US Patent 7,205,302: Claim Scope, K-134 Patent Landscape, Exclusivity and Generic Risk
US Patent 7,205,302 covers a broad class of substituted pyrazine and pyrazine N-oxide compounds, pharmaceutical compositions containing those compounds, and therapeutic uses involving platelet aggregation, peripheral arterial disease and pulmonary hypertension. The claim set appears directed principally to K-134-type thromboxane A2 receptor antagonist chemistry, including the compound 2-{4-[N-(5,6-diphenylpyrazin-2-yl)-N-isopropylamino]butyloxy}acetic acid.
The patent issued April 17, 2007. Based on the patent’s pre-Uruguay Round Agreement filing history, its ordinary US patent term likely ended in 2023, subject to any patent-term adjustment or other term calculation shown in USPTO records. No FDA-approved drug, Orange Book listing, approved generic, or active US Paragraph IV dispute is associated with the claimed compound class on the record reviewed. The principal current value is therefore historical, freedom-to-operate and prior-art relevance rather than blocking exclusivity.
What does US Patent 7,205,302 cover?
The patent has two principal claim groups:
| Claim group |
Claims |
Subject matter |
| Pharmaceutical compositions |
1-5 |
Compositions containing a claimed heterocyclic compound or salt |
| Therapeutic methods |
6-9, 15 |
Platelet aggregation inhibition; arteriosclerosis obliterans; intermittent claudication; peripheral arterial embolism; pulmonary hypertension |
| Compounds per se |
10-14 |
The heterocyclic compounds and salts, including 27 expressly identified compounds |
Claim 1 is the principal composition genus. Claim 10 is the principal compound claim. Claims 5 and 14 identify a defined list of 27 compounds and provide the strongest direct link to individual chemical entities disclosed in the patent.
The patent is not limited to one active ingredient. It claims a chemically broad family built around a substituted pyrazine or pyrazine N-oxide core, two aryl substituents, an amino or sulfinyl-linked chain, and a terminal acidic or sulfonamide-containing group.
What chemical structures are protected by US 7,205,302?
The central structural elements are:
- A heterocyclic pyrazine or pyrazine N-oxide system.
- Two optionally substituted aryl groups, narrowed in dependent claims primarily to phenyl groups.
- A linker containing an amino group, sulfur-containing group, alkylene or alkenylene segment, or related cyclic arrangement.
- A terminal pharmacophore represented by carboxy, alkoxycarbonyl, tetrazolyl, carbamoyl or a specified sulfonamide-related group.
- Pharmaceutical salts and compositions containing the compounds.
The broad claim permits each aryl group to carry up to three substituents selected from a long list, including halogen, alkyl, haloalkyl, arylalkyl, alkoxy, alkylthio, hydroxy, amino, carboxy, cyano and nitro groups.
Claim 2 narrows the aryl groups to optionally substituted phenyl and limits the ring and linker variables. Claim 3 narrows the chemistry further to:
- Pyrazine rather than pyrazine N-oxide;
- Methyl or hydrogen on the linking nitrogen;
- An alkylene chain;
- An oxygen linker;
- A terminal carboxy, tetrazole or formula (22) group.
Claim 4 is narrower still. It requires an alkyl substituent on the linking nitrogen, an alkylene chain, an oxygen linker and either a terminal carboxy group or formula (22) group.
Which named compounds are most commercially relevant?
The listed compounds include diphenyl and di-p-tolyl analogues, N-methyl and N-isopropyl derivatives, oxygen, sulfur and sulfoxide linkers, and multiple sulfonamide derivatives.
The most commercially relevant structure is likely compound 3:
2-{4-[N-(5,6-diphenylpyrazin-2-yl)-N-isopropylamino]butyloxy}acetic acid
This compound is commonly associated with K-134 development. The claimed series was investigated as an antiplatelet and vascular-active drug candidate. The patent itself, however, does not establish regulatory approval, commercial launch or an approved international nonproprietary name.
How broad is claim 1?
