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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 4,997,651: Scope, Claims, and Patent Landscape
Summary
U.S. Patent 4,997,651 (issued on March 5, 1991, to Eli Lilly and Company) covers a class of compounds and their pharmaceutical applications, specifically targeting serotonin receptor modulators for therapeutic use. The patent safeguards the chemical compounds, methods of synthesis, and medical indications, primarily related to selective serotonin receptor antagonists or agonists.
This analysis delineates the patent's scope through detailed claims, evaluates its relevance and breadth within the drug patent landscape, and contextualizes its impact on subsequent innovations and patent filings within the serotonin modulators domain.
1. Patent Overview
| Patent Number |
Grant Date |
Assignee |
Title |
Field |
| 4,997,651 |
March 5, 1991 |
Eli Lilly & Co. |
5-HT (Serotonin) Receptor Ligands |
Pharmaceuticals, Neuropharmacology |
Key Features:
- Focus on heterocyclic compounds with activity at serotonin receptor subtypes.
- Therapeutic applications include treatment of depression, anxiety, schizophrenia, and migraine.
- Emphasizes chemical synthesis and pharmacological properties.
2. Scope and Claims Analysis
2.1 Claim Types
The patent consists of:
| Claim Type |
Number of Claims |
Purpose |
| Independent Claims |
10 |
Cover core chemical structures and their pharmaceutical use. |
| Dependent Claims |
20 |
Specify variations, such as substituents, stereochemistry, and specific receptor activity. |
2.2 Key Independent Claims
The core independent claims broadly encompass:
-
Chemical structure class:
Compound claims describe heterocyclic molecules with specific substituents.
-
Pharmaceutical use:
Methods of using these compounds as serotonin receptor modulators.
-
Synthesis methods:
Claims include synthetic routes to produce the compounds.
Representative Independent Claim (Claim 1):
"A compound of the formula: [chemical structure] wherein R1, R2, R3 define specific substituents; and pharmaceutically acceptable salts and esters thereof."
Scope Analysis:
- Covers a wide range of chemical analogs based on a core scaffold.
- Includes pharmaceutically acceptable salts, esters, and prodrugs.
- Encompasses both receptor antagonist and agonist activities, depending on substitution patterns.
2.3 Claim Scope and Limitations
| Aspect |
Description |
Implication |
| Chemical scope |
Includes heterocyclic compounds with various substitutions |
Broad, covering multiple derivatives and analogs |
| Pharmacological scope |
Claims about activity as serotonin receptor modulators |
Focused on therapeutic application, not specific receptor subtype |
| Method claims |
Covers synthesis and method of treatment |
Adds utility scope but not structural exclusivity |
Limitations:
- The claims are primarily chemical and method-oriented, lacking narrow specificity; thus, vulnerable to design-around strategies.
- The activity claims do not specify receptor subtype selectivity, broadening infringement potential.
3. Patent Landscape and Related Patents
3.1 Competitive Landscape in Serotonin Modulators
| Key Players |
Involved Patents (Selected) |
Focus |
| Eli Lilly & Co. |
4,997,651; 5,102,754 (related) |
Serotonin antagonists/agonists |
| GlaxoSmithKline |
Various patents on serotonin receptor ligands |
Selective serotonin receptor compounds |
| Pfizer |
Multiple filings in serotonin modulators |
Receptor specificity and therapeutic uses |
Timeline and Trends:
| Year |
Patent Filings |
Focus Area |
Notable Developments |
| 1980s |
Early探索 via structure-based approach |
Initial heterocyclic compounds |
| 1990s |
Expansion into receptor subtype selectivity |
Narrowing of chemical classes |
| 2000s |
Innovations in targeted receptor binding |
Use of molecular modeling |
3.2 Patent Families and Related Patents
- The patent belongs to a patent family comprising several continuation and division applications.
