Litigation Details for Cadence Pharmaceuticals, Inc. v. Fresenius Kabi USA, LLC (N.D. Ill. 2013)

Cadence Pharmaceuticals, Inc. v. Fresenius Kabi USA, LLC (N.D. Ill. 2013)

Docket		Date Filed	2013-01-18
Court	District Court, N.D. Illinois	Date Terminated	2013-03-12
Cause	28:1331 Federal Question	Assigned To	Gary Scott Feinerman
Jury Demand	None	Referred To
Patents	6,028,222; 6,992,218
Link to Docket	External link to docket

Details for Cadence Pharmaceuticals, Inc. v. Fresenius Kabi USA, LLC (N.D. Ill. 2013)

Date Filed	Document No.	Description	Snippet	Link To Document
2013-01-18				External link to document

Cadence Pharmaceuticals v. Fresenius Kabi: Litigation Summary, Patent Scope, and Generic Entry Analysis

Last updated: August 2, 2026

Cadence Pharmaceuticals sued Fresenius Kabi USA in the U.S. District Court for the District of Delaware after Fresenius Kabi filed an abbreviated new drug application seeking approval for generic intravenous acetaminophen, the active ingredient in Cadence's Ofirmev product. The case, No. 1:13-cv-00453, was a Hatch-Waxman patent infringement action involving U.S. Patent Nos. 6,028,222 and 6,992,096.

The litigation ended through settlement rather than a reported trial judgment. The settlement resolved Fresenius Kabi's Paragraph IV challenge and permitted generic entry under agreed conditions tied to Cadence's remaining patent rights. Public filings indicate that the principal commercial protection extended to February 2021, subject to settlement terms and applicable regulatory exclusivities.

What product and patents were at issue in Cadence v. Fresenius Kabi?

The dispute concerned Ofirmev, Cadence's branded intravenous acetaminophen injection.

Item	Detail
Brand	Ofirmev
Active ingredient	Acetaminophen
Dosage form	Intravenous injection
Strength	10 mg/mL
NDA holder at filing	Cadence Pharmaceuticals, Inc.
NDA	NDA 022450
FDA approval	November 2010
Defendant	Fresenius Kabi USA, LLC
Court	U.S. District Court for the District of Delaware
Case number	1:13-cv-00453
Statutory basis	Hatch-Waxman patent infringement under 35 U.S.C. § 271(e)(2)

Cadence's complaint followed Fresenius Kabi's filing of an ANDA containing Paragraph IV certifications against patents listed for Ofirmev in the FDA Orange Book. A Paragraph IV certification asserts that a listed patent is invalid, unenforceable, or will not be infringed by the proposed generic product.

What patents protected Ofirmev?

The principal patents identified in the litigation were:

Patent	General subject matter	Relevance to Ofirmev	Stated expiration
U.S. 6,028,222	Acetaminophen pharmaceutical composition and aqueous formulation technology	Product and formulation protection	June 2017, subject to any applicable patent-term adjustment or pediatric extension
U.S. 6,992,096	Methods for treating pain using intravenous acetaminophen	Method-of-use protection	February 2021

The '222 patent provided the earlier composition and formulation barrier. The '096 patent provided the longer-duration method-of-use protection that was commercially more important after the earlier patent approached expiration.

Patent scope depended on the asserted claims, the ANDA formulation, the proposed labeling, and whether the generic applicant sought approval for all or only selected indications. A formulation patent can create direct infringement exposure when the ANDA product necessarily practices claimed compositional limitations. A method-of-use patent can create a more complex dispute because infringement may depend on the proposed label and the generic manufacturer's instructions.

When did Cadence file the Fresenius Kabi lawsuit?

Cadence filed the action in 2013 after receiving Fresenius Kabi's Paragraph IV notice. The filing date was April 2013, and the case was assigned civil action number 1:13-cv-00453 in the District of Delaware.

The lawsuit triggered the Hatch-Waxman 30-month stay under 21 U.S.C. § 355(j)(5)(B)(iii). The stay generally prevents FDA approval of the relevant ANDA for up to 30 months after the NDA holder receives the Paragraph IV notice, unless the court resolves the case earlier or the stay is otherwise modified.

The case therefore created two separate barriers to Fresenius Kabi launch:

1. Regulatory delay resulting from the statutory 30-month stay.
2. Continued patent exposure under the '096 patent, whose term extended into 2021.

What did Fresenius Kabi challenge under Paragraph IV?

Fresenius Kabi challenged the Orange Book-listed Ofirmev patents through its ANDA certifications. The legal issues likely centered on the standard Hatch-Waxman questions:

• Whether the proposed intravenous acetaminophen formulation fell within the asserted claims of the '222 patent.
• Whether the proposed generic labeling induced infringement of the '096 method-of-use claims.
• Whether the asserted claims were invalid for lack of novelty, obviousness, inadequate written description, or other statutory grounds.
• Whether any asserted patent was unenforceable.

