US Patent 10,695,329: Amlodipine Oral Suspension Scope, Expiration, Orange Book Status, and Generic Risk

US Patent 10,695,329 protects a specific 1 mg/mL amlodipine oral liquid architecture centered on amlodipine benzoate, citrate buffer, sodium benzoate, hydroxypropyl methylcellulose, silicon dioxide, simethicone, polysorbate 80, water, and defined stability performance. The patent is commercially relevant to Katerzia, an amlodipine benzoate oral suspension marketed by Azurity Pharmaceuticals. Its principal value is formulation protection, not protection for amlodipine as an active pharmaceutical ingredient.

The patent issued June 30, 2020. Its nominal 20-year term runs into 2035, subject to any patent-term adjustment. The claims do not cover every amlodipine liquid. They target a narrow but commercially important formulation with defined excipient concentrations, pH, active concentration, and degradation limits.

What does US Patent 10,695,329 protect?

The independent claim protects an oral liquid formulation containing the following required elements:

Claim element	Required limitation
Active ingredient	Amlodipine benzoate corresponding to 1.0 mg/mL amlodipine freebase
Buffer	3 mM citrate buffer
Sodium benzoate	0.2 mg/mL to about 10 mg/mL
Silicon dioxide	0.5 mg/mL
Hydroxypropyl methylcellulose	7.5 mg/mL
Simethicone	0.15 mg/mL
Polysorbate 80	1.0 mg/mL
Vehicle	Water
pH	4 to about 6
Refrigerated stability	At least 12 months at 5±5°C
Assay and impurities	At least 95% of initial amlodipine and no more than 5% total impurities or related substances

Claim 1 is an open-ended “comprising” claim. A formulation may therefore contain additional excipients and remain within the claim if it includes every required limitation.

The claim has two distinct components. The first is a composition-defined formulation. The second is a performance-defined stability requirement. A competing product must satisfy both categories to fall within the literal scope of claim 1.

How narrow is the composition claimed by US 10,695,329?

The composition is narrow in excipient identity and concentration but broad in the use of additional ingredients.

The claim requires exact or nearly exact concentrations for several components:

0.5 mg/mL silicon dioxide;
7.5 mg/mL hydroxypropyl methylcellulose;
0.15 mg/mL simethicone; and
1.0 mg/mL polysorbate 80.

The sodium benzoate limitation is broader because it covers a range from 0.2 mg/mL to about 10 mg/mL. The pH limitation is also relatively broad, covering pH 4 to about 6, with claim 10 narrowing the range to pH 5 to 6.

A formulation using a materially different suspending agent, omitting simethicone, or replacing polysorbate 80 may avoid literal infringement. A formulation with the same ingredients but materially different concentrations may also avoid literal infringement, although the doctrine of equivalents could become relevant in litigation.

The use of “about” creates potential claim-construction disputes for sodium benzoate and the upper pH boundary. The fixed numerical limitations are more vulnerable to design-around strategies than the two “about” limitations.

What do claims 2 through 5 add?

Claims 2 through 5 protect in situ formation of amlodipine benzoate.

Claim	Added limitation
2	Amlodipine benzoate is formed in situ
3	Formation uses a more water-soluble amlodipine salt and a molar excess of sodium benzoate
4	The starting salt may be besylate, tosylate, mesylate, succinate, salicylate, maleate, acetate, or hydrochloride
5	The starting salt is specifically amlodipine besylate

Claim 5 is commercially important because amlodipine besylate is the established pharmaceutical salt used in many amlodipine products. The claim reaches a manufacturing process in which amlodipine besylate reacts with excess sodium benzoate in the aqueous formulation to produce amlodipine benzoate.

These claims create a potential infringement issue even where the finished product is characterized as containing amlodipine benzoate. A manufacturer could avoid claims 2 through 5 by using preformed amlodipine benzoate, but it would still need to avoid claim 1.

What formulations are protected by claims 6 through 14?

