ZS Pharma & AstraZeneca v. Macleods: LOKELMA® Patent Case Ends in Consent Judgment
ZS Pharma, Inc. and AstraZeneca Pharmaceuticals LP brought a five-patent infringement action against Macleods Pharmaceuticals over generic versions of LOKELMA® (sodium zirconium cyclosilicate), a potassium binder used to treat hyperkalemia. The Delaware District Court case closed on 8 May 2025 via consent judgment after 990 days of litigation — a resolution consistent with a negotiated entry date agreement.
A five-patent LOKELMA® Hatch-Waxman battle ends by agreement in Delaware
ZS Pharma, Inc. and AstraZeneca Pharmaceuticals LP filed this infringement action on 22 August 2022 in the District of Delaware (Case No. 1:22-cv-01100), asserting five US patents against Macleods Pharmaceuticals and its US affiliate, Macleods Pharma USA, Inc. The patents — US9913860B2, US9592253B1, US10300087B2, US8877255B2, and US10695365B2 — cover formulations and methods related to sodium zirconium cyclosilicate, the active ingredient in LOKELMA®, a branded potassium binder approved for adults with hyperkalemia.
The case terminated on 8 May 2025 via a consent judgment, entered in connection with a lead case, No. 22-1055-JLH, before the same judge. A consent judgment in Hatch-Waxman litigation typically reflects a negotiated settlement in which the generic applicant accepts a specified market entry date or other agreed terms, without the court adjudicating validity or infringement on the merits. The precise terms of the agreed order — including any authorised entry date for Macleods — are not detailed in the publicly available termination record.
At 990 days, the resolution timeline suggests substantive negotiation took place rather than an early voluntary dismissal, consistent with a structured ANDA settlement. The existence of a lead case (22-1055-JLH) involving the same patents and judge indicates this case was one of potentially several consolidated or related proceedings against generic challengers to the LOKELMA® franchise. What drove the final terms — including whether Macleods obtained a near-term or distant authorised entry date — remains unknown from the public record.
Filing to Consent Judgment in 990 days
990 days — above the median for Hatch-Waxman ANDA cases in Delaware, which typically resolve in 24–30 months
Consent judgment: what this resolution means for both parties
Consent judgment in Hatch-Waxman: a negotiated order, not a merits ruling
A consent judgment is a court-entered order reflecting terms agreed by both parties. In Hatch-Waxman ANDA litigation, it typically functions as a settlement vehicle — the generic applicant acknowledges the patents and accepts a defined market entry date, while the innovator avoids the risk of an invalidity or non-infringement finding. No court determined whether the five LOKELMA® patents are valid or infringed.
Negotiated resolutionAstraZeneca retains LOKELMA® exclusivity under agreed terms
The consent judgment preserves the enforceability of all five asserted patents without subjecting them to invalidity scrutiny at trial. ZS Pharma and AstraZeneca likely secured a defined period of continued market exclusivity for LOKELMA®. The patents remain intact and available to assert against other generic filers, and no adverse claim construction or invalidity ruling was entered that could weaken future enforcement.
Patents intactMacleods secures a path to market — on the innovator’s schedule
Macleods accepted consent judgment terms that most likely include an agreed authorised entry date for its sodium zirconium cyclosilicate ANDA product. This provides commercial certainty and avoids the cost and risk of trial, but Macleods did not obtain an early, unrestricted entry. The terms also typically prohibit Macleods from launching before the agreed date, binding both entities — Macleods Pharmaceuticals and Macleods Pharma USA, Inc.
Delayed but certain entryLOKELMA® franchise protection extended across multiple generic filers
With a lead case (22-1055-JLH) and this companion matter both resolving by consent judgment, AstraZeneca appears to have structured coordinated settlements across the LOKELMA® ANDA litigation wave. This approach maximises exclusivity runway and avoids a single adverse ruling that could open the market to all generics simultaneously. Competitors and payers should monitor the agreed entry date, which will define when price competition begins.