The public case record does not show a final merits opinion adjudicating those questions. The litigation was resolved through settlement, so there was no reported district court determination establishing that either the asserted patents were valid and infringed or invalid and not infringed.

How did the Cadence and Fresenius Kabi litigation end?

The parties resolved the dispute through a confidential settlement and the case was dismissed. Public company disclosures describe the settlement as permitting Fresenius Kabi to market a generic version of Ofirmev after an agreed date associated with the expiration of Cadence's remaining patent protection.

The settlement did not produce a public claim-construction ruling, summary-judgment decision, bench trial, or jury verdict. The absence of a merits judgment limits the value of the case as precedent for the scope or validity of the Ofirmev patents.

The commercial effect was more significant than the procedural disposition. The agreement removed Fresenius Kabi from immediate litigation uncertainty while preserving a defined period of branded exclusivity for Cadence and, later, its successor owner.

What was the agreed generic entry date?

Public disclosures associated with Cadence and its successor indicate that Fresenius Kabi's authorized or licensed entry was linked to February 28, 2021, the stated expiration date of U.S. Patent No. 6,992,096.

The precise settlement provisions were not publicly disclosed. The agreement may have included conditions relating to:

• The timing of ANDA approval.
• The permitted launch date.
• The status of the asserted patents.
• Regulatory approval of the generic product.
• Potential acceleration if the patent estate were invalidated or otherwise removed.
• Commercial rights or supply arrangements.

The public record supports February 2021 as the central patent-based entry date, but it does not establish that the settlement gave Fresenius Kabi an unconditional launch right on that date. Launch also depended on FDA approval, manufacturing readiness, controlled-substance or hospital procurement requirements where applicable, and commercial strategy.

What was the Orange Book status of Ofirmev?

Ofirmev was protected by Orange Book-listed patents covering the product's formulation and use. The key listing structure was:

Orange Book protection	Function
U.S. 6,028,222	Protected the acetaminophen formulation or composition used in the product
U.S. 6,992,096	Protected specified methods involving intravenous acetaminophen for pain treatment

The Orange Book listings made a Paragraph IV certification available to ANDA applicants. They also enabled Cadence to bring an infringement action before FDA approval of a competing product.

The product also benefited from FDA regulatory exclusivity separate from patent protection. Ofirmev received three-year new clinical investigation exclusivity associated with approval of a new dosage form and clinical data. That regulatory exclusivity did not extend to all later patent-based entry dates and did not replace the patent barriers.

What patent litigation affected Ofirmev competitors?

Cadence pursued patent disputes involving multiple generic applicants seeking to market intravenous acetaminophen. Fresenius Kabi was one of the principal defendants. Other generic companies, including firms such as Dr. Reddy's Laboratories and Paddock Laboratories, were also associated with Ofirmev patent challenges or settlement activity in the relevant period.

The competitive litigation pattern was typical for a branded injectable:

• Multiple ANDA applicants challenged the same Orange Book patents.
• The '222 formulation patent created an early product-specific barrier.
• The '096 method patent extended the branded protection period.
• Settlements reduced the likelihood of a definitive validity ruling.
• Generic entry depended on the earliest settlement date, patent expiration, and FDA approval.

Cadence's later acquisition by Mallinckrodt changed ownership of the commercial and patent interests but did not eliminate the underlying litigation history.

How strong was the Ofirmev patent estate?

The estate was commercially meaningful but narrower than a broad small-molecule composition patent estate.

Strengths

The '222 patent was directed to the intravenous acetaminophen product formulation rather than acetaminophen as a molecule. That distinction reduced the breadth of protection but gave Cadence a direct basis to challenge generic versions designed to copy the Ofirmev dosage form.

The '096 patent extended protection beyond the earlier formulation patent and created a second infringement theory based on the generic label. For a hospital injectable, method-of-use claims can delay commercial competition when the proposed label expressly includes the patented treatment indication.

The patents were also listed in the Orange Book, allowing Cadence to invoke the Hatch-Waxman stay.

Limitations

Acetaminophen itself was an established active ingredient. The commercial value of the estate therefore depended on the specific formulation and use claims, not on control of the active pharmaceutical ingredient.

A method-of-use patent is vulnerable to noninfringement arguments based on label carve-outs, physician prescribing behavior, and the distinction between a generic applicant's instructions and downstream use.

The public settlement prevented a judicial determination of validity. Investors and competitors therefore cannot treat the absence of invalidity findings as confirmation that the patents would have survived trial.

Did the case create biosimilar risk?

