the specific excipients used by Defendants in their formulation fall within the claim scope. Practitioners may focus on this term because a defendant in a Hatch-Waxman case will often attempt to design around a patent by using alternative, non-infringing excipients that achieve a similar functional result.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification provides a list of exemplary pore formers, including "povidone, hypromellose, hydroxyethyl cellulose, hydroxypropyl cellulose, organic acids and salts amongst other excipients" (’204 Patent, col. 9:48-51). The use of "such as" and "amongst other excipients" suggests the list is not exhaustive.
    • Evidence for a Narrower Interpretation: Defendants may argue the term should be limited to the specific examples provided or to compounds with similar chemical and functional properties, potentially excluding a novel excipient they may have used.
  • The Term: "antagonizing 5-HT7 and 5HT1B receptor activity" (from claim 1 of the ’753 Patent)
  • Context and Importance: This phrase defines the novel biological mechanism that underpins the method-of-use patents from the Breder family. The infringement analysis for these patents depends on whether the administration of Defendants' product results in this specific receptor activity. Its construction is also central to any potential validity challenges based on prior art.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language does not specify a required degree or level of antagonism. Plaintiff may argue that any measurable antagonist activity resulting from administration for ADHD meets the claim limitation.
    • Evidence for a Narrower Interpretation: The specification describes specific assays and provides data showing viloxazine's antagonist effect, including IC50 values (’753 Patent, col. 5:1-12; Figs. 3, 6). A defendant may argue that the term "antagonizing" should be construed to require a specific, clinically significant level of antagonism consistent with the data disclosed in the patent, a level their product allegedly does not produce.

VI. Other Allegations

  • Indirect Infringement: The complaint's primary allegation for the method-of-use patents is inducement of infringement. It alleges Defendants will knowingly encourage and instruct third parties (e.g., physicians, patients) to infringe by distributing a product with labeling that directs its use for the treatment of ADHD (Compl. ¶¶78, 100, 144, 166, 188). Contributory infringement is also alleged on the basis that the ANDA products are not staple articles of commerce suitable for substantial noninfringing uses (Compl. ¶¶80, 102, 146).
  • Willful Infringement: Willfulness is alleged based on Defendants' knowledge of the patents-in-suit, as evidenced by their filing of a Paragraph IV certification that specifically identified each patent (Compl. ¶¶81, 103, 125, 147, 169, 191). The complaint alleges that despite this knowledge, Defendants have signaled their intent to engage in infringing activities.

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

  • A core issue will be one of structural versus functional equivalence: for the formulation patents, can Plaintiff prove that Defendants' bioequivalent generic product literally infringes the specific multi-layered structure and component ratios required by the claims, or have Defendants successfully designed a formulation that is functionally similar but structurally non-infringing?
  • A key legal and evidentiary question will be one of label-induced mechanism: for the method-of-use patents, does a product label that instructs administration for ADHD, without explicitly mentioning serotonin receptor antagonism, suffice to prove inducement of claims that require achieving that specific biological mechanism?
  • The case may also present a significant validity question: can the method claims reciting serotonin receptor antagonism withstand a challenge that this mechanism was inherent in the prior art use of viloxazine for other conditions (e.g., depression), even if that specific mechanism was not previously recognized or understood?