Litigation Details for Azurity Pharmaceuticals, Inc. v. ANI Pharmaceuticals, Inc. (D. Minnesota 2021)

Azurity Pharmaceuticals, Inc. v. ANI Pharmaceuticals, Inc. (D. Minnesota 2021)

Docket		Date Filed	2021-03-24
Court	District Court, D. Minnesota	Date Terminated	2022-02-22
Cause	35:271 Patent Infringement	Assigned To	Katherine M Menendez
Jury Demand	Both	Referred To	Elizabeth Cowan Wright
Patents	10,688,046
Link to Docket	External link to docket

Details for Azurity Pharmaceuticals, Inc. v. ANI Pharmaceuticals, Inc. (D. Minnesota 2021)

Date Filed	Document No.	Description	Snippet	Link To Document
2021-03-24				External link to document

Azurity Pharmaceuticals v. ANI Pharmaceuticals Patent Litigation: Case 0:21-cv-00796

Last updated: August 3, 2026

Azurity Pharmaceuticals, Inc. v. ANI Pharmaceuticals, Inc., No. 0:21-cv-00796, was a Hatch-Waxman patent dispute involving ANI's proposed generic version of Azurity's Katerzia product, amlodipine besylate oral suspension. Azurity sued after receiving notice of ANI's Paragraph IV certification. The case was resolved without a reported merits judgment establishing patent invalidity or infringement. The public record does not disclose material settlement economics or a definitive generic launch date.

What product was at issue in Azurity v. ANI?

The dispute concerned Katerzia, Azurity's branded amlodipine besylate oral suspension.

Katerzia is an oral liquid calcium-channel blocker used to treat hypertension. Its formulation is intended for patients who cannot reliably use conventional tablets or capsules, including pediatric patients and patients with swallowing limitations. The product is distinct from standard amlodipine tablets because the commercial value is tied to the liquid dosage form, concentration, excipient system, and dosing convenience.

Item	Case-related information
Brand	Katerzia
Active ingredient	Amlodipine besylate
Dosage form	Oral suspension
Strength	1 mg/mL
Reference sponsor	Azurity Pharmaceuticals
Generic applicant	ANI Pharmaceuticals
Regulatory pathway	ANDA
Litigation type	Hatch-Waxman patent litigation
Federal case	No. 0:21-cv-00796
Court	U.S. District Court for the District of Minnesota
Biologic issue	None; biosimilar rules do not apply

FDA approved Katerzia under NDA 211904 in 2019. The product is regulated as a small-molecule drug, so ANI's challenge proceeded through the ANDA and Paragraph IV framework rather than the Biologics Price Competition and Innovation Act pathway. [1]

What patents protected Katerzia?

Azurity's case relied on patents covering the amlodipine oral-suspension formulation and related pharmaceutical composition claims. The patents were directed to the liquid product rather than to the basic discovery of amlodipine as an antihypertensive agent.

The principal patent issues in a Katerzia-type case are:

1. Whether ANI's proposed suspension falls within the asserted composition claims.
2. Whether the asserted claims are valid over earlier amlodipine formulations and conventional suspension technology.
3. Whether the claims adequately distinguish a pharmaceutical suspension from an ordinary liquid dosage form.
4. Whether formulation-specific patent term extends beyond the underlying regulatory exclusivity period.

The publicly available case materials should be read together with the FDA Orange Book listings for NDA 211904. Orange Book listings identify patents that the NDA holder or sponsor submitted for patent certification purposes. They do not establish that every listed patent will survive validity review or necessarily cover every generic formulation. [2]

Because the litigation ended without a reported final merits opinion, the case does not provide a judicial ruling on the ultimate scope or validity of the asserted Katerzia patents.

What formulations were protected?

The commercial protection was formulation-based. The relevant claim categories generally concern:

• Amlodipine dispersed in an aqueous oral vehicle.
• Suspension stability during storage.
• Uniform dosing from the container.
• Excipient combinations that maintain dispersion and palatability.
• Concentration and administration characteristics suited to oral-liquid delivery.

Formulation claims can be commercially important even when the active ingredient itself is long off patent. A generic applicant may avoid infringement by changing excipients, particle-size distribution, viscosity, preservative system, or manufacturing parameters. That design-around question normally turns on the claim language and the ANDA's Paragraph IV notice, not on the generic label alone.

What was ANI's Paragraph IV challenge?

ANI's ANDA filing triggered a Paragraph IV dispute. Under the Hatch-Waxman Act, an ANDA applicant may certify that an Orange Book-listed patent is invalid, unenforceable, or will not be infringed by the proposed generic product. The applicant must send a detailed notice to the patent owner and NDA holder.

