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ZS Pharma & AstraZeneca v. Alkem Laboratories — Sodium Zirconium Cyclosilicate Patent Dispute | PatSnap
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Case ID1:23-cv-01187
FiledOct 2023
ClosedFeb 2024
Patent Litigation

AstraZeneca v. Alkem Laboratories: LOKELMA® Patent Dispute Resolved by Consent Judgment

ZS Pharma and AstraZeneca filed suit against Alkem Laboratories in Delaware District Court in October 2023, asserting six patents protecting LOKELMA® (sodium zirconium cyclosilicate), a hyperkalemia treatment. The parties reached a negotiated settlement within 112 days, resulting in a consent judgment enjoining Alkem from infringing the licensed patents without authorisation.

Resolution time
112days
112 days — faster than the majority of ANDA patent infringement cases in Delaware
Patents asserted
1
US11738044B2 and 5 further patents asserted covering sodium zirconium cyclosilicate
Outcome
Consent Judgment
Consent judgment with injunction — Alkem barred from marketing ANDA product without authorisation
Cost ruling
No costs
Dismissed with prejudice — no costs, disbursements or attorneys’ fees awarded to either party
Published by PatSnap Insights Team · Verified by PatSnap Eureka Data
Case overview

Swift ANDA settlement protects LOKELMA® patent estate in Delaware

ZS Pharma, Inc. and AstraZeneca Pharmaceuticals LP filed Case No. 1:23-cv-01187 in the Delaware District Court on 20 October 2023, asserting infringement of six U.S. patents — including US11738044B2, US8877255, US9592253, US9913860, US10300087, and US10695365 — by Alkem Laboratories Ltd. The asserted patents protect LOKELMA® (sodium zirconium cyclosilicate), a potassium-binder indicated for hyperkalemia, sold as an oral suspension in 5 g and 10 g packets. The trigger for litigation was Alkem’s Abbreviated New Drug Application No. 217558, a standard ANDA Paragraph IV challenge pathway.

The case closed on 9 February 2024 via a consent judgment stipulated by both parties and entered by Judge Jennifer L. Hall. The settlement resulted in an injunction prohibiting Alkem and its affiliates from making, using, selling, offering for sale, importing, or distributing the Alkem ANDA product without specific authorisation under a separate Settlement Agreement. All claims, counterclaims, affirmative defences, and demands were dismissed with prejudice, with no costs or attorneys’ fees awarded to any party. The court retained jurisdiction to enforce the consent judgment and supervise performance under the settlement.

Resolution in 112 days is notably swift for an ANDA patent case, where Hatch-Waxman litigation commonly runs for years given mandatory 30-month stays. The rapid resolution suggests the parties reached commercial terms — likely a licensed entry date — without proceeding to claim construction or validity challenges. The specific terms of the Settlement Agreement, including any authorised launch date granted to Alkem, remain confidential and are not disclosed in the public record. The injunction’s scope covering Alkem’s affiliates, successors, and assigns adds meaningful breadth to AstraZeneca’s enforcement position.

Case at a glance
Case no.1:23-cv-01187
CourtDelaware
JudgeJennifer L. Hall
FiledOctober 20, 2023
ClosedFebruary 9, 2024
Duration112 days
OutcomeConsent Judgment
Verdict causeInfringement Action
BasisConsent Judgment
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Case data sourced from PACER / Delaware District Court via PatSnap Eureka Litigation Intelligence Explore similar cases ↗
Case timeline

Filing to settlement in 112 days

112 days — faster than the majority of ANDA patent infringement cases in Delaware

Case timeline: Complaint filed May 13 2025, DEC–JAN — 112 days total Horizontal timeline showing the three key events in ZS Pharma, Inc. v Alkem Laboratories, Ltd. from filing to voluntary dismissal. Source: PACER, Delaware District Court. OCT 20 2023 Complaint filed DEC–JAN 2023 Pre-trial proceedings FEB 9 2024 Resolved consent judgment 112 DAYS TOTAL
Settlement terms

Consent judgment: injunction granted, all claims dismissed with prejudice

Legal mechanism

What a consent judgment means in ANDA litigation

A consent judgment is a court order entered by agreement of both parties, carrying full judicial enforceability. In ANDA cases, it typically memorialises settlement terms — here including an injunction — without requiring a trial or validity finding. The court retains jurisdiction to enforce compliance, giving AstraZeneca a direct enforcement mechanism if Alkem launches outside any agreed terms.

Enforceable by court order
Dismissal terms

Dismissed with prejudice — what this forecloses

Dismissal with prejudice means Alkem cannot relitigate the same patent infringement claims in a future action. It also forecloses Alkem from raising the same invalidity or non-infringement counterclaims asserted here. Combined with the injunction, this leaves AstraZeneca’s six licensed patents uncontested in this proceeding. Neither party bears the other’s legal costs, suggesting a balanced commercial resolution.

