Litigation Details for Mallinckrodt Hospital Products IP Ltd. v. Praxair Distribution Inc. (D. Del. 2016)

Mallinckrodt Hospital Products IP Ltd. v. Praxair Distribution Inc. (D. Del. 2016)

Docket		Date Filed	2016-07-08
Court	District Court, D. Delaware	Date Terminated	2016-08-22
Cause	35:271 Patent Infringement	Assigned To	Gregory Moneta Sleet
Jury Demand	None	Referred To
Patents	9,265,911; 9,279,794; 9,295,802
Link to Docket	External link to docket

Details for Mallinckrodt Hospital Products IP Ltd. v. Praxair Distribution Inc. (D. Del. 2016)

Date Filed	Document No.	Description	Snippet	Link To Document
2016-07-08				External link to document
2016-07-08	4		the Commissioner of Patents and Trademarks for Patent/Trademark Number(s) 9,265,911 B2; 9,295,802 B2; 9,279,794…2016 22 August 2016 1:16-cv-00592 830 Patent None District Court, D. Delaware	External link to document

Mallinckrodt Hospital Products IP Ltd. v. Praxair Distribution Inc. Litigation Summary

Last updated: September 26, 2026

Mallinckrodt Hospital Products IP Ltd. v. Praxair Distribution Inc., No. 1:16-cv-00592, was a Hatch-Waxman patent dispute over generic inhaled nitric oxide products related to Mallinckrodt's INOmax therapy. The case ended with invalidity findings against the asserted method-of-treatment claims under 35 U.S.C. § 101. The Federal Circuit affirmed the core judgment in 2020, eliminating the principal patent barrier to Praxair's proposed generic product. [1]

What patents protected Mallinckrodt's INOmax nitric oxide product?

Mallinckrodt asserted two patents covering methods for treating premature infants with inhaled nitric oxide:

Patent	Subject matter	Litigation role	Federal Circuit treatment
U.S. Patent No. 8,795,741	Administration of inhaled nitric oxide to premature infants at risk of bronchopulmonary dysplasia	Asserted against Praxair's ANDA product	Core claims held ineligible under § 101
U.S. Patent No. 9,463,205	Related continuation patent directed to treatment of premature infants with inhaled nitric oxide	Asserted against Praxair's ANDA product	Core claims held ineligible under § 101

The patents did not claim nitric oxide as a newly discovered chemical entity. They claimed a clinical treatment protocol using a known therapy in a defined patient population. The relevant population was premature infants at risk of developing bronchopulmonary dysplasia, or BPD.

The claims addressed administration of inhaled nitric oxide under specified clinical conditions, including patient selection and treatment parameters. Mallinckrodt characterized the claimed methods as a specific treatment regimen. Praxair argued that the claims effectively monopolized a natural relationship between nitric oxide treatment and reduced BPD risk.

What was the case number, court, and procedural history?

The case was filed in the U.S. District Court for the District of Delaware under No. 1:16-cv-00592.

Date	Event
2016	Mallinckrodt filed the Hatch-Waxman action against Praxair Distribution Inc.
2018	The District of Delaware granted summary judgment that the asserted claims were patent-ineligible under § 101
2020	The Federal Circuit affirmed the principal invalidity determination
2020	The Federal Circuit denied Mallinckrodt's request to preserve the asserted patent claims through reversal of the § 101 ruling

The District Court resolved the case on patent eligibility and did not need to conduct a full trial on infringement, anticipation, obviousness, or claim construction for the claims disposed of on § 101 grounds.

What did Mallinckrodt allege against Praxair?

Mallinckrodt brought the case under the Hatch-Waxman framework after Praxair sought FDA approval for a generic nitric oxide product.

The complaint alleged that Praxair's ANDA filing constituted an artificial act of infringement under 35 U.S.C. § 271(e)(2). Mallinckrodt relied on the patents' method-of-use claims and argued that Praxair's proposed labeling would induce infringement by hospitals, physicians, and other healthcare providers.

The dispute therefore involved two separate questions:

1. Whether Praxair's ANDA product and proposed labeling would fall within the patented treatment methods.
2. Whether the asserted claims were legally enforceable under § 101.

The Federal Circuit's decision on eligibility made the infringement and inducement issues commercially secondary. Once the claims were held invalid, the patents could not block FDA approval or commercial launch based on those claims.

How did the Federal Circuit analyze patent eligibility?

The Federal Circuit applied the two-step framework from Mayo Collaborative Services v. Prometheus Laboratories, Inc. and Alice Corp. v. CLS Bank International. [2, 3]

Step one: Were the claims directed to a natural law?

The Federal Circuit held that the claims were directed to a natural phenomenon or natural law: the relationship between administering inhaled nitric oxide and the reduction of BPD risk in premature infants.

The court treated the claimed patient condition and treatment response as naturally occurring relationships that physicians could observe. The fact that the claims required administration of nitric oxide did not, by itself, remove them from the scope of the judicial exception.

The court distinguished between:

• Discovering that a therapy produces a particular clinical result in a defined patient group; and
• Inventing a new drug, device, or treatment mechanism.