Azurity's lawsuit followed the Paragraph IV notice. Filing the action within the statutory period generally triggers a 30-month stay preventing FDA approval of the ANDA, subject to statutory exceptions and court action. The stay protects the branded sponsor while the parties litigate patent claims. [3]

The practical effect was to delay regulatory approval of ANI's proposed generic while the patent dispute remained pending. The Paragraph IV filing also created the possibility of an earlier generic entry date if the parties settled on terms favorable to ANI or if the patents were held invalid or not infringed.

When did Katerzia lose exclusivity?

Katerzia's market protection depends on three separate timelines:

Protection	Function	Relevance
FDA new-drug exclusivity	Blocks certain FDA approvals for a defined period	Does not itself create a permanent prohibition on ANDA filing
Orange Book patent protection	Supports patent certifications and litigation	Can delay approval through the 30-month stay
Formulation and method-of-use claims	May restrict specific generic designs or indications	Scope depends on claim construction and the ANDA

Katerzia's New Chemical Entity exclusivity was not the principal barrier in the 2021 litigation. Amlodipine was an established active ingredient before Katerzia's approval. The dispute therefore centered on formulation patents and any applicable regulatory exclusivity rather than exclusivity for a new active ingredient.

Patent expiration is not equivalent to an automatic commercial launch date. ANI's launch would also depend on:

• FDA approval of the ANDA.
• Any settlement restrictions.
• Patent-term adjustment or pediatric-exclusivity effects.
• A court order lifting or shortening the 30-month stay.
• Whether Azurity asserted additional patents.
• Whether ANI's final approved product matched the formulation described in the litigation.

What was the litigation timeline?

The core timeline is as follows:

Date or period	Event
2019	FDA approved Katerzia under NDA 211904.
2021	ANI submitted an ANDA and issued a Paragraph IV notice.
2021	Azurity filed Case No. 0:21-cv-00796 in the District of Minnesota.
2021 onward	The parties litigated the patent and ANDA issues under the Hatch-Waxman framework.
Case disposition	The action ended without a reported trial judgment or appellate merits decision.

The docket number indicates a 2021 civil action in the District of Minnesota. The case was not a standalone patent-validity test case. It was an ANDA dispute tied to a specific proposed product and the Orange Book patents asserted against that product.

What was the final litigation status?

The case did not produce a reported decision holding the asserted patents invalid, unenforceable, or infringed. The public record also does not provide a judicially determined generic entry date based on a contested merits ruling.

The absence of a merits opinion has several consequences:

• The case does not create binding precedent on the asserted claims.
• The court did not publicly establish the outer boundary of Azurity's formulation patent rights.
• ANI's litigation position cannot be treated as a final determination that the generic product was noninfringing.
• Azurity's patents were not judicially confirmed as valid and enforceable through a final judgment.
• The commercial result depends on the terms of the resolution and the later FDA status of ANI's ANDA.

Where a Hatch-Waxman case ends by settlement or stipulated dismissal, the settlement may determine the practical entry date without resolving patent validity. Settlement terms in pharmaceutical cases are often confidential. Unless the parties disclose a date or the Federal Trade Commission or another public filing reports the agreement, the case docket alone may not establish the exact commercial restrictions.

Did the case produce a Paragraph IV settlement?

The public case record does not provide a reported judicial opinion analyzing a final settlement agreement's detailed terms. Any settlement analysis should distinguish between:

1. A docket disposition terminating the lawsuit.
2. A confidential commercial agreement.
3. A public FDA approval date.
4. An actual commercial launch.

Those events can occur at different times. A dismissal does not necessarily mean that ANI could launch immediately. The parties may have agreed to a delayed entry date, an authorized-generic arrangement, a license, or other restrictions. Conversely, a dismissal can remove the litigation barrier if no contractual restriction remains.

No publicly reported authorized-generic transaction or royalty structure is established by the case materials alone.

What is the FDA and Orange Book status of Katerzia?

Katerzia is an FDA-approved small-molecule oral suspension. The relevant regulatory record is the NDA and Orange Book entry, not a biologics reference-product listing.

The FDA status has four commercial implications:

• The reference product is approved and eligible for ANDA-based competition.
• ANI's product would need to demonstrate pharmaceutical equivalence and bioequivalence or satisfy the applicable ANDA requirements.
• Orange Book-listed patents can generate Paragraph IV litigation.
• FDA approval and patent clearance are separate questions.

The FDA does not decide patent infringement when approving an ANDA. Patent disputes are handled through the Hatch-Waxman certification process and federal litigation. [2][3]

How strong was Azurity's patent estate?

Azurity's estate was commercially meaningful because it targeted a differentiated dosage form with fewer direct substitutes than conventional tablets. Its strength was narrower than a composition-of-matter estate covering amlodipine itself.

Strengths

• The patents were directed to a marketed formulation with clinical and administration advantages.
• Liquid formulations can create technical barriers involving suspension stability and dose uniformity.
• Generic substitution may be less straightforward when pediatric dosing and administration devices are part of the product profile.
• A Paragraph IV case can delay FDA approval even before a final merits decision.

