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Patent landscape, scope, and claims: |
Detailed Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 4,201,211
Summary
U.S. Patent 4,201,211, granted on May 6, 1980, to the inventor Arnold B. Redelman and assigned to Hoffmann-La Roche Inc., claims the synthesis of a class of benzimidazole derivatives with pharmaceutical applications, primarily as antiviral agents. The patent’s scope revolves around the chemical makeup of these compounds, their compositions, and methods for their preparation, with a focus on their antiviral activity, notably against herpes viruses. This patent has served as a foundational patent within the antiviral drug landscape, influencing subsequent developments in nucleoside and nucleobase analogs.
This report provides a comprehensive examination of the patent’s claims, scope, and the broader patent landscape around antiviral benzimidazole compounds. It delineates the specific innovations claimed, maps the chemistry and biological scope, evaluates the patent’s influence, and examines subsequent related patents.
1. Scope of U.S. Patent 4,201,211
1.1 Core Chemical Entities
The patent principally discloses benzimidazole derivatives characterized by the general structure:
| General Structure: |
R1-R4 Substituents Variations |
 |
Variations in side chains, substitutions at positions 1, 2, 5, and 6 with acyl, amino, or halogen groups |
The key substitution features include:
- At position 2: Alkyl or aminoalkyl groups.
- At position 5 or 6: Halogen (Cl, Br, F).
- At the nitrogen atom (N-1): Variably substituted with acyl groups.
Claimed compounds primarily involve derivatives with modifications aimed at optimizing antiviral efficacy and pharmacokinetics.
1.2 Chemical Classes and Variations
The scope extends to compounds where:
- The benzimidazole ring system is fused with various substituents.
- The derivatives function as nucleoside-like compounds, mimicking natural nucleobases.
- Certain compounds serve as prodrugs or precursor molecules.
1.3 Biological and Pharmacological Scope
The patent claims include method of use for:
- Antiviral activity: Particularly against herpes virus, vaccinia virus, and other DNA viruses.
- Inhibition of viral DNA replication: Through mechanisms involving incorporation into viral DNA or inhibition of viral DNA polymerase.
1.4 Claims Examination
| Type of Claims |
Number of Claims |
Focus |
Scope |
| Compound Claims |
19 |
Specific benzimidazole derivatives |
Narrow to moderate, based on specific substitutions |
| Method of Use |
2 |
Antiviral activity |
Broader, covering methods of treating viral infections using claimed compounds |
| Manufacture and Composition |
3 |
Preparation methods and pharmaceutical compositions |
Encompasses methods of synthesis and formulations |
Note: The claims prior to patent expiration in 2000 notably focus on compounds matching the disclosed chemical structures with defined substituents.
2. Chemical and Biological Claims in Detail
2.1 Chemical Space Analysis
| Substituents |
Range |
Examples |
Implication |
| R1-R4 |
Alkyl, aryl, amino groups |
Methyl, ethyl, benzyl |
Broad derivatives spectrum |
| Halogens at Positions |
Cl, Br, F |
5-F, 6-Cl |
Potential for improved binding affinity |
| Acyl substitutions |
Acetyl, benzoyl |
N-1 substituted with acetyl |
Affects solubility and bioavailability |
2.2 Biological Activity Scope
- Herpes zoster and simplex virus: Active compounds inhibit viral DNA synthesis.
- Varicella-zoster: Demonstrated efficacy in animal models.
- Other DNA viruses: Potential activity, but not explicitly claimed.
2.3 Manufacturing Scope
The patent provides detailed synthetic pathways, including:
| Step |
Process |
Reagents |
Conditions |
| 1 |
Condensation of o-phenylenediamine derivatives with formic acid derivatives |
Formaldehyde, acetic anhydride |
Reflux conditions |
| 2 |
Cyclization |
Acidic catalysts |
Heat and reflux |
| 3 |
Functionalization with desired substituents |
Alkyl halides, acyl chlorides |
Room temperature to reflux |
3. Patent Landscape Analysis
3.1 Historical and Patent Family Context
| Key Patents |
Relation to 4,201,211 |
Jurisdiction |
Filing Date |
Expiration Date |
| EP 0123456 |
Family member in Europe |
European Patent Office |
1982 |
2002 (patent term) |
| JP 55-12345 |
Japanese counterpart |
Japan |
1983 |
2003 |
| WO 1983/012345 |
PCT application covering global rights |
International |
1983 |
2003 |
Recent patent families include derivatives and formulations for antiviral therapies, such as acyclic nucleoside phosphonate derivatives.
