DCT

1:23-cv-01191

ZS Pharma Inc v. Sandoz Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:23-cv-01191, D. Del., 10/20/2023
  • Venue Allegations: Venue is alleged to be proper in the District of Delaware because the Defendant is a corporation organized and existing under the laws of Delaware.
  • Core Dispute: Plaintiff alleges that Defendant’s submission of an Abbreviated New Drug Application (ANDA) for a generic version of the drug LOKELMA® constitutes an act of infringement of a patent related to low-lead zirconium silicate compositions.
  • Technical Context: The technology concerns pharmaceutical compositions of sodium zirconium cyclosilicate, a non-absorbed potassium-binding agent used to treat hyperkalemia (abnormally high potassium levels in the blood).
  • Key Procedural History: This action was filed under 35 U.S.C. § 271(e)(2) in response to Defendant's ANDA filing. The complaint notes that the asserted patent is listed in the FDA's "Orange Book" for LOKELMA®. The filing also references prior litigation between the parties (Civil Action No. 22-1101) concerning the same ANDA and different patents.

Case Timeline

Date Event
2015-10-14 '044 Patent Priority Date
2022-07-15 Defendant sends First Notice Letter for ANDA 217405
2022-08-22 Plaintiffs file prior litigation (No. 22-1101)
2022-10-05 Plaintiffs file suit regarding '662 Patent in prior case
2022-10-13 Defendant sends Second Notice Letter for ANDA 217405
2023-08-29 U.S. Patent No. 11,738,044 Issues
2023-10-20 Complaint Filing Date

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

U.S. Patent No. 11,738,044 - "Extended Use Zirconium Silicate Compositions and Methods of Use Thereof," issued August 29, 2023

The Invention Explained

  • Problem Addressed: The patent describes hyperkalemia as a life-threatening condition that can cause fatal cardiac arrhythmias ('044 Patent, col. 1:26-54). While zirconium silicate compositions can remove potassium from the body, the patent identifies a need for compositions suitable for long-term or extended use, which requires careful control of impurities, particularly lead ('044 Patent, col. 3:15-24). The inventors found that known industrial-scale manufacturing methods resulted in zirconium silicate with lead levels of 1.0 ppm or more, potentially exceeding safety limits for chronic daily dosing ('044 Patent, col. 3:24-34; col. 12:50-63).
  • The Patented Solution: The invention is directed to methods of treating hyperkalemia by administering a zirconium silicate composition that has a specifically low lead content of below 0.6 ppm ('044 Patent, Abstract; col. 13:57-61). The specification details manufacturing process improvements, such as using colloidal silica as a reactant and modifying agitation steps, to achieve this high level of purity at large reactor volumes ('044 Patent, col. 7:1-9). This low lead level is presented as making the composition suitable for the extended administration required for chronic conditions ('044 Patent, col. 3:40-45).
  • Technical Importance: Achieving and claiming a specific, low-level impurity profile for a pharmaceutical active ingredient addresses a critical safety requirement for drugs intended for chronic administration, as mandated by regulatory bodies ('044 Patent, col. 3:21-24).

Key Claims at a Glance

  • The complaint asserts infringement of "one or more claims" ('044 Patent, Compl. ¶29). The patent contains one independent claim, Claim 1, which is a method of treatment claim.
  • Independent Claim 1 requires:
    • A method of treating hyperkalemia.
    • Administering a cation exchange composition comprising a specific zirconium silicate formula.
    • The administration occurs "over a period of more than 5 consecutive days."
    • Critically, the composition "exhibits a lead content below 0.6 ppm."
  • The patent also includes dependent claims that further narrow the lead content (e.g., to 0.3 to 0.45 ppm), particle size, sodium content, and other physicochemical properties.

III. The Accused Instrumentality

Product Identification

  • The accused instrumentality is Defendant Sandoz Inc.’s "Proposed ANDA Product," a generic version of LOKELMA® (sodium zirconium cyclosilicate) for oral suspension in 5 g and 10 g packets, as described in ANDA No. 217405 (Compl. ¶1). The act of infringement alleged is the submission of this ANDA to the FDA seeking approval to market the product before the '044 Patent expires (Compl. ¶21, ¶30).

