Details for Patent: 9,023,391

Summary for Patent: 9,023,391

Title:	Stable benzimidazole formulation
Abstract:	A stable composition with a benzimidazole derivative, such as Omeprazole, which does not contain a separating layer between the active compound and an enteric coating layer. Instead, the enteric coating layer is applied as a solution with a pH value of at least 6.5, and more preferably in a range of from about 7 to about 10, directly to the benzimidazole derivative substrate. This solution, with the optional addition of a plasticizer, can be directly coated onto the substrate without any necessity for an intermediate layer. Furthermore, in this pH range, the enteric coating is optionally applicable in an aqueous solution, thereby obviating the need for organic solvents for dissolving the enteric coating material. The resultant formulation maintains the stability of the benzimidazole derivative during storage and at the same time protects the product during passage through the acidic environment of the stomach. The problem of interaction between the enteric coat and the alkaline core is thus completely eliminated as the enteric coat at this stage is no longer acidic.
Inventor(s):	Raffael Lahav, Valerie Azoulay
Assignee:	DEXCEL Ltd , Dexcel Ltd Israel
Application Number:	US11/785,300
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 9,023,391
Patent Claim Types: see list of patent claims	Composition; Formulation; Dosage form;

US Patent 9,023,391: Claim Scope, Formulation Coverage, Expiration Risk, and Competitive Patent Landscape

US Patent 9,023,391 protects a narrow oral dosage-form architecture for benzimidazole proton-pump inhibitors. The core inventive combination is sodium stearate used as a stabilizer inside a single tablet core, covered directly by one neutralized enteric-coating layer. The claims reach formulations containing omeprazole, pantoprazole, lansoprazole, rabeprazole and related benzimidazoles, but they do not cover every enteric-coated proton-pump inhibitor.

The principal design-around variables are the stabilizer, core composition, coating structure, coating pH, neutralizing agent, and use of multiple coating layers.

What does US Patent 9,023,391 protect?

The independent claims protect stable oral compositions with five central requirements:

1. A benzimidazole derivative.
2. A single tablet core.
3. Sodium stearate in the core at approximately 0.09% to 4% by weight, functioning as a stabilizer.
4. At least one non-stabilizing excipient.
5. A single enteric layer applied directly to the core from a coating solution or dispersion with a pH of at least 6.5 and containing sodium, potassium or ammonium hydroxide as the neutralizing agent.

Claim 13 creates a narrower species directed to a single core containing approximately 4% sodium stearate and a single neutralized HPMCAS layer prepared with ammonium hydroxide. Claims 6 through 8 narrow the degree of polymer neutralization to at least 60%, 80% and 95%, respectively.

The patent is therefore a formulation and manufacturing-process patent. It is not an API composition-of-matter patent, a therapeutic method patent, or a patent covering the general use of proton-pump inhibitors.

Patent identification and technical focus

Item	Description
U.S. patent	US 9,023,391 B2
Grant date	May 5, 2015
Technology	Stabilized, enteric-coated benzimidazole tablet
Dosage form	Oral tablet
Core	Single tablet core
Stabilizer	Sodium stearate
Stabilizer range	About 0.09% to about 4% by core weight
Coating	Single enteric layer applied directly to core
Coating pH	At least pH 6.5
Neutralizing agents	Sodium hydroxide, potassium hydroxide or ammonium hydroxide
Key polymers	HPMCAS, CAP, PVAP, CAT, methacrylic-acid methacrylate polymers and ethyl-methacrylate polymers
Active ingredients expressly identified	Omeprazole, pantoprazole, lansoprazole, leminoprazole, perprazole and rabeprazole
Patent category	Pharmaceutical formulation and coating technology

The claims use “consisting essentially of.” That language generally permits components that do not materially alter the claimed stabilization and coating characteristics, but it can exclude additional stabilizing materials or formulation elements that materially change the claimed invention. The precise effect depends on the intrinsic record, prosecution history and infringement theory.

How broad are the independent claims?

Claim 1 is broad in active ingredient selection but constrained by dosage-form structure. A competing product must satisfy the full combination, not merely contain sodium stearate or an enteric polymer.