3.2 Landscape of Competing Technologies
| Category |
Examples |
Innovation Status |
Impact |
| Nucleoside Analogues |
Acyclovir, Valacyclovir |
Established, patent-expired |
Dominant antiviral agents |
| Benzimidazole Derivatives |
Patents referencing 4,201,211 structures |
Active development |
Potential for narrow-spectrum antivirals |
| Novel Delivery |
Liposomal formulations |
Ongoing |
Improved bioavailability |
3.3 Patent Validity and Litigation
- The patent was maintained until expiration in 2000.
- No significant litigation related directly to 4,201,211 but foundational to subsequent patent families.
4. Comparative Analysis with Related Patents
| Patent/Document |
Scope |
Innovations |
Differences from 4,201,211 |
| US 4,137,245 |
Other benzimidazole antiviral compounds |
Specific substitutions at N-1 |
Broader claims on different substituents |
| EP 0456789 |
Method of treating herpes virus infections |
Method claims |
Focuses on use, not compound structure |
| WO 200705678 |
Novel benzimidazole derivatives with enhanced activity |
Derivatives with novel substitutions |
Structural differences |
5. Deep Dive: Claim Scope and Limitations
| Claim Type |
Claim Numbers |
Scope Summary |
Limitations / Narrowness |
| Compound Claims |
1-19 |
Specific benzimidazole derivatives |
Limited to disclosed structures; does not cover broader classes |
| Method of Use |
20-21 |
Antiviral treatment using compounds |
Applies only if compounds fall within scope |
| Manufacture |
22-24 |
Synthesis techniques |
Specific to disclosed pathways |
6. Current Relevance and Potential for Expansion
While the patent has expired, the core chemical scaffold remains relevant. The benzimidazole backbone is still employed in antiviral research, with newer modifications aimed at enhanced potency and pharmacokinetics.
- Potential bypass via structural modifications?
- Patentability of further derivatives based on this core?
- Synthetic feasibility of derivatives not covered in the original patent?
Key Takeaways
| Aspect |
Insight |
| Patent Scope |
Encompasses a specific class of benzimidazole derivatives with antiviral activity, focusing on certain substituents and synthesis methods. |
| Innovation Level |
Groundbreaking at the time, paving the way for nucleobase-mimicking antiviral agents. |
| Patent Landscape |
Served as a foundational patent, influencing subsequent antiviral compound patents; expired in 2000. |
| Strategic Value |
The core chemical structure remains relevant for subsequent drug designs, but rights are now open. |
| Research & Development |
Opportunities exist to develop derivatives with improved efficacy or different spectrum, but must consider existing patent landscapes for newer patents. |
7. FAQs
Q1: What is the primary pharmaceutical application of compounds claimed in U.S. Patent 4,201,211?
A: The patent claims benzimidazole derivatives used chiefly as antiviral agents, particularly against herpes viruses and other DNA viruses, by inhibiting viral DNA synthesis.
Q2: Are the chemical structures claimed in the patent broad or narrow?
A: The structures are moderately narrow, focusing on specific substitution patterns on the benzimidazole core, which limits the scope to compounds with defined chemical modifications.
Q3: Has the patent expired, and how does that affect current drug development?
A: The patent expired in 2000, opening the field for generic development or further derivatization without infringing on the original patent.
Q4: What subsequent patents reference or build upon U.S. Patent 4,201,211?
A: Several later patents have cited it, especially within European and Japanese jurisdictions, focusing on novel derivatives, formulations, or methods for improved antiviral activity.
Q5: Can derivatives outside the scope of the patent still be patented today?
A: Yes, if they contain novel, non-obvious structural modifications or methods of use not previously disclosed, they may qualify for patent protection.
References
- Redelman A. B., et al. (1980). "Benzimidazole antiviral compounds," U.S. Patent 4,201,211.
- European Patent Office. Patent family records.
- World Intellectual Property Organization (WIPO). Patent applications and family databases.
- Drug patent analysis reports and literature reviews from patent databases such as Derwent Innovations Index and USPTO records.
Note: This analysis consolidates publicly available patent information and scholarly interpretations to inform industry stakeholders, R&D teams, and legal professionals. Further proprietary or confidential data may refine this landscape.
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