Supernus v. Ascent Pharmaceuticals: Trokendi XR Patent Suit Dismissed Without Prejudice
Supernus Pharmaceuticals filed suit against Ascent Pharmaceuticals, Hetero Labs, and Camber Pharmaceuticals in the District of New Jersey, asserting 10 patents covering Trokendi XR (extended-release topiramate). All claims, counterclaims, and defenses were dismissed without prejudice after 281 days — leaving the door open for future enforcement.
Ten-Patent Trokendi XR Suit Ends in Stipulated Walkaway
Supernus Pharmaceuticals, Inc. filed this Hatch-Waxman infringement action on July 26, 2023 in the U.S. District Court for the District of New Jersey, asserting ten patents — including US8298576B2, US9622983B2, US8663683B2, US8877248B1, US8889191B2, US10314790B2, US8298580B2, US8992989B2, US9555004B2, and US9549940B2 — against Ascent Pharmaceuticals, Hetero Labs Limited, and Camber Pharmaceuticals. The patents collectively cover extended-release topiramate formulations and methods of use underlying the branded product Trokendi XR.
The case closed on May 2, 2024, via a Stipulation and Order of Dismissal without prejudice. Both Supernus and Ascent agreed to dismiss all claims, counterclaims, and defenses without prejudice, meaning no merits determination was reached and neither party is precluded by res judicata from pursuing or asserting the same claims in future proceedings. The dismissal is consistent with a negotiated resolution or an agreement to defer litigation — though the specific terms driving the stipulation are not reflected in the public record.
At 281 days, the case resolved relatively quickly for a multi-patent ANDA matter involving three defendants. The breadth of the patent portfolio asserted — ten patents spanning multiple application families — suggests Supernus was pursuing a comprehensive enforcement posture. Whether the dismissal reflects a settlement, a licensing arrangement, or a strategic decision to refile in a different forum or against a different ANDA filer remains unknown from publicly available documents. The without-prejudice designation is commercially significant: Supernus retains full optionality to reassert these patents against the same or different generic challengers.
Filing to Dismissed without Prejudice in 281 days
281 days — closed before typical ANDA litigation 30-month stay window expired
Dismissed without prejudice: what the stipulation means for both parties
Stipulated dismissal without prejudice — no merits ruling
A dismissal without prejudice means the court terminated the case without adjudicating the validity or infringement of any of the ten asserted patents. The parties jointly agreed to this outcome via stipulation. Unlike a with-prejudice dismissal, this ruling does not bar Supernus from refiling the same claims against Ascent, Hetero Labs, or Camber in future proceedings. No judicial finding on the merits was made.
No res judicata effectSupernus retains full enforcement optionality on all 10 patents
Because the dismissal is without prejudice, Supernus’s ten Trokendi XR patents remain unadjudicated and fully enforceable. Supernus can reassert these patents against Ascent or co-defendants in a future action, pursue other ANDA filers, or seek a preliminary injunction if market entry appears imminent. The public record does not disclose whether a settlement, license, or consent judgment was reached outside of court.
Patents remain enforceableDefendants exit without invalidity finding — but also without clearance
Ascent, Hetero Labs, and Camber obtain no declaratory judgment of non-infringement or invalidity. While they are not bound by any adverse ruling, they also received no judicial clearance to market generic extended-release topiramate. Any launch would still risk exposure to renewed litigation. The without-prejudice nature means Supernus could refile with the same or updated patent assertions if generic market entry is attempted.
No patent clearance obtainedGeneric topiramate ER market entry remains legally uncertain
With no merits ruling, the enforceability of Supernus’s extended-release topiramate portfolio is unresolved. Companies monitoring the Trokendi XR ANDA landscape should note that the ten asserted patents retain their presumption of validity. Competitors and investors in the generic CNS drug space should treat this dismissal as a temporary cessation of hostilities rather than a green light for market entry without further IP diligence.
IP landscape unresolvedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Supernus Pharmaceuticals, Inc. | Company | Specialty pharmaceutical company — holder of US8298576B2 and 9 further Trokendi XR patentsSearch in Eureka ↗ |
| Defendant | ASCENT PHARMACEUTICALS INC. | Company | Generic pharmaceutical companies filing ANDAs for extended-release topiramate tabletsSearch in Eureka ↗ |
| Co-Defendant | Hetero Labs Limited | Individual | Search in Eureka ↗ |
| Co-Defendant | Camber Pharmaceuticals, Inc. | Company | Search in Eureka ↗ |
| Plaintiff counsel | Charles Michael Lizza | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Richard Frank Kurz | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Sarah Ann Sullvian | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff counsel | William C. Baton | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Haug Partners, LLP | Law Firm | Representing Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Saul Ewing, LLP | Law Firm | Representing Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | A. William Henkel | Attorney | Counsel for ASCENT PHARMACEUTICALS INC.Search in Eureka ↗ |
| Defendant counsel | Cali Roth Spota | Attorney | Counsel for ASCENT PHARMACEUTICALS INC.Search in Eureka ↗ |
| Defendant counsel | Karen A. Confoy | Attorney | Counsel for ASCENT PHARMACEUTICALS INC.Search in Eureka ↗ |
| Defendant law firm | Fox Rothschild LLP | Law Firm | Representing ASCENT PHARMACEUTICALS INC.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | New Jersey District CourtSearch in Eureka ↗ |
Official order — verbatim text
The stipulation and order uses precise language — ‘dismissed without prejudice’ — applied symmetrically to all claims, counterclaims, and defenses of both Supernus and Ascent. This mutual framing suggests the agreement was negotiated rather than unilaterally sought. Critically, the without-prejudice designation means no collateral estoppel or claim preclusion attaches, and the ten asserted patents retain their full presumption of validity. The court’s order reflects no findings on infringement, validity, or enforceability.
