Bayer & Janssen v. Auson Pharmaceuticals: Rivaroxaban Patent Dispute Dismissed With Prejudice
Bayer AG, Bayer Pharma AG, and Janssen Pharmaceuticals brought a patent infringement action in Delaware against Auson Pharmaceuticals over two patents covering rivaroxaban tablets — a blockbuster anticoagulant. The case ended with a mutual dismissal with prejudice after 386 days, with all parties bearing their own costs.
Rivaroxaban formulation patents tested — and quietly resolved — in Delaware
On October 5, 2023, Bayer AG, Bayer Pharma AG, and Janssen Pharmaceuticals, Inc. filed suit in the Delaware District Court (Case No. 1:23-cv-01103) against Auson Pharmaceuticals, Inc. and its Chinese parent Shanghai Auson Pharmaceuticals Co., Ltd. The complaint alleged infringement of US9539218B2 and US10828310B2 — two patents protecting rivaroxaban tablet formulations — based on Auson’s 2.5 mg and 10 mg rivaroxaban generic tablet products.
The case closed on October 25, 2024, via a stipulated dismissal filed jointly under Federal Rules of Civil Procedure 41(a)(1) and 41(c). Crucially, the dismissal was entered with prejudice, meaning all claims and counterclaims by both sides are permanently extinguished. Neither party can relitigate these specific claims in a new action. All parties agreed to bear their own costs and attorneys’ fees, signalling a negotiated resolution rather than a court-imposed outcome.
The 386-day duration and the with-prejudice, own-costs structure is broadly consistent with pharmaceutical patent disputes that resolve through confidential licensing or market-access agreements before trial — though the public record does not confirm any such commercial arrangement. The fact that Auson’s counterclaims were also dismissed suggests the generic manufacturer did not extract a patent invalidation ruling. What drove the resolution — whether a license, a market delay agreement, or commercial considerations — remains undisclosed.
Filing to Case Dismissed in 386 days
386 days — resolved before reaching trial, consistent with pre-trial ANDA settlement patterns
Dismissed with prejudice: what the stipulated resolution means for both parties
Rule 41 dismissal with prejudice operates as a final judgment on the merits
A stipulated dismissal with prejudice under Rules 41(a)(1) and 41(c) is legally equivalent to a final judgment. No court adjudicated the patent validity or infringement questions — but the with-prejudice designation bars either party from refiling the same claims. Auson cannot later challenge these patents on the same grounds in a new district court action arising from the same facts.
Res judicata effect appliesBayer and Janssen’s patents survive without a validity challenge on the record
The dismissal with prejudice means US9539218B2 and US10828310B2 emerge from this litigation without any adverse validity or enforceability ruling. Bayer and Janssen retain the right to assert these patents against other generics. The outcome is strategically favourable for the patent holders: no court has weakened the patents, and Auson’s defences — which typically include invalidity and non-infringement — are now extinguished as against these plaintiffs.
Patents intact, fully enforceableAuson’s path to market — and its counterclaims — are both closed off via this record
By agreeing to a with-prejudice dismissal, Auson gives up its counterclaims — most likely invalidity and non-infringement defences — without obtaining a court ruling. This suggests Auson either reached a commercial accommodation with the patent holders or determined litigation was not commercially viable. Auson cannot re-assert the same defences against these plaintiffs in a fresh action, raising the bar for any future market entry challenge.
Counterclaims permanently extinguishedOwn-costs clause and confidential resolution consistent with licensing or delay agreement
The mutual own-costs arrangement — uncommon in fully litigated cases — typically signals that both sides received something of commercial value, often a future market entry date or royalty licence. For the rivaroxaban sector, this outcome reinforces the strength of Bayer and Janssen’s formulation patent portfolio. Other generic manufacturers targeting rivaroxaban should treat these two patents as live enforcement risks and conduct FTO analysis before filing ANDAs.
Monitor for related ANDA filingsFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Bayer AG | Company | Global pharmaceutical innovator — holder of US9539218B2 and US10828310B2 covering rivaroxabanSearch in Eureka ↗ |
| Co-Plaintiff | Bayer Pharma AG | Company | Search in Eureka ↗ |
| Co-Plaintiff | Janssen Pharmaceuticals, Inc. | Company | Search in Eureka ↗ |
| Co-Plaintiff | Bayer AG | Company | Search in Eureka ↗ |
| Defendant | Auson Pharmaceuticals, Inc. | Company | Generic pharmaceutical company seeking to market 2.5 mg and 10 mg rivaroxaban tablets in the USSearch in Eureka ↗ |
| Co-Defendant | Auson Pharmaceuticals Co., Ltd. | Company | Search in Eureka ↗ |
| Plaintiff counsel | Derek James Fahnestock | Attorney | Counsel for Bayer AGSearch in Eureka ↗ |
| Plaintiff counsel | Keith J. Miller | Attorney | Counsel for Bayer AGSearch in Eureka ↗ |
| Plaintiff law firm | Morris, Nichols, Arsht & Tunnell LLP | Law Firm | Representing Bayer AGSearch in Eureka ↗ |
| Plaintiff law firm | Robinson Miller LLC | Law Firm | Representing Bayer AGSearch in Eureka ↗ |
| Defendant counsel | Gerard Norton | Attorney | Counsel for Auson Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Howard S. Suh | Attorney | Counsel for Auson Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Jonathan J. Madara | Attorney | Counsel for Auson Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Jonathan R. Lagarenne | Attorney | Counsel for Auson Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Kasey Hacker DeSantis | Attorney | Counsel for Auson Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Paul W. Kalish | Attorney | Counsel for Auson Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant law firm | Fox Rothschild LLP | Law Firm | Representing Auson Pharmaceuticals, Inc.Search in Eureka ↗ |
| Presiding judge | Judge Richard G. Andrews | Judge | Delaware District CourtSearch in Eureka ↗ |
Official order — verbatim text
The stipulated dismissal invokes Rule 41(a)(1) for plaintiffs’ claims and Rule 41(c) for counterclaims, ensuring symmetric with-prejudice effect across all parties. The explicit listing of all named entities — including the Chinese parent Shanghai Auson — confirms the dismissal covers the entire corporate group. The own-costs clause suggests a negotiated resolution; had one side clearly prevailed, a cost award would typically follow. No merits findings were made on infringement, validity, or enforceability of either patent.
