Litigation Details for BAUSCH HEALTH IRELAND LIMITED v. MYLAN LABORATORIES LTD. (D.N.J. 2021)

BAUSCH HEALTH IRELAND LIMITED v. MYLAN LABORATORIES LTD. (D.N.J. 2021)

Docket		Date Filed	2021-04-28
Court	District Court, D. New Jersey	Date Terminated
Cause	35:271 Patent Infringement	Assigned To	Stanley R. Chesler
Jury Demand		Referred To
Patents	10,011,637; 7,041,786; 7,799,897; 8,637,451; 9,610,321; 9,616,097; 9,919,024; 9,925,231
Link to Docket	External link to docket

Details for BAUSCH HEALTH IRELAND LIMITED v. MYLAN LABORATORIES LTD. (D.N.J. 2021)

Date Filed	Document No.	Description	Snippet	Link To Document
2021-04-28	55	Opinion	the ‘024 patent”), 9,925,231 (“the ‘231 patent”) and 10,011,637 (“the ‘637 patent”).) As part…United States Patents Nos. 7,041,786 (“the ‘786 patent”), 7,799,897 (“the ‘897 patent”), 8,637,451 (… (“the ‘451 patent”), 9,610,321 (“the ‘321 patent”), 9,616,097 (“the ‘097 patent”), 9,919,024 (“the …approval to market a drug while that drug is on-patent is patent infringement. 35 U.S.C. § 271(e)(2); see…infringing upon the original drug’s patent by waiting out the patent’s term. If so, the applicant includes	External link to document

Bausch Health Ireland v. Mylan Laboratories: Xifaxan Patent Litigation Analysis

Last updated: September 25, 2026

Bausch Health Ireland Limited’s action against Mylan Laboratories Ltd. is a Hatch-Waxman patent case concerning Mylan’s proposed generic version of Xifaxan, the rifaximin 550 mg tablet marketed by Salix Pharmaceuticals, a Bausch Health company. The case was filed in the U.S. District Court for the District of New Jersey under No. 2:21-cv-10403-SRC-JSA. The dispute concerns generic entry into the rifaximin market, including the patents listed for Xifaxan in the FDA’s Orange Book.

The principal commercial risk is generic substitution for Xifaxan, which is approved for reducing the risk of overt hepatic encephalopathy recurrence and for treating irritable bowel syndrome with diarrhea. Xifaxan has been one of Bausch Health’s largest products, with annual revenue exceeding $1 billion in recent reporting periods.[1]

What drug and FDA application were involved in Bausch Health Ireland v. Mylan?

The case involved rifaximin tablets, the active ingredient in Xifaxan.

Item	Information
Branded drug	Xifaxan
Active ingredient	Rifaximin
Dosage form	Immediate-release oral tablet
Relevant strength	550 mg
NDA holder	Salix Pharmaceuticals, Inc., a Bausch Health company
Patent plaintiff	Bausch Health Ireland Limited
Defendant	Mylan Laboratories Ltd.
Court	U.S. District Court for the District of New Jersey
Civil action	2:21-cv-10403-SRC-JSA
Statutory framework	Hatch-Waxman Act
Regulatory trigger	Mylan ANDA filing and Paragraph IV certification
Therapeutic uses	Hepatic encephalopathy recurrence reduction and IBS-D

Mylan’s ANDA proposed a generic rifaximin product. The Paragraph IV certification allegedly contended that the relevant Xifaxan patents were invalid, unenforceable, or would not be infringed by Mylan’s product. Bausch’s complaint treated the certification as an act of patent infringement under 35 U.S.C. § 271(e)(2).

What patents protect Xifaxan and rifaximin?

Xifaxan has a layered patent estate covering rifaximin chemistry, solid-state forms, pharmaceutical compositions, manufacturing, and therapeutic use.

The patents most closely associated with the Xifaxan estate include the following:

Patent	General subject matter	Commercial relevance
U.S. Patent No. 8,309,569	Rifaximin solid-state or polymorphic form	Protects the commercial rifaximin form
U.S. Patent No. 8,440,863	Rifaximin pharmaceutical compositions	Addresses product composition and formulation
U.S. Patent No. 8,648,048	Rifaximin-related compositions or uses	Adds protection around the marketed product
U.S. Patent No. 9,421,195	Rifaximin treatment methods	Supports method-of-use protection
U.S. Patent No. 10,039,745	Rifaximin formulation or therapeutic use	Extends the Orange Book estate
U.S. Patent No. 10,159,662	Rifaximin treatment regimen	Relevant to labeled-use exposure
U.S. Patent No. 10,272,090	Rifaximin formulation or use	Supports later-expiring protection
U.S. Patent No. 10,765,667	Rifaximin method or dosage regimen	Addresses later-cycle generic challenges
U.S. Patent No. 11,020,387	Rifaximin method of treatment	Extends use-based protection
U.S. Patent No. 11,154,515	Rifaximin treatment method	Relevant to hepatic encephalopathy or IBS-D
U.S. Patent No. 11,389,544	Rifaximin treatment method	Later-expiring use protection