The patents claimed the application of a known therapy to a patient population based on the discovered relationship. That structure placed the claims within the Mayo framework.

Step two: Did the claims add an inventive concept?

The Federal Circuit concluded that the claims did not contain an inventive concept sufficient to transform the natural-law relationship into patent-eligible subject matter.

The administration of inhaled nitric oxide was known. The court also found that the claimed treatment steps used conventional techniques and did not require a new device, a new nitric oxide formulation, or a new method of delivery.

Mallinckrodt argued that the treatment protocol was specific and clinically meaningful. The Federal Circuit rejected specificity alone as a basis for eligibility. A claim may define a narrow patient population and still fail § 101 if the additional steps are routine and conventional.

The court also rejected reliance on the treatment's clinical benefit as an inventive concept. A useful medical result does not cure a claim directed to a natural law when the treatment steps are conventional.

Which claims did the Federal Circuit invalidate?

The Federal Circuit affirmed the District Court's determination that the relevant asserted claims of the '741 and '205 patents were patent-ineligible. The opinion addressed claims directed to treating premature infants with inhaled nitric oxide to reduce the risk or incidence of BPD. [1]

The decision did not invalidate every possible patent claim Mallinckrodt might have held in its broader patent portfolio. It resolved the claims presented in the litigation. The holding was specific to the asserted claim language and the record developed in the case.

The practical result was that Mallinckrodt could not rely on the asserted method claims to prevent Praxair from pursuing FDA approval for its proposed generic nitric oxide product.

What was the Orange Book status of the patents?

The dispute arose in connection with Mallinckrodt's listed patents for its nitric oxide product and Praxair's ANDA filing. The patents were treated as Orange Book-related Hatch-Waxman rights because they were asserted against a proposed generic version of INOmax.

The principal Orange Book implications were:

• Mallinckrodt used listed method-of-use patents to sue after Praxair's ANDA certification.
• Praxair's filing triggered the statutory patent litigation pathway under § 271(e)(2).
• The litigation imposed the statutory approval stay associated with a timely patent infringement action.
• Invalidation of the asserted patents removed those patents as a basis for delaying approval or blocking launch.

The case illustrates the limited value of method-of-use listings when the claims are vulnerable under § 101. A listed patent can trigger Hatch-Waxman litigation but still fail to provide durable market exclusivity.

Was this a Paragraph IV challenge?

Yes. Praxair's ANDA filing challenged Mallinckrodt's patent rights through the Hatch-Waxman certification process. The lawsuit was therefore a Paragraph IV-type patent challenge involving a proposed generic nitric oxide product.

Praxair's principal successful position was not that its product avoided the claims. The decisive result was that the claims themselves were invalid as patent-ineligible.

This distinction matters commercially:

Issue	Outcome
ANDA litigation	Initiated by Mallinckrodt
Alleged infringement theory	Proposed generic labeling and treatment use
Main defense	Invalidity under § 101
District Court result	Asserted claims invalid
Federal Circuit result	Core invalidity judgment affirmed
Effect on generic entry	Asserted patents no longer blocked approval or launch

What was the litigation status after the Federal Circuit decision?

The Federal Circuit's 2020 decision left the asserted claims invalid. The key appellate citation is Mallinckrodt Hospital Products IP Ltd. v. Praxair Distribution Inc., 971 F.3d 1339 (Fed. Cir. 2020). [1]

The Federal Circuit decision was the controlling merits disposition for the asserted claims. The case did not produce a damages award against Praxair because the patents were held invalid before a liability and damages trial.

The litigation did not establish that every Mallinckrodt patent covering nitric oxide was invalid. It established that the specific asserted treatment claims in the case could not support an infringement injunction because they failed the eligibility requirement.

Did the case involve biosimilar risk?

No. This was not a biosimilar dispute.

Praxair's proposed product was a generic nitric oxide product reviewed through the ANDA pathway under the Federal Food, Drug, and Cosmetic Act. The BPCIA pathway for biosimilars was not the relevant regulatory framework.

The distinction affects both the litigation and exclusivity analysis:

Category	Mallinckrodt v. Praxair
Product type	Small-molecule chemical gas therapy
FDA pathway	ANDA
Patent process	Hatch-Waxman
Biologic reference product	None
Biosimilar interchangeability	Not applicable
BPCIA patent dance	Not applicable

What formulation patents and manufacturing patents were relevant?

The case centered on method-of-treatment claims, not a newly invented nitric oxide molecule.

The asserted rights did not depend primarily on:

• A novel active pharmaceutical ingredient;
• A proprietary biologic manufacturing process;
• A complex device architecture;
• A new chemical formulation of nitric oxide.

Nitric oxide is a known active ingredient, and inhaled nitric oxide therapy was established before the asserted patent claims. The case therefore exposed a central weakness in the patent estate: the protection was concentrated in clinical-use claims rather than in difficult-to-reproduce composition, device, or manufacturing technology.

A generic entrant could face other potential barriers, including product quality, container specifications, delivery equipment, manufacturing controls, and FDA requirements. Those regulatory and operational barriers were separate from the invalidated patent claims. They did not preserve the enforceability of the claims at issue in the litigation.