Coordinated ANDA settlementFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | ZS Pharma, Inc. | Company | Pharmaceutical innovator and AstraZeneca subsidiary — holder of US9913860B2 and four further LOKELMA® patentsSearch in Eureka ↗ |
| Co-Plaintiff | Astrazeneca pharmaecuticals, LP | Company | Search in Eureka ↗ |
| Defendant | Macleods Pharmaceuticals | Individual | Indian generic pharmaceutical manufacturer and its US affiliate pursuing ANDA approval for sodium zirconium cyclosilicateSearch in Eureka ↗ |
| Co-Defendant | Macleods Pharma USA, Inc. | Company | Search in Eureka ↗ |
| Plaintiff counsel | Alexandra M. Joyce | Attorney | Counsel for ZS Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Daniel M. Silver | Attorney | Counsel for ZS Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Daniel O’boyle | Attorney | Counsel for ZS Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Gyuhyun (joanne) Bae | Attorney | Counsel for ZS Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Hassen Sayeed | Attorney | Counsel for ZS Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | James Yi Li | Attorney | Counsel for ZS Pharma, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Mark A. Hayden | Attorney | Counsel for ZS Pharma, Inc.Search in Eureka ↗ |
| Plaintiff law firm | McCarter & English LLP | Law Firm | Representing ZS Pharma, Inc.Search in Eureka ↗ |
| Defendant counsel | April M. Ferraro | Attorney | Counsel for Macleods PharmaceuticalsSearch in Eureka ↗ |
| Defendant counsel | Corey Weinstein | Attorney | Counsel for Macleods PharmaceuticalsSearch in Eureka ↗ |
| Defendant counsel | G. Mason Thomson | Attorney | Counsel for Macleods PharmaceuticalsSearch in Eureka ↗ |
| Defendant counsel | John M. Seaman | Attorney | Counsel for Macleods PharmaceuticalsSearch in Eureka ↗ |
| Defendant counsel | Seth A. Neal | Attorney | Counsel for Macleods PharmaceuticalsSearch in Eureka ↗ |
| Defendant law firm | Abrams & Bayliss, LLP | Law Firm | Representing Macleods PharmaceuticalsSearch in Eureka ↗ |
| Presiding judge | Judge Jennifer L. Hall | Judge | Delaware District CourtSearch in Eureka ↗ |
Official order — verbatim text
The verdict references a consent judgment entered in lead Case No. 22-1055-JLH, indicating this companion docket was resolved under coordinated terms negotiated across related proceedings. A consent judgment carries the full force of a court order but reflects agreed — not adjudicated — terms. No judicial finding on infringement, validity, or claim construction was made. The phrase ‘lead case’ suggests the court managed multiple ANDA challenges to the LOKELMA® franchise under a common framework, with this case disposed of consistently with that lead resolution.
US9913860B2 and four further patents — sodium zirconium cyclosilicate formulations
The five asserted patents — US9913860B2, US9592253B1, US10300087B2, US8877255B2, and US10695365B2 — collectively protect the formulation, composition, synthesis, and therapeutic use of sodium zirconium cyclosilicate (SZC), the active ingredient in LOKELMA®. The applications were filed between 2013 and 2018, reflecting a deliberate continuation strategy that layered successive patent protection across the product lifecycle. SZC is a selective cation exchanger that captures potassium ions in the gastrointestinal tract, representing a novel non-polymer mechanism for treating hyperkalemia.
The breadth of this five-patent portfolio — spanning composition, method-of-manufacture, and method-of-treatment claims — presents a significant clearance challenge for any generic filer. AstraZeneca’s acquisition of ZS Pharma in 2015 brought this patent estate into a major pharma portfolio, and the coordinated ANDA litigation strategy suggests active management of the exclusivity timeline. For competitors in the potassium binder space — including patiromer calcium (Veltassa) and any pipeline SZC generics — understanding the claim boundaries of each patent is essential for freedom-to-operate planning.
