Novartis v. Zenara Pharma: PROMACTA® Patent Suit Ends in 39 Days
Novartis AG filed suit against Zenara Pharma Private Ltd. in the Delaware District Court, asserting US8828430B2 to protect its PROMACTA® eltrombopag olamine tablets against generic competition. The case was voluntarily dismissed just 39 days after filing, with each party bearing its own costs.
A 39-day ANDA skirmish over Novartis’s eltrombopag franchise
On 23 May 2025, Novartis AG and Novartis Pharmaceuticals Corporation filed suit against Zenara Pharma Private Ltd. in the District of Delaware before Judge Gregory B. Williams. The complaint asserted US8828430B2, a patent covering eltrombopag olamine tablet formulations in 12.5 mg, 25 mg, 50 mg, and 75 mg strengths — the same doses marketed under Novartis’s brand PROMACTA®, used to treat chronic immune thrombocytopenia and related conditions.
On 1 July 2025, just 39 days after the complaint was filed, Novartis voluntarily dismissed all claims pursuant to Federal Rule of Civil Procedure 41(a)(1)(A)(i). The stipulation specifies that each party will bear its own attorneys’ fees and costs. The public record is silent on whether the dismissal was with or without prejudice, which carries material consequences for Novartis’s ability to refile against Zenara.
The extremely short duration — 39 days from filing to dismissal — is consistent with ANDA litigation dynamics in which brand companies file to trigger the 30-month stay under the Hatch-Waxman framework, then assess their litigation posture before the case develops. Whether the parties reached a licensing agreement, consent decree, or simply evaluated the strength of the generic’s challenge is not disclosed in the public record. The absence of any defendant law firm on record suggests this matter resolved before Zenara had formally appeared.
Filing to Voluntary dismissal in 39 days
39 days — well below the median ANDA patent litigation duration of 2+ years
Voluntarily dismissed: what the Rule 41 filing means for both parties
Rule 41(a)(1)(A)(i): plaintiff-initiated dismissal before answer
Federal Rule of Civil Procedure 41(a)(1)(A)(i) allows a plaintiff to dismiss a case without a court order if filed before the defendant has served an answer or motion for summary judgment. Novartis invoked this mechanism after just 39 days. Critically, the stipulation is silent on whether the dismissal is with or without prejudice — under Rule 41, a first voluntary dismissal is presumed without prejudice unless the notice states otherwise.
Rule 41(a)(1)(A)(i) — pre-answerWith or without prejudice? The public record is silent
A dismissal ‘with prejudice’ permanently bars Novartis from refiling the same patent claims against Zenara. A dismissal ‘without prejudice’ preserves that right. The filed stipulation invokes Rule 41(a)(1)(A)(i) and says each party bears its own costs, but does not explicitly state which applies. Under default Rule 41 doctrine, a first voluntary dismissal is treated as without prejudice — but practitioners should review the actual docket filing before drawing conclusions.
Prejudice status: not stated on recordNovartis exits early — PROMACTA® enforcement posture preserved
Novartis’s swift exit before Zenara formally appeared suggests a recalibration of litigation strategy rather than a concession on the merits. If the dismissal is without prejudice (the Rule 41 default), Novartis retains the option to refile US8828430B2 against Zenara should the ANDA process advance. The own-costs structure is consistent with a negotiated resolution or a unilateral assessment that prosecution was not yet warranted.
Novartis — early exit, rights likely preservedZenara avoids early litigation cost — but ANDA pathway remains uncertain
Zenara Pharma did not appear to have retained U.S. counsel before the dismissal, suggesting the case resolved or was withdrawn before meaningful litigation costs were incurred on the defence side. Without a court ruling on validity or infringement of US8828430B2, Zenara’s ANDA pathway for eltrombopag tablets in the U.S. market remains subject to the risk of renewed patent enforcement by Novartis.
Zenara — no merits ruling, risk remainsFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Novartis, AG | Company | Global pharmaceutical company — holder of US8828430B2 (PROMACTA® eltrombopag olamine)Search in Eureka ↗ |
| Defendant | Zenara Pharma Private, Ltd. | Company | Indian generic pharmaceutical manufacturer seeking U.S. approval for eltrombopag tabletsSearch in Eureka ↗ |
| Plaintiff counsel | Alexandra M. Joyce | Attorney | Counsel for Novartis, AGSearch in Eureka ↗ |
| Plaintiff counsel | Daniel M. Silver | Attorney | Counsel for Novartis, AGSearch in Eureka ↗ |
| Plaintiff law firm | McCarter & English LLP | Law Firm | Representing Novartis, AGSearch in Eureka ↗ |
| Presiding judge | Judge Gregory B. Williams | Judge | Delaware District CourtSearch in Eureka ↗ |
Official order — verbatim text
The stipulation of dismissal invokes Rule 41(a)(1)(A)(i), the pre-answer unilateral mechanism, and contains no merits ruling on infringement or validity of US8828430B2. The own-costs provision is standard for this mechanism but is notable in that it forecloses any fee award to either party. The absence of a prejudice designation in the filing means the legal default — dismissal without prejudice — likely governs, leaving Novartis’s claims technically available for reinstatement.