Claim 1 element-by-element analysis

Claim element	Scope	Commercial significance
Stable composition	Requires stability as a claimed property	Creates a potential performance dispute over degradation, assay or impurity data
Oral administration	Excludes non-oral dosage forms	Injectable, buccal and transdermal products are outside the literal limitation
Benzimidazole derivative	Broad genus	Covers multiple proton-pump inhibitor actives
Single tablet core	Requires one core	Multiparticulates, pellets and capsule-filled systems may avoid this limitation
Sodium stearate	Must be present as the stabilizing material	Substitution with another fatty-acid salt is a potential design-around
0.09% to 4% by core weight	Quantitative limitation	Products below or above the range may avoid literal infringement
Non-stabilizing excipient	Requires at least one such excipient	The excipient cannot be characterized as another stabilizing material
Single enteric layer	Requires one relevant enteric layer	Multi-layer systems create a possible noninfringement position
Directly layered onto core	No intermediate subcoat is permitted under the literal wording	Seal coats, barrier coats or separate subcoats may be important design-around tools
Enteric polymer	Limited to identified polymer classes	Alternative polymers may avoid literal coverage
Coating solution or dispersion pH of at least 6.5	Process or product-history limitation	Coating prepared below pH 6.5 may fall outside the claim
Specified hydroxide neutralizer	Limits the neutralization chemistry	Amine, carbonate or other neutralizers may create a design-around

The claim does not require a particular tablet strength, dissolution profile, release time, active-to-excipient ratio other than sodium stearate, or therapeutic indication. It also does not require a specific brand, manufacturer or commercial product.

What formulations are protected by US 9,023,391?

The strongest literal coverage applies to a compressed tablet with a homogeneous or otherwise integrated sodium-stearate-containing core and one directly applied neutralized enteric layer.

Protected formulation configurations

The claims potentially cover:

• Omeprazole tablets containing sodium stearate at 0.09% to 4% of core weight.
• Pantoprazole tablets using the same stabilization concept.
• Lansoprazole tablets with a directly applied neutralized enteric coating.
• Rabeprazole and other listed benzimidazole derivatives in the claimed architecture.
• Cores containing sodium stearate and sodium stearyl fumarate.
• Cores containing sodium stearate and sodium starch glycolate.
• Cores containing sodium stearate and lactose.
• Cores containing sodium stearate and povidone.
• HPMCAS coatings neutralized with ammonium hydroxide.
• Enteric layers containing citric-acid or phthalic-acid ester plasticizers.
• Coatings containing sodium lauryl sulfate, talc, glidants, coloring agents or polishing agents.
• Compressed active cores covered by claims 11 and 12.

Claim 13 is especially important for HPMCAS products. It requires neutralized HPMCAS, ammonium hydroxide, a pH of at least 6.5 and approximately 4% sodium stearate in the core.

Formulations that may fall outside literal claim scope

Potential noninfringing configurations include:

• A core containing calcium stearate, magnesium stearate or another stabilizer instead of sodium stearate.
• Sodium stearate outside the 0.09% to 4% range.
• A capsule containing enteric-coated pellets rather than a single tablet core.
• A tablet with a seal coat or barrier layer between the core and enteric coating.
• A product with two enteric layers.
• A coating neutralized with an agent other than sodium, potassium or ammonium hydroxide.
• A coating prepared below pH 6.5.
• An enteric polymer outside the listed classes.
• A dosage form without a benzimidazole derivative.
• A composition in which sodium stearate is present but not the stabilizing material.

The doctrine of equivalents could still create risk where a substituted component performs substantially the same function in substantially the same way to obtain substantially the same result. The viability of that theory would depend on prosecution-history estoppel and the claim amendments made during examination.

How do claims 1, 13 and 14 differ?

Claim	Scope	Relative breadth
Claim 1	Broad composition covering listed polymer classes, hydroxide neutralizers and benzimidazole derivatives	Broadest independent formulation claim
Claim 13	HPMCAS only, ammonium hydroxide, pH at least 6.5 and approximately 4% sodium stearate	Narrower but technically specific
Claim 14	Claim 1 with approximately 4% sodium stearate	Narrower quantitative species

Claim 13 may be commercially important even if claim 1 is vulnerable. A product that uses approximately 4% sodium stearate and an ammonium-hydroxide-neutralized HPMCAS coating could implicate both claims.