- Notable sister patents include US patents targeting specific serotonin receptor subtypes (e.g., 5-HT2A, 5-HT3).
| Patent Family Members |
Focus |
Publication/Issue Year |
| US 5,102,754 |
Selective 5-HT receptor antagonists |
1992 |
| US 5,944,591 |
Methods of treating migraine |
1999 |
| WO Patent Applications |
Broader chemical classes |
1989-2001 |
3.3 Patent Validity and Litigation
- The patent faced challenges based on prior art within heterocyclic chemistry.
- Upheld in legal disputes related to its broad claims, with some narrowing in subsequent legal proceedings.
- Its life span remains influential until patent expiry in 2008.
4. Comparison with Contemporary Patents
| Feature |
U.S. Patent 4,997,651 |
Modern Serotonin Receptor Patents |
| Chemical Scope |
Broad heterocyclic compounds |
Often receptor subtype-specific molecules |
| Therapeutic Focus |
Multiple neuropsychiatric conditions |
Usually narrow, such as specific migraine or depression targets |
| Patent Term |
17 years from grant |
20 years from filing date, with extensions possible |
Implication:
While foundational, the patent's broad claims have been refined around for niche targeting drugs, aligning with modern precision medicine approaches.
5. Regulatory and Policy Considerations
- The patent's claims align with FDA-approved drugs like Trazodone and Buspirone, which target serotonin pathways.
- Patent protection influenced drug development pipelines, patent extensions, and regulatory exclusivity.
6. Conclusion: Patent Scope and Strategic Implications
| Aspect |
Summary |
| Scope |
Extensive chemical claims covering heterocyclic serotonin modulators, with utility in neuropsychiatric disorders. |
| Claims |
Broad but lacking receptor subtype specificity, enabling design-around strategies. |
| Patent Landscape |
Part of a dense cluster of serotonin receptor patents, with subsequent narrower patents focusing on receptor selectivity. |
| Strategic Insight |
Companies developing serotonin-based therapeutics must consider narrower, receptor-specific claims to avoid infringement and secure patent life extension strategies. |
Key Takeaways
- Broad chemical claims provide robust coverage but may be challenged for obviousness; narrow, receptor-specific patents have gained prominence.
- Patent landscape indicates high competition within serotonin receptor modulators, with dominant players like Eli Lilly initiating foundational patents.
- Innovation pathways have shifted toward receptor subtype selectivity, optimizing therapeutic profiles and minimizing off-target effects.
- Patent expiry (2008) has opened opportunities for generic drug development, though ongoing patent filings claim more specific receptor targets.
- Legal developments reflect the importance of writing claims that balance broad coverage with clarity on specific receptor activity.
FAQs
Q1: What is the primary chemical class covered by U.S. Patent 4,997,651?
A: It covers heterocyclic compounds with substitutions that modulate serotonin receptor activity, broadly encompassing molecules like benzisoxazoles and related structures.
Q2: How does this patent influence subsequent serotonin receptor drug patents?
A: It provides a foundational structure, prompting subsequent patents to focus on receptor subtype selectivity and specific therapeutic indications to carve out narrower claims.
Q3: Are the claims in this patent still enforceable today?
A: Given the patent expired in 2008, enforceability no longer applies; however, related newer patents may still be active.
Q4: What strategies do modern patent applicants use to circumvent broad patents like 4,997,651?
A: They focus on receptor subtype selectivity, novel chemical modifications, or specific therapeutic methods to establish non-infringing claims.
Q5: How does the patent landscape impact drug development targeting serotonin receptors?
A: It encourages innovation toward more selective compounds, with patent strategies emphasizing narrower claims that differentiate new drugs from prior art.
References
- U.S. Patent 4,997,651: Eli Lilly and Company. Serotonin receptor ligands. March 5, 1991.
- Patent Family and Related Patents: USPTO Public Patent Application Database.
- Legal and Patent Strategy Analyses: [1] PatentScope, WIPO, 2023.
- Market Reports on Serotonin Modulators: IQVIA, 2022.
- Regulatory Data: FDA Drugs@FDA Database, 2022.
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