Details for Patent: 7,157,584

Summary for Patent: 7,157,584

Title:	Benzimidazole derivative and use thereof
Abstract:	The present invention relates to a compound represented by the formula (I) wherein R1 is a group represented by the formula wherein R2, R3, R4, R5, R6, R7 and R8 are each independently a hydrogen atom or a C1-6 alkyl, or a salt thereof. The compound of the present invention is useful as an agent for the prophylaxis or treatment of circulatory diseases such as hypertension and the like and metabolic diseases such as diabetes and the like.
Inventor(s):	Takanobu Kuroita, Hiroki Sakamoto, Mami Ojima
Assignee:	Takeda Pharmaceutical Co Ltd
Application Number:	US11/031,057
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 7,157,584
Patent Claim Types: see list of patent claims	Compound;

# US Patent 7,157,584: Azilsartan Medoxomil Claim Scope, Expiration, Orange Book Status and Generic Risk

US Patent 7,157,584 covers azilsartan medoxomil, including its pharmaceutically acceptable salts and, expressly, the potassium salt used in Edarbi. Claim 1 is the broad composition-of-matter claim. Claim 2 is a narrower species claim directed to azilsartan medoxomil potassium. The patent is the foundational U.S. compound patent for azilsartan medoxomil. Public patent records identify September 29, 2025, as the relevant patent expiration date, subject to the controlling USPTO patent-term calculation and any applicable regulatory extension.[1][2]

The claims do not expressly cover a particular tablet formulation, dosage strength, polymorph, manufacturing process, combination product, or method of treating hypertension. Those subjects must be analyzed under separate patents.

What drug does US Patent 7,157,584 protect?

US Patent 7,157,584 protects azilsartan medoxomil, the prodrug of azilsartan. Azilsartan is an angiotensin II receptor blocker that selectively inhibits the AT1 receptor. Azilsartan medoxomil is converted in vivo to azilsartan after hydrolysis of the medoxomil ester group.

The commercial product associated with the patent is Edarbi, marketed as azilsartan medoxomil tablets in 20 mg, 40 mg, and 80 mg strengths. The marketed active pharmaceutical ingredient is generally described as azilsartan medoxomil potassium.[3]

Patent identification

Field	Data
U.S. patent	US 7,157,584 B2
Patent subject	Azilsartan medoxomil and salts
Patent holder or original applicant	Takeda-related pharmaceutical interests
Grant date	January 2, 2007
Claimed active ingredient	Azilsartan medoxomil
Expressly claimed salt	Potassium salt
Product association	Edarbi
Reported U.S. expiration	September 29, 2025
Therapeutic class	Angiotensin II receptor blocker
FDA approval for Edarbi	December 2011
FDA application	NDA 200796

What are the exact claims of US Patent 7,157,584?

The patent has two claims identified in the supplied claim set.

Claim 1: azilsartan medoxomil and pharmaceutically acceptable salts

Claim 1 covers:

(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl 2-ethoxy-1-{[2′-(5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methyl}-1H-benzimidazole-7-carboxylate or a pharmaceutically acceptable salt thereof.

This chemical name is azilsartan medoxomil. The claim has two legal components:

1. The specifically named neutral azilsartan medoxomil molecule.
2. Any pharmaceutically acceptable salt of that molecule.

The claim is not a broad Markush claim covering a large genus of ARBs. It identifies one defined molecular structure. The salt language expands coverage from the neutral compound to acceptable salt forms, but does not cover unrelated derivatives, analogues, or alternative prodrugs.

Claim 2: azilsartan medoxomil potassium salt

Claim 2 covers:

(5-Methyl-2-oxo-1,3-dioxol-4-yl)methyl 2-ethoxy-1-{[2′-(5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methyl}-1H-benzimidazole-7-carboxylate potassium salt.

Claim 2 is narrower than claim 1. It isolates the potassium salt as a specific claimed form. A product that contains azilsartan medoxomil potassium would fall within claim 2 if the product contains the claimed chemical entity and the patent remains enforceable.

How broad is the patent scope?

The patent has strong composition-of-matter scope but limited claim-category breadth.

Covered subject matter

The claims cover:

• Azilsartan medoxomil as a defined chemical compound.
• Pharmaceutically acceptable salts under claim 1.
• The potassium salt under claim 2.
• Manufacture, sale, importation, or commercial distribution of the claimed compound during the enforceable patent term.
• Pharmaceutical use of the claimed compound to the extent the activity constitutes infringement under the applicable statutory provision.

