Analysis of US Patent 5,821,236: Scope, Claims, and Patent Landscape
Introduction
United States Patent 5,821,236, granted on October 13, 1998, to invigorate pharmaceutical innovation, primarily claims a novel class of compounds with therapeutic utility. This patent's scope, claims, and surrounding patent landscape have critical implications for drug development, licensing, and litigation. This analysis offers a comprehensive examination of the patent's claims and contextualizes their significance within the broader pharmaceutical patent landscape.
Patent Overview
Title: 2-Aryl-4-oxo-3,4-dihydroquinazoline-6-carboxylic acids and their derivatives
Inventors: Vincent F. DeMoff, William M. Freidinger, et al.
Assignee: The Regents of the University of California
Filing Date: August 10, 1995
Issue Date: October 13, 1998
This patent claims compounds exhibiting anti-inflammatory and analgesic activity, with a specific emphasis on quinazoline derivatives. Its primary focus is on the chemical structures' innovative synthesis and therapeutic applications, especially as inhibitors of certain enzymes.
Scope of the Patent
The patent’s scope encompasses chemical compounds, methods of synthesis, and therapeutic uses of quinazoline derivatives. Its claims carve out a protective niche around a specific class of compounds, their pharmaceutical compositions, and their utility in treating inflammatory conditions.
The innovation resides in the chemical structure, notably the quinazoline core substituted at specific positions with various aromatic groups and functional modifications that confer biological activity. The patent covers both compound claims (individual chemical structures) and method claims (methods of preparation and therapeutic use).
Detailed Analysis of Claims
1. Composition of Claims
The patent includes independent claims, primarily directed at:
- Compound claims: Monoclonal chemical structures with specific substitutions at defined positions.
- Method claims: Methods for synthesizing these compounds.
- Therapeutic claims: Uses of these compounds for treating inflammation, pain, and related conditions.
2. Key Elements in the Claims
- Structural specificity: The core quinazoline ring with substitutions at positions 2 and 4, notably aryl groups and carboxylic acid functionalities.
- Substituent variability: A broad range of possible aromatic groups, heterocyclic attachments, and functional groups, allowing extensive scope for derivative compounds.
- Pharmaceutical formulations: Claims extend to compositions and methods deploying these compounds as medicaments.
3. Claim Breadth and Limitations
The patent employs a moderate breadth to encompass numerous chemical variations, balancing broad protection with structural specificity. Notably, the claims specify particular substituents and positions, but also include broader Markush groups, allowing a wide compound class coverage.
4. Critical Claim Sections
- Claim 1: Generally claims a chemical compound with a quinazoline core substituted at specified positions with defined groups.
- Claims 2-20: Further narrow down to particular derivatives or specific substituents, including specific aromatic groups, methods of synthesis, and therapeutic applications.
- Method Claims: Cover synthetic routes and therapeutic methods, broad but anchored to specific compounds.
Patent Landscape Context
1. Related Patents and Patent Families
The quinazoline scaffold is a well-explored chemical space with numerous related patents, especially for kinase inhibitors and anti-inflammatory agents. Among these, US patents such as 5,837,862 and 6,153,237 further elaborate on quinazoline derivatives and their pharmacological applications, reflecting a crowded landscape.
2. Patent Trends and Competitors
Pre- and post-dating the '236 patent, companies and research institutions, including Merck and GlaxoSmithKline, have filed patents covering quinazoline-based compounds, especially as cancer therapeutics (e.g., kinase inhibitors). The '236 patent occupies a niche in anti-inflammatory applications, differentiating it from more oncology-focused patents.
3. Patent Life and Potential Expiry
Filing in 1995, the patent expired in 2015, opening the landscape to generic development for compounds within its scope. However, related patents or divisional filings may still confer select rights, especially in specific jurisdictions or for specific uses.
Implications for Industry and Innovation
-
Freedom to Operate (FTO): Given its expiration, the patent no longer restricts generic or biosimilar development, but active patent filings covering specific derivatives or newly discovered uses may still pose barriers.
-
Research and Development: The broad claims around a class of quinazoline derivatives provide a foundation for further innovation, especially if novel substitutions or formulations are developed outside the patent's scope.
-
Litigation and Licensing: As an expired patent, it has limited litigation value for enforcement but may serve as prior art or licensing baseline for newer inventions.
Conclusion
US Patent 5,821,236 defines a significant chemical space within quinazoline derivatives with anti-inflammatory utility, featuring moderate claim breadth that balances specificity with scope. Its landscape reflects a competitive field centered on quinazoline compounds, particularly kinase inhibitors and anti-inflammatory agents, over time this patent’s influence waned with its expiration but continues to impact related innovations through its foundational chemical disclosures.
Key Takeaways
- The patent's claims cover a broad class of quinazoline derivatives with therapeutic potential, primarily as anti-inflammatory agents.
- Its scope includes specific chemical structures, synthesis methods, and therapeutic methods, effectively protecting a significant chemical space during its active years.
- The patent landscape for quinazoline derivatives is densely populated, especially with compounds targeting kinase activity and cancer, but this patent mainly pertained to anti-inflammatory applications.
- With its expiration in 2015, the patent no longer impedes generic development but remains a key prior art reference for subsequent innovations.
- Future R&D efforts may leverage this foundational chemical class, especially through modifications or novel therapeutic indications, without infringing on this expired patent.
FAQs
Q1: Can I develop a drug based on quinazoline compounds now that US Patent 5,821,236 has expired?
Yes. The expiration of the patent generally permits research, development, and commercialization of compounds within its scope, barring other active patents covering specific derivatives or uses.
Q2: Does the patent cover all quinazoline derivatives with anti-inflammatory activity?
No. It claims a subset of derivatives with specific substitutions and structures. Novel compounds outside these parameters might not infringe.
Q3: How does this patent influence current patent filings in quinazoline chemistry?
While expired, it serves as prior art, informing scope and patentability assessments for new quinazoline-based inventions.
Q4: Are there ongoing patents that build upon this patent?
Yes, subsequent filings often cite this patent, particularly in the context of kinase inhibitors and specific therapeutic uses.
Q5: What should companies consider when developing drugs based on the compounds in US Patent 5,821,236?
They should verify the patent landscape for overlapping patents, especially for specific derivatives, methods of use, or formulations, and consider patent expiration and potential for new inventive steps.
References
- US Patent 5,821,236. "2-Aryl-4-oxo-3,4-dihydroquinazoline-6-carboxylic acids and their derivatives."
- Additional related patents and literature within the quinazoline patent landscape, including references [1], [2], and [3].
(Note: For a comprehensive review, consulting the full patent document and related literature is recommended.)
