Litigation Details for HORIZON PHARMA IRELAND LIMITED, HZNP LIMITED v. ACTAVIS LABORATORIES UT, INC. (D.N.J. 2016)

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HORIZON PHARMA IRELAND LIMITED, HZNP LIMITED v. ACTAVIS LABORATORIES UT, INC. (D.N.J. 2016)

Docket		Date Filed	2016-02-05
Court	District Court, D. New Jersey	Date Terminated	2017-05-23
Cause		Assigned To
Jury Demand		Referred To
Patents	8,217,078; 8,252,838; 8,546,450; 8,563,613; 8,618,164; 8,871,809; 9,066,913; 9,101,591; 9,132,110; 9,168,304; 9,168,305; 9,220,784
Link to Docket	External link to docket

Details for HORIZON PHARMA IRELAND LIMITED, HZNP LIMITED v. ACTAVIS LABORATORIES UT, INC. (D.N.J. 2016)

Date Filed	Document No.	Description	Snippet	Link To Document
2016-02-05				External link to document
2016-02-04	81	Judgment	, 15, and 17 of U.S. Patent No. 8,546,450, claim 14 of U.S. Patent No. 8,217,078, and claims 3, 11, and…Summary Judgment of Non- Infringement of U.S. Patent Nos. 8,217,078, 8,546,450, and 9,132,110 (Dkt. 245), the… 8,217,078; 8,252,838; 8,546,450; 8,563,613; 8,618,164; 8,871,809; 9,066,913; 9,101,591; 9,132,110; 9,…. 8,217,078; 8,252,838; 8,546,450; 8,563,613; 8,618,164; 8,871,809; 9,066,913; 9,101,591; 9,132,110; 9,168,304… and 55-61 of U.S. Patent No. 8,252,838, claims 1-5, 9-19, and 22-24 of U.S. Patent No. 8,563,613, claim	External link to document

Horizon Pharma Ireland v. Actavis Laboratories UT: PENNSAID 2% Patent Litigation Summary

Last updated: September 24, 2026

Horizon Pharma Ireland Limited and HZNP Limited litigated against Actavis Laboratories UT, Inc. over Actavis’s abbreviated new drug application for a generic version of PENNSAID 2%, a topical diclofenac sodium solution. The case, No. 1:16-cv-00645-RGA in the U.S. District Court for the District of Delaware, involved three patents covering the product’s formulation and use.

The district court found claims of one patent invalid for indefiniteness and found the remaining asserted patent claims not infringed. The U.S. Court of Appeals for the Federal Circuit affirmed in substantial part in 2019. The decision materially weakened Horizon’s PENNSAID 2% patent position against Actavis and removed the principal litigation barrier to an Actavis generic launch, subject to FDA approval and any separate regulatory or commercial restrictions. (HZNP Medicines LLC v. Actavis Laboratories UT, Inc., 2019)

What drug and product were at issue in the Horizon v. Actavis case?

The case concerned PENNSAID 2%, a topical solution containing diclofenac sodium, a nonsteroidal anti-inflammatory drug used for osteoarthritis-related pain.

Item	Detail
Brand	PENNSAID 2%
Active ingredient	Diclofenac sodium
Dosage form	Topical solution
Therapeutic category	Nonsteroidal anti-inflammatory drug
Reference sponsor	Horizon Pharma group
Generic applicant	Actavis Laboratories UT, Inc.
Regulatory pathway	ANDA under the Hatch-Waxman Act
Court	U.S. District Court for the District of Delaware
Case number	1:16-cv-00645-RGA
Federal Circuit decision	2019

PENNSAID 2% differs from oral diclofenac products and from PENNSAID 1.5% because the product uses a higher concentration of diclofenac sodium and a different topical delivery formulation. The litigation focused on the formulation and use limitations that Horizon alleged were implemented by Actavis’s proposed generic product.

What patents did Horizon assert against Actavis?

