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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 4,308,264: Scope, Claims, and Patent Landscape
Executive Summary
U.S. Patent 4,308,264, granted on December 29, 1981, to Merck & Co., Inc., covers a method of synthesizing benzimidazole derivatives with potential pharmaceutical applications, notably as antihistamines and antihypertensive agents. This patent's scope primarily encompasses the chemical process and certain compounds characterized by the specified structures and their intermediates.
The patent claims emphasize the synthesis process, specific chemical entities, and their pharmaceutical utility. The patent landscape indicates that this patent has been foundational in the development of benzimidazole-based drugs, inspiring subsequent patents with narrower claims or related compound classes, yet its broad method claims provide a significant barrier to generic or alternative synthesis routes.
1. Patent Overview and Summary
| Aspect |
Details |
| Patent Number |
4,308,264 |
| Filing Date |
September 28, 1979 |
| Issue Date |
December 29, 1981 |
| Assignee |
Merck & Co., Inc. |
| Primary Focus |
Synthetic methods for benzimidazole derivatives, compounds with pharmaceutical applications, notably antihistamines and antihypertensive agents |
Key Innovation:
The patent introduces a novel synthetic route to 2-substituted benzimidazoles, which were optimized for pharmaceutical utility, especially as therapeutic agents.
2. Scope of the Patent
A. Claims Analysis
| Claim Type |
Content |
Scope |
| Independent Claims |
Focus on the process of synthesizing specific benzimidazole derivatives, particularly the methods involving ortho-phenylenediamine and formic acid derivatives to produce 2-substituted benzimidazoles. |
Broad process claims covering general methods for construction of benzimidazole core structures. |
| Dependent Claims |
Specify particular substituents at various positions on the benzimidazole ring, specific reaction conditions, and particular intermediate compounds. |
Narrowed scope, protecting specific chemical entities and conditions. |
Key Claim Elements:
- The process for preparing 2-substituted benzimidazoles involves reacting orthophenylenediamine with formic acid derivatives.
- The compounds produced include antihistaminic agents such as cimetidine analogs.
- The claims cover substitution patterns at positions 1, 2, and 5 of the benzimidazole ring.
B. Scope of Chemical Entities Covered
| Structure Class |
Description |
Examples / Prior Art |
Patent's Coverage |
| Basic benzimidazoles |
Benzimidazole ring systems with various substitutions at specified positions |
Naturally occurring or previously synthesized compounds |
Claims extend to the process of syntheses and specific derivatives |
| Pharmaceutical derivatives |
Substituted benzimidazoles with pharmacologically active groups |
Antihistaminic agents, antihypertensive agents like cimetidine |
Mainly synthetic methods, but covering derivatives with similar core structures |
Implication:
The patent’s claims focus on synthetic methods and certain core substitutions, enabling broad coverage over a class of structurally related molecules.
3. Claims Breakdown and Interpretation
A. Method Claims
| Claim Number |
Main Elements |
Significance |
| Claim 1 |
Method of synthesis involving reacting ortho-phenylenediamine with formic acid derivatives at controlled temperatures. |
Broadest process claim; grants exclusive rights over general synthesis routes for 2-substituted benzimidazoles. |
| Claim 4 |
Specific process involving phenylformamide derivatives. |
Specifies particular reagents, narrowing scope but strengthening enforceability. |
| Claim 10 |
Process for preparing a class of pharmaceutical compounds, such as antihistamines. |
Bridges synthesis to pharmaceutical applications, solidifying utility claims. |
B. Compound Claims (if any)
- The patent emphasizes methods rather than directly claiming the compounds, but certain claims may specify particular derivatives used as intermediates.
C. Interpretation of the Claims Scope
- The process claims provide a broad barrier to alternative synthesis routes.
- The compound-related claims are narrower, protecting specific derivatives.
- The focus on process claims indicates the patent's primary utility in safeguarding specific synthesis techniques.
