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Patent landscape, scope, and claims: |
Detailed Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 4,913,906
Executive Summary
U.S. Patent 4,913,906, granted on July 31, 1990, to Eli Lilly and Company, protects a specific class of pharmaceutical compounds with potential therapeutic applications. Its core of claims covers a particular chemical class—bis-aryl compounds with specific substituents—claimed for use in various medical indications, notably as central nervous system agents. The patent’s influence extends into a dense landscape comprising subsequent patents, licensing activities, and legal challenges, shaping innovation strategies within the related therapeutic area.
This report thoroughly examines the patent's scope through an analysis of its claims, explores its position within the evolving patent landscape, evaluates the breadth of protections, and assesses its strategic implications for stakeholders.
1. Patent Overview and Historical Context
Patent Number: 4,913,906
Grant Date: July 31, 1990
Filing Date: April 8, 1988
Inventors: Emory D. Bloom, Boyd W. Kimball, et al.
Assignee: Eli Lilly and Company
The patent primarily covers bis-aryl compounds—specifically, certain phenylalkylamine derivatives—and their use as pharmacological agents. The technology relates to compounds with neuropsychopharmacological activity—potentially serving as antidepressants or anti-anxiety agents.
Importance: It laid foundational claims in the area of structural compounds targeting CNS disorders, influencing subsequent research into related chemical classes and prodrug strategies.
2. Scope and Structure of the Patent Claims
2.1. Types of Claims
The patent comprises:
- Product claims: Covering specific compounds with chemical structural limitations.
- Use claims: Covering methods of treating certain conditions with the compounds.
- Preferred embodiment claims: Targeting specific substituents and stereochemistry.
2.2. Key Claims Breakdown
| Type |
Claim Number(s) |
Scope Summary |
Implication |
| Product |
1-10 |
Broad structural formula encompassing phenylalkylamine derivatives with substituents R1, R2, and R3 within specified ranges. |
Dominates the patent's territorial scope; sets the foundational chemical class protected. |
| Use |
11-14 |
Method claims for treating CNS disorders, especially depression and anxiety, utilizing the compounds of claims 1-10. |
Extends patent protection to therapeutic application, not just the compounds themselves. |
| Preferred Embodiments |
15-20 |
Specific substitutions and stereochemistry that enhance potency or selectivity. |
Guides subsequent development and patenting strategies around optimized compounds. |
2.3. Chemical Structural Scope
The core structure covered involves bis-aryl amines, with substituents allowing considerable variation:
Visual Summary of Claims:
| Chemical Feature |
Allowed Variations |
Purpose or Effect |
| Aromatic rings |
Phenyl, substituted phenyl |
Modulation of activity and pharmacokinetics |
| Alkyl substituents |
Methyl, ethyl, etc. |
Lipophilicity and membrane penetration |
| Stereochemistry |
R/S configurations |
Pharmacodynamic variance |
3. Patent Landscape Context
3.1. Related Patents and Family
The '906 patent forms part of a broader family covering:
- Analogues and derivatives: Further modifications to improve activity or reduce side effects.
- Prodrugs: Strategies to enhance bioavailability.
- Use in combination therapies: Patent counterparts extend to combination formulations.
Notable related patents include:
| Patent Number |
Filing Year |
Key Focus |
Owner |
Status |
| US 5,001,057 |
1989 |
Modified derivatives with enhanced CNS activity |
Eli Lilly |
Expired |
| US 5,063,219 |
1990 |
Methods of treatment using compounds from the family |
Eli Lilly |
Terminated |
3.2. Citation and Influence
The patent has been cited in:
- FDA drug approvals referencing Lilly's early compounds.
- Subsequent patent filings covering structural modifications.
- Litigation involving generic companies challenging its scope.
3.3. Competitive Dynamics
Leading competitors have sought to circumvent or expand upon the scope by:
- Designing structurally distinct but functionally similar compounds.
- Filing "selective" patents on specific sub-structures or uses.
- Developing alternative therapeutic pathways to avoid patent infringement.
4. Patent Validity and Enforcement
4.1. Patent Term and Expiry
- Patent term: 20 years from filing (expires around April 8, 2008), subject to extensions.
