Salix v. Norwich & Alvogen: Xifaxan® Patent Suit Transferred to Camden Division
Salix Pharmaceuticals and Bausch Health Ireland sued Norwich Pharmaceuticals and Alvogen entities over two rifaximin patents covering Xifaxan® 200 mg and 550 mg tablets, including the IBS-D indication. Filed in New Jersey District Court, the case was transferred to the Camden Division within 145 days, reassigned as 1:24-cv-7140.
Xifaxan® Rifaximin Patents Draw ANDA Challenge From Generics Duo
On June 20, 2024, Salix Pharmaceuticals, Inc., Salix Pharmaceuticals, Ltd., and Bausch Health Ireland, Ltd. filed a patent infringement action in the District of New Jersey against Norwich Pharmaceuticals, Inc. and multiple Alvogen entities. The suit asserts US11779571B2 and US11564912B2 — two patents covering rifaximin tablet formulations — in connection with Xifaxan® 200 mg and Xifaxan® 550 mg tablets, the latter indicated for treatment of irritable bowel syndrome with diarrhea in adults.
The case closed procedurally on November 12, 2024, when it was transferred to the Camden Division of the District of New Jersey and assigned a new case number: 1:24-cv-7140. A transfer of this nature does not constitute a merits ruling; no verdict, judgment, or consent order was entered in the originating docket. The underlying infringement claims remain live and are expected to proceed before a Camden-based judge.
The 145-day period before transfer is consistent with routine administrative reassignment within the District of New Jersey, which periodically redistributes cases across its Trenton and Camden vicinages. The public record for this docket is silent on any substantive claim construction, motion practice, or settlement discussions, leaving the ultimate outcome of the rifaximin patent dispute unresolved at this stage.
Filing to Case Transferred in 145 days
145 days from filing to transfer — procedural close before any merits ruling
What the transfer to Camden Division means for both parties
Intra-district transfer: same court, new vicinage
A transfer to the Camden Division reassigns the case within the District of New Jersey — the same federal district, but a different courthouse and judge. The originating Trenton docket (3:24-cv-07140) is administratively closed; all future proceedings occur under 1:24-cv-7140. No merits determination is made, and all pleadings, claims, and defences carry over in full. This is distinct from a transfer to a different district under 28 U.S.C. § 1404.
Procedural reassignmentSalix’s infringement claims survive intact
The transfer does not prejudice the plaintiffs’ position. Both rifaximin patents — US11779571B2 and US11564912B2 — remain asserted, and Salix retains the benefit of any Hatch-Waxman 30-month stay that attached at filing. The Camden vicinage is equally competent to adjudicate ANDA-related pharmaceutical infringement, and Salix’s litigation timeline is unlikely to be materially disrupted by the reassignment.
Claims remain liveNorwich and Alvogen face continued litigation in Camden
For Norwich Pharmaceuticals and the Alvogen entities, the transfer means the case proceeds before a different judge in the Camden courthouse, but the underlying invalidity and non-infringement defences are unaffected. Any prior motions or scheduling orders may be revisited by the incoming judge. Generic market entry for the rifaximin products at issue remains blocked pending resolution of the Hatch-Waxman patent dispute.
Defence posture unchangedXifaxan® exclusivity clock keeps ticking during transfer
Xifaxan® 550 mg is a high-revenue branded product for Bausch Health. Every month of continued litigation — including procedural steps like this transfer — extends the period before generic entry. Competitor manufacturers watching this docket should note that the Camden docket now governs timing, and any FTO or monitoring strategy must be updated to track 1:24-cv-7140 rather than the Trenton docket.
Monitor Camden docketFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Salix Pharmaceuticals, Inc. | Company | Pharmaceutical IP licensor — holder of US11779571B2 and US11564912B2 covering rifaximinSearch in Eureka ↗ |
| Co-Plaintiff | Salix Pharmaceuticals, Ltd. | Company | Search in Eureka ↗ |
| Co-Plaintiff | Bausch Health Ireland, Ltd. | Company | Search in Eureka ↗ |
| Defendant | NORWICH PHARMACEUTICALS, Inc. | Company | Generic drug manufacturer (Norwich) and Alvogen Group entities seeking ANDA approvalSearch in Eureka ↗ |
| Co-Defendant | Alvogen Group, Inc. | Company | Search in Eureka ↗ |
| Co-Defendant | Alvogen, Inc. | Company | Search in Eureka ↗ |
| Co-Defendant | Alvogen Pb Research & Development, LLC | Company | Search in Eureka ↗ |
| Plaintiff counsel | Harvey Bartle , IV | Attorney | Counsel for Salix Pharmaceuticals, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Morgan, Lewis & Bockius, LLP | Law Firm | Representing Salix Pharmaceuticals, Inc.Search in Eureka ↗ |
| Defendant counsel | Arnold B. Calmann | Attorney | Counsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗ |
| Defendant counsel | Katherine Ann Escanlar | Attorney | Counsel for NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗ |
| Defendant law firm | Saiber LLC | Law Firm | Representing NORWICH PHARMACEUTICALS, Inc.Search in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | New Jersey District CourtSearch in Eureka ↗ |
Official order — verbatim text
The transfer order is purely administrative: ‘Case transferred to Camden Division on 11/12/24. New Case Number 1:24-cv-7140.’ No infringement finding, validity ruling, or damages assessment was made on this docket. Both rifaximin patents remain in active dispute. Practitioners should update all monitoring, deadline calendaring, and court-filing alerts to reflect the Camden docket number and the incoming judge’s individual procedures.