Should you run an FTO against the LOKELMA® patent portfolio?
Any pharmaceutical company developing a generic, biosimilar-adjacent, or novel potassium binder — including sodium zirconium cyclosilicate oral suspension formulations — should conduct a thorough freedom-to-operate analysis against this five-patent estate. The patents span composition and method claims filed across multiple application families, meaning design-around strategies that clear one patent may not clear another. R&D teams and regulatory affairs professionals preparing ANDA filings should map claim coverage before committing to a specific formulation approach.
PatSnap Eureka’s FTO Search Agent enables IP teams to run structured clearance queries across all five patent numbers simultaneously, mapping active claim scope against proposed formulation parameters. Eureka can surface related continuation applications, identify co-pending prosecution history, and flag any third-party challenges — providing R&D leaders with a consolidated risk view before investment decisions are made on potassium binder pipeline assets.
Run a freedom-to-operate analysis on US9913860B2 to assess your product’s exposure
Run FTO in Eureka →Similar Hatch-Waxman ANDA cases involving potassium binder patents in Delaware
Explore related patent infringement actions asserting sodium zirconium cyclosilicate or potassium binder formulation patents before the Delaware District Court.
What this case signals for the potassium binder IP landscape
A five-patent consent judgment in Delaware reinforces AstraZeneca’s strategy of portfolio-based ANDA defence for LOKELMA®.
Multi-patent ANDA portfolios raise the settlement bar for generics
Asserting five patents across formulation and method claims forces a generic challenger to either design around multiple claim families or negotiate entry timing. This case illustrates how a layered patent portfolio — built through continuation and divisional filings on sodium zirconium cyclosilicate — translates directly into settlement leverage in Hatch-Waxman proceedings.
Lead case architecture concentrates judge exposure and settlement risk
Structuring related ANDA cases with a lead docket before a single judge — as seen here with Case 22-1055-JLH — creates consistent claim construction risk and incentivises coordinated settlements. Generic filers should anticipate that unfavourable rulings in the lead case will ripple across companion dockets, increasing pressure to resolve early.
ZS v Macleods — key questions answered
The case closed on 8 May 2025 via a consent judgment entered in connection with lead Case No. 22-1055-JLH before Judge Jennifer L. Hall in the Delaware District Court. No merits ruling on infringement or validity was made. The consent judgment reflects a negotiated resolution, typically including an agreed market entry date for the generic applicant.
Five patents were asserted: US9913860B2, US9592253B1, US10300087B2, US8877255B2, and US10695365B2. All cover aspects of sodium zirconium cyclosilicate — the active ingredient in LOKELMA® — including formulation compositions, synthesis methods, and therapeutic use claims for the treatment of hyperkalemia.
A consent judgment in Hatch-Waxman litigation is a court-entered order reflecting terms agreed by both the innovator and the generic applicant. It typically specifies an authorised market entry date for the generic product and acknowledges the patents without an adjudication of validity or infringement. It is a common mechanism for resolving ANDA disputes without the cost and risk of trial.
LOKELMA® (sodium zirconium cyclosilicate) is an FDA-approved oral suspension marketed by AstraZeneca for the treatment of hyperkalemia — elevated blood potassium — in adults. It works as a selective cation exchanger in the gastrointestinal tract. As a branded pharmaceutical with patent protection, it is subject to ANDA challenges from generic manufacturers seeking to market lower-cost equivalents before patent expiry.
The verdict entry references a consent judgment entered in lead Case No. 22-1055-JLH, suggesting the two matters were coordinated before the same judge (Jennifer L. Hall) and involved overlapping or identical patents and products. The lead case structure is common in Delaware ANDA litigation where multiple generic filers challenge the same branded drug, allowing coordinated claim construction and settlement across related dockets.
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