Ajanta & Torrent v. Supernus: 10-Patent Topiramate ER Appeal Voluntarily Dismissed
Ajanta Pharma, Torrent Pharma, and affiliated entities challenged Supernus Pharmaceuticals at the Federal Circuit over ten US patents covering topiramate extended-release capsules. After 589 days, the parties jointly agreed to dismiss the appeal under Fed. R. App. P. 42(b), with each side absorbing its own costs — leaving the underlying patent landscape unresolved on the merits.
Ten-Patent Federal Circuit Appeal Ends Without Merits Adjudication
Filed on 26 March 2024 at the Court of Appeals for the Federal Circuit, Case No. 24-1606 pitted Ajanta Pharma, Ajanta Pharma USA Inc., Torrent Pharmaceuticals Ltd., and Torrent Pharma, Inc. against Supernus Pharmaceuticals, Inc. The dispute centred on ten US patents — including US8298576B2, US9622983B2, US8663683B2, and seven related grants — all protecting topiramate extended-release capsule formulations sold at 25 mg, 50 mg, 100 mg, and 200 mg dosage strengths. The underlying cause of action was patent infringement, consistent with a standard ANDA (Hatch-Waxman) challenge brought by generic entrants.
The appeal concluded on 5 November 2025 via a voluntary dismissal ordered under Federal Rule of Appellate Procedure 42(b). Critically, the dismissal order states only that the parties ‘having so agreed’ consented to the dismissal, with each side bearing its own costs. The public record is silent on whether the dismissal carries a with-prejudice or without-prejudice designation, meaning the precise preclusive effect on future litigation between these parties cannot be confirmed from the docket alone.
A 589-day lifespan — nearly 20 months — before resolution suggests the parties may have engaged in substantive negotiations during the pendency of the appeal, though the record does not disclose any settlement terms or licensing arrangement. The symmetrical cost allocation, rather than a fee award to either side, is consistent with a negotiated resolution rather than a unilateral capitulation. What drove the parties to agreed dismissal — whether commercial, clinical, or litigation-risk considerations — remains unknown from publicly available information.
Filing to Voluntary dismissal in 589 days
589 days from filing to voluntary dismissal — typical Federal Circuit ANDA appeals resolve in 12–24 months
Voluntarily dismissed: what the agreed order means for both parties
Fed. R. App. P. 42(b): consensual appellate exit
Rule 42(b) allows parties to a Federal Circuit appeal to dismiss by stipulation without a merits ruling. The court issues an order rather than an opinion, meaning no precedential or even persuasive authority is created. The underlying district court record — including any findings on claim construction, validity, or infringement — formally remains intact, though its preclusive weight in future proceedings will depend on the dismissal’s prejudice designation, which the public order does not specify.
No merits ruling issuedWith or without prejudice? The public record is silent
A voluntary dismissal with prejudice bars the dismissed party from re-filing the same claims; one without prejudice leaves that door open. The order in Case 24-1606 does not specify which applies. Practitioners monitoring future ANDA filings by Ajanta or Torrent against Supernus’s topiramate portfolio should therefore treat the prejudice question as unresolved. If a new ANDA notice letter or follow-on suit emerges, it may clarify the agreed terms not visible in the current public docket.
Prejudice designation undisclosedGeneric challengers exit without a validity win — or loss
Ajanta, Torrent, and their affiliates do not emerge from this dismissal with a court ruling invalidating or limiting any of Supernus’s ten topiramate ER patents. Any generic market-entry rights would need to come from a separate regulatory pathway, a future litigation, or an undisclosed commercial arrangement. The agreed cost-split suggests neither party was in a position of obvious legal strength at the appellate stage.
No patent invalidity rulingSupernus’s ten-patent ER portfolio survives the appeal unchallenged
Without a Federal Circuit merits ruling, Supernus’s topiramate extended-release patents remain enforceable on their face. The dismissal does not constitute a judicial endorsement of the patents’ validity, but it equally provides no ammunition for other generic challengers seeking to cite adverse appellate findings. Supernus may continue to assert this portfolio against other ANDA filers, though any undisclosed licensing terms agreed with Ajanta or Torrent could constrain commercial strategy in ways the public record does not reveal.
Portfolio enforceable on faceFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Ajanta Pharma | Individual | Generic pharmaceutical challengers — appellants asserting ANDA rights against Supernus’s topiramate ER patentsSearch in Eureka ↗ |
| Co-Plaintiff | Torrent Pharma, Inc. | Company | Search in Eureka ↗ |
| Co-Plaintiff | Ajanta Pharma USA Inc. | Company | Search in Eureka ↗ |
| Co-Plaintiff | Torrent Pharmaceuticals, Ltd. | Company | Search in Eureka ↗ |
| Defendant | Supernus Pharmaceuticals, Inc. | Company | Supernus Pharmaceuticals, Inc. — branded CNS drug company and holder of ten topiramate ER patentsSearch in Eureka ↗ |
| Defendant counsel | Andrew Wasson | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Anna Naomi Lukacher | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Edgar Haug | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Jonathan Herstoff | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Nicholas F. Giove | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Richard Kurz | Attorney | Counsel for Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant law firm | Haug Partners LLP | Law Firm | Representing Supernus Pharmaceuticals, Inc.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Court of Appeals for the Federal CircuitSearch in Eureka ↗ |
Official order — verbatim text
The dismissal order is deliberately spare: it records mutual consent and a symmetric cost allocation, but issues no opinion on infringement, validity, or claim construction. Under Fed. R. App. P. 42(b), this is a procedural exit — no precedent is set and no merits finding can be inferred. The absence of a prejudice designation in the public order means practitioners cannot reliably determine whether the same claims could be re-litigated. The equal cost split is notable: it suggests neither side extracted a concession significant enough to justify a cost award, and is consistent with a negotiated commercial resolution whose substantive terms, if any, are not reflected in the docket.