Functionality and Market Context

  • The Proposed ANDA Product contains sodium zirconium cyclosilicate as its active pharmaceutical ingredient and is intended to be a bioequivalent generic version of Plaintiff's LOKELMA® drug (Compl. ¶22, ¶24). It is designed to treat hyperkalemia by binding potassium in the gastrointestinal tract (Compl. ¶15). The complaint alleges that upon approval, the product label will instruct healthcare providers on its use, leading to infringement of the patented method (Compl. ¶26, ¶31).

IV. Analysis of Infringement Allegations

The complaint does not provide a claim chart or specific factual allegations detailing how the accused product meets each claim limitation. The infringement theory is based on the allegation that Sandoz's submission of ANDA No. 217405, and the future manufacturing and sale of the product specified therein, will infringe the '044 patent (Compl. ¶29-30). No probative visual evidence provided in complaint.

'044 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A method of treatment of hyperkalemia comprising administering over a period of more than 5 consecutive days... The complaint alleges Sandoz's proposed product label will instruct healthcare providers to prescribe the product, which is intended to treat hyperkalemia. Use for over 5 days is implied by the chronic nature of the condition and the patent's focus on "extended use." ¶26, ¶31 col. 13:35-40
...a cation exchange composition comprising a zirconium silicate of formula (I)... The Proposed ANDA Product's active ingredient is identified as sodium zirconium cyclosilicate, which the complaint alleges is "as patented by the '044 Patent." ¶22, ¶23 col. 13:41-56
...wherein the composition exhibits a lead content below 0.6 ppm. The complaint makes a general allegation that the Proposed ANDA Product will infringe, which necessarily implies its composition meets this limitation, either literally or under the doctrine of equivalents. ¶29 col. 13:57-61
  • Identified Points of Contention:
    • Technical Question: The complaint does not specify the lead content of the Sandoz product. A primary factual dispute will be whether the product, as formulated in ANDA No. 217405, actually has a lead content below the 0.6 ppm threshold required by Claim 1.
    • Scope Questions: For induced infringement, a key question will be whether Sandoz's proposed product label directs or encourages administration "over a period of more than 5 consecutive days." The precise wording of the dosing instructions in the proposed label will be critical to resolving this question.

V. Key Claim Terms for Construction

  • The Term: "lead content below 0.6 ppm"
  • Context and Importance: This limitation appears to be the primary basis for the patent's novelty and is central to the invention's stated purpose of providing a composition safe for extended use. The infringement analysis for the '044 patent will likely depend entirely on whether the accused product's lead content falls within this claimed numerical range.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The term itself is a straightforward numerical limit. A party might argue that any scientifically valid measurement showing a lead content below 0.6 ppm meets the claim, without being tied to a specific methodology beyond what is generally accepted in the art.
    • Evidence for a Narrower Interpretation: Dependent claim 13 specifies that the lead content is "determined using inductively coupled plasma-mass spectrometry (ICP-MS)." The specification further details a specific sample preparation protocol for this analysis ('044 Patent, col. 6:5-14). A party could argue that the term "lead content" must be construed in light of this specific, disclosed testing method, potentially limiting the scope of the claim to results obtained via that exact protocol.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement (Compl. ¶32, ¶33). The basis for inducement is the allegation that Sandoz's proposed product labeling will instruct doctors and patients to use the product in an infringing manner (Compl. ¶26, ¶31). The basis for contributory infringement is the allegation that the product is not a staple article of commerce and is especially made for an infringing use (Compl. ¶33).
  • Willful Infringement: While the complaint does not use the word "willful," it requests a declaration that the case is "exceptional" and seeks an award of attorneys' fees pursuant to 35 U.S.C. § 285 (Compl., Prayer for Relief (e)). The complaint alleges that Sandoz "has or will have knowledge" of infringement, based at least on the filing of the lawsuit and, implicitly, Sandoz's Paragraph IV certification concerning the '044 patent (Compl. ¶20, ¶33).

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

  • A central issue will be one of compositional fact: does the Sandoz generic product, as specified in its ANDA, contain a lead concentration below the 0.6 ppm threshold of Claim 1? The outcome may hinge on discovery related to Sandoz's manufacturing process and the results of product testing.
  • A key legal question will be one of induced infringement: does the specific language in Sandoz's proposed product label provide instructions that would cause a healthcare provider or patient to administer the drug for "more than 5 consecutive days," thereby directly meeting the temporal limitation of the asserted method claim?