US8828430B2 — Eltrombopag olamine tablet formulations (PROMACTA®)
US8828430B2 (application number US13/272367) covers eltrombopag olamine tablet formulations, the active pharmaceutical ingredient in Novartis’s PROMACTA® product. Eltrombopag is a thrombopoietin receptor agonist approved to treat chronic immune thrombocytopenia (ITP) and other conditions associated with low platelet counts. The patent’s formulation claims covering specific dose strengths — 12.5 mg, 25 mg, 50 mg, and 75 mg — are precisely those targeted by Zenara’s ANDA.
PROMACTA® is a commercially significant product in Novartis’s haematology portfolio. Formulation patents like US8828430B2 are a key secondary line of defence for brand companies after composition-of-matter patents expire, as they cover specific solid-dose forms that generics must design around or challenge via paragraph IV certification. The enforceability of this patent remains untested following the voluntary dismissal, making it a material risk for any eltrombopag ANDA applicant.
Should you run an FTO against US8828430B2 for eltrombopag tablets?
Any company developing or commercialising generic eltrombopag olamine tablets in the 12.5 mg to 75 mg dose range should treat US8828430B2 as an active risk. This case demonstrates that Novartis is willing to assert the patent against ANDA filers, and the voluntary dismissal without a prejudice finding means enforcement risk has not been extinguished. R&D and regulatory teams preparing ANDA submissions should conduct a freedom-to-operate analysis before finalising formulation and dosage strategies.
PatSnap Eureka’s FTO Search Agent allows you to map the full claim scope of US8828430B2, identify related continuations or divisionals in Novartis’s eltrombopag portfolio, cross-reference prosecution history for claim narrowing, and benchmark your formulation against the cited prior art. Teams can also monitor for new ANDA-related enforcement filings by Novartis in Delaware to anticipate litigation posture shifts.
Run a freedom-to-operate analysis on US8828430B2 to assess your product’s exposure
Run FTO in Eureka →Similar ANDA patent cases: eltrombopag & thrombopoietin receptor agonists
Explore comparable Hatch-Waxman patent enforcement actions in the Delaware District Court involving small-molecule haematology formulations and ANDA paragraph IV certifications.
What this case signals for the ANDA and small-molecule patent landscape
Ultra-short Hatch-Waxman actions in Delaware often mask strategic manoeuvres invisible in the public record.
39-day filings are Hatch-Waxman tactics, not accidents
Brand companies routinely file ANDA patent suits to trigger the 30-month FDA approval stay under 21 U.S.C. § 355(j)(5)(B)(iii), even before fully committing to litigation. A 39-day dismissal is consistent with this playbook: the stay mechanism is engaged, then the brand reassesses. Generic entrants should not interpret an early dismissal as a cleared path.
Silence on prejudice status is itself a risk signal for generics
When a voluntary dismissal does not explicitly state ‘with prejudice,’ the default favours the brand patentee. Zenara and other eltrombopag ANDA filers should assume US8828430B2 remains a live enforcement risk. Monitoring Novartis’s ANDA-related filings against other generic applicants for this product is advisable.
Novartis v Zenara — key questions answered
Novartis voluntarily dismissed all claims against Zenara Pharma on 1 July 2025, 39 days after filing, under Federal Rule of Civil Procedure 41(a)(1)(A)(i). Each party bears its own costs. The dismissal notice does not specify whether it is with or without prejudice; under Rule 41 defaults, a first voluntary dismissal is presumed without prejudice.
Novartis asserted US8828430B2 (application no. US13/272367), a patent covering eltrombopag olamine tablet formulations in 12.5 mg, 25 mg, 50 mg, and 75 mg strengths — the doses used in its branded PROMACTA® product for treatment of chronic immune thrombocytopenia.
No. A voluntary dismissal without a merits ruling does not clear US8828430B2 as an obstacle for generic eltrombopag developers. Because the dismissal is silent on prejudice, Novartis likely retains the right to refile. Zenara and other ANDA applicants should treat the patent as an active enforcement risk and conduct appropriate freedom-to-operate analysis.
Rule 41(a)(1)(A)(i) allows a plaintiff to dismiss a civil action without court approval before the defendant has served an answer. In ANDA litigation, brand companies sometimes use this mechanism after filing to trigger the Hatch-Waxman 30-month stay, then reassess strategy. Dismissal under this rule is presumed without prejudice on a first filing, preserving the brand’s ability to refile.
Novartis was represented by Alexandra M. Joyce and Daniel M. Silver of McCarter & English LLP. No defendant counsel was listed on the public docket, consistent with the case resolving before Zenara formally appeared in the Delaware District Court proceedings.
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