Weaknesses

• Amlodipine is an old active ingredient with extensive prior art.
• Formulation claims are vulnerable to obviousness and written-description challenges.
• A generic applicant may pursue an alternative excipient or manufacturing system.
• The patent estate may cover only particular formulation parameters rather than every oral suspension.
• The lack of a reported merits judgment leaves enforceability and claim scope unresolved.

The estate should therefore be characterized as formulation-focused and commercially relevant, but not equivalent to broad active-ingredient exclusivity.

Which companies were challenging Katerzia?

ANI was the defendant in Case No. 0:21-cv-00796. The case reflects the competitive pattern for specialty oral liquids: a branded sponsor seeks to protect a differentiated formulation while a generic company tests whether the product can be replicated or designed around through an ANDA.

Potential competitors would include other ANDA applicants, but the cited case establishes ANI's challenge only. It does not establish that every competing generic applicant was involved in the litigation.

What generic entry risks existed for Azurity?

Azurity faced four primary risks.

Formulation design-around

ANI could seek approval for a formulation that avoided one or more asserted claim limitations. This is the principal risk in a formulation-patent case.

Patent invalidity

Prior art involving amlodipine suspensions, oral liquid drug delivery, taste masking, and suspension stabilization could support obviousness arguments.

Settlement-based entry

A settlement could permit entry before patent expiration. The actual date would depend on the agreement and any regulatory exclusivity held by ANI.

Price erosion

Even a single generic entrant can produce substantial price pressure in a small specialty market. The effect depends on payer substitution, pharmacy practice, product availability, and whether the generic is therapeutically substitutable for the reference suspension.

What revenue exposure did the case create?

The case created direct exposure for Azurity's Katerzia franchise rather than for all amlodipine sales. The relevant revenue base is the branded oral-suspension market, not the much larger market for amlodipine tablets.

Revenue risk would increase if:

• ANI received FDA approval soon after the litigation ended.
• The generic was substitutable at the pharmacy level.
• Other applicants entered around the same time.
• Azurity lacked a materially differentiated pediatric or specialty distribution channel.
• The settlement allowed early entry before the last meaningful formulation patent expired.

Revenue risk would be lower if Azurity retained a long patent runway, ANI's ANDA was delayed, the generic required a non-substitutable label, or the parties agreed to a later entry date.

How does this case compare with biosimilar litigation?

This was not biosimilar litigation. Katerzia is a small-molecule drug, and ANI's product would proceed through an ANDA. The comparison matters because:

Issue	Katerzia generic case	Biosimilar case
Statute	Hatch-Waxman Act	BPCIA
Application	ANDA	351(k) application
Product	Small molecule	Biologic
Core showing	Equivalence and bioequivalence	Biosimilarity or interchangeability
Patent process	Paragraph IV certification	BPCIA patent-exchange framework
Orange Book	Applicable	Not the primary listing system

Key Takeaways

• Azurity Pharmaceuticals v. ANI Pharmaceuticals, No. 0:21-cv-00796, was a Hatch-Waxman dispute involving ANI's proposed generic Katerzia oral suspension.
• Azurity's protection was formulation-based, not a broad patent on amlodipine.
• ANI's Paragraph IV certification triggered patent litigation and the statutory approval stay.
• The case ended without a reported merits ruling on infringement, validity, or enforceability.
• Public case materials do not establish a detailed settlement structure or definitive commercial launch date.
• Biosimilar law is irrelevant because Katerzia is a small-molecule drug.
• The principal business risk was formulation design-around followed by generic price erosion in the specialty oral-liquid market.

FAQs

Does Azurity v. ANI establish that Katerzia's patents are valid?

No. The case did not produce a reported final merits decision confirming validity or infringement.

Can ANI launch a generic Katerzia after the case ended?

Case termination alone does not establish an immediate launch right. Launch depends on FDA approval, any applicable patent rights, and the terms of any private settlement.

Is Katerzia protected by a patent on amlodipine itself?

No. The litigation concerned the specialized oral-suspension formulation. Amlodipine is an established active ingredient.

Does Katerzia have biosimilar competition?

No. Katerzia is a small-molecule drug. Any competing product would generally follow the generic-drug pathway, not the biosimilar pathway.

What is the main patent risk for a Katerzia generic?

The principal risk is infringement of formulation claims covering the composition, suspension characteristics, excipients, stability, or manufacturing process used in the ANDA product.

References

1. U.S. Food and Drug Administration. (2019). Katerzia (amlodipine besylate) oral suspension, NDA 211904: Approval information and prescribing information. FDA.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

3. U.S. Congress. (1984). Drug Price Competition and Patent Term Restoration Act of 1984, Pub. L. No. 98-417, 98 Stat. 1585.

4. U.S. District Court for the District of Minnesota. (2021). Azurity Pharmaceuticals, Inc. v. ANI Pharmaceuticals, Inc., No. 0:21-cv-00796, docket materials. U.S. Courts.