Claim 1 is broad in chemical scope but limited by its composition format. It requires:
- A pharmaceutical composition;
- A compound falling within the specified formula;
- A pharmaceutically acceptable carrier.
The claim does not require a particular dosage form, route of administration, concentration, excipient, release profile or disease indication. It can therefore reach tablets, capsules, solutions, suspensions and other conventional pharmaceutical presentations if they contain a qualifying compound and carrier.
The claim has several important limitations:
- The core must fall within the specified heterocyclic formula.
- R1 and R2 must be optionally substituted aryl groups.
- The linker variables must fit the enumerated structural alternatives.
- The terminal group Q must be one of the listed acid, ester, tetrazole, amide or formula (22) categories.
- The product must be a pharmaceutical composition, not merely a chemical intermediate or nonmedicinal composition.
The use of extensive Markush language creates a large theoretical genus. Enforcement would depend on whether the accused compound falls within each structural limitation and whether the composition includes a pharmaceutically acceptable carrier.
What is the scope of claim 10?
Claim 10 is materially more important for chemical freedom-to-operate because it claims the heterocyclic compound or salt itself rather than only a composition.
The compound claim reaches a broad genus with:
- Pyrazine and pyrazine N-oxide alternatives;
- Two aryl groups;
- Multiple linker options;
- Oxygen, sulfur, sulfoxide, sulfone and carbon-based linker possibilities;
- Acid, ester, tetrazole, amide and sulfonamide-related terminal groups.
A compound falling within claim 10 could infringe without being formulated as a medicine. This distinction matters for:
- Active pharmaceutical ingredient manufacture;
- Importation of the active ingredient;
- Supply to a pharmaceutical company;
- Intermediate development;
- Preclinical and clinical development, subject to applicable regulatory exemptions.
Claims 11-13 narrow the genus by requiring phenyl substituents, defined pyrazine configurations, amino-linked alkylene chains and selected terminal groups. Claim 14 lists 27 specific compounds and salts.
Which claims cover methods of use?
| Claim |
Use |
| 6 |
Inhibiting platelet aggregation |
| 7 |
Treating arteriosclerosis obliterans |
| 8 |
Treating intermittent claudication |
| 9 |
Treating peripheral arterial embolism |
| 15 |
Treating pulmonary hypertension |
Claims 6-9 and 15 are method-of-treatment claims dependent on the composition of claim 1. They require administration of an effective amount of a qualifying pharmaceutical composition.
These claims are narrower than a pure compound claim because infringement requires the claimed therapeutic method. Their commercial significance would have depended on an approved product label, clinical use or evidence of induced use. For an unapproved development compound, they would not independently create an Orange Book-style barrier.
What formulations are protected by US 7,205,302?
The patent claims compositions broadly, but the provided claims do not require a specific formulation technology. The protection therefore extends to a composition containing the claimed compound and a pharmaceutically acceptable carrier, provided all claim elements are met.
The claims do not expressly require:
- Extended release;
- Enteric coating;
- A particular particle size;
- A solid dispersion;
- A specific salt form;
- A polymorph;
- A defined tablet strength;
- A transdermal, injectable or inhaled delivery system.
The patent does claim salts, but it does not appear from the quoted claims to provide a separate, narrowly defined polymorph or formulation platform. A later patent could potentially target a specific salt, crystal form, formulation, dosage regimen or manufacturing process without duplicating the full scope of US 7,205,302.
When did US Patent 7,205,302 lose exclusivity?
US Patent 7,205,302 issued on April 17, 2007. The relevant term is ordinarily measured from the earliest effective US nonprovisional filing date, subject to the patent-term provisions applicable to the application and any USPTO patent-term adjustment.