Claims 6 through 14 extend the patent to consumer-use and storage variants.

Flavoring and sweeteners

Claim 6 covers formulations containing a flavoring agent. Claim 7 covers a sweetener, and claim 8 specifically identifies sucralose.

Because claim 1 is open-ended, flavoring and sweetener limitations are not needed for infringement of the independent claim. They provide narrower fallback positions if claim 1 is challenged.

Suspension form

Claim 9 requires the formulation to be in suspension form. This limitation aligns the patent with products such as Katerzia, which is an oral suspension rather than a conventional tablet or simple aqueous solution.

pH range

Claim 10 narrows the pH to 5 through 6. This claim may be easier to practice than claim 1 if the commercial product is controlled within that narrower range.

Stability claims

Claims 11 through 14 add longer or alternative stability periods:

Claim	Stability limitation
11	At least 12 months at 25±5°C
12	At least 6 months at 25±5°C
13	At least 24 months at 25±5°C
14	At least 24 months at approximately 5±5°C

Claim 13 is the strongest room-temperature stability claim. Claim 14 is the strongest refrigerated-storage claim. The claims are cumulative in practical effect, although the dependency structure means each must be analyzed under the specific language of the issued patent.

When does US Patent 10,695,329 lose exclusivity?

US Patent 10,695,329 has a nominal expiration in 2035 based on its earliest priority framework and 20-year patent term. The precise expiration date depends on the earliest effective nonprovisional filing date and any patent-term adjustment shown in the USPTO patent record.

The patent was issued on June 30, 2020. Patent issuance does not establish the expiration date. For a post-1995 US utility patent, the baseline term generally runs 20 years from the earliest effective US nonprovisional or international application date, subject to patent-term adjustment and terminal disclaimers. The patent term is therefore materially longer than any ordinary FDA marketing exclusivity associated with the product.

FDA exclusivity and patent protection operate independently:

Protection type	Relevance
New chemical entity exclusivity	Not expected for amlodipine, an established active ingredient
Three-year exclusivity	Could apply only to qualifying new clinical investigations, but does not replace the patent
Pediatric exclusivity	Requires an FDA-issued pediatric extension
Patent term	Controlled by the patent record and any applicable adjustment
Listed patent protection	Relevant to ANDA Paragraph IV certification and FDA approval timing

No biosimilar pathway applies because amlodipine is a small-molecule drug, not a biologic. Competition would proceed through an ANDA, a 505(b)(2) application, or an ordinary abbreviated or hybrid regulatory pathway depending on the product and reference listed drug.

What is the Orange Book status of the patent?

The relevant commercial question is whether US 10,695,329 is listed against the applicable FDA-approved amlodipine oral suspension product, rather than whether the patent merely covers the product technically.

Katerzia is an amlodipine benzoate oral suspension approved by FDA. The product has a 1 mg/mL strength and uses a formulation consistent with the subject matter of US 10,695,329. FDA Orange Book listing status should be evaluated against the specific NDA and product presentation because Orange Book listings can change through patent-listing submissions, corrections, delistings, and FDA updates.

An Orange Book-listed formulation patent can require an ANDA applicant to make a Paragraph IV certification if the applicant seeks approval before patent expiration. The applicant may instead certify that it will not market until patent expiry or file a Paragraph III certification where appropriate.

The patent does not automatically block:

an amlodipine tablet;
a capsule;
an oral liquid with a different excipient system;
a preformed amlodipine salt other than the claimed benzoate formulation;
a product outside the claimed pH and concentration limitations; or
a product that cannot satisfy the claimed stability limitations.

Which companies are challenging the patent?

No publicly established Paragraph IV challenger or final judgment is identified in the materials supplied with the claims. A reliable challenger analysis requires matching FDA ANDA filings, Orange Book certifications, district-court complaints, and docket outcomes to the specific NDA and patent.

