DCT

1:23-cv-13764

Curia Holdings LLC v. Salix Pharma Ltd

Log In

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:23-cv-13764, D.N.J., 08/31/2023
  • Venue Allegations: Venue is alleged based on Defendants' principal places of business, regular business activities, and systematic contacts within New Jersey. The complaint also alleges that certain defendants have previously submitted to the court's jurisdiction in prior litigation.
  • Core Dispute: Plaintiff alleges that Defendants’ XIFAXAN® antibiotic tablets, manufactured after certain process changes in 2015, infringe a patent directed to a specific polymorphic mixture of the active ingredient rifaximin.
  • Technical Context: The lawsuit operates in the field of pharmaceutical chemistry, focusing on the polymorphism of active pharmaceutical ingredients (APIs), where controlling the specific crystalline structure of a compound is critical for its stability, bioavailability, and therapeutic efficacy.
  • Key Procedural History: The complaint constructs a narrative distinguishing between a non-infringing "Early XIFAXAN®" sold before 2015 and an infringing "Later XIFAXAN®" sold after manufacturing changes, a strategy that may be intended to preempt an on-sale bar invalidity defense. Plaintiff alleges Defendants were aware of the patent's family as early as 2017 due to a European patent opposition proceeding involving a related patent. The complaint also notes a separate, pending litigation in the same district between the same parties involving other patents in the same family.

Case Timeline

Date Event
2004-07-01 Alleged launch of "Early XIFAXAN®" 200 mg dose
2010-05-01 Alleged launch of "Early XIFAXAN®" 550 mg dose
2014-03-31 '099 Patent Priority Date
2015-04-23 Date of first alleged manufacturing change to XIFAXAN®
2017-11-08 Alleged date of Defendant Alfasigma’s European patent opposition filing
2023-08-29 '099 Patent Issue Date
2023-08-31 Complaint Filing Date

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

U.S. Patent No. 11,739,099 - Polymorphic Mixture of Rifaximin and its Use for the Preparation of Solid Formulations, issued August 29, 2023

The Invention Explained

  • Problem Addressed: The patent’s background section describes the difficulty in manufacturing the antibiotic Rifaximin with a consistent and stable crystalline structure, or polymorph ('099 Patent, col. 2:40-51). Different polymorphs possess different physical properties, such as systemic absorption, which is undesirable for a gut-targeted drug ('099 Patent, col. 2:10-15). The patent notes that prior manufacturing processes, including crystallization, drying, and granulation, could lead to inconsistent or undesirable polymorphic forms ('099 Patent, col. 2:24-29, 55-61).
  • The Patented Solution: The invention is a specific, stable polymorphic mixture of Rifaximin containing its alpha (α) and beta (β) forms in a defined ratio (85/15±3), characterized by a unique X-ray diffraction pattern ('099 Patent, col. 3:3-6). The patent also discloses a manufacturing process that can consistently produce this stable mixture, which resists further polymorphic changes during the physical stresses of dry granulation and tableting ('099 Patent, col. 3:7-14).
  • Technical Importance: The claimed invention addresses a critical manufacturing challenge by providing a method to produce a Rifaximin drug product with a reproducible and stable polymorphic composition, which is essential for consistent product quality and regulatory approval ('099 Patent, col. 2:48-51).

Key Claims at a Glance

  • The complaint asserts independent claim 1 ('099 Patent, col. 11:1-12).
  • The essential elements of independent claim 1 are:
    • A tablet obtained by a dry granulation and tableting procedure
    • comprising a Rifaximin polymorphic mixture that comprises α and β Rifaximin polymorphs in a α/β relative ratio of 85/15±3,
    • wherein the Rifaximin polymorphic mixture is characterized by an X-Ray spectrum with characteristic 2theta values at about: 5.32, 5.78, 6.50, 7.24, 7.82, 8.80, 10.50, 11.02, 11.58, 13.08, 14.42, 17.32, 17.68, 18.58, 19.52, 21.04, 21.60, and 21.92.
  • The complaint reserves the right to assert dependent claims 2-14 (Compl. ¶35).

III. The Accused Instrumentality

Product Identification

The accused products are the 200 mg and 550 mg dosage forms of XIFAXAN® tablets manufactured and sold after alleged manufacturing changes that began in 2015, which the complaint designates "Later XIFAXAN®" (Compl. ¶¶47, 64).

Functionality and Market Context

XIFAXAN® is an antibiotic containing rifaximin, indicated for the treatment of traveler's diarrhea, the reduction of risk of overt hepatic encephalopathy recurrence, and the treatment of irritable bowel syndrome with diarrhea (Compl. ¶37). The complaint alleges that while XIFAXAN® has been sold since 2004, manufacturing changes initiated around 2015 altered the polymorphic character of the rifaximin active ingredient to an infringing form (Compl. ¶¶38, 44, 47).

