Last updated: August 7, 2026
Azurity Pharmaceuticals, Inc. v. Alkem Laboratories Ltd., No. 1:19-cv-02100, was a Hatch-Waxman patent case in the U.S. District Court for the District of Delaware. Azurity sued Alkem after receiving notice of an abbreviated new drug application, or ANDA, challenging patent protection for an Azurity oral-liquid pharmaceutical product. The case ended without a publicly reported merits decision establishing infringement or invalidity. The docket reflects a negotiated resolution and does not disclose the commercial terms.
What was Azurity Pharmaceuticals v. Alkem Laboratories about?
The dispute concerned Alkem's proposed generic oral solution and Azurity's listed formulation patent rights. The case was filed in 2019 under the Hatch-Waxman Act, which permits a branded drug company to sue after receiving a Paragraph IV certification that an Orange Book-listed patent is invalid, unenforceable, or will not be infringed by the proposed generic product.
Azurity's complaint sought the standard Hatch-Waxman remedies:
- A declaration that Alkem's ANDA product would infringe the asserted patent;
- An injunction preventing FDA approval or commercial launch before patent expiration;
- A statutory 30-month stay of FDA approval under 21 U.S.C. § 355(j)(5)(B)(iii);
- Costs and other relief authorized by the patent laws.
The case was assigned to the District of Delaware under civil action number 1:19-cv-02100.
Which drug and formulation were involved?
Public patent and regulatory records associate the litigation with Azurity's prescription oral-liquid product portfolio, including the formulation technology used for pediatric and other patients who have difficulty swallowing tablets. The relevant commercial issue was an oral solution rather than a conventional tablet or capsule.
Azurity's business model relies heavily on liquid dosage forms, which can create patent value through:
- Active-ingredient solubilization;
- pH control;
- Chemical stability;
- Taste masking;
- Preservative systems;
- Dose uniformity;
- Storage stability;
- Pediatric administration.
These formulation characteristics can support Orange Book-listed patents even when the active pharmaceutical ingredient itself is old and off-patent.
What formulation patents protect Azurity products?
The asserted rights were formulation-focused rather than composition-of-matter patents covering a new molecular entity. That distinction matters. A formulation patent generally does not prevent all use of the active ingredient. It targets a particular combination of excipients, concentration range, pH, stability profile, manufacturing process, or dosage form.
Formulation claims can cover:
| Protection category |
Typical claim scope |
| Liquid composition |
Active ingredient combined with specified solvents, buffers, preservatives, or stabilizers |
| Concentration |
Defined amount of drug per milliliter |
| pH range |
pH limits that improve stability or palatability |
| Stability |
Product remaining within impurity or potency limits over a specified period |
| Manufacturing method |
Order of addition, mixing, filtration, or packaging steps |
| Use |
Administration to a defined patient population or through a particular dosing regimen |
The commercial strength of such claims depends on whether the generic applicant can alter excipients or pH without losing bioequivalence, stability, or FDA approval.
What patent did Azurity assert against Alkem?
The litigation is associated with Azurity's oral-liquid formulation patent estate, including U.S. Patent No. 9,669,036. The patent was issued in 2017 and relates to oral liquid pharmaceutical formulations. Its term was projected into the 2030s based on the patent's filing and priority history. The relevant expiration date should be taken from the current FDA Orange Book and USPTO records because patent-term adjustment and terminal-disclaimer information can affect the operative date.
The asserted patent was not a biologic patent and did not create biosimilar exclusivity. It was a small-molecule formulation patent used in an ANDA dispute.
How strong was Azurity's patent estate?
The estate had moderate commercial value but narrower legal breadth than a new-chemical-entity patent.
Strengths included:
- The patent targeted the marketed liquid dosage form.
- A generic applicant may have limited flexibility to change excipients while maintaining stability and bioequivalence.
- The patent could delay approval through the Hatch-Waxman 30-month stay.
- Pediatric and oral-liquid formulations have fewer direct substitutes than tablets.
Limitations included:
- The active ingredient was not protected by a new-molecule composition patent.
- Alkem could challenge written description, enablement, anticipation, obviousness, and claim construction.
- A generic company could attempt a non-infringing formulation design-around.
- The patent's remaining term was shorter than the life of a typical new chemical entity patent.
- The formulation claims may have covered only specific excipient and concentration combinations.
The resolution without a merits ruling means the public record does not establish whether the patent would have survived invalidity challenges or whether Alkem's ANDA product would have infringed.
Was this a Paragraph IV patent challenge?
Yes. The litigation was a Hatch-Waxman case triggered by Alkem's ANDA certification. A Paragraph IV certification alleges that an Orange Book-listed patent is invalid, unenforceable, or not infringed by the proposed generic product.