US11779571B2 & US11564912B2 — Rifaximin Formulations for IBS-D
US11779571B2 and US11564912B2 are US utility patents protecting rifaximin-based tablet formulations, including the 200 mg and 550 mg dosage forms commercialised as Xifaxan®. The 550 mg formulation carries FDA approval for treatment of irritable bowel syndrome with diarrhea in adults — a large and commercially valuable indication. Both patents derive from application numbers in the US17/xxxxxxx series, suggesting prosecution timelines consistent with lifecycle management filings rather than first-generation composition patents.
Xifaxan® is among the most commercially significant branded GI drugs in the US market. Asserting two distinct patents against a generics manufacturer and a major generic group signals that Salix and Bausch Health view these patents as enforceable barriers to entry. Competitors developing rifaximin generics, reformulations, or biosimilar-adjacent GI antibiotics should treat both patents as active blocking IP and conduct thorough FTO analysis before committing to regulatory or commercial timelines.
Should your team run an FTO against US11779571B2 and US11564912B2?
Any company developing, manufacturing, or seeking ANDA/NDA approval for a rifaximin-containing product — particularly in 200 mg or 550 mg tablet form for GI indications — should treat these two patents as live blocking IP. The ongoing litigation against Norwich and Alvogen confirms that the patent holders are actively enforcing. In-house IP and regulatory teams at generic manufacturers, contract development organisations, and branded GI drug developers should assess whether their product designs, formulations, or use claims fall within the scope of either patent.
PatSnap Eureka’s FTO Search Agent enables R&D and IP teams to map claim scope for US11779571B2 and US11564912B2, identify relevant prior art that could support design-around or challenge strategies, and surface related Salix and Bausch Health filings in the rifaximin space. Automated docket monitoring on the Camden proceeding (1:24-cv-7140) ensures your team is alerted to any claim construction orders, expert reports, or consent judgments that materially affect the FTO landscape.
Run a freedom-to-operate analysis on US11779571B2 to assess your product’s exposure
Run FTO in Eureka →Similar Hatch-Waxman Rifaximin & GI Drug Patent Cases in D.N.J.
Cases below involve Hatch-Waxman pharmaceutical patent enforcement in the District of New Jersey, focusing on rifaximin and branded GI drug formulation disputes.
What this case signals for the rifaximin and branded GI drug IP landscape
Hatch-Waxman suits over blockbuster GI drugs draw sustained enforcement — this transfer extends Salix’s litigation timeline.
Two late-stage rifaximin patents signal continued Xifaxan® enforcement
Asserting US11779571B2 and US11564912B2 — both with application dates suggesting later-generation claim strategies — indicates Salix and Bausch Health are actively layering protection around Xifaxan®. Generic entrants should expect additional patent filings and litigation waves, consistent with a typical pharmaceutical ‘patent thicket’ defence around a high-value branded product.
Multiple Alvogen entities named: enforcement risk extends across the group
Naming Alvogen Group, Inc., Alvogen, Inc., and Alvogen PB Research & Development, LLC as co-defendants suggests the plaintiffs are seeking to capture all corporate entities potentially involved in ANDA preparation or commercialisation. Companies in complex generic holding structures should ensure IP risk assessment covers affiliated entities, not just the ANDA filer of record.
Salix v NORWICH — key questions answered
The transfer is an administrative reassignment within the District of New Jersey. The case moves from the Trenton vicinage (docket 3:24-cv-07140) to the Camden vicinage (1:24-cv-7140). All claims, defences, and any Hatch-Waxman stay provisions carry over. No merits ruling was made on the Trenton docket.
Two patents are asserted: US11779571B2 and US11564912B2. Both cover rifaximin-based formulations and are tied to Xifaxan® 200 mg and 550 mg tablets. The 550 mg product carries FDA approval for treatment of IBS-D in adults, making it the higher-value commercial asset at issue.
The transfer does not affect any Hatch-Waxman 30-month stay that attached at the time of filing in June 2024. If a stay is in effect, it would provisionally expire around late 2026 unless modified by court order. Parties and third-party monitors should track the Camden docket for any orders affecting the stay.
Salix named Alvogen Group, Inc., Alvogen, Inc., and Alvogen PB Research & Development, LLC alongside Norwich Pharmaceuticals to capture all corporate affiliates potentially involved in ANDA preparation, development, or future commercialisation. This is a common plaintiff strategy in Hatch-Waxman litigation to prevent any single entity from disclaiming liability based on corporate structure.
Following the November 12, 2024 transfer, the case was reassigned to the Camden Division of the District of New Jersey under case number 1:24-cv-7140. All future filings, scheduling orders, and substantive proceedings will occur under this new docket number.
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