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Details for Patent: 3,669,966
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Summary for Patent: 3,669,966
| Title: | Pyrazine derivatives and process for their preparation | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract: | Pyrazine derivatives wherein a pyrazine ring is introduced into benzenesulphonyl-urea compounds, typified by the compound ARE DISCLOSED. These compounds have hypoglycemic properties and are useful in the treatment of diabetic conditions. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inventor(s): | Vittorio Ambrogi, Willy Logemann | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assignee: | Pfizer Italia SRL | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Application Number: | US22389A | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Patent Claim Types: see list of patent claims | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Patent landscape, scope, and claims: | # United States Drug Patent 3,669,966: Claim Scope, Glyclopyramide Coverage, and Patent Landscape US Patent 3,669,966 is an early sulfonylurea patent directed to antidiabetic compounds containing a substituted pyrazine carboxamide, a para-substituted phenylsulfonyl group, and an N-substituted urea. The disclosed compounds include glyclopyramide, particularly the 5-methylpyrazine derivative recited in claim 6. The patent issued June 13, 1972, and its original United States term expired June 13, 1989. It therefore creates no current U.S. patent barrier to development, manufacture, or sale of the claimed compounds.[1] The patent’s principal value is historical and technical. It illustrates an early medicinal-chemistry strategy for extending sulfonylurea antidiabetic activity through pyrazine-carboxamide substitution. Its composition claims are narrower than the broad chemical genus described in the specification, while claims 13-15 protect manufacturing routes rather than the compounds themselves. What drug and chemical class does US Patent 3,669,966 cover?The patent covers substituted N-sulfonyl-N'-alkyl or N'-cycloalkyl ureas. The central structural architecture is:
The compounds can be represented at a high level as:
where R4 may be lower alkyl, lower alkenyl, or a five- to eight-membered cycloaliphatic radical, subject to the limitations in the independent claims. The patent’s named examples include compounds with:
The compound in claim 6 corresponds to glyclopyramide, also known as glyclopyramide or glyclopiramide in some historical sources. The chemical description is:
Glyclopyramide is a first-generation sulfonylurea antidiabetic agent. It is not a U.S.-approved reference-listed drug with an active FDA Orange Book patent or exclusivity listing.[2] What patents protect the compounds in claims 2 through 12?Claims 2 through 12 are dependent compound claims. Each incorporates every limitation of claim 1 and adds a specific structural restriction.
Claims 3-12 are composition claims, not process claims. A product falling within one of these claims would have been subject to direct composition-of-matter infringement during the patent term, regardless of whether it was manufactured by the process described in claims 13-15. The dependent claims also establish a prosecution strategy common to pharmaceutical patents of the period: a broad genus in the independent claim, a preferred cycloalkyl limitation in claim 2, and individually named species in later claims. The species claims would have provided fallback positions if the broad genus were challenged for lack of novelty or obviousness. How broad is the chemical genus in US Patent 3,669,966?The genus is materially broader than the named glyclopyramide species. The disclosed substituent definitions permit variation at both the pyrazine ring and terminal urea nitrogen. Pyrazine-ring substitutionsThe R1, R2, and R3 definitions include:
The lower alkyl, lower alkoxy, and phenyl groups may themselves be substituted by halogen, lower alkyl, or lower alkoxy. This creates a potentially extensive Markush genus, although its enforceable scope would depend on the precise wording of claim 1, the specification’s disclosure, and whether the claimed breadth is supported by the examples. The named claims concentrate on pyrazine substituents that are electronically modest and synthetically accessible: methyl, methoxy, chloro, and combinations of these groups. Terminal urea substitutionThe R4 definition includes:
Claim 2 narrows the cycloaliphatic group to five or six carbon atoms. Claims 3-12 then select cyclohexyl. The repeated use of cyclohexyl indicates that the cyclohexyl species was the primary commercial or pharmacological target. Claim construction issuesSeveral terms would require construction under modern U.S. patent practice:
The old chemical nomenclature contains typographical and formatting inconsistencies. Claim 8, for example, appears to contain “benzene-sulphony” rather than “benzene-sulphonyl.” Such errors would ordinarily be analyzed against the specification, prosecution history, and the understanding of a skilled chemist at the filing date. What manufacturing methods are protected by claims 13 through 15?Claims 13 and 15 are process claims. They do not protect every method of making the compounds. They protect specified reaction sequences using defined functional groups and reaction conditions. Claim 13: urea-forming processClaim 13 covers a process in which:
The claim is directed to assembling the terminal urea portion through reaction of complementary amine and isocyanate functionality or related protected intermediates. The broad temperature range is a process limitation, but it is unlikely to provide meaningful current protection because the claim expired with the patent. During the term, infringement would have required performance of the claimed reaction using reactants falling within the defined formulae. Claim 14: dependent process limitationClaim 14 depends on claim 13 and narrows the definition of R5. The supplied claim text does not reproduce the chemical structures following “R5 is selected from the group consisting of.” Its scope therefore cannot be independently mapped from the text provided. Claim 15: carboxamide-forming processClaim 15 covers a separate process route using:
This route is directed to formation of the pyrazine carboxamide linkage. It is distinct from the urea-forming route in claim 13. The process claims could have been relevant to a manufacturer using the claimed synthetic sequence even if the manufacturer did not practice a separately claimed composition route. They would not, however, necessarily reach a chemically distinct process using different activated intermediates or different coupling chemistry. When did US Patent 3,669,966 lose exclusivity?The patent issued June 13, 1972, under the pre-Uruguay Round patent-term regime. The applicable U.S. term was generally 17 years from grant. On that basis, the patent expired June 13, 1989.[1]
Patent term adjustment did not apply in its modern form to this patent. Patent term extension under 35 U.S.C. § 156 was enacted after the patent issued and would not create a current term for this historical compound. What is the FDA Orange Book status of glyclopyramide?Glyclopyramide does not have the commercial U.S. regulatory profile of glyburide, glipizide, or other FDA-approved sulfonylureas. It is not identified as a current FDA reference-listed drug with an active Orange Book patent listing.[2] The practical consequences are significant:
The absence of an Orange Book listing does not itself establish that every form of regulatory approval would be unnecessary. It means the patent is not operating as an FDA-listed blocking right. Which companies challenged or litigated US Patent 3,669,966?No significant modern U.S. Paragraph IV or patent litigation campaign is associated with US 3,669,966. The patent predates the Hatch-Waxman Act by more than a decade, and its expiration occurred before the modern generic-litigation framework became commercially important. The historical commercial context was dominated by established sulfonylurea manufacturers, including:
The patent’s assignee and commercial history should be distinguished from current ownership. Any recorded assignment today would have no practical enforcement value because the patent is expired. How does this patent compare with competing sulfonylurea patent estates?US Patent 3,669,966 is narrower in product architecture than the earliest sulfonylurea patents but broader than a patent limited to glyclopyramide alone.