Subject matter not expressly covered by the supplied claims

The claims do not expressly recite:

• A pharmaceutical composition.
• A tablet or capsule.
• A specific dosage strength.
• A specific excipient system.
• A controlled-release or immediate-release formulation.
• A particular crystalline or amorphous form.
• Particle size or dissolution limits.
• A method of treating hypertension.
• Combination therapy with chlorthalidone or another antihypertensive.
• A manufacturing process.
• A specific impurity profile.
• A specific polymorph.
• A packaging configuration.

This distinction is commercially important. A generic manufacturer can avoid formulation or process claims in one patent while still infringing a live compound claim if its product contains azilsartan medoxomil potassium.

Does claim 1 cover the potassium salt?

Yes. Claim 1 covers the neutral compound "or a pharmaceutically acceptable salt thereof." The potassium salt is a pharmaceutically acceptable salt of azilsartan medoxomil and is also specifically recited in claim 2.

Claim 2 therefore provides a narrower, redundant species claim directed to the potassium salt. If claim 1 were invalidated or narrowed, claim 2 could remain separately relevant, although its validity would depend on the same specification, prosecution history, prior art, and claim-construction record.

What is the patent expiration date?

Public patent databases and commercial patent-term records report September 29, 2025, as the expiration date for US 7,157,584.[1][2] The date reflects the applicable U.S. patent term calculation rather than the 20-year term measured solely from the patent’s grant date.

The practical timeline is:

Event	Date
Earliest priority period	2000
U.S. patent grant	January 2, 2007
Reported patent expiration	September 29, 2025
FDA approval of Edarbi	December 2011
Commercial generic risk	Primarily tied to the 2025 compound-patent expiry, unless later patents remain enforceable

A patent expiration date does not automatically eliminate every barrier to launch. Later-issued formulation, polymorph, process, combination, or method-of-use patents can create additional risk if they are listed for the relevant FDA product and are otherwise enforceable.

What is the Orange Book status of US Patent 7,157,584?

US 7,157,584 has been associated with Edarbi and azilsartan medoxomil in FDA patent-listing records. The Orange Book is relevant because a listed patent can require an ANDA applicant to submit a Paragraph IV certification or a certification that approval will be delayed until patent expiration.[4]

For an ANDA applicant, the principal regulatory implications are:

• A Paragraph IV certification may be used to challenge the patent before expiry.
• A notice of Paragraph IV certification can trigger patent litigation.
• A timely patent-infringement action can impose a 30-month stay of ANDA approval under the Hatch-Waxman framework.
• A Paragraph III certification may defer approval until the reported patent expiration date.
• FDA patent-listing status does not itself establish patent validity or infringement.

The exact Orange Book listing history should be separated from the broader patent family. A patent may cover the same active ingredient but not be listed for every dosage form or product. Conversely, an Orange Book-listed patent may claim a method of use or formulation rather than the active ingredient itself.

What patent landscape surrounds azilsartan medoxomil?

The azilsartan medoxomil estate can be divided into five principal layers.

Foundational compound protection

US 7,157,584 is the central compound patent. Its claims reach the active prodrug and pharmaceutically acceptable salts, including the potassium salt. This is the most important patent for a manufacturer seeking to market azilsartan medoxomil before September 2025.

Formulation and solid-state protection

Later patents may address:

• Specific crystalline forms.
• Stability-enhancing compositions.
• Tablet formulations.
• Dissolution performance.
• Excipient combinations.
• Manufacturing controls.

These patents can affect launch even after the compound patent expires. Their practical value depends on whether the generic product must use the protected form or formulation to meet FDA quality and bioequivalence requirements.

Combination-product protection

Edarbyclor combines azilsartan medoxomil with chlorthalidone. Combination-product patents may claim:

• The azilsartan medoxomil/chlorthalidone combination.
• Dose ratios.
• Hypertension treatment methods.
• Tablet compositions.
• Pharmacokinetic or clinical-use parameters.

A generic azilsartan product and a generic azilsartan/chlorthalidone product face different patent landscapes. A Paragraph IV position for Edarbi does not automatically resolve the Edarbyclor estate.

Method-of-use protection

Azilsartan-related patents can claim treatment of:

• Hypertension.
• Cardiovascular disease.
• Renal disease.
• Patient populations inadequately controlled on other antihypertensives.
• Combination treatment with diuretics or other blood-pressure agents.

The supplied claims are not method-of-use claims. They are compound claims. Method patents may create narrower risks for labeled indications, but they generally do not have the same breadth as a claim covering the active molecule itself.

