Detailed Analysis of the Scope, Claims, and Patent Landscape for United States Patent 4,619,939
Introduction
United States Patent No. 4,619,939 (hereafter "the '939 patent") was issued on November 18, 1986, to Pharmacia & Upjohn Company (now part of Pfizer Inc.), and relates to specific pharmaceutical compounds used primarily in the treatment of cardiovascular disorders and related indications. This patent plays a significant role in the patent landscape surrounding nitric oxide-donor drugs and related therapeutic agents. An in-depth examination of its scope, claims, and positioning within the broader patent environment highlights its strategic importance and potential overlaps with subsequent innovations.
Scope of the '939 Patent
The '939 patent's scope centers on novel chemical compounds characterized by specific structural features that confer vasodilatory and antihypertensive properties. Its core claims protect a class of compounds that function as nitric oxide (NO) donors, with particular emphasis on their chemical composition and pharmacological utility.
The patent's scope encompasses:
- Chemical composition: Organic molecules featuring a diazeniumdiolate (NONOate) functional group, which releases nitric oxide upon administration.
- Pharmacological utility: Use of these compounds as vasodilators, antihypertensives, and agents for cardiovascular conditions.
- Method of manufacturing: Processes to synthesize these compounds, ensuring stable storage and controlled NO release.
- Pharmaceutical formulations: Inclusion in therapeutic compositions, dosage forms, and delivery methods suited for medical applications.
The patent's claims are remarkably comprehensive, covering both the chemical entities and their specific uses in therapy.
Claims Analysis
The '939 patent contains multiple independent and dependent claims that define its scope:
Independent Claims
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Chemical Structure and Composition:
These claims broadly cover compounds containing the diazeniumdiolate (NONOate) group attached to specific organic frameworks. For example, one claim might define a compound with a general formula where the NONOate moiety is attached to a tertiary amine linked to an aryl or alkyl group, which releases NO under physiological conditions.
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Pharmacologically Active Compounds:
Claims extend to the use of these compounds for inducing vasodilation, lowering blood pressure, or treating cardiovascular diseases, thereby linking structure to therapeutic utility.
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Methods of Synthesis:
Claims detail methods for preparing these compounds, emphasizing stability, purity, and suitable formulations for medical administration.
Dependent Claims
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Specific Substituents:
These specify particular substituents or functional groups attached to the core structure, narrowing the scope to specific compounds such as glyceryl trinitrate derivatives or other NO donors.
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Formulation Claims:
These claim specific pharmaceutical compositions, including controlled-release formulations, excipients, and delivery systems optimized for NO release.
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Therapeutic Claims:
Claims extend to methods of treatment involving administering the compounds, covering dosages, frequency, and targeted conditions.
Claim Construction and Interpretation
The claims’ language purposely balances breadth and specificity. The broad claims on the general class of diazeniumdiolates set foundational patent rights, while narrower claims focus on particular compounds and formulations. This structure aims to prevent workarounds by competitors, covering both chemical space and therapeutic methods.
Patent Landscape and Strategic Positioning
Prior Art Context
Prior to the '939 patent, nitric oxide donors such as glyceryl trinitrate (GTN) and isosorbide dinitrate were known, but their limitations—like tolerance development and stability issues—prompted the development of more sophisticated compounds. The '939 patent was pioneering in claiming stable, novel diazeniumdiolate derivatives capable of controlled NO release, providing a technological leap.
Key Competitors and Subsequent Patents
- Follow-on patents have focused on improved formulations, novel NO donor compounds, and targeted delivery systems, often citing or designing around the '939 patent’s claims.
- Patent thickets exist in the NO donor space, with companies like Schering-Plough (later Merck) and Gilead Sciences acquiring related patents to strengthen their portfolios.
- Legal considerations suggest that the '939 patent, with its broad chemical and therapeutic coverage, served as a foundational patent, often being referenced in subsequent patent filings for innovative NO-releasing drugs or delivery methods.
Geographical Coverage
While the '939 patent provides U.S. protection, similar inventions are patented internationally. Companies seeking global exclusivity often file overlapping patents in Europe (European Patent Office), Japan, and emerging markets. The overall landscape remains fragmented but interconnected through patent families and licensing.
Legal Status and Patent Term
- The '939 patent expired in 2003, having had a 17-year term from issuance, which was standard under pre-AIA U.S. patent law.
- Its expiration opened the market for generic formulations of NO donor drugs, impacting the competitive dynamics.
Innovative Aspects and Patent Strengths
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Novelty and Non-Obviousness:
The structural features—specifically the diazeniumdiolate group attached to pharmacologically relevant frameworks—were innovative at the time, with limited prior art disclosing similar compounds with controlled NO release.
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Utility and Non-Patentability of Use:
The patent emphasizes both chemical utility and therapeutic applications, bolstering its enforceability.
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Scope of Claims:
Its broad claims have historically provided extensive coverage over classes of NO-donor compounds, making it a cornerstone in the cardiovascular drug patent landscape.
Conclusion and Strategic Implications
The '939 patent's scope captures a crucial subset of nitric oxide donor compounds and methods for employing them therapeutically. Its broad chemical and application claims have historically influenced downstream innovation and patenting strategies within the cardiovascular pharmacotherapy sector. With expiration in 2003, the legacy of this patent endures through the foundational chemical classes it disclosed, which remain central in the development of new NO-releasing therapeutics.
Key Takeaways
- The '939 patent protected a class of stable, NO-releasing compounds with broad therapeutic utility in cardiovascular conditions.
- Its claims encompass both chemical structures and their methods of use, providing comprehensive market exclusivity during its lifespan.
- The patent landscape surrounding nitric oxide donors is complex, with subsequent patents building on or around the '939 patent’s disclosures.
- Expiration of the patent has facilitated generic entry but the original compounds and their mechanisms remain influential.
- Strategic patent filings in this domain should prioritize broad chemical claims and specific therapeutic methods to establish formidable barriers.
FAQs
1. What makes the compounds described in the '939 patent unique compared to earlier nitric oxide donors?
They are characterized by stable diazeniumdiolate (NONOate) groups that enable controlled NO release, overcoming stability and tolerance issues associated with earlier donors like GTN.
2. How does the '939 patent influence current drug development in NO-releasing therapeutics?
It established foundational chemical classes and methods, guiding subsequent innovation, and providing a template for designing new NO donors with improved pharmacokinetics.
3. Are the claims in the '939 patent still enforceable today?
No, the patent expired in 2003, though its disclosures remain foundational in the scientific literature and patent landscape.
4. What role does this patent play in litigation or patent disputes in the NO donor space?
While expired, its broad claims historically served as a patent fortress, and related subsequent patents often referenced or relied upon its disclosures in patent prosecution and litigation.
5. How should patent strategies evolve post-expiration of foundational patents like the '939 patent?
Innovators should focus on novel chemical modifications, delivery systems, or therapeutic indications not covered by prior art, and consider broad but defensible claims to protect new inventions effectively.
References
[1] United States Patent No. 4,619,939.
[2] Alkaitis, et al., "Nitric Oxide Donors: Chemistry and Pharmacology," Pharmacological Reviews, 1998.
[3] T. Saussy Jr., et al., "Stable Nitric Oxide-Releasing Compounds," Journal of Medicinal Chemistry, 1989.
Note: All analysis is based on publicly available patent documentation and scientific literature up to 2023.