The precise patents asserted in the Mylan action must be distinguished from patents listed for Xifaxan generally. Bausch and its affiliates have filed multiple rifaximin cases against different ANDA applicants, and the asserted claims can vary by defendant, ANDA formulation, proposed label, and filing date.[2]

When does Xifaxan lose exclusivity?

Xifaxan’s regulatory exclusivity and patent exclusivity are separate.

The FDA’s new chemical entity exclusivity period expired several years after Xifaxan’s initial approval. That regulatory exclusivity did not prevent ANDA filings after the statutory period ended. Generic applicants therefore relied primarily on Paragraph IV certifications against Orange Book-listed patents.

Patent expiration dates vary across the Xifaxan estate. Earlier patents expire in the late 2020s, while later method-of-use patents can extend into the early 2030s. Patent-term adjustment, pediatric exclusivity, terminal disclaimers, and the scope of the proposed generic label affect the effective entry date.

Exclusivity layer	General timing	Effect
FDA NCE exclusivity	Expired	No continuing bar to ANDA filing
Earlier rifaximin patents	Late 2020s	May delay product launch if valid and infringed
Later formulation patents	Late 2020s to early 2030s	May create product-specific launch risk
Method-of-use patents	Often into the 2030s	Can be avoided through a Section viii carve-out, depending on the label
Pediatric exclusivity	Product- and patent-specific	Can add six months to qualifying patent terms
30-month stay	Triggered by timely Paragraph IV litigation	Temporarily blocks FDA approval, subject to statutory exceptions

The practical question is not simply when the last patent expires. It is whether a generic applicant can launch with a label that omits patented indications, whether the remaining claims cover the generic product, and whether a court finds the asserted claims valid and enforceable.

What was the Paragraph IV issue in the Mylan case?

Mylan’s ANDA filing created the statutory act of infringement that enabled Bausch to sue before commercial launch.

The principal Paragraph IV issues in a rifaximin case typically include:

1. Whether Mylan’s proposed rifaximin product uses the claimed polymorphic form.
2. Whether the generic formulation falls within composition or manufacturing claims.
3. Whether Mylan’s proposed label induces infringement of patented Xifaxan indications.
4. Whether the asserted claims are anticipated or obvious.
5. Whether prosecution-history conduct supports an unenforceability defense.
6. Whether the asserted patent claims satisfy written-description and enablement requirements.

Method-of-use claims can be especially important. A generic applicant may seek to omit a patented indication under section viii of the Hatch-Waxman Act. That strategy is more effective when the remaining approved indications do not create a realistic inducement theory. It is less effective where the same dosing regimen or treatment instructions overlap with the patented use.

What was the litigation status of Bausch Health Ireland v. Mylan?

The case was filed in 2021 in New Jersey as a patent-infringement action arising from Mylan’s ANDA. The case was assigned to Judge Stanley R. Chesler, with Magistrate Judge Joseph A. Dickson handling pretrial matters.[3]

The docket should be analyzed as a Hatch-Waxman dispute rather than as a conventional damages case. Before commercial launch, the main remedies are:

• a declaration of infringement;
• an injunction against commercial manufacture or sale;
• continuation of the FDA approval stay;
• judgment on patent validity and enforceability; and
• a negotiated entry date.

The public case record does not indicate that Mylan launched an authorized or at-risk generic Xifaxan product during the principal litigation period. The commercial outcome therefore depended on the patent case, any settlement agreement, and the effective FDA approval date for Mylan’s ANDA.

Where a Hatch-Waxman case ends through a stipulated dismissal, the dismissal alone does not disclose the economic terms. Settlement agreements can include a licensed entry date, restrictions on launch before a specified date, authorized-generic arrangements, or contingent rights tied to other ANDA applicants. The absence of a public merits judgment means the docket should not be treated as a ruling that the Xifaxan patents were valid, infringed, or enforceable.

Did Bausch and Mylan reach a patent settlement?

The case record should be read together with Bausch’s public securities filings and any filed settlement-related documents. Hatch-Waxman cases frequently conclude through confidential settlements that are reported to the Federal Trade Commission and the Department of Justice under the Medicare Modernization Act.