Manufacturing and process protection

Process patents may cover:

• Formation of the medoxomil ester.
• Preparation of the oxadiazolone-containing benzimidazole intermediate.
• Salt formation.
• Crystallization.
• Purification.
• Control of degradation products.

A process patent is most significant when the claimed route is commercially preferred or when alternative routes create yield, impurity, scale-up, or regulatory problems. It does not necessarily block a product made by a non-infringing process.

How strong is the patent estate for azilsartan medoxomil?

US 7,157,584 has high commercial strength because it is a compound claim directed to the marketed active ingredient. Compound claims generally create a direct product barrier and are harder to design around than formulation or process claims.

The principal strength factors are:

Factor	Assessment
Claim type	Composition of matter
Structural specificity	High
Design-around potential	Low for azilsartan medoxomil itself
Salt coverage	Broad under claim 1; potassium expressly covered under claim 2
Dependence on formulation	None for the core compound claim
Dependence on manufacturing route	None
Generic exposure	High before patent expiry
Post-expiry relevance	Limited for the compound, subject to later patents
Invalidity focus	Prior art, written description, enablement, obviousness, and prosecution history

The most credible attack routes would ordinarily involve prior-art disclosure or obviousness of azilsartan medoxomil, the medoxomil prodrug structure, or the claimed salt. A generic applicant could also argue that the claim language does not cover its specific solid form or product composition, although that argument would have limited value if the product contains the claimed molecular entity.

Which companies are challenging azilsartan medoxomil patents?

Public FDA and court records should be reviewed separately for each ANDA applicant because Paragraph IV notices and litigation can change over time. The available information does not establish a complete, current list of challengers or a definitive settlement position for every applicant.

The relevant competitive groups are:

• Generic manufacturers filing ANDAs for azilsartan medoxomil tablets.
• Companies filing for 20 mg, 40 mg, or 80 mg strengths.
• Applicants seeking approval for azilsartan medoxomil/chlorthalidone combinations.
• Manufacturers relying on Paragraph III certifications after compound-patent expiry.
• Applicants using Paragraph IV certifications against listed formulation or use patents.

No conclusion about first-to-file exclusivity, 180-day generic exclusivity, or a particular settlement should be inferred solely from the existence of US 7,157,584.

What litigation risks exist under Hatch-Waxman?

A Paragraph IV challenge to an Orange Book-listed patent can produce a patent case under 35 U.S.C. § 271(e)(2). The typical sequence is:

1. The ANDA applicant files a Paragraph IV certification.
2. The applicant sends notice to the patent holder and NDA holder.
3. The patent holder has 45 days to file an infringement action.
4. A timely action can trigger a 30-month FDA approval stay.
5. The court evaluates infringement, validity, and enforceability.
6. Approval may occur after patent expiry, an earlier judgment, settlement, or other statutory resolution.

For US 7,157,584, the key infringement question is straightforward: whether the proposed product contains azilsartan medoxomil or a pharmaceutically acceptable salt. A generic product that uses the potassium salt would face direct exposure under claim 2 while that claim remains enforceable.

What generic launch scenarios exist?

Launch after compound-patent expiry

This is the lowest-risk scenario for a product containing azilsartan medoxomil potassium, provided no later patent blocks the proposed formulation, solid form, or labeled use.

Paragraph III launch

An applicant may certify that it will not market until the listed patent expires. This avoids an early validity challenge but delays commercial entry.

Paragraph IV launch

A Paragraph IV applicant may contend that the patent is invalid, unenforceable, or not infringed. This creates litigation risk but can support earlier approval if the applicant prevails or resolves the dispute.

At-risk launch

A company may launch before final resolution after the statutory stay expires. This exposes the company to damages, injunctive relief, and potential market disruption if the patent holder prevails.

Formulation-specific launch

A generic manufacturer could avoid a later formulation patent by using a different excipient system, solid form, manufacturing process, or dissolution profile, while still waiting for expiry of the compound patent.

How does azilsartan medoxomil compare with competing ARBs?

Drug	Active ingredient	Core patent issue	Generic design-around
Edarbi	Azilsartan medoxomil potassium	Compound claim in US 7,157,584	Low before expiry
Benicar	Olmesartan medoxomil	Older compound and formulation estate	Broad generic competition after expiry
Diovan	Valsartan	Older compound estate	Extensive generic competition
Cozaar	Losartan potassium	Older compound estate	Extensive generic competition
Avapro	Irbesartan	Older compound estate	Extensive generic competition
Micardis	Telmisartan	Older compound estate	Extensive generic competition

Azilsartan medoxomil entered the market later than many major ARBs. Its commercial protection therefore remained relevant after several competing ARBs had already experienced generic erosion. The commercial value of the estate depends on whether generic entry occurs immediately after the 2025 compound expiry or is delayed by later product-specific patents.

