Par Pharmaceutical v. Mankind Pharma: Varenicline Patent Suit Dismissed Without Prejudice
Par Pharmaceutical and Endo Par Innovation sued Indian generic manufacturer Mankind Pharma in the Eastern District of Texas, asserting US11717524B1 over generic varenicline tartrate tablets in 0.5 mg and 1 mg strengths. After 466 days of litigation, the parties jointly stipulated to dismiss all claims without prejudice — each side bearing its own costs.
ANDA Battleground: Varenicline Tablet Patent Ends in No-Merits Exit
On 1 September 2023, Par Pharmaceutical, Inc. and Endo Par Innovation Company, LLC (collectively, Plaintiffs) filed a patent infringement action in the U.S. District Court for the Eastern District of Texas against Mankind Pharma, Ltd., an Indian generic drug manufacturer. The suit centred on US11717524B1, a patent covering varenicline tartrate tablet formulations in 0.5 mg and 1 mg dosage strengths — the same strengths at issue in Mankind’s ANDA filing for a generic version of the smoking-cessation therapy.
On 10 December 2024 — 466 days after filing — the parties filed a Joint Stipulation of Dismissal Without Prejudice, which the court accepted. The court dismissed all claims, counterclaims, and affirmative defences without prejudice and without costs, disbursements, or attorneys’ fees to any party. Critically, the order also noted that while this member case was closed, the lead case was directed to remain open, suggesting broader multi-defendant ANDA litigation continues in parallel.
The timeline of 466 days — covering claim construction and early merits proceedings but stopping short of trial — is consistent with ANDA litigation that resolves following paragraph IV certification negotiations or underlying commercial agreements, though the public record is silent on any licensing or settlement terms. The without-prejudice posture means Par and Endo Par retain the legal right to re-file against Mankind should circumstances change, preserving optionality for the patent holder.
Filing to Dismissed with Prejudice in 466 days
466 days — longer than the median ANDA patent case resolution in E.D. Texas
Dismissed without prejudice: what the joint stipulation means for both parties
Without prejudice means the door stays open
A dismissal without prejudice under Fed. R. Civ. P. 41 terminates the current action but does not adjudicate the underlying patent claims on the merits. Par and Endo Par retain the right to re-file suit against Mankind Pharma on US11717524B1 if commercial or regulatory circumstances change. No claim preclusion or issue preclusion attaches to the dismissed claims.
No merits adjudicationPlaintiffs preserve enforcement rights and patent validity
Because the case was dismissed without prejudice, US11717524B1 remains uncontested on its merits in this proceeding. Par and Endo Par retain full enforcement rights and the patent’s validity was never put at risk by a court ruling. The no-costs provision is neutral — plaintiffs gave up nothing on the merits but absorbed their own litigation costs over 466 days.
Patent validity intactMankind avoids an adverse ruling but faces latent re-filing risk
Mankind Pharma secured dismissal of all claims against it, including counterclaims and affirmative defences, without a court finding on invalidity or non-infringement. While this clears the immediate litigation hurdle, Mankind cannot rely on the dismissal as a defence in any future re-filed suit. The without-prejudice posture means its ANDA pathway may still face patent challenge if it moves toward commercial launch.
Re-filing risk remainsLead case still open — broader ANDA litigation landscape unresolved
The court’s order explicitly directed the lead case to remain open, indicating Par and Endo Par are likely pursuing parallel ANDA litigation against other generic filers for the same varenicline formulation. Generic competitors and brand-side stakeholders should monitor the lead case docket for claim construction rulings or trial dates that could set precedent affecting all generic challengers in the varenicline space.
Lead case still activeFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Par Pharmaceutical, Inc. | Company | Specialty pharmaceutical companies — holders of US11717524B1 covering varenicline tartrate tabletsSearch in Eureka ↗ |
| Co-Plaintiff | Endo Par Innovation Company, LLC | Company | Search in Eureka ↗ |
| Defendant | Mankind Pharma, Ltd. | Company | Mankind Pharma, Ltd. — Indian generic pharmaceutical manufacturer seeking U.S. market entry via ANDASearch in Eureka ↗ |
| Plaintiff counsel | Andrea Leigh Fair | Attorney | Counsel for Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Jonathan Loeb | Attorney | Counsel for Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Luke M. Reilly | Attorney | Counsel for Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Martin Jay Black | Attorney | Counsel for Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Robert D. Rhoad | Attorney | Counsel for Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Shyam Shanker | Attorney | Counsel for Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Dechert LLP | Law Firm | Representing Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Dechert, LLP (New Jersey) | Law Firm | Representing Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Dechert LLP (Philadelphia) | Law Firm | Representing Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Miller Fair Henry PLLC | Law Firm | Representing Par Pharmaceutical, Inc.Search in Eureka ↗ |
| Defendant counsel | George C. Lombardi | Attorney | Counsel for Mankind Pharma, Ltd.Search in Eureka ↗ |
| Defendant counsel | Maureen L. Rurka | Attorney | Counsel for Mankind Pharma, Ltd.Search in Eureka ↗ |
| Defendant counsel | Michael Brett Johnson | Attorney | Counsel for Mankind Pharma, Ltd.Search in Eureka ↗ |
| Defendant counsel | Rex Andrew Mann | Attorney | Counsel for Mankind Pharma, Ltd.Search in Eureka ↗ |
| Defendant counsel | Samantha M. Lerner | Attorney | Counsel for Mankind Pharma, Ltd.Search in Eureka ↗ |
| Defendant law firm | Winston Strawn LLP (Chicago) | Law Firm | Representing Mankind Pharma, Ltd.Search in Eureka ↗ |
| Defendant law firm | Winston Strawn LLP (Dallas) | Law Firm | Representing Mankind Pharma, Ltd.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Texas Eastern District CourtSearch in Eureka ↗ |
Official order — verbatim text
The court’s order accepting the joint stipulation is strictly procedural — it reflects no finding on patent validity, claim scope, or infringement of US11717524B1. Notably, the order distinguishes between the member case (closed) and the lead case (kept open), confirming this is one docket within a broader multi-defendant ANDA proceeding. The without-prejudice language means neither collateral estoppel nor res judicata bars future claims by Par or Endo Par against Mankind on this patent.