US8298576B2 and nine related patents — topiramate extended-release capsule formulations
The ten patents in suit — anchored by US8298576B2 (application 11/941475) and extending through grants including US9622983B2, US8663683B2, US8877248B1, US8889191B2, US10314790B2, US8298580B2, US8992989B2, US9555004B2, and US9549940B2 — collectively protect topiramate extended-release capsule technology across a range of application dates spanning 2007 to 2016. Topiramate is an anticonvulsant and migraine-prophylaxis agent; extended-release formulation technology enables once-daily dosing, a clinically and commercially significant differentiator over immediate-release alternatives. The breadth of the family across multiple application numbers suggests a layered continuation strategy designed to maintain exclusivity across formulation, dosing, and manufacturing dimensions.
For the CNS and epilepsy pharmaceutical sector, a ten-patent estate covering a single drug’s ER formulation represents a substantial exclusivity barrier. Supernus’s Qudexy XR and Trokendi XR products are anchored by this portfolio, and the patents’ staggered expiry dates — a consequence of the multi-year filing spread — extend the effective exclusivity window beyond what a single patent grant would provide. Generic manufacturers seeking ANDA approval for topiramate ER capsules face not only the clinical bioequivalence burden but also a complex Paragraph IV certification challenge spanning an entire patent family, materially raising litigation cost and timeline risk.
Should your topiramate ER product be cleared against US8298576B2 and related patents?
Any pharmaceutical company developing, manufacturing, or seeking ANDA approval for topiramate extended-release capsules in the US market should treat Supernus’s ten-patent portfolio as a primary FTO concern. The patents span formulation composition, dosing methods, and likely manufacturing processes — meaning a freedom-to-operate gap in any one dimension could expose a product to infringement exposure even if alternative formulation approaches are adopted. The Federal Circuit appeal’s non-merits exit means no claim has been judicially narrowed or invalidated, leaving the full scope of each grant intact.
PatSnap Eureka’s FTO Search Agent can map each of the ten asserted patents against your topiramate ER formulation, identify claim-level risk across the family, and surface prior art that may support design-around or IPR petition strategies. Eureka also tracks continuation applications in the Supernus family, so your IP team receives early warning of newly granted claims before they become litigation risks — critical for any generic manufacturer planning a Paragraph IV ANDA filing in this space.
Run a freedom-to-operate analysis on US8298576B2 to assess your product’s exposure
Run FTO in Eureka →Similar Federal Circuit ANDA appeals involving extended-release pharmaceutical patents
Cases at the Federal Circuit involving multi-patent Hatch-Waxman challenges to extended-release CNS drug formulations — comparable in scope and procedural posture to Case 24-1606.
What this case signals for the CNS generic pharmaceutical IP landscape
A ten-patent Federal Circuit appeal resolved by agreed dismissal raises pointed questions about ANDA litigation strategy and topiramate ER market access.
Agreed dismissals without prejudice clarity create docket monitoring obligations
When a Federal Circuit ANDA appeal ends under Rule 42(b) with no prejudice designation disclosed, IP teams at competing generic manufacturers should track both parties’ future ANDA dockets. A subsequent Paragraph IV certification against the same Supernus patents by Ajanta or Torrent would signal the dismissal was without prejudice and that the challenge remains live.
Ten-patent claim stacking in Hatch-Waxman cases raises appeal complexity
Supernus’s portfolio of ten patents covering topiramate ER capsules across overlapping application families creates a high-cost appellate burden for generic challengers. Firms considering ANDA filings against similarly stacked portfolios should model appellate cost and timeline risk early — this case consumed nearly 20 months at the Federal Circuit alone before a non-merits exit.
Pharma v Supernus — key questions answered
The Federal Circuit appeal was voluntarily dismissed on 5 November 2025 under Fed. R. App. P. 42(b) by agreement of all parties. No merits ruling was issued on the ten topiramate extended-release patents at issue. Each side was ordered to bear its own costs. The public order does not specify whether the dismissal was with or without prejudice.
Ten US patents were asserted: US8298576B2, US9622983B2, US8663683B2, US8877248B1, US8889191B2, US10314790B2, US8298580B2, US8992989B2, US9555004B2, and US9549940B2. All relate to topiramate extended-release capsule formulations at 25 mg, 50 mg, 100 mg, and 200 mg dosage strengths — the formulation basis for Supernus’s branded CNS products.
No. A Rule 42(b) voluntary dismissal at the Federal Circuit issues no opinion on validity, infringement, or claim construction. The patents remain enforceable on their face but have not received a judicial endorsement of validity. Other ANDA challengers cannot rely on any adverse merits finding from this case because none was issued.
Under Federal Circuit practice, the default in a dismissed appeal is that costs follow the agreed order. A symmetric cost allocation — rather than awarding costs to the prevailing party — typically signals a negotiated exit where neither side achieved a clear litigation advantage. It is consistent with, though does not confirm, an underlying commercial or licensing arrangement between the parties.
The public dismissal order does not specify a with-prejudice or without-prejudice designation, so the preclusive effect is uncertain from the docket alone. A without-prejudice dismissal would permit re-filing; a with-prejudice one would bar the same claims. Practitioners should monitor FDA ANDA filings and any subsequent Paragraph IV certifications by these entities for signals of the agreed terms not visible in the court record.
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