Claims 6 through 8 create a stepped neutralization hierarchy:

Claim	Minimum neutralization
Claim 6	At least 60%
Claim 7	At least 80%
Claim 8	At least 95%

These claims may create dependent-claim fallback positions if a court narrows the broader pH limitation or rejects a broader construction.

What is the patent expiration timeline for US 9,023,391?

The patent issued on May 5, 2015. For a modern U.S. utility patent, the ordinary term is generally 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers and any applicable patent-term extension under 35 U.S.C. §§ 154 and 156.

The grant date alone does not establish the expiration date. The controlling analysis requires:

• The earliest effective nonprovisional priority date.
• Any international application relationship.
• Patent-term adjustment shown on the front page or USPTO record.
• Any terminal disclaimer.
• Any patent-term extension.
• Whether a continuation or divisional relationship affects the term calculation.

The patent’s expected commercial relevance is therefore determined by its statutory term and any related family members, not by the 2015 grant date. A freedom-to-operate opinion should review the complete INPADOC or U.S. family, continuation practice and USPTO patent-term data rather than rely on the claims alone.

Is US 9,023,391 an Orange Book patent?

US 9,023,391 is a formulation patent, but its Orange Book status cannot be inferred solely from the claim language. Orange Book listing depends on whether an NDA holder submitted the patent to FDA and whether the patent claims an approved drug, drug substance, drug product or approved method of use under the listing rules.

The patent is not inherently an Orange Book-listed patent merely because it covers a pharmaceutical composition. The relevant records are the FDA Orange Book patent listing and the NDA holder’s certification history. FDA’s Orange Book identifies patents submitted for approved drug products and distinguishes drug-substance, drug-product and method-of-use listings.[2]

A formulation claim of this type would most plausibly be submitted as a drug-product patent if the approved product used the claimed sodium-stearate and direct-enteric-coating architecture. It would not ordinarily qualify as a drug-substance patent.

What Paragraph IV risks exist?

A generic applicant could challenge the patent through an ANDA Paragraph IV certification if the reference listed drug has a relevant patent and the applicant asserts that the patent is invalid, unenforceable or will not be infringed.

The principal Paragraph IV theories would be:

Noninfringement

A generic applicant could design around one or more limitations:

• Use a different stabilizer.
• Use sodium stearate outside the claimed concentration.
• Use a multilayer coating.
• Add a subcoat between the core and enteric layer.
• Use a different neutralizing agent.
• Prepare the coating below pH 6.5.
• Use a different enteric polymer.
• Use pellets or granules rather than a single tablet core.

The strongest noninfringement position usually targets a required structural limitation rather than the functional word “stable.”

Invalidity based on anticipation

An anticipation challenge would require a single prior-art reference to disclose every limitation, including the sodium-stearate concentration, single-core architecture, direct single-layer coating and specified neutralization conditions. A general prior-art disclosure of enteric-coated omeprazole would not necessarily anticipate the claims.

Invalidity based on obviousness

An obviousness challenge could combine prior art relating to:

• Benzimidazole degradation and alkaline stabilization.
• Fatty-acid salts as tablet excipients.
• HPMCAS or other enteric polymers.
• Neutralized aqueous coating systems.
• Direct coating of compressed cores.
• pH-controlled coating dispersions.

The most defensible patentability position is the combination of these variables and the claimed stability result. The principal vulnerability is that each individual formulation component was likely known in pharmaceutical development before the relevant filing date.

Written description and enablement

Potential challenges could examine whether the specification supports the full genus of listed benzimidazoles and all identified enteric polymers across the entire sodium-stearate range. Claim 1 covers a substantial combination space. The strength of the claim depends on the examples, stability data and disclosure of representative species.

What manufacturing and intellectual-property barriers does the patent create?

The patent can affect both formulation development and commercial manufacturing.

A generic manufacturer must control:

• Sodium stearate identity and grade.
• Sodium stearate concentration as a percentage of core weight.
• Distribution of sodium stearate in the compressed core.
• Core hardness and friability.
• Coating pH during application.
• Degree of polymer neutralization.
• Hydroxide selection.
• Coating weight gain.
• Absence or presence of intermediate layers.
• Enteric dissolution and acid-stage resistance.
• Degradation products and assay stability.