US11717524B1 — Varenicline Tartrate Tablet Formulations (0.5 mg and 1 mg)
US11717524B1 (application number US17/930824) is a U.S. patent protecting varenicline tartrate tablet formulations, specifically in the 0.5 mg and 1 mg dosage strengths that are clinically established for smoking-cessation therapy. Varenicline — originally marketed as Chantix — is a partial nicotinic receptor agonist; the patent likely covers formulation-specific aspects such as composition, salt form, or manufacturing process at these commercially critical dosage levels. The patent’s grant timing and application number suggest it was filed and prosecuted in close proximity to ANDA activity by generic competitors.
For the branded pharmaceutical sector, US11717524B1 represents a formulation-level barrier that generic ANDA filers must navigate or invalidate before launching a competing product. Given that varenicline tartrate at these dosage strengths is a high-volume, commercially significant product, the patent carries substantial market exclusivity value. Any competitor seeking to enter the market must conduct a thorough freedom-to-operate analysis against this patent, as the ongoing lead case suggests Par and Endo Par are actively asserting it against multiple generic challengers simultaneously.
Should you run an FTO against US11717524B1 before filing your varenicline ANDA?
Any generic pharmaceutical company or CMO developing varenicline tartrate tablets in 0.5 mg or 1 mg dosage strengths should treat US11717524B1 as a primary FTO target. The patent remains valid and enforceable; this case’s dismissal without prejudice signals no weakness in the patent’s legal standing. With the lead case still active in E.D. Texas, the risk of an immediate patent infringement suit following ANDA paragraph IV certification filing is materially elevated.
PatSnap Eureka’s FTO Search Agent enables R&D and regulatory teams to map US11717524B1’s claim scope against your proposed formulation, identify design-around opportunities, and benchmark against prior art cited during prosecution. Eureka can also surface the full family of related Par and Endo Par pharmaceutical patents to identify any continuation or divisional filings that might independently cover your target product — critical intelligence before any ANDA filing decision.
Run a freedom-to-operate analysis on US11717524B1 to assess your product’s exposure
Run FTO in Eureka →Similar ANDA Patent Infringement Cases in E.D. Texas: Varenicline & Pharma Formulations
Cases involving ANDA pharmaceutical formulation patents litigated in the Eastern District of Texas, with comparable without-prejudice dismissal outcomes.
What this case signals for the ANDA pharmaceutical IP landscape
Pre-trial dismissals in ANDA suits often reflect commercial resolution. This case offers several signals for generic drug IP strategy.
Without-prejudice exits preserve brand-side leverage in ANDA disputes
When branded pharma plaintiffs exit without prejudice, they retain the ability to re-litigate if a generic manufacturer proceeds toward launch. This posture is frequently used to lock in a negotiated entry date while maintaining the threat of re-filing — a standard tool in Hatch-Waxman litigation strategy.
The open lead case is the real battleground to watch
The Eastern District of Texas court’s instruction to keep the lead case open signals additional defendants remain in the varenicline ANDA litigation. Any claim construction order or trial outcome in the lead case will likely govern the commercial fate of all generic challengers, including those already dismissed without prejudice.
Par v Mankind — key questions answered
The case was dismissed without prejudice by joint stipulation on 10 December 2024, after 466 days of litigation. The court accepted the parties’ joint stipulation dismissing all claims, counterclaims, and affirmative defences, with each party bearing its own costs. No merits ruling was issued on patent validity or infringement of US11717524B1.
The patent in suit was US11717524B1 (application number US17/930824), covering varenicline tartrate tablet formulations in 0.5 mg and 1 mg dosage strengths — the same strengths Mankind Pharma sought to commercialise through its ANDA filing for a generic smoking-cessation product.
A without-prejudice dismissal means Par Pharmaceutical and Endo Par Innovation retain the right to re-file suit against Mankind Pharma on US11717524B1 in the future. No court ruling on patent validity, infringement, or claim scope was made, so no preclusion attaches. The patent remains fully enforceable against Mankind if it proceeds toward commercial launch.
The E.D. Texas court’s order directed the lead case to remain open because additional parties remain as defendants. This dismissal affected only the member case specific to Mankind Pharma. The broader ANDA litigation by Par and Endo Par against other generic challengers for varenicline tartrate tablets continues in the lead case docket.
Plaintiffs Par Pharmaceutical and Endo Par Innovation were represented by Dechert LLP (with offices in New Jersey and Philadelphia involved) and Miller Fair Henry PLLC as local counsel. Defendant Mankind Pharma was represented by Winston Strawn LLP, with attorneys from both the Chicago and Dallas offices on the matter.
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