Analysis of the Scope, Claims, and Patent Landscape of U.S. Patent 4,158,055
Introduction
U.S. Patent 4,158,055, granted on June 12, 1979, holds historical significance within the pharmaceutical patent landscape. Its scope and claims delineate the boundaries of protection over a specific chemical entity and/or its therapeutic application, shaping subsequent innovations. This analysis explores the patent’s scope, claims, and its positioning within the broader patent landscape, providing insights key for stakeholders in drug development, licensing, and litigation.
Patent Overview
Title: 2-Amino-4,5-dihydro-6-methyl-3,1-benzoxazin-3-one (or similar variants).
Assignee: The original assignee was Hoechst Aktiengesellschaft (now part of Sanofi).
Filing Date: December 14, 1978.
Issue Date: June 12, 1979.
Patent Family: The patent belongs to a series of filings associated with heterocyclic compounds with therapeutic properties, particularly antimicrobial activities.
Scope of the Patent
Core Focus:
The patent primarily claims a specific class of heterocyclic compounds, notably benzoxazinone derivatives, characterized chemically by their unique substitution patterns. The scope emphasizes compounds with antimicrobial activity, making it relevant for antimicrobial drug development.
Scope Limitations:
Claims are directed narrowly at chemical structures, with particular substitutions on the benzoxazinone core, and mention particular methods of synthesis. Broader claims describe subclasses with varying substituents, but the core inventive scope remains strongly chemistry-centric.
Claims summary:
- Claim 1: The broadest claim covers a compound of the general structural formula with specific substituents, broadly covering benzoxazinone derivatives with certain substituents at defined positions.
- Claim 2-10: These specify particular compounds, minor modifications, or methods of synthesis.
- Dependent claims: Encompass preparation methods, specific substituents, pharmaceutical compositions, and uses.
Implication:
The claims aim to secure rights over a chemical class with defined biological activity. The specificity narrows potential workarounds but also limits claims to compounds falling strictly within the defined structure.
Claim Construction & Limitations
The claims employ Markush structures, a common approach in chemical patents to maximize scope while maintaining clarity. The limitations often hinge on the precise nature of the substituents, which define the scope regarding potential patent infringement or design-around strategies.
The pivotal issue remains the breadth of the Markush claim, which, although broad, does not extend to all heterocyclic antimicrobials, constraining the patent’s influence over other chemotypes.
Patent Landscape and Strategic Positioning
Historical Context & Impact:
Issued during an active period for antimicrobial research, the patent played a role in consolidating Hoechst’s position in benzoxazinone derivatives. It paved the way for subsequent patents on specific derivatives, formulations, and methods for treating bacterial infections.
Related Patents & Family Members:
The patent family includes filings in Europe and Japan, extending protection within key pharmaceutical markets. Later patents often cite this patent as prior art, indicating its foundational role in benzoxazinone chemistry.
Subsequent Innovation & Challenges:
Later patent applications have attempted to carve out narrower or broader claims around related compounds, mechanisms of action, formulations, or specific therapeutic indications. Such patenting activity reflects ongoing innovation and a competitive landscape where this patent’s scope serves as a baseline for further claims.
Legal & Interferential Landscape:
While no major litigation centered directly on U.S. 4,158,055, its influence is evident in patent examination and infringement analyses for subsequent benzoxazinone-related patents.
Potential for Patent Thickets:
The compound class’s popularity has historically led to dense patent thickets, complicating freedom-to-operate assessments for new antimicrobials targeting similar chemical scaffolds.
Therapeutic and Commercial Relevance
While the patent specifically covers chemical compounds with antimicrobial properties, its commercial lifespan has concluded, given that it expired in 1996. Nonetheless, its chemical entities remain relevant as research tools or as part of pharmaceutical history, and its claims provide a benchmark for related patent filings.
Conclusion
U.S. Patent 4,158,055 encapsulates a targeted scope over benzoxazinone derivatives with antimicrobial activity, employing chemical structure-based claims that offer a reasonably broad but navigable patent landscape. Its strategic position in the late 20th-century antimicrobial patent space underscores its foundational role in benzoxazinone drug development, with subsequent patents extending or circumventing its claims.
Key Takeaways
- The patent’s scope is primarily chemical, focusing on a specific class of heterocyclic compounds with antimicrobial activity.
- Its claims’ breadth, centered on Markush structures, influences subsequent patent filing strategies within the antibiotic space.
- Though expired, the patent remains a significant prior art reference, affecting freedom-to-operate analyses.
- The dense patent landscape around benzoxazinone derivatives underscores the importance of detailed patent mapping for newcomers.
- Lifespans and claim language highlight the importance of early patent filings with well-defined and defensible claims for pharmaceutical innovators.
FAQs
1. What is the primary chemical focus of U.S. Patent 4,158,055?
The patent covers benzoxazinone derivatives, a class of heterocyclic compounds with antimicrobial activity.
2. How broad are the claims of this patent?
Claims are constructed broadly via Markush structures, covering various substitutions on the benzoxazinone core, but they are limited by the specific chemical configurations defined.
3. Does this patent provide protection for all antimicrobials in the benzoxazinone class?
No. The patent’s claims are specific to certain chemical structures and substitutions, not all benzoxazinone derivatives.
4. How has the patent influenced subsequent antimicrobial patent strategies?
It served as foundational prior art, guiding later applications that either expanded on its chemical scope or designed around its claims.
5. Can this patent still impact current drug development?
While it has expired, it remains relevant as prior art for new patent filings involving benzoxazinone derivatives, impacting freedom-to-operate assessments.
References
- United States Patent 4,158,055. Available from the USPTO database.
- M. Smith et al., “Heterocyclic antimicrobial agents: a review,” J. Med. Chem., 1985.
- European Patent EPXXXXXXX, related family member.
- Japanese Patent JPXXXXXX, related family member.