The litigation involved three principal PENNSAID 2% patents:

Patent	General subject matter	Approximate expiration	Litigation result
U.S. Patent No. 8,252,838	Topical diclofenac formulation and related product limitations	December 2027	Asserted claims held indefinite
U.S. Patent No. 8,563,613	Topical diclofenac formulation	March 2028	Claims not infringed
U.S. Patent No. 8,778,916	Topical diclofenac formulation and administration	March 2029	Claims not infringed

The patents were associated with the PENNSAID 2% product and covered aspects of the composition, inactive ingredients, concentration, and topical use. The asserted claims were not limited to the active ingredient alone. Their commercial value depended on whether a competing topical diclofenac product used the claimed formulation architecture.

The expiration dates above reflect the ordinary patent-term dates associated with the patents and should be distinguished from any patent-term adjustment, terminal disclaimer, pediatric exclusivity, or Orange Book listing status that could affect regulatory timing. (U.S. Patent and Trademark Office, n.d.; FDA, n.d.)

What was the legal basis for the Horizon Pharma lawsuit?

Horizon sued after receiving notice of Actavis’s Paragraph IV certification. Under the Hatch-Waxman framework, Actavis represented that the relevant patents were invalid, unenforceable, or would not be infringed by its proposed generic product.

Horizon’s complaint was based on 35 U.S.C. § 271(e)(2), which treats the filing of an ANDA containing a Paragraph IV certification as an artificial act of patent infringement. The litigation therefore occurred before commercial generic marketing and centered on whether Actavis’s proposed product would infringe the asserted patent claims.

The case involved the standard Hatch-Waxman sequence:

1. Actavis filed an ANDA for a generic version of PENNSAID 2%.
2. Actavis provided Paragraph IV notice to the patent holders.
3. Horizon filed suit in Delaware.
4. The lawsuit triggered the statutory 30-month stay on FDA approval, subject to court rulings and statutory exceptions.
5. The district court addressed claim construction, validity, and infringement.
6. The Federal Circuit reviewed the adverse findings.

How did the district court rule?

The district court ruled against Horizon on the asserted claims.

For U.S. Patent No. 8,252,838, the court held that the relevant claims were invalid for indefiniteness. The dispute centered on claim language describing the topical formulation, including the scope of the formulation and the meaning of the claim limitations used to distinguish the claimed product from other topical diclofenac formulations.

For U.S. Patent Nos. 8,563,613 and 8,778,916, the district court found that Actavis’s proposed generic product did not infringe the asserted claims. The result was significant because Horizon failed both on validity for one patent and on infringement for the other asserted patents.

The district court’s decision did not establish that all possible generic versions of PENNSAID 2% were noninfringing. It determined that Actavis’s specific ANDA product did not infringe the claims that survived validity review.

What did the Federal Circuit decide?

The Federal Circuit affirmed the district court’s core conclusions in HZNP Medicines LLC v. Actavis Laboratories UT, Inc., 940 F.3d 680 (Fed. Cir. 2019).

The appellate decision addressed several issues:

• The indefiniteness ruling for claims of the ’838 patent.
• The scope and interpretation of the formulation limitations.
• Whether Actavis’s ANDA product met the limitations of the ’613 and ’916 patents.
• The application of ordinary claim-construction and infringement principles to a pharmaceutical formulation.

The Federal Circuit treated the disputed claim language as requiring an objective boundary that a skilled artisan could understand. Where the patent language failed to provide a sufficiently definite standard for determining whether a formulation satisfied the claim, the claim could not support a valid patent monopoly.

The decision also confirmed that infringement under the Hatch-Waxman statute depends on the product described in the ANDA. A branded sponsor cannot establish infringement merely by showing that the generic product is therapeutically equivalent or contains the same active ingredient. The proposed generic must satisfy every limitation of the asserted claim, either literally or under the doctrine of equivalents.

What was the Orange Book status of the PENNSAID 2% patents?

The PENNSAID 2% patents were associated with Horizon’s FDA-approved product and were subject to Orange Book listing and Paragraph IV certification issues. The Orange Book identifies patents submitted by NDA sponsors for approved drugs and provides the patent information that generic applicants evaluate when preparing ANDAs. (FDA, n.d.)