The patent’s differentiation lies in the beta-(pyrazine-carboxamido)ethyl substituent. That feature separates the claimed genus from simpler sulfonylureas such as tolbutamide and chlorpropamide. What generic-entry risks exist for the claimed compounds?Patent risk is effectively zero from US 3,669,966 because the patent expired. The remaining barriers would be commercial and regulatory. Generic and reformulation riskA company could potentially pursue:
The key risks would include:
Biosimilar riskThere is no biosimilar risk. Glyclopyramide is a small molecule, not a biological product. The relevant competitive pathway is generic or 505(b)(2) development, not the Biologics Price Competition and Innovation Act pathway. What manufacturing and intellectual-property barriers remain?No enforceable barrier remains under US Patent 3,669,966. A current developer would instead assess:
The historical patent does not appear, from the supplied claims, to contain modern formulation claims, solid-state claims, pharmaceutical-composition claims, or treatment-method claims. Its focus is on compounds and preparation processes. A new patent estate could therefore be built around manufacturing efficiency, impurity reduction, particle engineering, dosage-form performance, or a newly supported therapeutic indication. Such patents would not restore exclusivity to the expired compound claim, but they could protect differentiated products. What is the commercial exposure associated with the patent?There is no current revenue exposure attributable to the patent as an enforceable right. The patent cannot block generic manufacture or third-party development in the United States. Historical revenue exposure would have depended on whether the patented cyclohexyl pyrazine compounds were commercialized at scale. Glyclopyramide did not achieve the U.S. commercial position of glyburide or glipizide. Its likely economic importance was regional and substantially lower than that of the leading sulfonylureas. The commercial opportunity today would be constrained by:
How strong is the patent estate for US Patent 3,669,966?The estate was technically meaningful when active but is legally inactive today.
Key Takeaways
Frequently Asked QuestionsIs glyclopyramide the compound claimed in US Patent 3,669,966?Yes. Claim 6 identifies the 5-methylpyrazine-2-carboxamide derivative with an N'-cyclohexylurea substituent, corresponding to glyclopyramide. Can a company manufacture glyclopyramide in the United States without a license to US Patent 3,669,966?Yes, the patent expired in 1989. A license to that patent is not required for current U.S. manufacture based solely on the claims identified. Does US Patent 3,669,966 cover glyburide or glipizide?No. The claimed pyrazine-carboxamide structure is distinct from the chemical structures of glyburide and glipizide. Are any formulation patents identified in the supplied claims?No. The supplied claims are directed to chemical compounds and synthetic processes. They do not recite tablets, capsules, controlled release, salts, polymorphs, excipients, or other dosage-form limitations. Could a new patent be obtained for a glyclopyramide formulation?Potentially, if the formulation contains a novel and non-obvious feature with patentable technical support. A new formulation patent would need to claim the formulation or its use rather than merely re-claiming the expired compound. References
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Drugs Protected by US Patent 3,669,966
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Patented / Exclusive Use | Submissiondate |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| >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: 3,669,966
| Foriegn Application Priority Data | ||
| Foreign Country | Foreign Patent Number | Foreign Patent Date |
| Italy | 18301 A/69 | Jun 18, 1969 |
| Italy | 14581 A/69 | Mar 26, 1969 |
International Family Members for US Patent 3,669,966
| Country | Patent Number | Estimated Expiration | Supplementary Protection Certificate | SPC Country | SPC Expiration |
|---|---|---|---|---|---|
| Austria | 305305 | ⤷ Start Trial | |||
| Belgium | 747405 | ⤷ Start Trial | |||
| Canada | 952112 | ⤷ Start Trial | |||
| Switzerland | 547809 | ⤷ Start Trial | |||
| >Country | >Patent Number | >Estimated Expiration | >Supplementary Protection Certificate | >SPC Country | >SPC Expiration |
