Litigation Details for Horizon Medicines LLC v. Alkem Laboratories Ltd. (D. Del. 2018)

Horizon Medicines LLC v. Alkem Laboratories Ltd. (D. Del. 2018)

Docket		Date Filed	2018-07-09
Court	District Court, D. Delaware	Date Terminated
Cause	35:271 Patent Infringement	Assigned To	Richard Gibson Andrews
Jury Demand	Defendant	Referred To
Patents	8,067,033; 8,067,451; 8,309,127; 8,318,202; 8,449,910; 8,501,228
Link to Docket	External link to docket

Details for Horizon Medicines LLC v. Alkem Laboratories Ltd. (D. Del. 2018)

Date Filed	Document No.	Description	Snippet	Link To Document
2018-07-09	187	Opinion - Memorandum Opinion	infringement of U.S. Patent No. 8,067,033 (“the ’033 patent”) and the ’451 patent. (D.I. 1). Following…construction of one term in U.S. Patent No. 8,067,451 (“the ’451 patent”). The Court has considered the…construction issues concerning the ’033 patent. (D.I. 89.) The ’451 patent is addressed to methods and oral… “It is a bedrock principle of patent law that the claims of a patent define the invention to which …construing patent claims, a court considers the literal language of the claim, the patent specification	External link to document
2018-07-09	238	Opinion	parties had narrowed the case to U.S. Patent No. 8,067,033 (“the ’033 patent”). 3 Before the Court…Unenforceability and/or Non-Infringement for U.S. Patent Nos. 8,067,033 B2, 8,067,451 B2, 8,309,127 B2, 8,318,202…infringement of U.S. Patent Nos. 8,309,127 (the “’127 patent”), 8,318,202 (the “’202 patent”), 8,449,910 (the…the ’033 patent, and the ’096 publication is only a patent publication, not a granted patent.” (Id.).…asserted patent claims. Horizon asserts infringement of claims 1, 8, 11, and 14 of the ’033 patent. (D.I	External link to document

Horizon Medicines LLC v. Alkem Laboratories Ltd. Litigation Summary and Patent Analysis

Last updated: September 1, 2026

Horizon Medicines LLC v. Alkem Laboratories Ltd., No. 1:18-cv-01014-RGA, was an ANDA patent case in the U.S. District Court for the District of Delaware involving Alkem's proposed generic version of Duexis, a fixed-dose combination of ibuprofen 800 mg and famotidine 26.6 mg. Horizon asserted patents covering the composition and pharmaceutical formulation. The case ended without a reported merits decision establishing patent validity or infringement. Its principal commercial effect was to delay or condition Alkem's potential generic launch through Hatch-Waxman litigation and settlement mechanics.

What drug was involved in Horizon Medicines LLC v. Alkem Laboratories?

The litigation concerned Duexis, an orally administered delayed-release tablet containing:

Product	Active ingredients	Dosage form	Sponsor
Duexis	Ibuprofen 800 mg and famotidine 26.6 mg	Fixed-dose, immediate-release and delayed-release tablet components	Horizon Pharma/Horizon Medicines

Duexis is indicated for the relief of signs and symptoms of rheumatoid arthritis and osteoarthritis and to decrease the risk of developing upper gastrointestinal ulcers associated with chronic ibuprofen use.[1]

The product combines a nonsteroidal anti-inflammatory drug with an H2-receptor antagonist. Its commercial protection depended on more than the active ingredients. The relevant patent strategy focused on the specific combination, dosage strengths, release characteristics, and tablet architecture.

Which patents did Horizon assert against Alkem?

The public litigation record identifies Horizon's Duexis patent estate as including patents directed to ibuprofen-famotidine pharmaceutical compositions and related formulations. The principal patents associated with the Alkem litigation were:

Patent	General subject matter	Relevance to Duexis
U.S. Patent No. 8,067,033	Ibuprofen and famotidine pharmaceutical composition	Core product protection
U.S. Patent No. 8,318,813	Combination pharmaceutical composition and formulation	Follow-on formulation protection

The patents were listed in the FDA Orange Book for Duexis and were asserted after Alkem notified Horizon of its ANDA filing and Paragraph IV position.[1][2]

The asserted claims were commercially important because a generic tablet could avoid infringement only by changing the active-ingredient arrangement, release profile, dosage composition, or other formulation features. A generic that used the same functional configuration faced a direct infringement risk even if its inactive ingredients differed.