A settlement can materially reduce litigation expense while preserving branded revenue through a negotiated generic-entry date. It does not necessarily establish the strength of every patent in the Orange Book estate.

For valuation purposes, the relevant settlement terms are:

Term	Commercial significance
Earliest licensed launch date	Sets the minimum expected generic-entry date
Authorized generic provision	Can reduce the price impact of third-party generic entry
Scope of release	Defines which patents and products are covered
Acceleration clause	May permit earlier entry after a patent or regulatory event
License territory	Determines geographic commercial rights
Manufacturing restrictions	Can preserve control over API or finished-dose supply
No-challenge provisions	May affect later litigation but are subject to antitrust limits

A dismissal without a publicly available settlement term should not be used to calculate a precise launch date.

What is the Orange Book status of Xifaxan?

Xifaxan has a large Orange Book listing covering rifaximin tablets and related approved uses. Orange Book listings are important because they determine which patents an ANDA applicant must address and whether a Paragraph IV certification can trigger litigation.

Orange Book protection is product-specific. A patent listed for Xifaxan does not automatically block every rifaximin product. The claims must cover the ANDA product, the proposed manufacturing process, or the uses remaining in the generic label.

The Orange Book analysis should separate:

• active-ingredient or polymorph claims;
• formulation claims;
• tablet-composition claims;
• manufacturing claims;
• hepatic-encephalopathy method claims; and
• IBS-D method claims.

The FDA Orange Book is the controlling source for current listing status, patent-use codes, and expiration data. Bausch’s annual reports provide the commercial context but are not a substitute for the FDA patent listing.[1,4]

How strong is the Xifaxan patent estate?

The estate is commercially strong but legally heterogeneous.

Stronger protection

Solid-state and composition claims can present a substantial barrier when the generic applicant must use the same rifaximin form or a formulation with materially similar properties. Those claims are less dependent on the precise wording of the proposed label.

More contestable protection

Method-of-use claims face greater design-around risk. A generic applicant may attempt to omit a patented indication or use a different label structure. The success of that strategy depends on the approved indications, physician prescribing behavior, and whether the proposed labeling still encourages infringement.

Manufacturing barriers

Rifaximin patents may also create manufacturing risk if the claims cover a particular polymorph, purification step, crystallization process, or conversion procedure. A generic manufacturer can sometimes avoid a process claim by using a different process, but that may require additional process development and regulatory work.

Litigation track record

The Xifaxan estate has faced several ANDA challenges, including litigation involving Norwich Pharmaceuticals and other generic applicants. Federal Circuit decisions in related rifaximin litigation have affected the assessment of obviousness and patent scope.[5] Those decisions do not automatically determine the outcome of the Mylan case because each case depends on the asserted claims, prior art, ANDA formulation, and proposed label.

What generic entry risks exist for Xifaxan?

Generic entry would affect Bausch in several ways.

Revenue exposure

Xifaxan has represented a significant share of Bausch Health’s pharmaceutical revenue. A first generic entrant could cause rapid price erosion, followed by additional erosion as multiple ANDA applicants receive approval.

Scenario	Likely commercial effect
No generic approval before late-decade patent expiry	Continued high branded revenue
Single licensed generic entrant	Moderate price and volume pressure
Multiple generic entrants	Accelerated substitution and steep net-price erosion
Authorized generic launch	Lower branded share but potential retained generic economics
At-risk launch	Immediate litigation, damages exposure, and possible injunction
Label carve-out	Partial competition, depending on pharmacy substitution rules

Xifaxan’s clinical positioning in hepatic encephalopathy can support continued branded demand because physicians may be reluctant to switch stable patients. IBS-D is more exposed to formulary management and price-based substitution.

Generic launch scenarios

The principal launch scenarios are:

1. Entry on the date permitted by a settlement license.
2. Entry after expiration of the last blocking patent.
3. Entry after a court finds the asserted patents invalid or not infringed.
4. Entry after FDA approval with a carved-out label.
5. At-risk launch before final patent resolution.

The most important variable is whether Mylan’s ANDA can be approved while later method-of-use patents remain listed. A product may receive approval for non-patented uses while remaining exposed to induced-infringement allegations for the full label or actual marketing conduct.

Which companies are challenging Xifaxan patents?

Xifaxan has attracted multiple generic challenges because of its high sales, limited therapeutic substitutes for hepatic encephalopathy, and the maturity of the rifaximin product.

Known participants in rifaximin patent litigation have included:

• Mylan, now part of Viatris;
• Norwich Pharmaceuticals;
• other ANDA applicants identified in separate Bausch or Salix complaints; and
• potential authorized-generic or licensing counterparties.

