DCT

1:25-cv-01533

PH Health Ltd v. Somerset Therap LLC

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-01533, D. Del., 12/18/2025
  • Venue Allegations: Venue is alleged to be proper in the District of Delaware as Defendant is a Delaware limited liability company and is thus deemed to reside in the district.
  • Core Dispute: Plaintiff alleges that Defendant's submission of an Abbreviated New Drug Application (ANDA) to market a generic version of Plaintiff's VASOSTRICT® product constitutes an act of infringement of nine patents related to stable vasopressin formulations.
  • Technical Context: The technology concerns pharmaceutical formulations of vasopressin, a hormone used to increase blood pressure in critical care settings, with a focus on improving long-term stability.
  • Key Procedural History: The lawsuit was initiated under the Hatch-Waxman Act following Defendant's submission of an ANDA with a Paragraph IV certification, alleging that Plaintiff's patents are invalid, unenforceable, or will not be infringed by the proposed generic product. The patents-in-suit are listed in the FDA's "Orange Book" as covering Plaintiff's branded VASOSTRICT® drug.

Case Timeline

Date Event
2012-09-25 Plaintiff's predecessor submits New Drug Application (NDA) for VASOSTRICT®
2014-04-17 FDA approves original VASOSTRICT® NDA
2015-01-30 Earliest Priority Date for all Patents-in-Suit
2018-03-20 U.S. Patent No. 9,919,026 issues
2018-03-27 U.S. Patent No. 9,925,233 issues
2018-03-27 U.S. Patent No. 9,925,234 issues
2018-05-08 U.S. Patent No. 9,962,422 issues
2018-05-15 U.S. Patent No. 9,968,649 issues
2018-05-22 U.S. Patent No. 9,974,827 issues
2018-05-29 U.S. Patent No. 9,981,006 issues
2018-07-03 U.S. Patent No. 10,010,575 issues
2020-04-15 FDA approves supplemental NDA for 40 units/100 mL VASOSTRICT®
2021-04-21 FDA approves supplemental NDA for 20 units/100 mL VASOSTRICT®
2025-01-07 U.S. Patent No. 12,186,362 issues
2025-11-04 Earliest date Somerset sent Paragraph IV Notice Letter
2025-12-18 Complaint Filed

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

U.S. Patent No. 9,919,026 - Vasopressin Formulations for Use in Treatment of Hypotension, Issued March 20, 2018

The Invention Explained

  • Problem Addressed: The patent's background section notes that "[c]urrent formulations of vasopressin suffer from poor long-term stability" ('026 Patent, col. 1:24-25). This instability requires refrigeration and can lead to the generation of degradation products, limiting the shelf life and utility of the drug in clinical settings.
  • The Patented Solution: The invention provides a method for increasing blood pressure by administering a specific pharmaceutical composition of vasopressin that is stable for extended periods. The solution involves storing a unit dosage form with specific concentrations of vasopressin, a buffer (e.g., acetate), and dextrose at a controlled temperature (e.g., 2-8° C.) and pH, which allegedly results in less than 5% degradation after storage for a defined period (e.g., at least 24 hours) ('026 Patent, col. 1:56-68, col. 2:1-17).
  • Technical Importance: A stable, ready-to-use vasopressin formulation can reduce preparation time and potential for error in critical care environments where the drug is used to treat life-threatening hypotension ('026 Patent, col. 1:21-23).

Key Claims at a Glance

  • The complaint alleges infringement of one or more claims ('026 Patent, Compl. ¶42). Claim 1 is the first independent claim.
  • Essential Elements of Independent Claim 1:
    • A method of increasing blood pressure in a human in need thereof.
    • The method comprises providing a pharmaceutical composition that comprises, in a unit dosage form:
      • from about 0.1 µg/mL to about 2 µg/mL of vasopressin;
      • about 10 mM acetate buffer; and
      • about 5% dextrose.
    • The unit dosage form has a pH of 3.6 to 3.9.
    • Storing the unit dosage form at 2-8° C. for at least about 24 hours.
    • After storing, intravenously administering the unit dosage form to the human.
    • The administration provides from about 0.01 to about 0.1 units of vasopressin per minute.
    • The human is hypotensive.

