Last updated: February 19, 2026
This report summarizes the patent litigation between Azurity Pharmaceuticals, Inc. and Alkem Laboratories Ltd. in U.S. District Court for the District of Delaware. The case, Azurity Pharmaceuticals, Inc. v. Alkem Laboratories Ltd., Case No. 1:19-cv-02100, concerns Alkem's Abbreviated New Drug Application (ANDA) seeking to market a generic version of Azurity's albuterol sulfate inhalation solution.
What is the core dispute in Azurity Pharmaceuticals, Inc. v. Alkem Laboratories Ltd.?
The central issue in this litigation is the alleged infringement of U.S. Patent No. 7,575,761 (the '761 patent) by Alkem Laboratories Ltd. Azurity Pharmaceuticals, Inc. filed the lawsuit alleging that Alkem's proposed generic albuterol sulfate inhalation solution infringes claims of the '761 patent. Alkem denies infringement and challenges the validity of the patent.
What are the key patents and products involved?
The primary patent at issue is U.S. Patent No. 7,575,761, titled "Albuterol Sulfate Inhalation Solution." This patent is listed in the U.S. Food and Drug Administration's (FDA) Orange Book for Azurity's albuterol sulfate inhalation solution, marketed under the brand name ProAir HFA.
ProAir HFA is a metered-dose inhaler (MDI) used to treat or prevent bronchospasm in patients 4 years of age and older with reversible bronchospasm owing to an associated with the condition of a reversible obstructive airway disease. The active ingredient is albuterol sulfate.
Alkem Laboratories Ltd. filed an ANDA with the FDA seeking approval to market a generic version of ProAir HFA.
What are the alleged acts of infringement?
Azurity alleges that Alkem's proposed generic albuterol sulfate inhalation solution, if approved and marketed, would infringe one or more claims of the '761 patent. Specifically, Azurity contends that Alkem's ANDA certification under 21 U.S.C. § 355(j)(2)(A)(vii)(IV) (Paragraph IV certification) constitutes an assertion that the '761 patent is invalid, unenforceable, or will not be infringed by Alkem's generic product.
Alkem's Paragraph IV certification asserts that the '761 patent is invalid and/or will not be infringed.
What are Alkem's defenses and arguments?
Alkem has raised several defenses and arguments in response to Azurity's infringement claims. These typically include:
- Non-infringement: Alkem argues that its generic product does not infringe any valid and enforceable claims of the '761 patent. This often involves detailed technical arguments about the composition, formulation, or method of use of the respective products.
- Invalidity: Alkem challenges the validity of the '761 patent on grounds such as lack of novelty, obviousness, or insufficient written description. This involves analyzing prior art and patent law principles to demonstrate why the patent should not have been granted or should not be enforceable.
What has been the procedural history of the case?
The litigation commenced with Azurity filing its complaint on December 3, 2019. Alkem filed its answer and counterclaims on January 3, 2020.
Key procedural milestones include:
- Complaint Filing: December 3, 2019
- Answer and Counterclaims: January 3, 2020
- Discovery: The parties engaged in extensive fact and expert discovery, including depositions, interrogatories, and production of documents.
- Claim Construction (Markman Hearing): The court held a Markman hearing to construe the disputed claims of the '761 patent. The court's claim construction order is critical in defining the scope of the patent protection. The court issued its Claim Construction Opinion on May 4, 2021.
- Motions for Summary Judgment: Both parties may file motions for summary judgment seeking to resolve certain issues without a full trial.
- Trial: If issues remain unresolved after summary judgment motions, the case proceeds to trial.
What was the outcome of the Markman hearing?
The Markman hearing is a critical stage where the court interprets the meaning and scope of patent claims. In this case, the court issued its Claim Construction Opinion on May 4, 2021. The court construed several key terms within the '761 patent.
For example, the court construed the term "pharmaceutically acceptable salt" in claim 1. Azurity argued that the term encompassed albuterol sulfate. Alkem argued for a narrower construction that would not encompass albuterol sulfate. The court adopted Azurity's proposed construction, finding that "albuterol sulfate" is a "pharmaceutically acceptable salt" of albuterol.
The court also construed the term "unit dose container." The parties presented differing interpretations, and the court's construction clarified the scope of this term in the context of the patent claims.
What were the key arguments presented at trial (if applicable)?