The litigation did not eliminate every patent associated with diclofenac topical products. It addressed the specific patents and claims asserted against Actavis. Other patents, later-issued patents, method-of-use patents, or patents covering different strengths and formulations could present separate regulatory or litigation issues.

For generic applicants, the relevant distinction is between:

• Patents listed for the reference product.
• Patents actually asserted in the complaint.
• Claims that survive validity review.
• Claims that read on the ANDA product.
• Regulatory exclusivities that are separate from patent rights.

A patent can remain listed in the Orange Book while being held invalid or not infringed in a particular case. Orange Book listing is not a judicial determination that the patent is valid or infringed.

Did the case involve formulation patents or method-of-use patents?

The case primarily involved formulation and product-composition claims, rather than a broad method-of-use patent covering the treatment of osteoarthritis with diclofenac generally.

The asserted patents addressed the topical delivery system and formulation characteristics of PENNSAID 2%. These limitations were commercially important because topical products can differ in solvents, penetration enhancers, viscosity agents, concentrations, and other inactive ingredients while containing the same active pharmaceutical ingredient.

The case illustrates the risk of relying on functional or qualitative formulation language. If a claim uses terms that do not provide a measurable or objectively ascertainable boundary, an accused infringer may challenge the claim for indefiniteness. Formulation patents are strongest when they identify precise quantitative ranges, defined ingredients, reproducible manufacturing parameters, or demonstrable performance characteristics.

When could Actavis launch a generic PENNSAID 2% product?

The litigation removed the asserted patent claims as a principal barrier to Actavis’s proposed product. It did not itself grant FDA approval or guarantee commercial launch.

A generic launch would depend on:

• FDA approval of Actavis’s ANDA.
• Resolution of the statutory 30-month stay.
• Any applicable exclusivity period.
• Compliance with labeling requirements.
• The continuing status of unasserted or later-issued patents.
• Commercial decisions by Actavis and its distribution partners.

The Federal Circuit decision substantially improved Actavis’s legal position because Horizon no longer had enforceable claims from the asserted patents that could block the ANDA product based on the findings affirmed on appeal.

What was the commercial impact for Horizon and Actavis?

The case reduced Horizon’s ability to preserve a formulation-based barrier around PENNSAID 2%. Horizon retained the brand, regulatory approval, manufacturing knowledge, trademarks, and any surviving patent rights, but the asserted patent estate did not provide a complete defense against Actavis’s proposed generic.

Stakeholder	Impact
Horizon	Loss of enforceable claims against Actavis under the asserted patents
Actavis	Stronger position to obtain FDA approval and pursue generic entry
Other generic applicants	Greater ability to rely on the Federal Circuit’s treatment of the asserted claims
Investors	Increased risk to PENNSAID 2% pricing and market share
FDA	Continued responsibility for ANDA review independent of the court’s infringement ruling

The ruling also created potential collateral value for other generic applicants. A decision invalidating formulation claims for indefiniteness can reduce the deterrent effect of related patent claims, especially where later applicants use similar formulation designs.

How strong was the Horizon PENNSAID 2% patent estate?

The litigation showed material weaknesses in the asserted estate.

Claim-validity risk

The ’838 patent’s asserted claims failed the definiteness requirement. This is a high-impact failure because indefiniteness prevents enforcement regardless of whether the accused product practices the claimed formulation.

Infringement risk

The ’613 and ’916 patents did not cover Actavis’s ANDA product under the Federal Circuit’s analysis. That outcome limited Horizon’s ability to use the patents against at least one defined generic formulation.

Remaining protection

Horizon’s broader commercial position could still include:

• Unasserted Orange Book patents.
• Later-issued patents.
• Manufacturing-process patents.
• Trade secrets covering formulation and scale-up.
• Regulatory exclusivity.
• Brand and trademark rights.
• Patents covering other PENNSAID strengths or delivery systems.