The certification gave Azurity a statutory basis to sue. Filing the action within the applicable 45-day period triggered the FDA approval stay. The stay generally prevents FDA approval for up to 30 months, unless the court resolves the case earlier or another statutory event terminates the stay.
The case therefore created two separate effects:
- A patent dispute over infringement and validity;
- A regulatory delay affecting the timing of Alkem's potential FDA approval.
A Paragraph IV filing is not itself proof that a patent is weak. It is the mechanism used by generic applicants to challenge listed patents before launch.
What was the litigation timeline?
| Date or period |
Event |
| 2019 |
Alkem submitted an ANDA containing a Paragraph IV certification directed to Azurity's listed patent rights. |
| 2019 |
Azurity filed Civil Action No. 1:19-cv-02100 in the District of Delaware. |
| 2019-2020 |
The parties litigated under the Hatch-Waxman framework, including pleadings, patent-infringement issues, and discovery. |
| 2020-2021 |
The parties reached a negotiated resolution. |
| Case disposition |
The action terminated without a publicly reported trial judgment on infringement or patent validity. |
The docket does not provide a reported claim-construction ruling, summary-judgment decision, Federal Circuit opinion, or final judgment invalidating the asserted patent.
Did Azurity and Alkem enter a settlement agreement?
The case was resolved by agreement, but the publicly available docket does not disclose the principal commercial terms. The record does not establish:
- The agreed generic launch date;
- Whether Alkem received a license;
- Whether Alkem agreed to an authorized-generic restriction;
- Any supply or co-promotion arrangement;
- Any payment from Azurity to Alkem;
- Whether Alkem's ANDA was amended;
- The precise scope of any patent-license grant.
A settlement normally ends the immediate litigation risk but does not necessarily eliminate generic-entry risk. The key commercial question is whether the settlement permits Alkem to launch before patent expiration and under what conditions. Where that date is confidential, market participants cannot determine the launch impact solely from the dismissal docket.
What was the FDA and Orange Book status?
The dispute arose from the Orange Book listing of Azurity patent rights for an FDA-approved prescription oral-liquid product. Under the Hatch-Waxman framework, the Orange Book listing enabled Azurity to receive notice of Alkem's Paragraph IV certification and to invoke the 30-month approval stay.
The regulatory sequence was:
- Azurity obtained FDA approval for its oral-liquid product.
- Azurity listed qualifying patent information in the Orange Book.
- Alkem filed an ANDA referencing the branded product.
- Alkem certified under Paragraph IV to the listed patent.
- Azurity sued within the statutory period.
- FDA approval was stayed during the statutory period or until earlier resolution.
- The litigation ended through settlement rather than a public merits judgment.
FDA approval and patent clearance are separate questions. Even if Alkem obtained FDA approval after the stay, commercial launch could remain subject to the settlement agreement or continuing patent rights.
When does Azurity's product lose exclusivity?
The product's exclusivity is divided into regulatory exclusivity and patent exclusivity.
Regulatory exclusivity
Regulatory exclusivity depends on the product's NDA classification and approval date. For a conventional small-molecule drug, the principal periods may include:
- Five-year new chemical entity exclusivity;
- Three-year exclusivity for certain clinical investigations supporting a new indication, dosage form, or change;
- Six-month pediatric exclusivity, if granted;
- Orphan-drug exclusivity, if applicable.
Formulation products containing previously approved active ingredients generally do not receive five-year new chemical entity exclusivity solely because the product is an oral solution.
Patent exclusivity
Patent protection depends on the listed patent's enforceable expiration date, including patent-term adjustment, terminal disclaimers, pediatric extensions, and any later patent grants. For the Azurity formulation estate, the relevant patent term extended into the 2030s, subject to the applicable USPTO and FDA records.
The settlement may permit an earlier launch than the nominal patent expiration. That launch date cannot be inferred from the public docket when the agreement is confidential.
What generic-entry risks exist for Azurity?
Azurity faced three principal risks.
Alkem launch risk
A settlement can give the generic applicant a defined launch right before patent expiration. If Alkem received an agreed entry date, Azurity would lose exclusivity earlier than the statutory patent term suggests.
Formulation design-around risk
Alkem could develop a liquid formulation outside the asserted claim scope. This risk is greater where the active ingredient is old and the patent claims are limited to excipients, pH, or concentration.
Additional ANDA applicants
A settlement with Alkem does not bind unrelated generic companies unless they obtain a license or rely on the same patent resolution. Other manufacturers can submit their own ANDAs and Paragraph IV challenges, creating separate litigation.
Which companies could challenge Azurity's patent estate?
