Axsome Malta v. Hetero USA: Solriamfetol Patent Suit Dismissed Without Prejudice
Axsome Malta, Ltd. filed a patent infringement action in the District of New Jersey against Hetero USA, Inc. over US12090126B2, a patent covering solriamfetol oral tablets marketed as Sunosi®. After 225 days, the parties stipulated to dismiss all claims without prejudice and without costs, leaving the door open to future litigation.
Sunosi® Patent Suit Ends in Stipulated Dismissal — But Door Stays Open
On 20 November 2024, Axsome Malta, Ltd. and Axsome Therapeutics, Inc. (collectively ‘Axsome’) filed a patent infringement action in the U.S. District Court for the District of New Jersey against Hetero USA, Inc. and related Hetero Labs entities. The complaint centred on US12090126B2 — a patent covering solriamfetol oral tablet formulations — asserted against Hetero’s proposed generic version of Sunosi®, the 75 mg and 150 mg base strength solriamfetol tablets indicated to improve wakefulness in adults with excessive daytime sleepiness.
The case concluded on 3 July 2025, when the parties filed a joint stipulation of dismissal under Federal Rule of Civil Procedure 41(a)(1)(A)(ii), dismissing all claims, counterclaims, and affirmative defenses without prejudice and without costs or attorneys’ fees to any party. The District of New Jersey retained jurisdiction to enforce and resolve any disputes relating to the subject matter of the action, a standard reservation clause that signals the parties may have entered into a confidential settlement or licensing agreement governing Hetero’s ANDA.
The 225-day duration is notably brief for ANDA patent litigation, where cases frequently extend well beyond two years. The rapid resolution — and the absence of any fee or cost award — is consistent with a negotiated business resolution rather than litigation attrition. The public record does not disclose any licensing terms, launch date restrictions, or supply arrangements; any such commercial terms, if agreed, remain confidential.
Filing to Dismissed without Prejudice in 225 days
225 days — faster than the median ANDA patent case in D.N.J., which typically runs 2–4 years to trial
Dismissed without prejudice: what the stipulation means for both parties
Rule 41(a)(1)(A)(ii) dismissal: no merits ruling, no finality
A stipulated dismissal under FRCP 41(a)(1)(A)(ii) requires consent of all parties who have appeared and results in no adjudication on the merits. ‘Without prejudice’ means Axsome is not barred from re-filing the same infringement claims against Hetero in the future — the patent is not invalidated, and no claim or counterclaim is given preclusive effect.
No merits adjudicationWithout prejudice: refiling remains possible
Dismissal without prejudice preserves Axsome’s right to sue again on the same patent and product if circumstances change — for example, if a negotiated launch window lapses or a licensing arrangement breaks down. This contrasts with a with-prejudice dismissal, which would permanently extinguish the asserted claims. The public record does not specify whether a settlement agreement governs the relationship going forward.
Refiling rights preservedHetero avoids invalidity ruling — but faces lingering patent risk
Hetero did not obtain a finding of invalidity or non-infringement for US12090126B2. While the dismissal ends this action, the patent remains in force and Hetero’s ANDA pathway is unresolved on the merits. Any commercial launch of a generic solriamfetol product before US12090126B2 expires would carry infringement risk unless a licence or agreed entry date is in place.
No invalidity findingConfidential deal likely governs Hetero’s generic entry timeline
The combination of a swift resolution, mutual cost waiver, and court retention of jurisdiction is consistent with a confidential settlement — potentially including an authorised generic licence or agreed launch date. Competing ANDA filers and branded competitors should monitor FDA approval timelines for Hetero’s solriamfetol ANDA, as any agreed entry date would signal the effective exclusivity window for Sunosi®.
Possible authorised entry dealFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Axsome Malta, Ltd. | Company | Specialty CNS pharmaceutical company — holder of US12090126B2 covering Sunosi® solriamfetol tabletsSearch in Eureka ↗ |
| Defendant | Hetero USA, Inc. | Company | U.S. arm of Hetero Labs, Indian generics manufacturer seeking ANDA approval for solriamfetol oral tabletsSearch in Eureka ↗ |
| Plaintiff counsel | Alexander Lee Callo | Attorney | Counsel for Axsome Malta, Ltd.Search in Eureka ↗ |
| Plaintiff counsel | Charles Michael Lizza | Attorney | Counsel for Axsome Malta, Ltd.Search in Eureka ↗ |
| Plaintiff counsel | Sarah Ann Sullvian | Attorney | Counsel for Axsome Malta, Ltd.Search in Eureka ↗ |
| Plaintiff counsel | William C. Baton | Attorney | Counsel for Axsome Malta, Ltd.Search in Eureka ↗ |
| Plaintiff law firm | Saul Ewing LLP | Law Firm | Representing Axsome Malta, Ltd.Search in Eureka ↗ |
| Defendant counsel | Kaan Ekiner | Attorney | Counsel for Hetero USA, Inc.Search in Eureka ↗ |
| Defendant law firm | Cozen O’connor PC | Law Firm | Representing Hetero USA, Inc.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | New Jersey District CourtSearch in Eureka ↗ |
Official order — verbatim text
The stipulation invokes FRCP 41(a)(1)(A)(ii) — a bilateral dismissal requiring all parties’ consent — and expressly states dismissal is ‘without prejudice’ and ‘without costs or attorneys’ fees.’ This phrasing confirms no party secured a litigation advantage: Axsome’s infringement claims and Hetero’s invalidity counterclaims are extinguished equally, with no admissions. The court’s retained jurisdiction clause is a material provision, typically included when a confidential settlement agreement underpins the dismissal and the parties anticipate the need to enforce its terms.