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

'099 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A tablet obtained by a dry granulation and tableting procedure The complaint alleges that the "Later XIFAXAN®" tablets infringe Claim 1, which recites a tablet obtained by this process. ¶73, ¶74 col. 11:1-2
comprising a Rifaximin polymorphic mixture that comprises α and β Rifaximin polymorphs in a α/β relative ratio of 85/15±3, The "Later XIFAXAN®" product allegedly contains a polymorphic mixture of α and β rifaximin in a relative ratio that falls within the scope of the claims. ¶64, ¶66 col. 11:3-6
wherein the Rifaximin polymorphic mixture is characterized by an X-Ray spectrum with characteristic 2theta values at about: 5.32, 5.78, 6.50, 7.24, 7.82, 8.80, 10.50, 11.02, 11.58, 13.08, 14.42, 17.32, 17.68, 18.58, 19.52, 21.04, 21.60, and 21.92. The complaint alleges that the "Later XIFAXAN®" product contains a polymorphic mixture that falls within the scope of the claims, which implicitly includes this characterizing X-Ray spectrum. ¶66, ¶68 col. 11:7-12

Identified Points of Contention

  • Evidentiary Question: The complaint asserts that "Plaintiff has found" that the accused "Later XIFAXAN®" product contains the claimed polymorphic mixture (Compl. ¶47, ¶64). A central issue will be what analytical evidence Plaintiff can produce to substantiate this claim, and whether Defendants' product testing confirms or refutes this finding.
  • Validity and Scope Question: The complaint carves out an earlier, "non-infringing" version of the product ("Early XIFAXAN®") from a later, "infringing" version ("Later XIFAXAN®") (Compl. ¶¶46-47). This narrative raises the question of whether the product sold before the patent's critical date was truly different or if it inherently contained the claimed polymorphic mixture. The historical composition of XIFAXAN® will likely be a key battleground for a potential on-sale bar defense.

V. Key Claim Terms for Construction

The Term: "a α/β relative ratio of 85/15±3"

  • Context and Importance: This quantitative limitation is the core of the invention's composition. The outcome of the infringement analysis will depend heavily on whether the accused product's composition falls within the 82/18 to 88/12 range defined by this term and its tolerance.
  • Intrinsic Evidence for a Broader Interpretation: A party could argue the term should be given its plain meaning, applying to the ratio as measured by any scientifically acceptable method.
  • Intrinsic Evidence for a Narrower Interpretation: The specification describes a specific analytical methodology, using a calibration curve based on X-ray diffraction (DRX) peaks, to determine the ratio ('099 Patent, col. 8:3-21; FIG. 1). A party may argue that this detailed disclosure limits the claim's scope, requiring that the ratio be determined by the patent's own taught method.

The Term: "obtained by a dry granulation and tableting procedure"

  • Context and Importance: This "product-by-process" language raises a fundamental question of claim scope. Practitioners may focus on this term because its interpretation will determine whether the manufacturing process itself is a limitation on the claimed product.
  • Intrinsic Evidence for a Broader Interpretation (Process not Limiting for Infringement): A party could argue that under established case law, infringement is established if the accused product meets the patent's structural and compositional definitions (the ratio and spectrum), rendering the process language non-limiting for the infringement analysis.
  • Intrinsic Evidence for a Narrower Interpretation (Process as a Limitation): The patent repeatedly emphasizes the stability of the mixture specifically during dry granulation and tableting ('099 Patent, col. 3:11-14). A party could argue this makes the process an essential feature of the invention, and therefore Plaintiff must prove the accused tablets were made by such a process.

VI. Other Allegations

Indirect Infringement

The complaint alleges contributory infringement, asserting that Defendant Alfasigma supplies rifaximin to the other defendants with knowledge of the '099 patent and knowing it is especially adapted for use in the infringing tablets and is not a staple commodity (Compl. ¶77). It also alleges inducement based on product labeling that directs infringing uses (Compl. ¶76).

Willful Infringement

Willfulness is alleged based on both pre-suit and post-suit conduct. Post-suit knowledge is based on the filing of the lawsuit after the patent issued on August 29, 2023 (Compl. ¶78). Pre-suit knowledge is alleged to have existed since at least November 2017, based on Defendant Alfasigma's participation in a European opposition to a related patent in the same family (Compl. ¶69). The complaint alleges continued sales despite this knowledge constitute objectively reckless conduct (Compl. ¶79).

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

  • A central issue will be one of historical fact and validity: does evidence show that the "Early XIFAXAN®" product, sold by Defendants before the patent's critical date, was compositionally distinct from the "Later XIFAXAN®" product as the complaint alleges, or did it already contain the claimed polymorphic mixture, potentially rendering the '099 patent invalid under the on-sale bar?
  • A key evidentiary question will be one of compositional proof: what analytical data will Plaintiff and Defendants present regarding the polymorphic ratio and X-ray spectrum of the accused XIFAXAN® tablets, and will that evidence demonstrate, by a preponderance of the evidence, that the product falls within the specific numerical limits of Claim 1?
  • A dispositive legal question will be one of claim construction: does the "product-by-process" language in Claim 1 limit the patent's scope to only those tablets made by "a dry granulation and tableting procedure," or does the claim cover any tablet that possesses the specified structural and compositional properties, regardless of how it was made?