The public case concerns Alkem. Other potential challengers would include generic companies with pediatric-liquid manufacturing capabilities or established portfolios in the relevant active ingredient. The existence of an ANDA challenge by Alkem does not establish that other companies filed Paragraph IV certifications.
The practical challenger profile includes:
- Indian generic manufacturers with U.S. ANDA operations;
- U.S. generic companies with oral-liquid manufacturing capacity;
- Contract manufacturers able to produce preservative-controlled liquids;
- Companies seeking a first generic or limited-competition launch.
The commercial value of a challenge depends on whether the product has meaningful prescription volume and whether a generic can manufacture at scale without stability or supply problems.
Does biosimilar risk affect this case?
No. The dispute involved a small-molecule oral solution and an ANDA, not a biologic licensed under the Public Health Service Act. Biosimilar concepts such as reference-product exclusivity, interchangeability, and the Biologics Price Competition and Innovation Act do not govern this case.
The relevant competitive pathway was generic substitution under the Hatch-Waxman Act.
How did the case affect Azurity's commercial position?
The litigation protected the branded product against immediate ANDA approval, but the ultimate economic effect depends on the settlement terms and Alkem's launch behavior.
A generic oral solution can produce rapid price erosion if:
- The generic is therapeutically substitutable;
- State substitution rules apply;
- Multiple manufacturers enter;
- Wholesalers maintain generic inventory;
- The branded product lacks a significant clinical differentiation.
Azurity could retain pricing power if the product serves a specialized pediatric or medically complex population and generic manufacturing remains difficult. Liquid products can have higher manufacturing and packaging costs than tablets, which may reduce the number of entrants.
Publicly available case materials do not establish Azurity's product-specific revenue, the percentage of company revenue exposed to Alkem's proposed product, or the financial terms of the settlement.
What patent litigation affects Azurity's oral-liquid portfolio?
Azurity's broader patent risk extends beyond this single case. Its portfolio depends on formulation patents, method-of-use patents, and regulatory exclusivity for products that often contain mature active ingredients.
The primary legal vulnerabilities are:
- Obviousness based on known oral-liquid excipients;
- Anticipation by earlier liquid formulations;
- Lack of written description across broad formulation ranges;
- Enablement challenges for stability claims;
- Non-infringement through excipient substitution;
- Orange Book listing disputes;
- Patent-term and terminal-disclaimer issues.
Method-of-use patents are generally narrower than formulation patents in an ANDA case. A generic applicant may certify that it will omit a patented indication or use a skinny label, reducing method-of-use infringement exposure. Formulation patents are often more important for an oral solution because they can cover the product as manufactured and sold.
Key Takeaways
- Azurity Pharmaceuticals sued Alkem Laboratories in the District of Delaware in Hatch-Waxman litigation under case number 1:19-cv-02100.
- The dispute involved an ANDA and a Paragraph IV challenge to Azurity's oral-liquid formulation patent rights.
- U.S. Patent No. 9,669,036 is associated with the asserted oral-liquid formulation estate.
- The case ended through a negotiated resolution without a public merits ruling on infringement or validity.
- Settlement terms, including any agreed generic launch date, are not publicly disclosed in the docket.
- The dispute involved a small-molecule ANDA, not a biosimilar application.
- Azurity's principal exposure is formulation-patent erosion, design-around activity, and future Paragraph IV challenges by other generic applicants.
- The commercial impact cannot be measured from the docket because product-specific revenue and settlement economics are not public.
FAQs
What court handled Azurity v. Alkem?
The case was filed in the U.S. District Court for the District of Delaware as Civil Action No. 1:19-cv-02100.
Did Alkem win the patent case?
No public merits decision establishes that Alkem won on infringement or invalidity. The litigation ended through negotiated resolution.
Was Azurity's patent invalidated?
The public case record does not report a judgment invalidating the asserted patent.
Can another generic company still challenge Azurity's patents?
Yes. A settlement with Alkem does not automatically prevent unrelated ANDA applicants from filing separate Paragraph IV challenges.
Is Azurity v. Alkem relevant to biosimilar litigation?
No. The case involved a small-molecule oral solution and the ANDA pathway, not a biologic and biosimilar application.
References
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U.S. District Court for the District of Delaware. (2019). Azurity Pharmaceuticals, Inc. v. Alkem Laboratories Ltd., No. 1:19-cv-02100. PACER/RECAP docket records.
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U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
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U.S. Patent and Trademark Office. (2017). U.S. Patent No. 9,669,036, oral liquid pharmaceutical formulations. USPTO.
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Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j).
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Drug Price Competition and Patent Term Restoration Act of 1984, Pub. L. No. 98-417, 98 Stat. 1585.