These parameters can be difficult to assess from public labeling. Reverse engineering may reveal the active ingredient and broad excipient profile but not necessarily the coating-pH history or neutralization percentage. That creates evidentiary issues in ANDA litigation.

The claims also create process-record exposure. Batch records, coating instructions, in-process pH records and manufacturing specifications may become relevant to determine whether a product was made using a coating solution or dispersion meeting the claimed conditions.

How strong is the patent estate?

The patent appears stronger as a targeted formulation patent than as a broad barrier to all proton-pump-inhibitor competition.

Strengths

• Claim 1 covers several commercially relevant benzimidazole derivatives.
• The claim combines composition and processing limitations.
• Sodium stearate is specified quantitatively.
• The claims cover multiple established enteric polymer families.
• Dependent claims provide fallback positions for neutralization level, excipients and coating additives.
• Claim 13 targets a technically specific HPMCAS/ammonium-hydroxide embodiment.

Weaknesses

• The patent does not cover the active pharmaceutical ingredient itself.
• It does not cover every enteric-coated tablet.
• The single-core and single-layer limitations create practical design-around routes.
• The concentration range is measurable and can support a noninfringement defense.
• The pH and neutralization limitations may depend on manufacturing evidence.
• Prior art combining benzimidazole stabilization with enteric coating technology could support an obviousness challenge.
• Product claims using “stable” can create disputes over the required stability threshold and test conditions.

Overall, the estate is commercially relevant where a product closely follows the claimed architecture, but it is unlikely to block all generic proton-pump-inhibitor formulations.

How does this patent compare with other proton-pump-inhibitor patents?

Patent type	Typical protected subject matter	Relationship to US 9,023,391
API composition patent	New molecule or chemical form	Separate and generally broader against all dosage forms
Salt or polymorph patent	Specific solid state, salt or crystal form	May overlap with the active used in the core
Formulation patent	Excipients, stabilization, release and coating	US 9,023,391 falls in this category
Method-of-use patent	Treatment of a disease or dosing regimen	No direct coverage in the supplied claims
Manufacturing patent	Synthesis, purification or coating process	US 9,023,391 includes coating-history limitations but is primarily a composition patent
Device or delivery patent	Capsule, pump, multiparticulate or release device	Potential design-around or separate blocking right
Pediatric or dose patent	Age group, dose, timing or regimen	Not covered by the supplied claims

For generic entry, the practical question is whether the approved reference product and proposed ANDA product use the same protected formulation architecture. A generic can avoid this patent while still infringing a separate API, polymorph, method-of-use or manufacturing patent.

Does biosimilar risk apply to this patent?

No. Biosimilar risk is not the relevant regulatory category because the claims concern small-molecule benzimidazole drugs, not biologics. Generic entry would proceed through the ANDA pathway under section 505(j) of the Federal Food, Drug, and Cosmetic Act, not through the abbreviated biologics license application pathway under the Public Health Service Act.[3]

The relevant competitive risks are:

• ANDA Paragraph IV litigation.
• Paragraph III certification and delayed entry.
• Formulation design-around.
• Authorized generic competition.
• OTC conversion or nonprescription competition.
• Patent litigation involving related family members.

Which companies may be exposed to this patent?

Potentially exposed companies are those marketing or developing oral products that combine:

• A listed benzimidazole active.
• A compressed single tablet core.
• Sodium stearate within the claimed range.
• A directly applied single enteric coating.
• Neutralized HPMCAS or another listed polymer.
• A coating pH of at least 6.5.

Exposure cannot be assigned from the active ingredient alone. Omeprazole, pantoprazole or lansoprazole products using different stabilizers, subcoats, multiparticulate systems or coating chemistry may not practice the claims.

The key diligence targets are the innovator’s NDA formulation, ANDA product labeling, publicly available inactive-ingredient information, FDA patent listings and any district-court or Federal Circuit litigation involving the patent or its family.

What is the likely generic launch scenario?

