DCT

2:23-cv-13764

Curia Holdings LLC v. Salix Pharma Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:23-cv-13764, D.N.J., 08/31/2023
  • Venue Allegations: Venue is asserted based on Defendants maintaining a presence in New Jersey, conducting business and deriving substantial revenue in the state, and having previously submitted to the court's jurisdiction in other matters.
  • Core Dispute: Plaintiff alleges that Defendants’ XIFAXAN® antibiotic, as manufactured and sold since 2015, infringes a patent related to a specific polymorphic mixture of the active pharmaceutical ingredient rifaximin.
  • Technical Context: The technology lies in pharmaceutical formulation, specifically controlling the crystalline structure (polymorphism) of an active ingredient to ensure product consistency and stability.
  • Key Procedural History: The complaint distinguishes between a pre-2015 "Early XIFAXAN®" product, alleged to be non-infringing, and a post-2015 "Later XIFAXAN®" product, which allegedly infringes due to manufacturing changes. Plaintiff notes that Defendant Alfasigma opposed a European counterpart patent in 2017, which may be used to support allegations of knowledge of the patented technology. The complaint also references a separate pending lawsuit between the same parties involving patents from the same family.

Case Timeline

Date Event
2004-07-01 Salix begins selling 200 mg "Early XIFAXAN®" (approximate date)
2010-05-01 Salix begins selling 550 mg "Early XIFAXAN®" (approximate date)
2014-03-31 ’099 Patent Priority Date
2015-04-23 FDA approval for XIFAXAN® manufacturing change
2015-10-15 FDA approval for XIFAXAN® manufacturing change
2016-06-16 FDA approval for XIFAXAN® manufacturing change
2017-01-06 FDA approval for XIFAXAN® manufacturing change
2017-11-08 Defendant Alfasigma files opposition to European counterpart patent
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 addresses the challenge of manufacturing the antibiotic Rifaximin with a consistent crystalline structure, or polymorph (’099 Patent, col. 2:40-52). Different polymorphs can have different properties, and the patent notes that prior art manufacturing processes could lead to inconsistent and undesirable polymorphic forms, or could cause the active ingredient to change form during formulation, creating regulatory and quality control issues (’099 Patent, col. 2:24-29, 55-63).
  • The Patented Solution: The invention is a specific and stable polymorphic mixture of Rifaximin, comprising its alpha (α) and beta (β) forms in a defined relative ratio of 85/15±3 (’099 Patent, col. 3:3-7). The patent discloses a manufacturing process, including specific crystallization and drying steps, designed to reliably produce this mixture, which is asserted to be stable through the subsequent steps of "dry granulation and tableting" used to create the final pill (’099 Patent, col. 3:8-24).
  • Technical Importance: By providing a method to create a consistent and stable form of the drug, the invention aims to ensure reproducibility in manufacturing, a critical requirement for pharmaceutical products (’099 Patent, col. 2:48-52).

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 2-14 (Compl. ¶¶ 35, 74).
  • 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, which add limitations related to specific excipients, coating agents, plasticizers, and other formulation components (’099 Patent, col. 11:13-12:15).

III. The Accused Instrumentality

Product Identification

The accused products are the 200 mg and 550 mg tablet versions of XIFAXAN® that have been manufactured and sold since 2015, which the complaint refers to as "Later XIFAXAN®" (Compl. ¶¶ 47, 64).

Functionality and Market Context

XIFAXAN® is a rifamycin-based antibiotic indicated for the treatment of traveler's diarrhea, irritable bowel syndrome with diarrhea, and for reducing the risk of recurrence of overt hepatic encephalopathy (Compl. ¶37). The complaint alleges that while XIFAXAN® has been sold since 2004, manufacturing changes implemented since 2015 altered the polymorphic character of the rifaximin active ingredient, resulting in the allegedly infringing "Later XIFAXAN®" product (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 accused "Later XIFAXAN®" products are tablets alleged to infringe the claim, which recites a product obtained by this process. ¶¶ 73, 75 col. 3:11-14
comprising a Rifaximin polymorphic mixture that comprises α and β Rifaximin polymorphs The "Later XIFAXAN®" product sold after manufacturing changes in 2015 allegedly contains a polymorphic mixture of both α and β forms of rifaximin. ¶¶ 47, 64, 66 col. 3:3-7
in a α/β relative ratio of 85/15±3, The mixture of α and β polymorphs in "Later XIFAXAN®" is alleged to be in a relative ratio that falls within the scope of the claims. ¶¶ 47, 64 col. 3:3-7
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 polymorphic mixture in "Later XIFAXAN®" falls within the scope of the claims, which requires this characteristic X-Ray diffraction profile. ¶¶ 64, 66, 74 col. 6:40-46