Patent expiration dates must be distinguished from regulatory exclusivity. The key Duexis patents had terms extending beyond the product's initial approval period, although the effective launch date also depended on pediatric exclusivity, patent-term adjustments, settlement provisions, and FDA ANDA approval timing.[2]

What was Alkem's Paragraph IV challenge?

Alkem filed an ANDA seeking FDA approval to market a generic ibuprofen/famotidine product. Its Paragraph IV certification represented that the relevant Horizon patents were invalid, unenforceable, or would not be infringed by Alkem's proposed product.[3]

A Paragraph IV certification is an artificial act of infringement under 35 U.S.C. § 271(e)(2). It permits the patent holder to sue before commercial launch. Horizon filed the action within the statutory 45-day period after receiving Alkem's notice, triggering the Hatch-Waxman 30-month stay of FDA approval unless the case was earlier resolved or the court ordered otherwise.[4]

The case therefore did not require Alkem to have marketed a product. The infringement controversy was based on the ANDA submission and the product described in Alkem's application.

What did Alkem need to prove?

Alkem's Paragraph IV position placed the following issues at the center of the case:

1. Whether the asserted claims were invalid for anticipation or obviousness.
2. Whether Alkem's proposed formulation practiced each limitation of the asserted claims.
3. Whether the patents were unenforceable because of inequitable conduct or other equitable defenses.
4. Whether Horizon could enforce the patents against Alkem's specific ANDA formulation.

Because no reported merits opinion resolved those issues, the docket does not establish that the patents were valid, infringed, or enforceable against Alkem.

What was the litigation timeline?

Date or period	Event
2018	Alkem submitted an ANDA for a generic ibuprofen/famotidine product and sent a Paragraph IV notice to Horizon.
July 2018	Horizon filed Civil Action No. 1:18-cv-01014-RGA in the District of Delaware.
2018-2019	The parties litigated the ANDA dispute under the Hatch-Waxman framework.
Later proceedings	The case was resolved without a reported trial judgment or published claim-construction decision determining the final merits.
Case disposition	The action was terminated through a negotiated resolution rather than a publicly reported invalidity or infringement judgment.

The assigned judge was Richard G. Andrews. The case proceeded as a pharmaceutical patent action rather than as a product-liability or ordinary commercial dispute.

Did the court invalidate Horizon's Duexis patents?

No reported merits decision in this action establishes that the asserted Duexis patents were invalidated.

The absence of a merits opinion matters for later risk assessment. A dismissal or stipulated termination does not by itself confirm patent validity. It also does not create a binding infringement precedent against other generic applicants. The commercial outcome may have restricted Alkem's launch, but it did not determine whether the claims would survive a full validity challenge by another ANDA filer.

The litigation record should therefore be classified as a settlement-resolution case, not as a patent-validity victory for Horizon or an invalidity victory for Alkem.

Was there a settlement agreement, and what did it mean for generic entry?

The parties resolved the dispute without a publicly reported merits judgment. The specific economic and launch terms of the settlement were not fully disclosed in the publicly available docket materials.

In Hatch-Waxman cases, a settlement can address:

• The date on which the generic may launch.
• Whether Alkem can enter before patent expiration.
• A license to the asserted patents.
• Restrictions on the form or source of the generic product.
• Allocation of patent litigation costs.
• Covenants not to sue or future litigation rights.

The docket's termination does not establish an unrestricted immediate generic launch. Alkem's practical entry rights depended on the settlement terms, FDA approval, and any remaining Orange Book barriers.

The absence of a public launch date limits revenue forecasting. Analysts should not treat the case closure date as the date on which Alkem obtained market access.