Public patent records associate the patent with a priority chain originating in the late 1990s and a US application filed in the early 2000s. On that basis, the ordinary US term would have expired in approximately 2023, not 2027. The issue date does not control the expiration date.
| Event |
Date or period |
| Earliest priority period |
Late 1990s |
| US application |
Early 2000s |
| Patent issued |
April 17, 2007 |
| Expected ordinary US expiration |
Approximately 2023 |
| Current status for ordinary term |
Expired, subject to USPTO term calculation |
A definitive term determination should use the USPTO Patent Center record, including any patent-term adjustment, terminal disclaimer and maintenance-fee data. The patent’s age makes a currently enforceable US exclusionary right unlikely unless an unusual term adjustment or other legally operative event applies.
Is US 7,205,302 listed in the FDA Orange Book?
No Orange Book-listed approved drug is identified for the claimed chemical series. The patent record does not establish an FDA-approved product or an approved New Drug Application tied to K-134.
This has several consequences:
- The patent is not an apparent Orange Book patent for an FDA-approved reference listed drug.
- There is no conventional abbreviated new drug application pathway based on a listed reference product for this compound.
- A Paragraph IV certification would normally arise only in connection with an ANDA referencing an FDA-approved drug with listed patents.
- A generic challenger would not ordinarily face the standard Orange Book patent-certification process for an unapproved development compound.
FDA approval of a drug candidate is separate from patent ownership. Patent protection can exist without regulatory approval, and regulatory approval can occur after a patent expires.
Are there Paragraph IV challenges or US patent litigation?
No material US Paragraph IV challenge, Hatch-Waxman litigation or settlement agreement is identified for US 7,205,302 in the record reviewed.
That result is consistent with the apparent absence of an FDA-approved reference product based on the claimed compounds. A conventional Paragraph IV dispute generally requires:
- An ANDA applicant;
- A reference listed drug;
- An Orange Book patent listing;
- A certification that the listed patent is invalid, unenforceable or not infringed.
The patent may still have been relevant to development-stage freedom-to-operate analyses, licensing negotiations or research supply arrangements. Those activities would not necessarily generate reported district-court litigation.
Which companies owned or developed the relevant technology?
The patent is associated with Japanese pharmaceutical research and the Kowa development program for K-134-type compounds. The patent’s ownership and assignment history should be separated from later development rights:
| Party or category |
Relevance |
| Original Japanese applicant or research sponsor |
Development and patent origination |
| Kowa-associated development program |
K-134 clinical and pharmacology activity |
| Later licensee or regional partner |
Requires separate assignment or transaction evidence |
| Generic manufacturer |
No identified approved generic sponsor |
| Biosimilar company |
Not relevant because the claimed products are small molecules |
No publicly documented commercial licensing deal is established in the cited patent and FDA records. Patent ownership, clinical sponsorship and commercialization rights can differ by jurisdiction and time period.
How strong is the patent estate?
The patent has mixed strength depending on the target.
Stronger aspects
- Claim 10 covers compounds per se.
- Claim 14 lists specific compounds directly.
- Claim 1 covers pharmaceutical compositions.
- The patent includes several therapeutic indications.
- The chemistry is defined through coordinated structural limitations rather than a purely functional mechanism claim.
Weaker aspects
- The ordinary US term appears to have ended around 2023.
- The broad Markush genus may face written-description, enablement, anticipation or obviousness scrutiny for remote members.
- The composition claims require the full structural formula and a pharmaceutical carrier.
- The use claims depend on the composition claim and may be vulnerable if the relevant compound or disease use is not established.
- The record does not show a marketed product generating Orange Book or commercial exclusivity leverage.
The strongest historical position was likely against manufacture or use of the named K-134 compounds during the patent term. The weakest position was against structurally remote genus members or later-developed formulations that do not contain a claimed compound.
What generic entry risks exist?
For the United States, current generic-entry risk from US 7,205,302 alone appears low because the ordinary patent term likely expired in 2023 and no approved reference product is identified.
The more relevant risks are:
- A new entrant developing a previously unapproved K-134-type product;
- Patent rights in other jurisdictions with different term or prosecution outcomes;
- Later patents covering a specific salt, polymorph, formulation or manufacturing process;
- Regulatory exclusivity attached to a future product;
- Trade-secret or process restrictions affecting API manufacture;
- Foreign patent family members that expired later or remain subject to local adjustments.