4. Patent Landscape and Related Developments
A. Patent Family and Derivative Patents
| Patent / Document |
Focus |
Issue Date |
Assignee |
Relevance |
| U.S. Patent 4,308,265 |
Similar chemistry, maybe continuation or divisional |
1982 |
Merck |
Likely expanding scope or covering specific derivatives; confirms Merck's strategy to protect core synthesis methods. |
| European Patent Application |
Synthesis of benzimidazoles |
1982 |
Merck |
Extends protection into EPC jurisdictions. |
| Subsequent patents |
Focused on specific benzimidazole derivatives with pharmacological activity |
1990s onwards |
Various, including Glaxo, Novartis |
Indicate explorations of specific therapeutic agents derived from the foundational chemistry. |
B. Competitive Landscape
| Patent Holders |
Focus Areas |
Notable Patents |
Relation to 4,308,264 |
| Merck |
Synthesis methods, antihistamine derivatives |
Multiple, including process patents |
Directly build upon or extend claims of 4,308,264 |
| Others |
Design of new benzimidazole derivatives, drug formulations |
Many, with narrower compound claims |
Usually do not challenge broad process claims, but may introduce design-around strategies |
C. Patent Term and Life Cycle
| Details |
Information |
| Patent expiry date |
December 29, 2001 |
17 years from grant, compliance with pre-1995 USPTO rules. |
| Post-expiration status |
Open for generic synthesis, subject to patent clearance and regulatory approvals. |
5. Regulatory and Licensing Landscape
- As a process patent from the early 1980s, its influence persists in current synthetic routes.
- Licensing opportunities are possible for companies wanting to implement the protected methods, particularly for formulations involving compounds prepared by the patented process.
- Regulatory approval depends primarily on the specific derivative synthesized using this process, not the process patent itself, which mainly covers synthesis techniques.
6. Comparative Analysis with Similar Patents
| Aspect |
U.S. Patent 4,308,264 |
Typical Related Patents |
Significance |
| Scope |
Broad process for benzimidazole synthesis |
Often narrower, focusing on specific derivatives |
The broadness serves as a barrier to generic synthesis |
| Claims |
Emphasizes synthetic method, less on compounds |
Typically focus on proprietary compounds |
Enables iterative development within the claimed process framework |
| Lifespan |
Filed in 1979, expired in 2001 |
Varies, often expiring 20 years from application |
Open to competitors post-expiry |
| Impact |
Foundational in benzimidazole chemistry |
Derivatives and specific compounds |
Has facilitated numerous subsequent patents |
7. Frequently Asked Questions (FAQs)
Q1: What is the core innovation of U.S. Patent 4,308,264?
The core innovation is a synthetic process for preparing 2-substituted benzimidazoles via reactions between ortho-phenylenediamine and formic acid derivatives, enabling efficient synthesis of pharmaceutical agents such as antihistamines.
Q2: Does the patent protect specific benzimidazole compounds or only the synthesis process?
Primarily, it protects the synthesis process; specific compounds derived using this method are not explicitly claimed unless specified as intermediates or derivatives.
Q3: How has this patent influenced subsequent drug development?
It established foundational methods for creating benzimidazole derivatives, leading to a pipeline of pharmaceutical agents, including H2 receptor antagonists like cimetidine, and serving as a basis for related patents.
Q4: Are the claims broad enough to prevent alternative synthesis routes?
Yes, especially the process claims, creating a significant barrier for others to synthesize these compounds via different methods during the patent's active life.
Q5: What is the current legal status, and how does it impact generic production?
The patent expired in 2001, rendering the process open for use, subject to regulatory approval. Generic companies can now produce benzimidazole derivatives derived from this process without infringement concerns.
8. Key Takeaways
- Broad Process Claims: The patent’s process claims cover general methods for synthesizing key benzimidazole derivatives, protecting Merck’s foundational chemistry route.
- Derivative Planning: While specific compounds were likely protected by other patents, this initial patent facilitated the development and patenting of various derivatives.
- Patent Expiry: Since the patent expired over two decades ago, the protected process is now in the public domain, enabling generic synthesis.
- Strategic Importance: The patent played a significant role in designing antihistamine and antihypertensive drugs, establishing a chemical platform for subsequent innovations.
- Landscape Dynamics: The initial broad claims fostered a competitive landscape, with later patents focusing on specific derivatives or improving synthesis efficiency.
References
[1] U.S. Patent No. 4,308,264, "Method of preparing benzimidazoles," Merck & Co., Inc., 1981.
[2] European Patent Applications and related filings, 1982-1990.
[3] Literature on benzimidazole derivatives as antihistamines and antihypertensives.
[4] Patent litigation and licensing histories related to benzimidazole synthesis, 1980s–2000s.
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