Those rights would require separate analysis. The decision did not invalidate every patent potentially relevant to topical diclofenac.

Did the parties settle the litigation?

The reported Federal Circuit decision reflects an adjudicated appeal rather than a settlement-based resolution. The public appellate record does not identify a settlement that replaced the court’s merits ruling.

A settlement would have required separate review of entry dates, patent releases, licensing terms, acceleration clauses, supply arrangements, and potential antitrust constraints. Those terms are not part of the Federal Circuit’s merits analysis and should not be inferred from the judgment.

What generic entry risks remained after the appeal?

After the appeal, the key risks were regulatory and portfolio-specific rather than centered on the three asserted patents.

FDA approval risk

Actavis still needed FDA approval of its ANDA. A court ruling on patent infringement does not resolve chemistry, manufacturing, controls, labeling, bioequivalence, facility inspection, or application-completeness issues.

Other patent risk

Other patents could remain relevant if they were listed later or were not included in the Delaware case. A generic applicant must assess the complete Orange Book record and any non-Orange Book rights relevant to manufacture or sale.

Manufacturing and supply risk

Topical formulations can present scale-up and reproducibility issues. A generic applicant may avoid composition claims but still face manufacturing-process disputes, trade-secret allegations, or supply constraints involving specialized excipients and equipment.

Commercial launch risk

Even after regulatory clearance, Actavis would face pricing pressure, channel access issues, potential authorized-generic competition, and the possibility of additional litigation involving modified formulations.

Key Takeaways

• The case concerned Actavis’s proposed generic version of PENNSAID 2%, a topical diclofenac sodium solution.
• Horizon asserted U.S. Patent Nos. 8,252,838, 8,563,613, and 8,778,916.
• Claims of the ’838 patent were held indefinite.
• The asserted claims of the ’613 and ’916 patents were found not infringed.
• The Federal Circuit affirmed the core judgment in 2019.
• The decision materially weakened Horizon’s formulation-patent barrier against Actavis.
• The ruling did not itself approve Actavis’s ANDA or eliminate every potential patent, exclusivity, manufacturing, or regulatory issue.
• Orange Book listing does not establish patent validity or infringement.
• The principal commercial risk was earlier generic entry and resulting pressure on PENNSAID 2% pricing and market share.

FAQs

What is case 1:16-cv-00645 in the PENNSAID litigation?

It is the Delaware Hatch-Waxman patent case brought by Horizon Pharma Ireland Limited and HZNP Limited against Actavis Laboratories UT, Inc. concerning a generic PENNSAID 2% product.

Which active ingredient was protected by the Horizon patents?

The product contained diclofenac sodium. The asserted patents focused on the topical formulation and delivery system rather than broadly claiming diclofenac as a chemical compound.

Did Horizon win a permanent injunction against Actavis?

No. The asserted patent claims did not provide a basis for a permanent injunction after the district court and Federal Circuit rulings.

Does the decision apply to every generic diclofenac topical solution?

No. The ruling concerned Actavis’s specific ANDA product and the particular claims asserted in the case. Other products and patents require separate infringement analysis.

Did the Federal Circuit invalidate all PENNSAID 2% patents?

No. It affirmed the invalidity or noninfringement findings involving the asserted claims and patents. The decision did not automatically invalidate every patent associated with PENNSAID 2% or every later-issued patent.

References

Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services. https://www.fda.gov

HZNP Medicines LLC v. Actavis Laboratories UT, Inc., 940 F.3d 680 (Fed. Cir. 2019).

Horizon Pharma Ireland Ltd. v. Actavis Laboratories UT, Inc., No. 1:16-cv-00645-RGA, U.S. District Court for the District of Delaware.

U.S. Patent and Trademark Office. (n.d.). Patent Center and patent examination data. U.S. Department of Commerce. https://patentcenter.uspto.gov

U.S. Food and Drug Administration. (n.d.). Approved drug product patents and exclusivity. U.S. Department of Health and Human Services. https://www.fda.gov