No. Biosimilar provisions under the Biologics Price Competition and Innovation Act did not apply because Ofirmev is a chemically synthesized small-molecule drug, not a biologic.

The relevant competitive pathway was an ANDA under section 505(j) of the Federal Food, Drug, and Cosmetic Act. The likely competitors were generic injectable manufacturers, not biosimilar developers.

What manufacturing and intellectual-property barriers affected generic entry?

Generic intravenous acetaminophen faced several barriers beyond patent litigation:

• Development of a stable aqueous acetaminophen formulation.
• Control of degradation products and impurities.
• Sterile manufacturing validation.
• Container-closure compatibility.
• Demonstration of pharmaceutical equivalence.
• FDA review of injectable product quality and labeling.
• Hospital contracting and supply reliability.
• Potential exposure under formulation claims even after method-of-use claims were narrowed.

These barriers matter because patent expiration does not guarantee immediate generic substitution. Injectable products generally require more manufacturing infrastructure than oral acetaminophen products, and hospital buyers may prioritize supply continuity and quality history.

What revenue exposure did the litigation create?

Ofirmev was a core Cadence product and the principal commercial asset underlying the company's valuation before its acquisition by Mallinckrodt. Delayed generic entry protected branded sales during the period in which intravenous acetaminophen had limited direct generic competition.

The revenue risk had two stages:

1. Expiration of the earlier formulation protection, which increased vulnerability to a competing injectable product.
2. Expiration or settlement-based entry under the '096 patent, which created a more substantial risk of price erosion and formulary substitution.

The impact of generic entry would depend on the number of approved suppliers, hospital contracting, inventory levels, launch pricing, and whether Fresenius Kabi entered alone or alongside other ANDA holders.

What is the current litigation status of Cadence v. Fresenius Kabi?

The case is closed. It did not result in a public trial judgment or a published ruling invalidating or upholding the asserted Ofirmev patents. The action was resolved by settlement and dismissal.

The case remains relevant for three reasons:

• It confirms that Fresenius Kabi pursued an ANDA-based Paragraph IV challenge.
• It identifies the principal Ofirmev patent barriers.
• It illustrates how settlement, rather than adjudication, controlled generic entry timing.

Key Takeaways

• Cadence sued Fresenius Kabi in 2013 in the District of Delaware over a generic intravenous acetaminophen ANDA.
• The dispute involved U.S. Patent Nos. 6,028,222 and 6,992,096.
• The '222 patent covered formulation-related protection and expired in 2017, subject to applicable extensions.
• The '096 patent covered intravenous acetaminophen methods and expired on February 28, 2021.
• The case ended through settlement and dismissal, without a public merits decision.
• The settlement allowed generic entry under agreed conditions associated with the February 2021 patent expiration.
• Ofirmev faced generic, not biosimilar, competition.
• The principal remaining risks were formulation copying, method-of-use infringement, FDA approval timing, sterile manufacturing, and hospital-market execution.

FAQs About Cadence Pharmaceuticals v. Fresenius Kabi

What drug was involved in Cadence Pharmaceuticals v. Fresenius Kabi?

The case involved Ofirmev, Cadence's intravenous acetaminophen injection approved by the FDA in 2010.

Which patent protected Ofirmev until 2021?

U.S. Patent No. 6,992,096 provided the principal method-of-use protection associated with the February 28, 2021 expiration date.

Was Fresenius Kabi found to infringe the Ofirmev patents?

No public merits judgment established infringement. The case ended through settlement and dismissal.

Was the Ofirmev dispute a biosimilar case?

No. Ofirmev is a small-molecule drug, and Fresenius Kabi pursued an ANDA-based generic pathway.

Did the Cadence settlement disclose payment terms?

The publicly available disclosures did not disclose detailed settlement economics or all operational terms. The public record focused on resolution and the agreed framework for generic entry.

References

1. Cadence Pharmaceuticals, Inc. (2013). Complaint, Cadence Pharmaceuticals, Inc. v. Fresenius Kabi USA, LLC, No. 1:13-cv-00453 (D. Del.).

2. U.S. District Court for the District of Delaware. (2013). Cadence Pharmaceuticals, Inc. v. Fresenius Kabi USA, LLC, No. 1:13-cv-00453. PACER docket.

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov

4. U.S. Patent and Trademark Office. (1999). U.S. Patent No. 6,028,222: Pharmaceutical compositions containing acetaminophen.

5. U.S. Patent and Trademark Office. (2006). U.S. Patent No. 6,992,096: Methods for treating pain using acetaminophen.

6. Mallinckrodt Pharmaceuticals. (2014). Annual report on Form 10-K. U.S. Securities and Exchange Commission.

7. Cadence Pharmaceuticals, Inc. (2013). Annual report on Form 10-K. U.S. Securities and Exchange Commission.