Identified Points of Contention:

  • Technical Question: A central factual question is whether the accused "Later XIFAXAN®" product actually contains the claimed α/β polymorphs in the specific 85/15±3 ratio. The complaint asserts this based on its own findings but does not provide the underlying analytical data (Compl. ¶64).
  • Scope Questions: The case raises a significant question regarding the on-sale bar defense. Plaintiff preemptively argues that the "Early XIFAXAN®" product sold before the patent's priority date contained only the α polymorph and therefore cannot invalidate the patent claims directed to a mixture (Compl. ¶¶ 63, 67). The validity of the ’099 patent may depend on the factual determination of the precise composition of the product sold before March 31, 2014.
  • Scope Questions: Claim 1 is for a tablet "obtained by a dry granulation and tableting procedure." This product-by-process language raises the question of whether infringement requires proof that Defendants use this specific manufacturing method, or whether the claim covers any tablet with the recited structural and compositional properties, regardless of how it was made.

V. Key Claim Terms for Construction

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

  • Context and Importance: The infringement analysis hinges on this precise numerical range. Practitioners may focus on this term because whether the accused product's composition falls within the narrow window of 82/18 to 88/12 will be a dispositive issue, likely decided by competing expert analyses.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent uses the term "about" when describing the 2theta values in the same claim, which could suggest that some degree of variability was contemplated by the inventors for numerical claim values (’099 Patent, col. 11:8).
    • Evidence for a Narrower Interpretation: The patent repeatedly and consistently recites the "85/15±3" ratio, distinguishing it from prior art that produced inconsistent results (’099 Patent, col. 3:3-14). The term includes its own explicit tolerance (±3), which may suggest that no further broadening (e.g., via the doctrine of equivalents) was intended or is appropriate.

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

  • Context and Importance: This is a product-by-process limitation. Practitioners may focus on this term because its interpretation will define what Plaintiff must prove. If the phrase is a strict process limitation, Plaintiff must show Defendants use dry granulation; if it is not, Plaintiff need only show the final product has the claimed characteristics.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation (i.e., less limiting): A party could argue that the novelty lies in the stable composition itself, and the process language is merely descriptive of one way to achieve it. The claim is for a "tablet," a product, not a method.
    • Evidence for a Narrower Interpretation (i.e., a true limitation): The patent specification directly links the process to the product's key feature, stating that the claimed mixture "is stable towards the influence of physical treatments employed for the dry granulation and tableting" (’099 Patent, col. 3:11-14). This suggests the process imparts a critical, distinguishing characteristic (stability) and is integral to the definition of the claimed invention.

VI. Other Allegations

Indirect Infringement

The complaint alleges contributory infringement against Defendant Alfasigma, asserting that it supplies rifaximin to Salix with the knowledge that it is especially adapted for infringing the ’099 patent and is not a staple commercial article (Compl. ¶77). It also alleges inducement against Defendants based on product labeling that allegedly directs infringing uses (Compl. ¶76).

Willful Infringement

The complaint alleges willfulness based on both post-suit and potential pre-suit knowledge. It asserts that Defendants knew of the ’099 patent upon its issuance on August 29, 2023, and continued to infringe (Compl. ¶78). It further alleges that Defendants knew of the patent's lineage and the underlying technology as early as 2017 due to Alfasigma's opposition to a European counterpart, suggesting they faced an "objectively high risk" of infringement (Compl. ¶¶ 69, 79).

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

  1. A core issue will be one of compositional identity: Does the accused "Later XIFAXAN®" product, as sold since 2015, contain the specific α/β polymorphic mixture in the claimed 85/15±3 ratio? The resolution of this factual question will likely depend on conflicting expert testimony and analytical testing conducted during discovery.
  2. The case presents a critical question of patent validity centered on historical fact: What was the actual polymorphic composition of the "Early XIFAXAN®" product sold prior to the patent's 2014 priority date? The patent's survival may depend on whether Defendants can prove that the earlier product anticipated or rendered obvious the claims of the ’099 patent.
  3. A key legal issue will be one of claim scope: How will the court construe the product-by-process limitation "obtained by a dry granulation and tableting procedure"? The determination of whether this phrase limits the claim's scope to a specific manufacturing method will significantly impact the evidence required for Plaintiff to prove infringement.