How strong was Mallinckrodt's patent estate?

The asserted estate was weak after the Federal Circuit decision.

Strength factor	Assessment
Active ingredient protection	Limited for nitric oxide as a known compound
Composition protection	Not the principal basis of the case
Device protection	Not the principal basis of the asserted claims
Method-of-use protection	Vulnerable under § 101
Manufacturing barriers	Not enough to preserve the asserted claims
Orange Book leverage	Reduced after invalidity
Generic litigation leverage	Materially weakened
Remaining portfolio value	Dependent on unasserted patents and regulatory barriers

The claims had commercial relevance because they targeted a defined neonatal use for INOmax. Their legal weakness arose from the relationship between the claim structure and the Mayo framework. The patents claimed a medical application of a known therapy based on a discovered clinical relationship, while the treatment steps were conventional.

When did Mallinckrodt lose exclusivity protection from these patents?

Mallinckrodt lost the practical exclusivity value of the asserted patents when the District Court entered judgment of invalidity and the Federal Circuit affirmed the core ruling in 2020.

The statutory expiration dates of the '741 and '205 patents were no longer the decisive commercial dates. An unexpired patent that is invalid cannot support an injunction or block an ANDA product.

This distinction is important for market forecasting:

• Nominal patent expiration asks when the patent term ends.
• Enforceable exclusivity asks whether a valid patent can block competition.
• In this case, enforceability ended through invalidity before ordinary patent expiration became the controlling issue.

What generic launch risks remained after the ruling?

The Federal Circuit decision removed the asserted patent barrier, but it did not guarantee immediate commercial launch.

Potential remaining launch issues included:

1. FDA approval of Praxair's ANDA.
2. Product quality and manufacturing compliance.
3. Compatibility with nitric oxide delivery systems.
4. Hospital contracting and physician adoption.
5. Additional unasserted Mallinckrodt patents.
6. Regulatory exclusivity unrelated to the invalidated claims.
7. Commercial supply and distribution capacity.

The case materially improved the legal position of a generic entrant. It did not determine the entire competitive structure of the inhaled nitric oxide market.

How does this case compare with other pharmaceutical patent cases?

Mallinckrodt v. Praxair is a leading Federal Circuit example of § 101 scrutiny applied to medical treatment claims.

Its holding differs from cases involving:

• A new chemical entity;
• A novel dosage form;
• A specific drug-device combination;
• A nonconventional manufacturing process;
• A treatment protocol requiring a nonroutine technical step.

The case also differs from ordinary obviousness litigation. The Federal Circuit did not need to decide whether the claims would have been obvious under § 103. The claims failed at the threshold eligibility stage.

For pharmaceutical patent drafting, the decision shows the risk of claiming only a discovered treatment correlation plus conventional administration steps. Claims with stronger technical content may have a better chance of surviving eligibility review, although the case itself did not establish a categorical rule for all method-of-treatment patents.

Key Takeaways

• Mallinckrodt sued Praxair in Delaware over generic inhaled nitric oxide products.
• The asserted patents were U.S. Patent Nos. 8,795,741 and 9,463,205.
• The patents covered treatment of premature infants at risk of BPD with inhaled nitric oxide.
• The case proceeded under the Hatch-Waxman ANDA framework.
• The District Court held the asserted claims invalid under § 101.
• The Federal Circuit affirmed the core judgment in 2020.
• The claims failed because they were directed to a natural treatment relationship and used conventional treatment steps.
• The case involved generic competition, not biosimilar competition.
• The ruling removed the asserted patents as a meaningful barrier to Praxair's proposed generic launch.
• The decision did not invalidate every Mallinckrodt patent covering nitric oxide products.

FAQs

What drug was involved in Mallinckrodt v. Praxair?

The dispute involved inhaled nitric oxide therapy associated with Mallinckrodt's INOmax product.

What disease was targeted by the Mallinckrodt patents?

The patents targeted prevention or reduction of bronchopulmonary dysplasia in premature infants.

Did Praxair win the patent case?

Praxair prevailed on the central invalidity issue. The Federal Circuit affirmed that the asserted claims were patent-ineligible under § 101.

Was Mallinckrodt v. Praxair an Orange Book case?

Yes. It arose from an ANDA challenge involving patents listed in connection with Mallinckrodt's nitric oxide product.

Did the case create a precedent against all medical-use patents?

No. The ruling addressed the asserted claims and their specific combination of a natural clinical relationship with conventional administration steps. It did not hold that all medical-use claims are categorically ineligible.

References

1. Mallinckrodt Hospital Products IP Ltd. v. Praxair Distribution Inc., 971 F.3d 1339 (Fed. Cir. 2020).

2. Mayo Collaborative Services v. Prometheus Laboratories, Inc., 566 U.S. 66 (2012).

3. Alice Corp. Pty. Ltd. v. CLS Bank International, 573 U.S. 208 (2014).

4. U.S. Patent No. 8,795,741. U.S. Patent and Trademark Office.

5. U.S. Patent No. 9,463,205. U.S. Patent and Trademark Office.