Three commercial pathways are available:

Scenario	Description	Patent impact
Direct copy	Generic replicates the reference formulation	Highest infringement and Paragraph IV exposure
Formulation design-around	Generic changes stabilizer, coating layers, polymer or neutralizer	Reduces literal infringement risk
Delayed entry	Generic accepts patent risk or waits for expiration	Avoids litigation cost but sacrifices market time
Litigation launch	Generic launches after Paragraph IV litigation or settlement	Creates damages, injunction and exclusivity risk

A formulation design-around may be commercially feasible because the claims contain several independently measurable limitations. The tradeoff is that changing sodium stearate, coating pH or layer structure can affect chemical stability, acid resistance, dissolution and manufacturing yield.

What litigation and settlement issues should be reviewed?

The relevant litigation review should include:

• ANDA suits under 35 U.S.C. § 271(e)(2).
• Declaratory-judgment actions filed by generic applicants.
• Claim-construction rulings addressing “single layer,” “directly,” “stable” and “effective amount.”
• Prosecution-history statements concerning sodium stearate and neutralization.
• Continuation patents with overlapping formulation claims.
• Terminal disclaimers linking expiration dates.
• Settlement agreements involving licensed generic entry.
• Any authorized-generic arrangement affecting the commercial launch date.

A settlement can materially change the effective exclusivity period even when the patent remains in force. Conversely, an unlisted patent may still support ordinary infringement litigation if the product practices the claims, although it may not create the same ANDA stay or certification consequences as an Orange Book-listed patent.

Key Takeaways

• US 9,023,391 is a formulation patent directed to stabilized, enteric-coated benzimidazole tablets.
• Its central limitation is sodium stearate in a single tablet core at approximately 0.09% to 4% by core weight.
• The core must be covered directly by one enteric layer prepared from a coating solution or dispersion at pH 6.5 or higher.
• HPMCAS, CAP, PVAP, cellulose acetate trimellitate and specified methacrylate polymers are within claim 1.
• Claim 13 is the most technically specific claim, covering approximately 4% sodium stearate, neutralized HPMCAS and ammonium hydroxide.
• The main design-arounds are a different stabilizer, a different concentration, a subcoat, multiple enteric layers, a different neutralizer or a different coating pH.
• The patent does not block all generic proton-pump-inhibitor products.
• The product is subject to small-molecule ANDA analysis, not biosimilar analysis.
• Patent expiration must be determined from the earliest effective filing date, patent-term adjustment, terminal disclaimers and any patent-term extension.
• Orange Book status and current litigation exposure require review of FDA and court records beyond the claim text.

FAQs

Can a tablet with magnesium stearate avoid US 9,023,391?

Potentially. The claims specifically require sodium stearate as the stabilizing material. Magnesium stearate is chemically distinct. Risk could remain if sodium stearate is also present or if an equivalents theory applies.

Does a subcoat between the core and enteric layer avoid the patent?

A subcoat creates a strong literal noninfringement argument because the claims require the enteric layer to be layered directly onto the single tablet core. The outcome depends on whether the alleged subcoat is legally treated as part of the core or as a separate intermediate layer.

Is HPMCAS alone enough to infringe?

No. HPMCAS alone is insufficient. The product must also satisfy the core, sodium-stearate, single-layer, direct-application, pH and neutralizer limitations, subject to claim construction.

Can a product outside the 0.09% to 4% sodium-stearate range infringe?

It may avoid literal infringement of claim 1 and claim 14 if the concentration is genuinely outside the claimed range. Claims must be assessed separately, and the doctrine of equivalents may remain relevant.

Does this patent cover lansoprazole’s chemical structure?

No. The patent covers a dosage-form composition containing a benzimidazole derivative, including lansoprazole. It does not claim the lansoprazole molecule itself.

References

1. United States Patent and Trademark Office. (2015). U.S. Patent No. 9,023,391 B2.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355(j).
4. Patent Act, 35 U.S.C. §§ 154, 156, 271(e)(2).

Drugs Protected by US Patent 9,023,391

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

Foreign Priority and PCT Information for Patent: 9,023,391

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Israel	130602	Jun 22, 1999

International Family Members for US Patent 9,023,391

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	390119
Australia	5423200
Canada	2377605
Germany	60038447
European Patent Office	1187599
Spain	2304349
Israel	130602