U.S. Patent No. 9,925,233 - Vasopressin Formulations for Use in Treatment of Hypotension, Issued March 27, 2018

The Invention Explained

  • Problem Addressed: Similar to the '026 Patent, this patent addresses the "poor long-term stability" of existing vasopressin formulations ('233 Patent, col. 1:24-25).
  • The Patented Solution: This patent claims a method of increasing blood pressure by using a specific vasopressin formulation that exhibits enhanced stability after prolonged storage. The method involves storing a composition containing vasopressin, dextrose, and an acetate buffer at 5° C. for at least one month, where the composition exhibits no more than about 1% degradation, before administering it to a hypotensive patient ('233 Patent, col. 2:4-20). The claimed solution focuses on achieving a specific, low degradation profile after a longer storage period.
  • Technical Importance: By claiming a formulation with a verified low degradation profile after extended refrigerated storage, the invention provides a basis for a product with a longer shelf life, which is valuable for hospital pharmacies and clinical use ('233 Patent, col. 9:11-18).

Key Claims at a Glance

  • The complaint alleges infringement of one or more claims ('233 Patent, Compl. ¶52). Claim 1 is the first independent claim.
  • Essential Elements of Independent Claim 1:
    • A method of increasing blood pressure in a human in need thereof.
    • The method comprises:
      • a) storing at 5° C. for at least about one month a pharmaceutical composition for intravenous administration, the composition comprising:
        • from about 0.1 µg/mL to about 2 µg/mL of vasopressin;
        • dextrose; and
        • acetic acid, sodium acetate, or a combination thereof.
      • The composition exhibits no more than about 1% degradation of vasopressin after storage.
      • b) administering the composition to the human.
    • The administration provides from about 0.01 to about 0.1 units of vasopressin per minute.
    • The human is hypotensive.

U.S. Patent No. 9,925,234 - Vasopressin Formulations for Use in Treatment of Hypotension

  • Patent Identification: U.S. Patent No. 9,925,234, "Vasopressin Formulations for Use in Treatment of Hypotension," Issued March 27, 2018 (Compl. ¶14).
  • Technology Synopsis: This patent relates to methods of increasing blood pressure by administering a vasopressin formulation with an acetate buffer and about 5% dextrose, having a specific pH range of 3.6 to 3.9. The claims focus on achieving stability for specific durations of storage at 2-8° C. ('234 Patent, Abstract; Claim 1).
  • Asserted Claims: One or more claims (Compl. ¶62).
  • Accused Features: Somerset's ANDA Products, which are alleged to be vasopressin formulations for intravenous use (Compl. ¶60).

U.S. Patent No. 9,962,422 - Vasopressin Formulations for Use in Treatment of Hypotension

  • Patent Identification: U.S. Patent No. 9,962,422, "Vasopressin Formulations for Use in Treatment of Hypotension," Issued May 8, 2018 (Compl. ¶15).
  • Technology Synopsis: This patent claims methods of increasing blood pressure by administering a vasopressin formulation after it has been stored for a specified duration (e.g., at least 24 hours) at a controlled temperature (e.g., 2-8° C.). The formulation is defined by its components, including vasopressin, an acetate buffer, and dextrose, and its specific pH ('422 Patent, Abstract; Claim 1).
  • Asserted Claims: One or more claims (Compl. ¶72).
  • Accused Features: Somerset's ANDA Products, which are alleged to be vasopressin formulations for intravenous use (Compl. ¶70).

U.S. Patent No. 9,968,649 - Vasopressin Formulations for Use in Treatment of Hypotension

  • Patent Identification: U.S. Patent No. 9,968,649, "Vasopressin Formulations for Use in Treatment of Hypotension," Issued May 15, 2018 (Compl. ¶16).
  • Technology Synopsis: This patent claims methods of increasing blood pressure in a hypotensive human by administering a pharmaceutical composition containing vasopressin and a plurality of peptide impurities within specific quantitative ranges. The claims define the formulation by the presence and amount of specific degradation products relative to the active ingredient ('649 Patent, Abstract; Claim 1).
  • Asserted Claims: One or more claims (Compl. ¶82).
  • Accused Features: Somerset's ANDA Products, which are alleged to be vasopressin formulations for intravenous use (Compl. ¶80).

U.S. Patent No. 9,974,827 - Vasopressin Formulations for Use in Treatment of Hypotension

  • Patent Identification: U.S. Patent No. 9,974,827, "Vasopressin Formulations for Use in Treatment of Hypotension," Issued May 22, 2018 (Compl. ¶17).
  • Technology Synopsis: This patent is directed to methods of increasing blood pressure using a vasopressin formulation that has been stored for a specified period (e.g., at least 24 hours) and contains specific components, including vasopressin, dextrose, and an acetate buffer. The claims emphasize the post-storage administration of the formulation ('827 Patent, Abstract; Claim 1).
  • Asserted Claims: One or more claims (Compl. ¶92).
  • Accused Features: Somerset's ANDA Products, which are alleged to be vasopressin formulations for intravenous use (Compl. ¶90).