No re-filing permitted
Injunction scope

Injunction extends to Alkem affiliates and assigns

The consent judgment defines ‘Affiliate’ broadly — covering entities with more than 50% common ownership or effective governance control. This prevents Alkem from routing product through a related entity to circumvent the injunction. The carve-out for activity ‘specifically authorised pursuant to the Settlement Agreement’ suggests a confidential licensed entry date was negotiated, consistent with standard Hatch-Waxman practice.

Broad affiliate coverage
Patent landscape

Six-patent portfolio creates layered exclusivity for LOKELMA®

AstraZeneca asserted six U.S. patents spanning multiple prosecution generations — from US8877255 through to US11738044B2 — covering sodium zirconium cyclosilicate composition and method claims. This layered portfolio, common in branded pharmaceutical ANDA defence strategy, means a generic challenger must design around or invalidate multiple independent patent families to achieve a clear FTO. No patent was found invalid or unenforceable in this proceeding.

Multi-patent ANDA defence
Legal analysis based on PACER docket records for case 1:23-cv-01187 and PatSnap Eureka litigation intelligence Search PatSnap Eureka ↗
Parties and representation

Full party and counsel information

RoleNameTypeDetail
PlaintiffZS Pharma, Inc.CompanyPharmaceutical IP holder — innovator and ANDA litigant for LOKELMA® hyperkalemia treatmentSearch in Eureka ↗
DefendantAlkem Laboratories, Ltd.CompanyIndian generic pharmaceutical manufacturer seeking U.S. market entry via ANDA No. 217558Search in Eureka ↗
Plaintiff counselAlexandra M. JoyceAttorneyCounsel for ZS Pharma, Inc.Search in Eureka ↗
Plaintiff counselDaniel M. SilverAttorneyCounsel for ZS Pharma, Inc.Search in Eureka ↗
Plaintiff counselHassen SayeedAttorneyCounsel for ZS Pharma, Inc.Search in Eureka ↗
Plaintiff counselJames Yi LiAttorneyCounsel for ZS Pharma, Inc.Search in Eureka ↗
Plaintiff counselMark A. HaydenAttorneyCounsel for ZS Pharma, Inc.Search in Eureka ↗
Defendant counselKevin M. CapuzziAttorneyCounsel for Alkem Laboratories, Ltd.Search in Eureka ↗
Presiding judgeJudge Jennifer L. HallChief JudgeDelaware District Court — Chief JudgeSearch in Eureka ↗
Official verdict

Stipulation of dismissal — official text

“ZS Pharma, Inc. and AstraZeneca Pharmaceuticals LP (hereinafter collectively “AstraZeneca”), and Alkem Laboratories Ltd. (hereinafter “Alkem”), the parties in the abovecaptioned actions, have agreed to terms and conditions representing a negotiated settlement of the actions and have set forth those terms and conditions in a Settlement Agreement (the “Settlement Agreement”). Now the parties, by their respective undersigned attorneys, hereby stipulate and consent to entry of judgment and an injunction in the actions, as follows: IT IS this ___ day of ____________, 2024: ORDERED, ADJUDGED AND DECREED as follows: 1. This District Court has jurisdiction over the subject matter of the above actions and has personal jurisdiction over AstraZeneca and over Alkem for the purpose of the above-captioned actions only. 2. As used in this Consent Judgment, (i) the term “Alkem Product” shall mean the drug product sold, offered for sale or distributed pursuant to Abbreviated New Drug Application No. 217558 (and defined in greater detail in the Settlement Agreement); (ii) the term 9th February Case 1:23-cv-01187-JLH Document 16 Filed 02/09/24 Page 1 of 3 PageID #: 85 2 “Licensed Patents” shall mean United States Patent Numbers 8,877,255; 9,592,253; 9,913,860; 10,300,087; 10,695,365; and 11,738,044; and (iii) the term “Affiliate” shall mean any entity or person that, directly or indirectly through one or more intermediaries, controls, is controlled by, or is under common control with Alkem; for purposes of this definition, “control” means (a) ownership, directly or through one or more intermediaries, of (1) more than fifty percent (50%) of the shares of stock entitled to vote for the election of directors, in the case of a corporation, or (2) more than fifty percent (50%) of the equity interests in the case of any other type of legal entity or status as a general partner in any partnership, or (b) any other arrangement whereby an entity or person has the right to elect a majority of the Board of Directors or equivalent governing body of a corporation or other entity or the right to direct the management and policies of a corporation or other entity. 3. Unless otherwise specifically authorized pursuant to the Settlement Agreement, Alkem, including any of its Affiliates, successors and assigns, is enjoined from infringing the Licensed Patents, on its own part or through any Affiliate, by making, having made, using, selling, offering to sell, importing or distributing of the Alkem Product. 4. Compliance with this Consent Judgment may be enforced by AstraZeneca and its successors in interest, or assigns, as permitted by the terms of the Settlement Agreement. 5. This District Court retains jurisdiction to enforce or supervise performance under this Consent Judgment and the Settlement Agreement. 6. All claims, counterclaims, affirmative defenses and demands in these actions are hereby dismissed with prejudice and without costs, disbursements or attorneys’ fees to any party. __________________________________________ Jennifer L. Hall, U.S.D.J. Case 1:23-cv-01187-JLH Document 16 Filed 02/09/24 Page 2 of 3 PageID #: 86 3 We hereby consent to the form and entry of this Order:”
Source: PACER Docket, Case 1:23-cv-01187, Delaware District Court · Filed February 9, 2024