US9539218B2 & US10828310B2 — Rivaroxaban tablet formulation patents
US9539218B2 (application no. 11/883,218) and US10828310B2 (application no. 16/264,032) both protect aspects of rivaroxaban — the active pharmaceutical ingredient in Xarelto, a direct oral anticoagulant (DOAC) used to prevent and treat blood clots. These patents cover formulation and composition claims for rivaroxaban tablets, including the 2.5 mg and 10 mg dosage strengths specifically at issue in this litigation. Rivaroxaban patent protection in the US spans a complex layered estate maintained by Bayer and its licensee Janssen.
Rivaroxaban is one of the highest-revenue pharmaceutical products globally, making its formulation patents prime targets for ANDA filers seeking early generic entry. The two patents at issue appear in Bayer and Janssen’s enforcement strategy as a second-wave barrier — protecting specific tablet formulations rather than the molecule itself. Any generic manufacturer filing an ANDA referencing Xarelto must assess these patents carefully, as Bayer has demonstrated consistent and rapid enforcement. The survival of both patents from this action strengthens their commercial deterrent value.
Should you run an FTO against US9539218B2 and US10828310B2?
Any company developing, filing ANDAs for, or commercialising rivaroxaban oral tablet products in the US — particularly 2.5 mg and 10 mg formulations — should treat these two patents as active enforcement risks. Bayer and Janssen filed suit within weeks of becoming aware of Auson’s product, and the with-prejudice outcome confirms these patents remain valid and enforceable. Both branded and contract manufacturers supplying rivaroxaban tablets should complete FTO analysis before any regulatory submission.
PatSnap Eureka’s FTO Search Agent can map the full claim scope of US9539218B2 and US10828310B2 against your proposed formulation, identify prosecution history estoppel, and surface related family members across jurisdictions. Eureka can also monitor PTAB activity, Orange Book listings, and new ANDA-triggered enforcement actions involving these patents — giving R&D and regulatory teams a live risk picture ahead of any US market filing.
Run a freedom-to-operate analysis on US9539218B2 to assess your product’s exposure
Run FTO in Eureka →Similar rivaroxaban and DOAC formulation patent cases in Delaware and beyond
Explore related ANDA patent infringement cases involving rivaroxaban, anticoagulant formulations, and Hatch-Waxman disputes litigated in the Delaware District Court.
What this case signals for the rivaroxaban and anticoagulant IP landscape
This with-prejudice settlement reinforces Bayer and Janssen’s hold over rivaroxaban formulation patents and signals active enforcement against generics.
Bayer’s rivaroxaban patent estate remains legally unscathed after this action
No adverse ruling on US9539218B2 or US10828310B2 emerged from this case. Generic challengers cannot rely on this docket as precedent for invalidity. Any new entrant targeting rivaroxaban tablets must assess both patents independently — and Bayer has demonstrated willingness to litigate promptly after ANDA filings.
With-prejudice structure bars Auson from re-litigating — but not third-party challengers
The res judicata effect binds only the named parties. Other generic manufacturers are not precluded from challenging these patents via IPR at the USPTO or in separate district court actions. The patents’ survival here does not mean they are unassailable — it means they have not yet been tested on the merits in any public proceeding.
Bayer v Auson — key questions answered
Bayer AG, Bayer Pharma AG, and Janssen Pharmaceuticals asserted US9539218B2 (application 11/883,218) and US10828310B2 (application 16/264,032) — both covering rivaroxaban tablet formulations — against Auson’s 2.5 mg and 10 mg rivaroxaban generic tablet products in Delaware District Court.
The parties filed a joint stipulation under Rules 41(a)(1) and 41(c) to dismiss all claims and counterclaims with prejudice. A with-prejudice dismissal is legally equivalent to a final judgment — neither party can re-file the same claims. No merits ruling on infringement or patent validity was issued. The outcome is consistent with a negotiated resolution, though no commercial terms were disclosed.
No. The dismissal with prejudice means Auson’s counterclaims — which typically include invalidity and non-infringement defences in ANDA cases — were extinguished without any court ruling in Auson’s favour. Both US9539218B2 and US10828310B2 remain valid and enforceable with no adverse ruling on the record.
Bayer and Janssen were represented by Morris, Nichols, Arsht & Tunnell LLP and Robinson Miller LLC, with attorneys Derek James Fahnestock and Keith J. Miller. Auson Pharmaceuticals was represented by Fox Rothschild LLP, with attorneys including Gerard Norton, Howard S. Suh, Paul W. Kalish, and Jonathan Lagarenne, among others.
The with-prejudice outcome leaves both patents intact and enforceable. Generic competitors planning US market entry for rivaroxaban tablets — especially 2.5 mg and 10 mg strengths — should treat US9539218B2 and US10828310B2 as live enforcement risks. Bayer has demonstrated rapid litigation response to ANDA filings. Conducting FTO analysis and monitoring Orange Book listings for these patents is advisable before any regulatory submission.
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