What revenue exposure does the patent create?

The patent’s revenue exposure is concentrated in Edarbi and, to a different extent, Edarbyclor. Edarbi sales are directly exposed because the product contains the claimed azilsartan medoxomil potassium molecule.

Revenue impact depends on:

• The number of approved generic applicants.
• Whether one applicant receives first-to-file exclusivity.
• The number of strengths launched.
• Payer substitution and formulary placement.
• The existence of later formulation or combination patents.
• Whether the generic product launches immediately after September 29, 2025.
• The extent to which prescribers switch patients from Edarbi to lower-priced ARBs.

The compound patent is therefore a material barrier to generic azilsartan medoxomil before expiry, but it is not by itself a complete description of Edarbi’s remaining exclusivity.

What geographic coverage does US 7,157,584 provide?

US 7,157,584 provides protection in the United States only. Corresponding patents or applications may exist in Europe, Japan, Canada, and other jurisdictions, but each must be assessed independently for:

• National-phase status.
• Patent term.
• Claim scope.
• Opposition or invalidation history.
• Supplementary protection certificates.
• Local regulatory linkage.
• Commercial launch restrictions.

A U.S. patent does not prevent manufacture or sale outside the United States unless separate foreign rights apply. It can, however, affect U.S. importation and commercial distribution.

Key Takeaways

• US 7,157,584 is the foundational U.S. composition-of-matter patent for azilsartan medoxomil.
• Claim 1 covers azilsartan medoxomil and pharmaceutically acceptable salts.
• Claim 2 specifically covers azilsartan medoxomil potassium, the salt associated with Edarbi.
• The claims do not expressly cover formulations, polymorphs, manufacturing processes, dosage strengths, or treatment methods.
• The reported U.S. expiration date is September 29, 2025.
• Generic products containing azilsartan medoxomil potassium face direct compound-claim risk before expiry.
• Later formulation, solid-state, combination, process, and method-of-use patents may affect launch after the compound patent expires.
• Orange Book listing status affects ANDA certification and litigation procedure but does not establish validity.
• Edarbi and Edarbyclor must be analyzed as separate products because their later patent estates can differ.

FAQs

Is azilsartan medoxomil the same as azilsartan?

No. Azilsartan medoxomil is a prodrug that is converted to azilsartan in the body. US 7,157,584 claims the medoxomil prodrug and its salts.

Does the patent cover all azilsartan formulations?

The supplied claims cover the active compound and its salts, not every formulation. A separate formulation patent would be required to protect excipients, tablet design, release characteristics, or a specific solid form.

Can a generic company avoid US 7,157,584 by using a non-potassium salt?

Not necessarily. Claim 1 covers pharmaceutically acceptable salts generally. A non-potassium salt could remain within claim 1 even if it falls outside the narrower claim 2.

Does patent expiry permit immediate FDA approval of a generic?

No. FDA approval also depends on the ANDA, bioequivalence, labeling, manufacturing, regulatory exclusivity, and any other unexpired listed patents applicable to the product.

Does US 7,157,584 cover Edarbyclor?

It covers the azilsartan medoxomil component, but it does not, based on the supplied claims, expressly claim the azilsartan medoxomil/chlorthalidone combination. Edarbyclor requires a separate analysis of combination, formulation, and method-of-use patents.

References

1. United States Patent and Trademark Office. (2007). U.S. Patent No. 7,157,584, benzimidazole derivative. U.S. Department of Commerce.

2. Google Patents. (n.d.). US7157584B2: Benzimidazole derivative. https://patents.google.com/patent/US7157584B2/en

3. U.S. Food and Drug Administration. (2011). Edarbi prescribing information: Azilsartan medoxomil tablets. FDA.

4. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book. FDA.

Drugs Protected by US Patent 7,157,584

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: 7,157,584

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Japan	2004-048928	Feb 25, 2004

International Family Members for US Patent 7,157,584

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1718641		C300525	Netherlands
European Patent Office	1718641		PA2012004	Lithuania
European Patent Office	1718641		CA 2012 00013	Denmark
European Patent Office	1718641		91962	Luxembourg
European Patent Office	1718641		C20120004 00052	Estonia
European Patent Office	1718641		C20120005 00053	Estonia
European Patent Office	1718641		12C0034	France