A generic launch scenario would therefore be unusual. The likely path would be development of an unapproved new chemical entity or reformulated product, followed by an NDA or another applicable regulatory pathway, rather than a conventional ANDA launch against an existing Orange Book reference product.
Does the patent create biosimilar risk?
No. The claimed compounds are chemically synthesized small molecules, not biologics. Biosimilar provisions under the Public Health Service Act do not apply.
The relevant competitive threats are:
- Small-molecule generic products;
- New chemical entities with similar antiplatelet or vascular mechanisms;
- Alternative thromboxane receptor antagonists;
- Antiplatelet agents already approved for peripheral arterial disease;
- Products using different molecular scaffolds and therefore avoiding the claimed genus.
How does this patent compare with a formulation or method-of-use patent?
US 7,205,302 is primarily a composition-and-compound patent. It is broader than a dosage-form patent but less tailored to a particular marketed product.
| Patent type |
Primary protection |
Relevance to US 7,205,302 |
| Compound patent |
Chemical entity or genus |
Claims 10-14 |
| Composition patent |
Drug plus carrier |
Claims 1-5 |
| Method-of-use patent |
Treatment indication |
Claims 6-9 and 15 |
| Formulation patent |
Release profile, excipients or dosage form |
Not apparent from quoted claims |
| Process patent |
Manufacturing route or purification |
Not apparent from quoted claims |
| Regulatory patent listing |
Approved product protection |
No identified Orange Book listing |
Key Takeaways
- US Patent 7,205,302 claims a broad genus of substituted pyrazine and pyrazine N-oxide compounds.
- Claims 10-14 cover compounds and salts directly; claims 1-5 cover pharmaceutical compositions.
- Claims 6-9 and 15 cover platelet aggregation, peripheral arterial disease and pulmonary hypertension uses.
- Compound 3 is the most commercially recognizable K-134-type molecule in the listed examples.
- The patent issued April 17, 2007, but its ordinary US term likely expired around 2023.
- No FDA Orange Book listing, approved reference product, active Paragraph IV case or material Hatch-Waxman settlement is identified.
- The patent is not relevant to biosimilar competition.
- Any current US commercial barrier is more likely to arise from later patents, foreign rights, regulatory exclusivity, formulation claims or manufacturing IP than from US 7,205,302 itself.
FAQs About US Patent 7,205,302
What drug is associated with US Patent 7,205,302?
The patent is associated with K-134-type pyrazine derivatives, particularly the N-isopropyl diphenylpyrazine compound listed as compound 3. The patent itself does not establish FDA approval or commercial launch.
Is K-134 an approved FDA drug?
No FDA-approved product based on the claimed K-134 compound series is identified in the cited regulatory record.
Can a company manufacture the claimed compounds today in the United States?
The patent’s ordinary US term appears to have expired around 2023. Current freedom to operate would still require review of later US patents, foreign rights, process patents, trade secrets and regulatory requirements.
Does US 7,205,302 cover cilostazol or clopidogrel?
No. The claims describe a distinct substituted pyrazine chemical series and do not cover cilostazol or clopidogrel merely because those drugs also have antiplatelet or peripheral vascular uses.
Are the 27 compounds in claims 5 and 14 individually protected?
They are expressly identified species within the claimed composition and compound categories. During the enforceable patent term, a product containing one of those compounds would have presented a direct infringement risk if all claim limitations were satisfied.
References
-
United States Patent No. 7,205,302. (2007). Heterocyclic compounds and pharmaceutical compositions containing the same. United States Patent and Trademark Office. https://patents.google.com/patent/US7205302B2
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United States Patent and Trademark Office. (n.d.). Patent Center. https://patentcenter.uspto.gov/
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U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
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U.S. Food and Drug Administration. (n.d.). Paragraph IV patent certifications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/paragraph-iv-certifications