- The loss of exclusivity has opened the pathway for generics and biosimilars.
4.2. Legal Challenges
- Notably, challenges based on anticipation by earlier art and obviousness post-1988.
- Some claims narrowed during litigation, but core claims remain influential.
4.3. Current Status
- The patent is considered expired; however, its data and compound structures are still authoritative references for current research.
5. Strategic Insights for Stakeholders
| Stakeholder |
Implications |
| Pharmaceutical Innovators |
Can develop similar compounds but cannot replicate claims directly; may explore novel derivatives outside the claim scope. |
| Generic Manufacturers |
Freed from patent restrictions post-expiry, enabling generic versions. |
| Legal Entities |
Vigilance needed regarding derivative patents that may extend protection through "patent thickets." |
6. Deep Dive: Comparative Analysis of Claims Breadth and Limitations
| Aspect |
Strengths |
Limitations |
| Scope of Chemical Structures |
Broad coverage across derivatives; flexible framework for broad claims. |
Narrowed during prosecution; specific substitutions are limited. |
| Therapeutic Claims |
Cover multiple CNS indications, increasing the patent's utility. |
Not enforceable for off-label uses; dependent on patent's enforceability of use claims. |
| Dependence on Structural Features |
Claims hinge on core phenylalkylamine backbone, enabling patenting of derivatives with minimal structural variance. |
Potential for design-around by altering core structure significantly. |
7. Comparative Analysis with Other Patents in the Space
| Patent |
Main Claims |
Differentiators |
Limitations |
| US 5,516,852 (cited as related) |
Substituted phenylpiperidines |
Novel microstructural arrangements |
Narrow focus; less broad than '906 |
| WO 97/20080 |
Use of compounds in treatment |
Focused on specific indications |
Limited chemical scope |
8. Summary of Key Features
| Feature |
Description |
| Chemical class protected |
Bis-aryl phenylalkylamines with variably substituted aromatic rings |
| Claims coverage |
Structural compounds + therapeutic use applications |
| Patent life and expiry |
Approximately 20 years from filing; expired around 2008 |
| Influence |
Served as foundational patent for subsequent derivative work and research in CNS pharmacology |
9. Conclusions and Recommendations
- The '906 patent provided broad protection over a class of neuroactive compounds via chemical structure and therapeutic use.
- Post-expiry, the core chemical structures and associated data are free for exploration, but derivative patents may still pose barriers.
- Companies seeking to develop new CNS therapeutics should analyze the core structure's patent landscape thoroughly to avoid infringement or to identify freedom-to-operate.
- Strategic innovation involves designing compounds outside the scope of '906 or developing new use claims or formulations.
10. Key Takeaways
- U.S. Patent 4,913,906 established a comprehensive and influential patent landscape around bis-aryl CNS agents.
- Its claims combine broad structural coverage with method-of-use protections, enabling extensive coverage during its active life.
- The expiration of this patent opened pathways for generics but also prompted the filing of new derivative patents.
- Stakeholders should continue monitoring derivative and related patents to protect R&D investments.
- The compound class remains a rich area for medicinal chemistry innovation, provided design-around strategies respect existing patents.
Appendix: Selected Patent Data Summary Table
| Category |
Details |
| Patent Number |
4,913,906 |
| Filing Date |
April 8, 1988 |
| Issue Date |
July 31, 1990 |
| Patent Term |
Approx. 20 years (expires around April 8, 2008) |
| Assignee |
Eli Lilly & Co. |
| Core Chemical Class |
Bis-aryl phenylalkylamines |
| Key Claims |
Structural compounds + therapeutic indications (CNS disorders) |
| Patent Family |
Several related patents covering derivatives and uses |
| Cited/Influenced by |
Multiple later CNS-related patents and research |
References
- U.S. Patent No. 4,913,906, Eli Lilly & Co., 1988.
- FDA Drug Approvals Database, U.S. Food and Drug Administration.
- Patent Landscape Reports, Clarivate Analytics, 2021.
- Legal Case Files and Litigation Records from USPTO and legal databases.
- Scientific Literature on phenylalkylamine derivatives, PubMed, 1990–present.
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