The absence of a publicly identified challenge in the supplied record does not establish that no ANDA has been filed. Paragraph IV activity may become visible through FDA litigation notices and federal court complaints before FDA approval of the ANDA.

Potential challengers would likely focus on:

anticipation by earlier amlodipine liquid or suspension formulations;
obviousness based on known amlodipine salts, buffers, preservatives, suspending agents, and surfactants;
lack of written description or enablement for the full concentration and stability scope;
indefiniteness of “about” and the stability language; and
noninfringement based on concentration, salt form, pH, or manufacturing route.

How strong is the patent estate for amlodipine oral liquid products?

The patent is strongest against close copies of the commercial formulation. It is weaker against products designed around the numerical limitations.

Strengths

The independent claim combines active concentration, excipient identity, exact concentrations, pH, and stability.
The claim covers a commercially useful pediatric-friendly dosage form.
Claims 2 through 5 add protection for in situ conversion from amlodipine besylate or other salts.
The stability limitations may distinguish the claimed formulation from earlier liquid preparations that suffered precipitation, degradation, or short shelf life.
The open-ended “comprising” language permits additional flavoring and sweetening components.

Weaknesses

The claim requires a specific concentration profile rather than a broad formulation concept.
Several excipient concentrations are fixed, enabling formulation design-arounds.
Functional stability limitations may raise reproducibility and proof issues.
A competitor using preformed amlodipine benzoate can avoid claims 2 through 5.
The patent does not broadly cover every aqueous amlodipine solution or suspension.
A competing product based on amlodipine besylate in solution may avoid the benzoate limitations entirely.

The estate is therefore commercially meaningful but technically narrow. It is more effective as a barrier to a Katerzia-equivalent product than as a barrier to all liquid amlodipine development.

How does Katerzia compare with Norliqva?

Katerzia and Norliqva occupy different formulation positions.

Attribute	Katerzia	Norliqva
Active salt	Amlodipine benzoate	Amlodipine besylate
Dosage form	Oral suspension	Oral solution
Typical strength	1 mg/mL	1 mg/mL
Patent relevance	Closely aligned with US 10,695,329	May avoid benzoate suspension claims
Pediatric administration	Liquid dosing	Liquid dosing
Primary design issue	Suspension stability and uniformity	Solubilized salt formulation

A besylate-based oral solution does not necessarily infringe a claim requiring amlodipine benzoate. The formulation would still need to be assessed for any other patents, FDA exclusivity, labeling restrictions, and regulatory reliance on a reference product.

This distinction gives competing manufacturers a practical design-around path: retain amlodipine besylate and develop a stable solution rather than converting the active to amlodipine benzoate and reproducing the claimed suspension system.

What generic launch risks exist?

A generic or alternative liquid manufacturer faces three principal risks.

Paragraph IV litigation risk

If the patent is listed for the reference product, an ANDA applicant seeking approval before patent expiry may trigger a Paragraph IV dispute. A lawsuit filed within the statutory period can create a 30-month stay of FDA approval, subject to statutory exceptions and court developments. [2]

Formulation-development risk

A product that avoids one limitation may introduce new problems:

precipitation of the active;
inadequate dose uniformity;
poor redispersibility;
degradation during storage;
unacceptable viscosity;
microbial-control problems; or
failure to meet pediatric-use requirements.

The patent’s stability limitations may reflect a genuine formulation barrier even where they do not create a complete legal barrier.

Regulatory substitution risk

A liquid amlodipine product may not receive automatic pharmacy substitution unless it satisfies the applicable therapeutic-equivalence requirements and is listed appropriately in the Orange Book. A 505(b)(2) product may face different clinical and labeling requirements from an ANDA.

What manufacturing and IP barriers remain after patent expiration?

The patent does not eliminate manufacturing know-how. A competitor may still need to reproduce:

controlled in situ salt conversion;
uniform suspension particle distribution;
viscosity and redispersibility;
preservative performance;
packaging compatibility;
dose-delivery accuracy; and
long-term impurity control.

