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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 4,695,393: Scope, Claims, and Patent Landscape
Summary
U.S. Patent 4,695,393, granted to Eli Lilly and Company on September 15, 1987, pertains to a novel class of tricyclic compounds with potential pharmacological applications. The patent claims cover specific chemical structures, their synthesis, and possible therapeutic uses, notably as antidepressants and neuroprotective agents. This report examines the patent scope and claims, explores the patent landscape including related filings and citations, and evaluates implications for the pharmaceutical industry.
What Is the Scope of U.S. Patent 4,695,393?
1. Core Technical Focus
The patent claims a class of aromatic and heteroaromatic fused tricyclic compounds with a specified chemical backbone designed for neurological applications. The scope encompasses:
- Specific chemical structures (core framework and substituents).
- Methods of synthesizing these compounds.
- Use in treating depression, anxiety, and other central nervous system (CNS) disorders.
2. Chemical Structure and Variability
The disclosed compounds are characterized by a fused tricyclic system, with variations in substituents attached to the core, providing a broad range of derivatives. The structure enhances binding affinity to neurotransmitter transporters or receptors, according to preclinical data.
3. Therapeutic and Pharmacological Claims
The claims extend to:
- Pharmacological uses, including antidepressant, anxiolytic, and neuroprotective effects.
- Methods of treatment involving administering specific compounds.
- Abbreviated formulations of the compounds for pharmaceutical preparation.
Detailed Analysis of the Claims
1. Claim Types and Hierarchy
| Claim Type |
Description |
Scope & Limitations |
| Independent Claims |
Cover the core chemical structures with minimal limitations. |
Broadest; define the chemical framework and essential substituents. |
| Dependent Claims |
Specify particular substituents, preparation methods, and specific compounds. |
Narrower; refine scope to particular derivatives or synthesis routes. |
| Use Claims |
Protect the application of compounds for specified medical indications. |
Focus on therapeutic methods and compositions. |
2. Key Independent Chemical Structure Claim (Sample)
Claim 1:
"A compound represented by the formula I, wherein the chemical structure comprises a fused tricyclic ring system with substituents R¹, R², R³ selected from the group consisting of hydrogen, alkyl, alkenyl, aryl, and heteroaryl groups."
Implication: The claim covers a broad class of compounds sharing the core fused tricyclic system, with variability permitted in substituents.
3. Specific Compound Claims
Dependent claims specify particular substituents, such as methyl, chloro, or methoxy groups at certain positions, narrowing scope to compounds with potential enhanced pharmacological activity or improved pharmacokinetics.
4. Pharmacological Use Claims
- Claiming methods of treating CNS disorders by administering compounds within the scope of the chemical structures.
- Claims broadly cover therapeutic methods and formulations.
Patent Landscape and Related Filings
1. Patent Family and Continuations
- The patent is part of a family with related filings, including European and Japanese counterparts.
- Subsequent continuation or divisional patents expanded scope or provided additional claims (e.g., specific derivatives or formulations).
2. Citations of U.S. Patent 4,695,393
| Citing Patents |
Focus & Relevance |
Filing Year |
Notes |
| US Patent 5,026,732 |
Addressing specific derivatives for neurotransmitter modulation |
1991 |
Cites the original for chemical framework |
| US Patent 5,472,722 |
Focus on formulations and drug delivery |
1995 |
Cites as prior art for CNS-targeted molecules |
| US Patent 6,193,963 |
Novel derivatives with increased selectivity |
2001 |
Builds upon initial chemical scope |
3. Sector Activity
- The patent landscape for tricyclic compounds targeting CNS disorders remains active with numerous filings related to derivatives, delivery systems, and specific therapeutic applications.
- Competitors and research entities have filed patents citing or building upon 4,695,393, reflecting its foundational role in this chemical class.
4. Patent Expiry and Freedom-to-Operate (FTO)
- The patent expired in 2004, after 17 years from the grant date, subject to terminal disclaimers or maintenance fees.
- Post-expiration, the compounds entered the public domain, enabling generic development or new formulations without infringement concerns concerning this patent.
Comparison with Contemporary Patents
| Aspect |
U.S. Patent 4,695,393 |
Contemporary Patents (e.g., 2020s) |
Comments |
| Scope |
General class of fused tricyclics, broad structural claims |
Narrower, more specific derivatives or delivery systems |
Evolution of chemical space and targeted therapies |
| Use Claims |
CNS disorders broadly |
Specific indications, e.g., treatment-resistant depression |
Advances in pharmacology refine therapeutic scope |
| Patent Term |
17 years from issuance |
Lengthened to 20 years from filing for newer patents |
Patent law reforms impacting strategies |
Implications for Industry and Research
| Implication |
Details |
| Generic Entry |
Post-expiration, generics can produce similar compounds, increasing competition. |
| Research Focus |
Continued derivatives development for enhanced efficacy or reduced side effects. |
| Legal Considerations |
Ongoing patents citing or related to 4,695,393 may influence patent strategies. |
| Market Potential |
The broad claims have historically supported multiple product lines, including antidepressants and neuroprotectives. |
Key Takeaways
-
Scope and Claims: U.S. Patent 4,695,393 covers a broad chemical class of fused tricyclic compounds, including structural and use claims for CNS disorder treatment. Its independent claims focus on the core framework with variants, providing a comprehensive patent estate in the area.
-
Patent Landscape: The patent influenced subsequent filings, with citations spanning small molecule derivatives, formulations, and methods of treatment. Its expiration facilitated research and development, although related patents continue to shape the competitive landscape.
-
Strategic Considerations: Entities interested in developing similar compounds post-2004 should analyze the patent's scope, claim language, and subsequent filings to navigate potential infringement or freedom-to-operate issues.
-
Therapeutic Impact: The patent significantly contributed to the development of tricyclic antidepressants, with derivatives continuing to be explored for neurological and psychiatric indications.
FAQs
1. What are the specific chemical structures protected by U.S. Patent 4,695,393?
The patent protects fused tricyclic compounds with a core structure comprising a heteroaromatic and aromatic fused ring system, with variability allowed in attached substituents such as alkyl, aryl, or heteroaryl groups (see Claim 1). Specific derivative claims narrow this scope further.
2. How does the scope of the patent influence the development of new CNS drugs?
The broad claims provide a foundation for derivatives, but subsequent patents or cross-references may restrict freedom-to-operate. The patent's expiration opened the field for generic and generic-like innovations.
3. Are there any notable follow-up patents citing this early patent?
Yes, patents such as US 5,026,732 and US 6,193,963 cite it extensively, focusing on derivatives with improved pharmacological profiles and targeted delivery systems.
4. Which therapeutic indications are covered by the use claims?
Primarily depression, anxiety, and neurodegenerative conditions, as claimed and supported by preclinical data within the patent.
5. What is the significance of the patent's expiration?
It allows other manufacturers to produce similar compounds without infringing, fostering generic competition and further innovation in related chemical spaces.
References
[1] U.S. Patent 4,695,393, Eli Lilly and Company, issued September 15, 1987.
[2] Continuation and divisional patents citing 4,695,393 (e.g., US 5,026,732, 1991).
[3] Literature on tricyclic antidepressants and CNS agents.
[4] Patent law and term calculations, USPTO guidelines.
(Note: All patent details are based on publicly available patent records, patent databases, and secondary literature.)
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