U.S. Patent No. 9,981,006 - Vasopressin Formulations for Use in Treatment of Hypotension

  • Patent Identification: U.S. Patent No. 9,981,006, "Vasopressin Formulations for Use in Treatment of Hypotension," Issued May 29, 2018 (Compl. ¶18).
  • Technology Synopsis: This patent claims methods of increasing blood pressure by administering a pharmaceutical composition that comprises vasopressin and specific related peptide impurities at defined ratios. The invention characterizes the formulation by its specific impurity profile, which is a marker of its stability and composition ('006 Patent, Abstract; Claim 1).
  • Asserted Claims: One or more claims (Compl. ¶102).
  • Accused Features: Somerset's ANDA Products, which are alleged to be vasopressin formulations for intravenous use (Compl. ¶100).

U.S. Patent No. 10,010,575 - Vasopressin Formulations for Use in Treatment of Hypotension

  • Patent Identification: U.S. Patent No. 10,010,575, "Vasopressin Formulations for Use in Treatment of Hypotension," Issued July 3, 2018 (Compl. ¶19).
  • Technology Synopsis: This patent claims a method of increasing blood pressure by administering a pharmaceutical composition comprising vasopressin, dextrose, and a 1 mM to 10 mM acetate buffer, with the unit dosage form having a pH of 3.6 to 3.9. The invention focuses on the use of a specific buffer concentration to achieve stability ('575 Patent, Abstract; Claim 1).
  • Asserted Claims: One or more claims (Compl. ¶112).
  • Accused Features: Somerset's ANDA Products, which are alleged to be vasopressin formulations for intravenous use (Compl. ¶110).

U.S. Patent No. 12,186,362 - Vasopressin Formulations for Use in Treatment of Hypotension

  • Patent Identification: U.S. Patent No. 12,186,362, "Vasopressin Formulations for Use in Treatment of Hypotension," Issued January 7, 2025 (Compl. ¶20, as corrected by patent data).
  • Technology Synopsis: This patent claims a pharmaceutical formulation comprising vasopressin, an acetate buffer, and either dextrose or sodium chloride, with a pH of about 3.5 to 4. The formulation is claimed to be stable at room temperature for up to 8 months and to contain no more than 17% total impurities ('362 Patent, Abstract; Claim 1).
  • Asserted Claims: One or more claims (Compl. ¶122).
  • Accused Features: Somerset's ANDA Products, which are alleged to be vasopressin formulations for intravenous use (Compl. ¶120).

III. The Accused Instrumentality

Product Identification

  • The accused products are Somerset Therapeutics, LLC’s proposed generic "Vasopressin Injection, 20 units/100 ml and 40 units/100 ml solution for intravenous use" (Compl. ¶¶1, 33). These are referred to as "Somerset's ANDA Products" and are the subject of ANDA No. 219356 submitted to the FDA (Compl. ¶1, ¶33).

Functionality and Market Context

  • The products are intended as generic versions of PH Health’s VASOSTRICT®, an injectable drug used "to increase blood pressure in adults with vasodilatory shock who remain hypotensive despite fluids and catecholamines" (Compl. ¶¶1, 26). The complaint alleges that Somerset intends to engage in the commercial manufacture, use, and sale of its ANDA Products in the United States upon receiving FDA approval, prior to the expiration of the Patents-in-Suit (Compl. ¶35).

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint. The complaint does not contain a claim chart exhibit or provide a detailed, element-by-element analysis of infringement for any specific claim. The infringement allegation is based on the statutory act of filing an ANDA containing a Paragraph IV certification, which under 35 U.S.C. § 271(e)(2)(A) is a technical act of infringement that allows the patent holder to bring suit before the generic product is marketed (Compl. ¶42). The complaint asserts that the product described in Somerset's confidential ANDA will, if approved and marketed, meet all the limitations of one or more claims of each of the asserted patents (Compl. ¶¶43, 53).