The consent judgment’s language — enjoining Alkem ‘unless otherwise specifically authorised pursuant to the Settlement Agreement’ — is a standard Hatch-Waxman formulation that strongly suggests a confidential licensed entry date exists. The breadth of enjoined acts (making, having made, using, selling, offering, importing, distributing) reflects maximum statutory coverage. Dismissal with prejudice and no costs award is consistent with a commercially balanced settlement rather than a capitulation, suggesting Alkem received something of value in the undisclosed agreement.

PACER case 1:23-cv-01187 · Public docket record Explore in Eureka ↗
Patent at issue

US11738044B2 — Sodium Zirconium Cyclosilicate Pharmaceutical Composition

Publication No.US11738044B2
Application No.US16/415550
Patent details
AssigneeZS Pharma, Inc.
ProductLOKELMA® — sodium zirconium cyclosilicate oral suspension, hyperkalemia treatment
Publication typeB2 — grant (with prior publication)
Cited in actionOctober 20, 2023

US11738044B2 is the most recently issued of the six patents asserted in this action, with application number US16/415550. The patent protects formulations of sodium zirconium cyclosilicate (SZC), an inorganic crystalline compound that selectively captures potassium ions in the gastrointestinal tract. LOKELMA® is indicated for adult hyperkalemia — elevated blood potassium — which carries serious cardiac risk. The SZC mechanism represents a distinct class from earlier potassium binders such as patiromer, and the patent portfolio spans composition, method of treatment, and formulation claims across multiple continuation families.

The six-patent estate asserted in this case — spanning issuance years from 2014 (US8877255) to 2023 (US11738044B2) — reflects a deliberate lifecycle management strategy by ZS Pharma and AstraZeneca. For competitors developing potassium-binder products or SZC-based formulations, each patent in this family represents an independent clearance requirement. The absence of any invalidity finding in this proceeding leaves the full portfolio intact. Given growing clinical interest in hyperkalemia management in heart failure and CKD populations, the commercial stakes of this patent estate are likely to increase.

Patent data sourced from USPTO via PatSnap Eureka patent database Search patent records in Eureka ↗
Freedom to operate

Should you run an FTO analysis against LOKELMA®’s patent estate?

Any company developing, manufacturing, or seeking to commercialise a sodium zirconium cyclosilicate-based product — or a potassium binder with structural similarities — should treat the six-patent LOKELMA® estate as a priority FTO target. This case confirms that AstraZeneca actively enforces all six patents at the point of ANDA filing, and the consent judgment leaves no patents invalidated. Generic manufacturers, API suppliers, and formulation development teams should assess claim scope before advancing to regulatory filing.

PatSnap Eureka’s FTO Search Agent can map your compound’s structural and functional claims against the full LOKELMA® patent family — including US11738044B2 and the five co-asserted patents — and flag independent claims requiring specific clearance opinions. Continuous claim monitoring on these patent numbers will alert your team if further continuations publish, ensuring your FTO remains current as AstraZeneca’s prosecution strategy evolves.

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Related litigation

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PatSnap Eureka tracks related litigation across truck body equipment, vehicle accessories, and comparable infringement actions in the Georgia district system.

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Strategic implications

What this case signals for the hyperkalemia drug IP landscape

AstraZeneca’s swift enforcement and settlement reinforces its LOKELMA® patent moat and sets a pattern for future ANDA challengers.

Multi-patent ANDA filings increase settlement leverage significantly

Asserting six patents across a layered portfolio — as AstraZeneca did here — raises the cost and risk profile for generic challengers substantially. Each patent represents an independent invalidity burden. Companies holding similar multi-generational pharmaceutical patent estates should audit their ANDA litigation posture to ensure all relevant patents are listed in the Orange Book and asserted promptly.

112-day resolution signals commercially negotiated entry date

ANDA cases that settle this quickly almost invariably involve a confidential authorised generic entry date granted to the challenger. IP teams monitoring LOKELMA® generic competition should track Alkem’s ANDA No. 217558 FDA approval status and any potential authorised-entry trigger dates that may be inferred from the settlement timeline.

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Includes sector IP trends, Judge Treadwell’s case history, and FTO risk assessment for the truck equipment space
Delaware ANDA settlement dataLOKELMA® next challenger signalPatent expiry risk timeline
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Frequently asked questions

ZS v Alkem — key questions answered

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Use PatSnap Eureka to map FTO risk across the LOKELMA® patent family, monitor new ANDA filings, and track AstraZeneca’s enforcement activity. Stay ahead of the next wave of hyperkalemia generic challenges.

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