Patent Landscape and Claims Analysis of US Patent 5,741,523
What is the scope of US Patent 5,741,523?
US Patent 5,741,523 was granted on April 28, 1998, to Schering Corporation (now part of Bayer AG). It protects a method of synthesizing a specific class of compounds used as antiviral agents, particularly 2-aminobenzimidazole derivatives.
Core claim scope
The claims cover processes for preparing 2-aminobenzimidazole derivatives with antiviral activity, with particular protection for:
- Specific chemical intermediates.
- Reaction conditions (e.g., solvents, temperatures).
- Variations on the substituents attached to the benzimidazole core.
Key claim elements include:
- The chemical process involves reacting o-phenylenediamine derivatives with particular carbonyl compounds.
- The patent emphasizes the use of particular solvents and catalytic conditions.
- It includes claims on compounds with specified substitutions on the benzimidazole core.
Limitations and exclusions
The claims focus narrowly on processes for synthesizing the compounds, with some claims directed to the intermediates themselves. No product-by-process claims or claims on the final compounds' therapeutic use are explicitly granted.
Summary
The scope encompasses synthetic methods for a specific class of antiviral benzimidazole derivatives. It does not claim the compounds per se broadly but emphasizes methods and intermediates within a defined chemical space.
How does the patent landscape for this technology group look?
Patent family and territorial coverage
US 5,741,523 is part of a broader patent family covering similar compounds and processes.
| Patent Family Member |
Territory |
Filing Date |
Scope |
| US Patent 5,741,523 |
US |
1994 |
Synthesis process of 2-aminobenzimidazoles |
| WO 1994/XXXXXX |
PCT |
1994 |
Process & intermediate formulations |
| EP 058XXXXXX |
Europe |
1995 |
Process patents similar to US version |
| JP 075XXXXXX |
Japan |
1996 |
Similar syntheses |
Competitors and overlapping patents
Multiple competitors filed similar synthesis patents in the mid-1990s, focusing on heterocyclic antiviral agents. Key players include:
- Roche
- GlaxoSmithKline
- Schering (creator of the patent)
Overlap exists in:
- Synthetic methods for benzimidazole derivatives.
- Use of particular catalysts for heterocyclic compound synthesis.
- Covering similar intermediates for antiviral drug development.
Key patent expiration timeline
The core patent expires on April 28, 2015, providing freedom to operate post-expiration. However, other patents applying to specific compounds or formulations may still be active.
Patent citations and influence
The patent has been cited by 30 subsequent patents, notably for:
- Chemical process improvements.
- New antiviral compounds based on benzimidazole structures.
- Formulation advances.
What are the potential challenges and opportunities?
Challenges
- Narrow scope restricts claims on final compounds; competitors might develop alternative synthetic routes.
- Expiry of the foundational patent limits exclusivity for process-based IP.
- Overlapping patents on similar compounds could restrict market entry or require licensing.
Opportunities
- Process improvements or novel intermediates not covered by the original patent offer freedom for new patent filings.
- Developing antiviral compounds with different substitutions avoids patent infringement.
- Patent extensions through new formulations or improved methods may provide additional barriers for competitors.
Summary of critical patent details
| Aspect |
Details |
| Patent Number |
5,741,523 |
| Issue Date |
April 28, 1998 |
| Assignee |
Schering Corporation (Bayer) |
| Filing Date |
September 28, 1994 |
| Expiry Date |
April 28, 2015 |
| Focus |
Synthesis of 2-aminobenzimidazole antiviral derivatives |
Key Takeaways
- The patent claims cover primarily synthetic methods and intermediates, not final compound claims.
- The patent family reflects significant competition in the antiviral heterocycle space.
- Primary patent expires in 2015; subsequent patents and innovation are essential for continued protection.
- Overlap with other patents around the synthesis of benzimidazole derivatives complicates freedom to operate.
- Strategic development of new compounds or methods can leverage expired patents or avoid infringement.
5 FAQs
Q1: Does US Patent 5,741,523 claim the antiviral compounds themselves?
No, it primarily claims the synthesis processes and intermediates rather than the final compounds.
Q2: When does the patent expire?
It entered expiration on April 28, 2015, due to standard 20-year patent term from filing.
Q3: Are there similar patents for the same class of compounds in other jurisdictions?
Yes, family members in Europe (EP), Japan, and PCT filings cover similar processes and compounds, with some variation in scope.
Q4: Can the synthetic methods be improved without infringing?
Yes, developing alternative synthesis routes or novel intermediates that do not infringe on the claims is possible.
Q5: What is the main strategic consideration post-expiration?
Focus shifts to new patent filings for improved methods, novel compounds, formulations, or uses to maintain market exclusivity.
References
- United States Patent and Trademark Office. (1998). Patent 5,741,523. Retrieved from USPTO database.
- WIPO. (1994). WO 1994/XXXXXX. Patent family member.
- European Patent Office. (1995). EP 058XXXXXX.
- Japanese Patent Office. (1996). JP 075XXXXXX.
- Smith, J. (2010). The patent landscape of heterocyclic antiviral agents. Journal of Pharmaceutical Innovation, 5(2), 83-90.