These barriers are not equivalent to patent exclusivity. They may delay development, raise cost, and support trade-secret protection, but they do not independently prevent market entry after patent expiration.

The geographic scope is also limited. US 10,695,329 is a United States patent. Parallel rights in Europe, Canada, Australia, or other jurisdictions must be analyzed separately. A US patent does not restrict manufacturing, sale, or importation outside the United States.

What patent litigation affects US 10,695,329?

The provided record does not establish a filed infringement case, Paragraph IV complaint, settlement, consent judgment, or license involving this patent. A complete litigation assessment must distinguish:

an FDA Paragraph IV notice;
a district-court infringement complaint;
an ANDA litigation settlement;
a covenant not to sue;
a license or supply agreement; and
a later appellate or Patent Trial and Appeal Board proceeding.

No biosimilar litigation is relevant because the product is a small-molecule amlodipine formulation.

Key Takeaways

US 10,695,329 is a formulation patent, not an API patent.
Claim 1 requires a highly specific 1 mg/mL amlodipine benzoate liquid system.
The claimed formulation includes citrate, sodium benzoate, silicon dioxide, hydroxypropyl methylcellulose, simethicone, polysorbate 80, and water.
Claims 2 through 5 protect in situ formation of amlodipine benzoate, particularly from amlodipine besylate.
Claims 11 through 14 make refrigerated and room-temperature stability part of the patent scope.
The patent is closely associated with the formulation profile of Katerzia.
Amlodipine besylate oral solutions such as Norliqva may provide a design-around route because they do not necessarily contain amlodipine benzoate.
The nominal patent term extends into 2035, subject to the official USPTO term calculation.
No biosimilar pathway applies.
The highest generic risk is a close copy using the same excipient concentrations and in situ benzoate-conversion process.

FAQs

Does US 10,695,329 cover amlodipine tablets?

No. The claims are directed to an oral liquid formulation. Conventional amlodipine tablets generally fall outside the claimed dosage-form and excipient limitations.

Can a competitor avoid the patent by using amlodipine besylate?

Possibly. A product that remains a besylate solution and does not contain the claimed amlodipine benzoate formulation may avoid the principal claim. The complete product and manufacturing process still require a separate infringement analysis.

Does adding a flavor avoid infringement?

No. Claim 1 is an open-ended “comprising” claim. Adding flavoring does not remove the required ingredients or limitations. Flavoring is separately addressed in claim 6.

Is a 1 mg/mL amlodipine solution automatically covered?

No. The patent requires amlodipine benzoate, defined excipients, specified concentrations, pH, water, and stability results. A different salt or excipient system may fall outside the claims.

Can the patent block a product made outside the United States?

The US patent can restrict making, using, selling, offering for sale, or importing the claimed product in the United States. It does not independently control conduct wholly outside the United States.

References

United States Patent and Trademark Office. (2020). U.S. Patent No. 10,695,329, Amlodipine formulations.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). Katerzia (amlodipine benzoate) oral suspension prescribing information.
U.S. Food and Drug Administration. (n.d.). Norliqva (amlodipine besylate) oral solution prescribing information.
U.S. Code, 21 U.S.C. § 355.
U.S. Code, 35 U.S.C. §§ 154, 271, and 282.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Azurity	KATERZIA	amlodipine benzoate	SUSPENSION;ORAL	211340-001	Jul 8, 2019		RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	3038989	⤷ Start Trial
European Patent Office	3522872	⤷ Start Trial
European Patent Office	3960158	⤷ Start Trial
European Patent Office	4585213	⤷ Start Trial
Spain	2886067	⤷ Start Trial
Spain	3035030	⤷ Start Trial
World Intellectual Property Organization (WIPO)	2018067959	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,695,329

Which drugs does patent 10,695,329 protect, and when does it expire?

Summary for Patent: 10,695,329