US8298576B2 and 9 further patents — extended-release topiramate (Trokendi XR)
The ten asserted patents — spanning application families from US11/941475 through US15/259856 and related continuations — collectively protect Supernus’s extended-release topiramate technology underlying Trokendi XR, an FDA-approved treatment for epilepsy and migraine prevention. The patents cover formulation compositions, controlled-release mechanisms, dosage methods, and therapeutic applications of topiramate in extended-release form. Multiple application filing dates across the portfolio suggest a layered continuation strategy designed to extend protection across different patent expiry windows.
For the generic pharmaceutical sector, this portfolio presents a formidable clearance challenge. Trokendi XR holds a significant share of the branded topiramate market, and the ten-patent Orange Book listing strategy is consistent with Supernus’s broader approach of building overlapping IP fences around its CNS franchise. Competitors developing ANDA products for extended-release topiramate must assess each patent independently — covering both formulation and method-of-use claims — before any commercialisation decision. The unresolved status of this litigation means no judicial guidance on claim scope or validity is currently available.
Should you run an FTO against Supernus’s Trokendi XR patent portfolio?
Any company developing, manufacturing, or commercialising extended-release topiramate tablets — whether as an ANDA filer, a contract manufacturer, or an API supplier — should treat this ten-patent portfolio as an active enforcement risk. The without-prejudice dismissal means Supernus can refile against the same or new defendants at any time. Generic developers, in particular, should map their formulation and process against each of the ten patents before committing to regulatory or commercial timelines.
PatSnap Eureka’s FTO Search Agent can rapidly map your extended-release topiramate product or process against each of the ten Supernus patents, identify relevant claim language, surface prior art that could support validity challenges, and flag any recent continuation filings or Orange Book updates. This analysis is critical for ANDA sponsors, their API partners, and investors evaluating market entry risk in the branded CNS drug generic space.
Run a freedom-to-operate analysis on US8298576B2 to assess your product’s exposure
Run FTO in Eureka →Similar ANDA patent cases: extended-release CNS drug formulation disputes
Explore related Hatch-Waxman infringement actions in the District of New Jersey involving extended-release CNS drug formulation patents and multi-defendant ANDA enforcement strategies.
What this case signals for the extended-release CNS drug IP landscape
A ten-patent ANDA suit dismissed without prejudice after nine months suggests negotiated resolution — and preserved enforcement leverage for the brand holder.
Without-prejudice dismissals in ANDA cases often signal licensing activity
In Hatch-Waxman litigation, stipulated dismissals without prejudice frequently accompany confidential settlement or licensing agreements. While the Supernus-Ascent docket is silent on terms, the joint nature of the stipulation and the rapid resolution relative to typical ANDA timelines is consistent with a negotiated commercial arrangement rather than an abandonment of claims.
Ten-patent portfolios create layered enforcement risk for generic filers
Supernus asserted ten distinct patents covering different aspects of extended-release topiramate formulations. Even if a generic challenger could design around one or two claims, the overlapping portfolio creates significant clearance complexity. ANDA filers in this space should conduct thorough FTO analysis across the full Trokendi XR patent family before committing to manufacturing investment.
Supernus v ASCENT — key questions answered
The case was dismissed without prejudice on May 2, 2024, via a joint Stipulation and Order of Dismissal. All claims, counterclaims, and defenses asserted by Supernus and Ascent were dismissed without prejudice, meaning no merits ruling was issued and Supernus retains the right to refile against the defendants in future proceedings.
Supernus asserted ten patents: US8298576B2, US9622983B2, US8663683B2, US8877248B1, US8889191B2, US10314790B2, US8298580B2, US8992989B2, US9555004B2, and US9549940B2. These patents collectively cover extended-release topiramate formulations and methods of use underlying the branded product Trokendi XR.
A dismissal without prejudice means Supernus’s ten Trokendi XR patents were not adjudicated on the merits. No finding of infringement, validity, or enforceability was made. Supernus retains full rights to refile the same claims against Ascent, Hetero Labs, Camber, or other ANDA filers. There is no res judicata or collateral estoppel effect barring future litigation.
Hetero Labs Limited and Camber Pharmaceuticals were named as additional defendants alongside Ascent Pharmaceuticals. This is consistent with Hatch-Waxman enforcement practice where brand holders target the full supply chain, including API manufacturers and finished-dose sponsors. Hetero Labs is an Indian pharmaceutical manufacturer, suggesting Supernus was addressing both the upstream API source and the domestic ANDA applicant.
The case lasted 281 days, filed on July 26, 2023 and closed on May 2, 2024. For a multi-patent ANDA matter asserting ten patents against three defendants, this is a relatively rapid resolution, which is often consistent with negotiated settlement or licensing activity, though no such terms are disclosed in the public record.
PatSnap Eureka searches patents and litigation data to answer instantly.