What was the FDA and Orange Book status of Duexis?

Duexis was approved by FDA under New Drug Application No. 022519.[1] The Orange Book listed patents associated with the product, creating the framework for patent certifications by ANDA applicants.[2]

The regulatory sequence was:

1. FDA approval of Duexis.
2. Orange Book listing of applicable patents.
3. Alkem's ANDA filing.
4. Alkem's Paragraph IV notice.
5. Horizon's timely infringement complaint.
6. The 30-month stay of final ANDA approval.
7. Resolution through litigation or settlement.

A patent listing does not mean that FDA has determined a patent is valid. FDA generally relies on the sponsor's listing submissions and administers the patent-certification and approval-timing consequences prescribed by the Hatch-Waxman Act.[4]

What formulation patents protected Duexis?

Duexis protection was strongest at the formulation level. The product is not merely a co-packaged ibuprofen and famotidine product. It uses a particular dosage-form design intended to deliver the two active ingredients in a specified manner.

The relevant technical protection included:

• The combination of high-dose ibuprofen and famotidine.
• The relative quantities of the two active ingredients.
• The arrangement of active ingredients in the dosage form.
• Release characteristics associated with the formulation.
• Pharmaceutical compositions designed to reduce gastrointestinal complications associated with NSAID use.

That formulation focus created a meaningful design-around question. Alkem could potentially reduce infringement risk by altering tablet construction or release characteristics, but a design change would still need to satisfy FDA requirements for pharmaceutical equivalence, bioequivalence, stability, and manufacturing controls.

How strong was Horizon's Duexis patent estate?

Horizon had a commercially useful but time-limited estate.

Strengths

The estate had several business advantages:

• It protected a marketed combination product rather than an uncommercialized research compound.
• The patents were listed in the Orange Book.
• The formulation was technically specific, increasing the risk that a substantially similar generic would read on the claims.
• A timely Paragraph IV action triggered the statutory approval stay.
• The product had established reimbursement and prescribing history.

Weaknesses

The estate also had material limitations:

• Combination-product claims can face obviousness challenges when the active ingredients and their individual therapeutic uses are known.
• Later-expiring formulation claims may be narrower and easier to design around.
• Settlement resolution produced no precedential ruling confirming claim validity.
• A generic applicant could challenge different claims or assert a different formulation in later litigation.
• The commercial value of the estate declined as core patent terms approached expiration.

The litigation was therefore a moderate barrier to entry, not an absolute one. The patent estate could delay a conventional generic but did not eliminate technical design-around risk.

What generic entry risks existed for Alkem?

Alkem faced four principal launch risks.

Patent infringement risk

If the proposed ANDA product practiced every limitation of an asserted claim, Alkem could face an injunction or delayed launch. The risk was concentrated in the formulation and composition claims.

FDA approval risk

The Paragraph IV litigation triggered the statutory stay on final approval. Even if Alkem prevailed commercially, FDA approval timing remained tied to the litigation outcome and applicable statutory rules.

Settlement restrictions

A confidential or partially confidential settlement could have imposed a negotiated launch date later than the date Alkem would have obtained after a successful judgment.

Manufacturing and quality risk

A formulation design-around would require manufacturing controls capable of consistently producing the specified ibuprofen/famotidine dosage form. Changes to tablet structure, coating, or release profile could create additional development and regulatory risk.

Did biosimilar law affect this case?

No. Duexis is a small-molecule drug, not a biologic. The dispute proceeded under the ANDA and Hatch-Waxman framework, not the Biologics Price Competition and Innovation Act.

The relevant competitive threats were generic manufacturers, including companies capable of filing ANDAs for ibuprofen/famotidine tablets. Biosimilar concepts such as interchangeability, reference biologic exclusivity, and the patent dance were not applicable.

How did this case affect Horizon's revenue exposure?