As of the latest available information, the case has seen significant proceedings, including a Markman hearing and potential for further dispositive motions. While a full trial may not have concluded or may still be pending, the parties' arguments center on:
Azurity's Arguments:
- Direct Infringement: Alkem's proposed generic product, when manufactured, used, or sold, will directly infringe claims of the '761 patent as construed by the court.
- Inducement and Contributory Infringement: Alkem is inducing others to infringe and contributing to the infringement of the '761 patent.
- Validity: The '761 patent is valid and enforceable.
Alkem's Arguments:
- Non-Infringement: Alkem's product does not fall within the scope of the construed claims.
- Invalidity: The '761 patent is invalid due to prior art that anticipates or renders the claimed invention obvious. This often involves arguments related to specific prior art references that disclose or suggest elements of the patented invention.
- Lack of Enablement/Written Description: In some cases, defendants may argue that the patent does not adequately describe or enable the full scope of its claims.
What are the potential outcomes of the litigation?
The potential outcomes of this litigation are:
- Judgment of Infringement: If the court finds that Alkem infringes the '761 patent, and the patent is found valid and enforceable, Alkem may be blocked from launching its generic product. The court could issue an injunction preventing such launch.
- Judgment of Non-Infringement: If the court finds that Alkem does not infringe the '761 patent, Alkem may be able to launch its generic product.
- Judgment of Invalidity: If the court finds the '761 patent invalid, Azurity's ability to prevent generic competition based on this patent would be eliminated.
- Settlement: The parties may reach a settlement agreement at any stage of the litigation, which could involve licensing or other terms allowing for the launch of a generic product under specific conditions.
What is the significance of the '761 patent for ProAir HFA?
The '761 patent is a key piece of intellectual property that provides Azurity with market exclusivity for its ProAir HFA product. Its expiration or successful challenge by a generic manufacturer directly impacts the competitive landscape and the potential for generic entry. The patent's claims define the scope of Azurity's protection against generic versions of its albuterol sulfate inhalation solution.
What is the status of the litigation and potential for generic entry?
As of recent filings, the litigation is ongoing. The court's claim construction ruling is a significant development. The parties continue to litigate the remaining issues, including validity and infringement. The final resolution will determine when, or if, Alkem can launch its generic albuterol sulfate inhalation solution. A final judgment or settlement will dictate the timeline for generic entry.
Key Takeaways
- Azurity Pharmaceuticals, Inc. is asserting U.S. Patent No. 7,575,761 against Alkem Laboratories Ltd.'s proposed generic albuterol sulfate inhalation solution.
- The core dispute involves allegations of patent infringement and defenses of non-infringement and patent invalidity.
- A critical ruling in the case was the court's claim construction order, which defined the scope of key patent terms.
- The outcome will determine Alkem's ability to launch its generic product and will significantly impact market exclusivity for Azurity's ProAir HFA.
Frequently Asked Questions
What is an Abbreviated New Drug Application (ANDA)?
An ANDA is the pathway for generic drug manufacturers to seek FDA approval to market a generic version of an already-approved brand-name drug. It demonstrates that the generic drug is bioequivalent to the brand-name drug.
What is a Paragraph IV certification?
A Paragraph IV certification is made by a generic drug applicant in their ANDA, asserting that the patent covering the brand-name drug is invalid, unenforceable, or will not be infringed by the generic drug. This action can trigger patent litigation.
What is a Markman hearing?
A Markman hearing is a pretrial proceeding in patent litigation where the court determines the meaning and scope of patent claims. The court's claim construction ruling is binding on the parties and often dictates the outcome of infringement and validity disputes.
What are the implications of the '761 patent's validity for Azurity's market exclusivity?
If the '761 patent is found to be valid and infringed, it can prevent Alkem from launching its generic product, thereby extending Azurity's market exclusivity for ProAir HFA. Conversely, if the patent is found invalid, it opens the door for generic competition.
What is prior art in the context of patent litigation?
Prior art refers to any evidence that a particular invention is already known. This can include existing patents, publications, or public uses that existed before the filing date of the patent in question. Defendants often use prior art to argue that a patent is invalid due to obviousness or lack of novelty.
Citations
[1] Azurity Pharmaceuticals, Inc. v. Alkem Laboratories Ltd., No. 1:19-cv-02100 (D. Del. Filed Dec. 3, 2019).
[2] Azurity Pharmaceuticals, Inc. v. Alkem Laboratories Ltd., No. 1:19-cv-02100, 2021 WL 1784508 (D. Del. May 4, 2021).