US12090126B2 — Solriamfetol oral tablet formulations (Sunosi®)
US12090126B2 (application number US18/491311) covers solriamfetol oral tablet formulations, the active ingredient in Jazz Pharmaceuticals’ Sunosi® — a dopamine and norepinephrine reuptake inhibitor approved to improve wakefulness in adults with excessive daytime sleepiness associated with narcolepsy or obstructive sleep apnea. As a pharmaceutical composition patent, it likely claims specific formulation parameters, dosage strengths (75 mg and 150 mg base equivalents), or manufacturing characteristics that distinguish it from prior solriamfetol art.
Axsome’s enforcement of US12090126B2 against Hetero’s ANDA application underscores the strategic importance of formulation patents in extending exclusivity beyond a compound’s primary patent term. For the CNS wakefulness sector — which includes competing products for narcolepsy and sleep apnea — the enforceability and scope of this patent are commercially significant. Any generic entrant capturing even a modest share of the solriamfetol market would represent substantial revenue displacement, making robust ANDA challenge deterrence a rational enforcement posture.
Should you run an FTO analysis against US12090126B2?
Any company developing, filing an ANDA for, or commercialising solriamfetol oral tablet formulations in the United States should treat US12090126B2 as a live enforcement risk. The patent has not been invalidated or found non-infringed — this case ended without any merits ruling. Pharmaceutical development teams working on CNS wakefulness agents with similar dopamine/norepinephrine reuptake inhibitor mechanisms should also review the broader Axsome formulation portfolio for related continuation applications.
PatSnap Eureka’s FTO Search Agent can map the independent and dependent claims of US12090126B2 against your proposed solriamfetol formulation, identify related continuation and divisional applications filed by Axsome, and surface prior art landscapes that could support invalidity arguments. For ANDA filers at the Paragraph IV certification stage, Eureka can accelerate claim charting and flag prosecution history estoppel risks before litigation exposure crystallises.
Run a freedom-to-operate analysis on US12090126B2 to assess your product’s exposure
Run FTO in Eureka →Similar ANDA solriamfetol and CNS formulation patent cases
Cases involving ANDA challenges to CNS wakefulness drug formulation patents in U.S. district courts — particularly in D.N.J. — most closely parallel Axsome v. Hetero.
What this case signals for the CNS wakefulness drug IP landscape
A rapid, cost-neutral dismissal in an ANDA case typically reflects commercial resolution — and has direct implications for generic entry timing and patent enforcement strategy.
Swift ANDA dismissals signal negotiated entry — track FDA approval dates
When ANDA patent suits resolve in under a year without a fee award, the most likely explanation is a licensing or settlement agreement governing launch timing. Generic competitors and payers tracking Sunosi® pricing should monitor Hetero’s ANDA approval status at FDA as a proxy for when agreed entry may occur.
US12090126B2 remains fully enforceable against other ANDA filers
The dismissal grants no preclusive benefit to any third-party generic filer. Axsome retains full enforcement rights under US12090126B2 against any other applicant seeking ANDA approval for solriamfetol oral tablets. Companies with pending or planned ANDAs should conduct FTO analysis against this patent before committing to development spend.
Axsome v Hetero — key questions answered
The case was dismissed without prejudice by joint stipulation on 3 July 2025 under FRCP 41(a)(1)(A)(ii). No costs or attorneys’ fees were awarded to either party, and no merits ruling was issued. The District of New Jersey retained jurisdiction to enforce the subject matter of the action, suggesting a confidential resolution may underpin the dismissal.
The patent at issue is US12090126B2 (application no. US18/491311), which covers solriamfetol oral tablet formulations. Solriamfetol is the active ingredient in Sunosi®, a dopamine and norepinephrine reuptake inhibitor approved for excessive daytime sleepiness in narcolepsy and obstructive sleep apnea patients. The case concerned Hetero’s ANDA for generic solriamfetol tablets at 75 mg and 150 mg base equivalent strengths.
No. A dismissal without prejudice under FRCP 41(a)(1)(A)(ii) carries no preclusive effect and involves no adjudication on the merits. US12090126B2 remains in force and fully enforceable. Neither validity nor infringement was determined by the court. Any third-party ANDA filer for solriamfetol tablets cannot rely on this dismissal as a basis for arguing non-infringement or invalidity of the patent.
The case resolved in approximately 225 days — well below the typical 2–4 year timeline for ANDA patent litigation in D.N.J. The mutual cost waiver, bilateral consent, and court retention of jurisdiction are collectively consistent with a negotiated business resolution, which may include a licensing agreement, authorised generic arrangement, or agreed generic entry date. The specific terms of any such agreement are not reflected in the public court record.
US12090126B2 remains a live enforcement barrier for any ANDA filer seeking to market solriamfetol oral tablets in the United States. The Axsome v. Hetero dismissal provides no invalidity defence for third parties. Companies with pending or planned ANDAs must independently assess their exposure under US12090126B2 — including conducting FTO analysis, claim charting, and reviewing Axsome’s continuation patent portfolio — before filing a Paragraph IV certification.
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