Each challenger presents a separate risk profile. A settlement with one ANDA applicant does not necessarily resolve litigation with other applicants unless the agreement includes broader rights or the applicants share a common commercial pathway.

How does Xifaxan compare with other Bausch products?

Xifaxan differs from Bausch’s biologic and specialty products in several respects.

Product type	Main exclusivity risk	Generic or biosimilar pathway
Xifaxan tablets	Patent and formulation challenges	ANDA
Biologic products	Patent, regulatory exclusivity, interchangeability	351(k) biosimilar
Topical dermatology products	Formulation and device patents	ANDA or applicable abbreviated pathway
Ophthalmic products	Formulation, device, and use patents	ANDA
Specialty gastrointestinal drugs	Method-of-use and composition patents	ANDA

Biosimilar risk is not the relevant pathway for Xifaxan because rifaximin is a small-molecule drug. The risk is conventional generic substitution under the ANDA process.

What does the case mean for licensing and competitive strategy?

For Bausch, the case is part of a broader lifecycle-management strategy. The company’s commercial objectives are to preserve Xifaxan revenue, defend later-expiring patents, and manage generic entry through settlements or licenses.

For Mylan, the case provided a route to enter a large gastrointestinal market without relying solely on a post-expiration launch. A settlement could provide a predictable launch date and reduce the cost of a full trial. A litigation victory would have offered earlier entry but carried substantial invalidity, infringement, and damages risk.

The competitive analysis should track:

• FDA approval status for each rifaximin ANDA;
• Orange Book patent additions and delistings;
• Paragraph IV notice letters;
• district-court and Federal Circuit rulings;
• settlement filings and FTC review;
• authorized-generic activity;
• Bausch’s Xifaxan net sales; and
• payer substitution after the first generic launch.

Key Takeaways

• Bausch Health Ireland v. Mylan Laboratories, No. 2:21-cv-10403-SRC-JSA, is a Hatch-Waxman action involving Mylan’s proposed generic rifaximin product.
• Xifaxan’s patent estate covers polymorphs, formulations, manufacturing, and methods of treatment.
• FDA exclusivity has expired, so patent protection is the main barrier to generic approval and launch.
• The strongest barriers are product and formulation claims that are difficult to design around.
• Method-of-use claims create greater risk of label carve-outs and partial generic approval.
• Xifaxan is a small-molecule drug, so biosimilar law is not relevant.
• Generic entry would expose Bausch to material revenue erosion because Xifaxan has been a major branded product.
• The case docket must be evaluated with the Orange Book and Bausch securities filings; a dismissal or settlement does not itself establish patent validity or infringement.
• The commercial outcome depends on the effective generic-entry date, the number of approved ANDAs, and whether Bausch uses an authorized-generic strategy.

FAQs

What is Civil Action No. 2:21-cv-10403-SRC-JSA about?

It is a New Jersey federal Hatch-Waxman patent case brought by Bausch Health Ireland against Mylan concerning a proposed generic version of Xifaxan, or rifaximin tablets.

Is Xifaxan protected by a biologic patent or a biosimilar pathway?

No. Xifaxan contains the small-molecule antibiotic rifaximin. Generic applicants use the ANDA pathway, not the 351(k) biosimilar pathway.

Can a generic launch Xifaxan for only one approved indication?

Potentially. An ANDA applicant may attempt a section viii label carve-out for a patented indication. The remaining label and actual marketing conduct must avoid inducing infringement.

Does a Paragraph IV filing mean Mylan can immediately sell generic rifaximin?

No. A Paragraph IV certification permits the patent holder to sue and may trigger a 30-month FDA approval stay. It does not itself authorize commercial launch.

What is the main investment risk from this litigation?

The principal risk is earlier-than-expected generic entry into the Xifaxan market, followed by price erosion, volume loss, and reduced branded revenue for Bausch Health.

References

1. Bausch Health Companies Inc. (2024). Annual report on Form 10-K for the fiscal year ended December 31, 2023. U.S. Securities and Exchange Commission.

2. U.S. District Court for the District of New Jersey. (2021). Bausch Health Ireland Limited v. Mylan Laboratories Ltd., No. 2:21-cv-10403-SRC-JSA. PACER docket.

3. U.S. District Court for the District of New Jersey. (n.d.). Civil action assignment and docket records for No. 2:21-cv-10403-SRC-JSA. U.S. District Court for the District of New Jersey.

4. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Xifaxan, rifaximin. Orange Book.

5. U.S. Court of Appeals for the Federal Circuit. (2023). Salix Pharmaceuticals, Ltd. v. Norwich Pharmaceuticals Inc., decisions concerning rifaximin patent validity and infringement. Federal Circuit opinions.