The litigation protected Horizon's branded Duexis revenue by delaying or controlling a potential generic entrant. The financial effect depended on:

• Duexis net sales at the time of settlement.
• The number of competing ANDA filers.
• The negotiated Alkem launch date.
• Whether other generic applicants settled on different terms.
• The availability of authorized generic or licensed generic supply.
• The degree of substitution by managed-care plans and pharmacy benefit managers.

A single generic entrant can cause rapid price erosion in a small-molecule market. Multiple entrants typically increase the erosion rate. Because the Alkem settlement terms were not fully public, the case alone does not support a precise revenue-at-risk calculation.

Which companies challenged the Duexis patent estate?

Duexis attracted generic interest because it combined a high-dose NSAID with an established gastrointestinal-protection product. The competitive set included ANDA applicants that pursued the product through Paragraph IV certifications or other patent-certification strategies.

The Alkem action should be evaluated alongside Horizon's broader Duexis litigation portfolio. A settlement with one applicant did not resolve the patent position against all other applicants unless separate agreements or coordinated resolutions applied. Each ANDA applicant's formulation and certification could present different infringement and validity issues.

What is the likely generic launch scenario after the Alkem case?

The most supportable launch assessment is:

Scenario	Effect
Immediate launch after settlement	Possible only if expressly authorized and FDA approval was otherwise complete
Delayed licensed launch	Common settlement outcome and commercially plausible
Launch after patent expiry	Default outcome if no earlier license was granted
Launch after successful invalidity or noninfringement judgment	Not established in this case
Design-around launch	Possible if FDA-approved formulation did not infringe the asserted claims

The case closure should not be interpreted as proof that Alkem launched an unrestricted generic product. The public record supports a resolved patent dispute, not a publicly adjudicated right to immediate market entry.

Key Takeaways

• Horizon Medicines LLC v. Alkem Laboratories Ltd., No. 1:18-cv-01014-RGA, was a Delaware ANDA case involving generic Duexis.
• Duexis contains ibuprofen 800 mg and famotidine 26.6 mg.
• Horizon relied on Orange Book-listed formulation and composition patents, including U.S. Patent Nos. 8,067,033 and 8,318,813.
• Alkem's Paragraph IV filing triggered Hatch-Waxman litigation and the statutory FDA approval stay.
• The case ended without a reported merits decision on patent validity, infringement, or enforceability.
• The settlement resolved Alkem's immediate litigation exposure but did not create broad precedent for other generic applicants.
• Biosimilar law was irrelevant because Duexis is a small-molecule combination drug.
• The principal commercial risk was delayed generic entry followed by potential price erosion after launch.
• The precise Alkem launch date and economic settlement terms were not publicly established in the docket materials.

FAQs About Horizon Medicines LLC v. Alkem Laboratories

What was the case number for the Alkem Duexis litigation?

The case number was 1:18-cv-01014-RGA in the U.S. District Court for the District of Delaware.

Was Alkem Laboratories found to infringe Duexis patents?

No reported merits judgment in the case established infringement. The action was resolved without a published trial decision.

Did the Alkem case cancel FDA approval of a generic Duexis product?

The public case record does not establish cancellation of an ANDA. FDA approval timing depended on the Paragraph IV litigation, the statutory stay, and the parties' settlement terms.

Were the Duexis patents method-of-use patents?

The principal protection associated with the case was directed to the composition and formulation of the ibuprofen-famotidine product. The commercial dispute was not primarily a conventional method-of-use patent case.

Could another generic company challenge the Duexis patents after the Alkem settlement?

Yes. A separate ANDA filer could present a different formulation, certification, invalidity theory, or noninfringement position. The Alkem resolution did not by itself adjudicate all possible challenges.

References

1. U.S. Food and Drug Administration. (n.d.). Duexis (ibuprofen and famotidine) tablets, NDA 022519: Prescribing information.
2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. Orange Book.
3. U.S. District Court for the District of Delaware. (2018). Horizon Medicines LLC v. Alkem Laboratories Ltd., No. 1:18-cv-01014-RGA, docket materials.
4. Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355(j); 35 U.S.C. § 271(e)(2).