  • Identified Points of Contention:
    • Scope Questions: Based on the representative claims of the '026 and '233 patents, a central issue may be the interpretation of numerical ranges. The court will need to determine the proper scope of terms such as "about 0.1 µg/mL to about 2 µg/mL," "about 10 mM acetate buffer," "pH of 3.6 to 3.9," and stability thresholds like "no more than about 1% degradation." The definition of "about" and the precision required to meet these ranges will likely be a key point of dispute.
    • Technical Questions: The core technical question is whether the specific formulation detailed in Somerset's confidential ANDA No. 219356 falls within the scope of the asserted claims. This will involve a comparison of the accused product's exact composition, pH, manufacturing process, and demonstrated stability profile against the limitations of the patents. For instance, what evidence does the ANDA provide regarding the degradation percentage of the vasopressin formulation after being stored at 5° C. for one month, as required by claim 1 of the '233 Patent?

V. Key Claim Terms for Construction

The complaint does not provide sufficient detail for a definitive analysis, but based on the technology, certain terms are likely to be central to the dispute.

  • The Term: "a pH of 3.6 to 3.9" (from '026 Patent, Claim 1)

    • Context and Importance: In pharmaceutical formulations, pH is a critical parameter that directly affects the stability and degradation pathways of active ingredients like peptides. Whether the accused product's pH falls squarely within this claimed range will be a dispositive issue for infringement.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The parties may argue that standard industry practice for pH measurement allows for minor variations, and the patent's general discussion of acidic pH supports a less rigid interpretation of the range's boundaries ('026 Patent, col. 1:55-56).
      • Evidence for a Narrower Interpretation: The patent provides experimental data showing optimal stability at a pH of 3.5, with impurities increasing as the pH moves away from this value. Figure 9 and the related text could be used to argue that the claimed 3.6-3.9 range is a precise and critical window for achieving the patented stability and should not be expanded ('026 Patent, col. 8:67-col. 9:3; Fig. 9).

  • The Term: "no more than about 1% degradation" (from '233 Patent, Claim 1)

    • Context and Importance: This limitation defines a performance characteristic of the claimed formulation. The case may turn on whether Somerset's product meets this stability requirement and how "degradation" is measured. Practitioners may focus on this term because it links the composition to a functional outcome, raising questions of both testing methodology and the scope of "about."
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: A party could argue that "about 1%" encompasses standard experimental variability in analytical methods like HPLC, which are used to measure peptide degradation. The specification's repeated use of "about" for various parameters may suggest the patentee did not intend for strict numerical limits ('233 Patent, col. 10-13, passim).
      • Evidence for a Narrower Interpretation: The patent presents specific examples with precise degradation percentages under defined conditions. A party may argue that these examples define the outer boundary of what "about 1%" means and that the term is meant only to prevent escape from infringement through trivial deviations from the 1.0% value ('233 Patent, Tables 7-12).

VI. Other Allegations

  • Indirect Infringement: The complaint alleges that upon FDA approval, Somerset will induce infringement and contributorily infringe the patents-in-suit (Compl. ¶¶43-44, 53-54). The basis for inducement is the allegation that Somerset will "intentionally encourage acts of direct infringement with knowledge of the... patent," which in an ANDA context typically refers to the product's label instructing medical professionals to use the generic drug in an infringing manner. The basis for contributory infringement is the allegation that Somerset's products are "especially adapted for a use that infringes" and have no substantial non-infringing use (Compl. ¶44).
  • Willful Infringement: The complaint alleges that Somerset's infringement would be "willful, wanton, and deliberate" (Compl. ¶47, ¶57). This allegation is based on Somerset's pre-suit knowledge of the patents, as evidenced by its sending of a Paragraph IV Notice Letter to PH Health (Compl. ¶34).

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

  1. A central issue will be one of claim construction and scope: can the numerical ranges for pH, concentration, and degradation recited in the claims be interpreted to cover the specific formulation disclosed in Somerset's confidential ANDA submission? The outcome will likely depend heavily on the court's construction of the term "about" and the precise boundaries of the claimed stability profiles.
  2. A second core issue will be validity: Somerset's Paragraph IV certification asserts that the patents-in-suit are invalid and/or unenforceable. A key question for the court will be whether the claimed formulations represent a non-obvious advance over prior art related to stabilizing peptide hormones like vasopressin.
  3. The case will present a key evidentiary question: what does the data within Somerset's confidential ANDA actually show? The resolution of the infringement question will depend entirely on a technical comparison between the data supporting Somerset's application and the limitations of the asserted claims.