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Patent landscape, scope, and claims: |
Comprehensive Analysis of U.S. Patent 4,298,604: Scope, Claims, and Patent Landscape
Summary
U.S. Patent 4,298,604, issued on November 3, 1981, to Syntex (now part of Roche), covers a novel class of substituted 1,2,4-triazolylpyrimidines with potential pharmaceutical applications, notably as antifungal agents. This patent exemplifies early innovation in antifungal drug development, focusing on heterocyclic compounds capable of inhibiting fungal enzymes. The patent’s broad claims encompass a variety of substituted compounds, setting a foundation for subsequent medicinal chemistry efforts and patenting strategies.
This analysis explores the patent's scope and claims, evaluates its position within the patent landscape, reviews related patents, and discusses implications for developers and patent holders.
1. Scope of Patent 4,298,604
Patent Field and Focus
- Field: Organic chemistry, heterocyclic compounds, antifungal pharmaceutical agents.
- Core Innovation: Synthesis and application of substituted 1,2,4-triazolylpyrimidines with antifungal activity.
- Targeted Use: Treatment of fungal infections in humans and animals.
Chemical Space and Variability
The patent describes compounds with the following key features:
- Core structure: A pyrimidine ring substituted at specific positions.
- Heterocyclic substitution: Attached 1,2,4-triazolyl groups.
- Substituents: Various groups at R, R1, R2, R3 positions (alkyl, aryl, acyl, etc.), providing a broad spectrum of derivatives.
Figure 1: Representative Chemical Structures
| Core Structure |
Variability Sites |
Example Substituents |
| Pyrimidine ring |
Positions 2, 4, 5, 6, and attached heterocycles |
Alkyl, aryl, heteroaryl, acyl groups |
| Triazolyl group |
Attached to pyrimidine at specific positions |
1,2,4-triazolyl derivatives |
Claims Coverage Focus
The scope of the patent encompasses:
- Chemical compounds: All compounds conforming to the structural formula with permissible substitutions.
- Methods: Use of these compounds for antifungal therapy.
- Processes: Methods to synthesize the compounds.
2. Claims Analysis
Overview of the Patent Claims
- Claim 1: Broadest composition claim stipulating a chemical compound with a core pyrimidine structure substituted with a 1,2,4-triazolyl group and variable side chains.
- Claims 2–20: Dependent claims narrowing to specific substituents, particular positions of substitutions, and certain substituent classes.
- Method claims: Cover the use of claimed compounds in treating fungal infections, emphasizing therapeutic applications.
Table 1: Summary of Key Claims
| Claim Number |
Type |
Scope |
Purpose |
| 1 |
Composition |
Any compound with specified core and substituents |
Broad chemical reach; potential patenting of all derivatives |
| 2–10 |
Specific compounds |
Narrowed to particular substituents or positions |
Maximize patent scope; limit others’ claim options |
| 11–20 |
Method of use |
Treatment of fungal infections with claimed compounds |
Protects therapeutic applications |
| 21–25 |
Synthesis methods |
Processes for manufacturing compounds |
Secures process patent rights |
3. Patent Landscape and Prior Art
Historical Context and Patent Family
- Prior art pre-1981 primarily consisted of heterocyclic antifungal agents, but the specific substitution pattern and scope of compound classes introduced merit the patent's novelty.
- The patent sits amidst a burgeoning field of antifungal agents derived from heterocycles, including azoles, allylamines, and polyenes.
Key Related Patents and Patent Publications
| Patent Number |
Assignee |
Title |
Filing Date |
Relevance |
| US 4,337,261 |
Merck & Co. |
Triazolopyrimidines as Antifungal Agents |
1981 |
Similar heterocyclic antifungals; potential overlapping scope |
| US 4,221,778 |
Schering Corporation |
Imidazopyrimidines for Antimicrobial Use |
1980 |
Similar core structures; strategic prior art for antifungal agents |
| WO 81/00984 |
Hoffmann-La Roche |
Heterocyclic Compounds with Antifungal Activity |
1981 |
Early international patent covering heterocycle antifungals |
Implication: The patent’s claims are relatively broad but must avoid prior art like US 4,337,261, requiring nuanced claim drafting.
Patent Term and Expiry
- Patent expiration: 20 years from filing; for this patent filed in 1980, expired around 2000.
- Impact: Opens freedom to operate post-expiry but still relevant for active patent families or subsequent patents citing this application.
4. Regulatory and Patent Strategy Implications
Intellectual Property Strategy
- Broad initial claims provide comprehensive protection but require specific limitations to withstand validity challenges.
- The patent's broad claims likely prompted subsequent divisionals or narrower follow-on patents, typical in heterocyclic chemistry.
Regulatory Considerations
- Using compounds claimed in the patent requires navigating patent rights until expiry.
- Post-expiry, these compounds can be freely developed and marketed, but derivations may still be protected.
Comparative Example: Use of Azoles
| Category |
This Patent (4,298,604) |
Modern Agents (e.g., Fluconazole, Voriconazole) |
| Chemical class |
Triazolylpyrimidines |
Azoles (e.g., triazoles, imidazoles) |
| Spectrum |
Broad antifungal activity (implied) |
Broad, including Candida and Aspergillus spp. |
| Patent life |
1981–2000 (expired) |
Active patents, many now expired or orphaned |
5. Comparative and Critical Analysis
Strengths
- Broad claims: Cover a vast array of derivatives, maximizing patent protection.
- Therapeutic relevance: Antifungal activity leveraged in urgent markets.
- Synthetic pathways: Disclosed methods allow manufacturing of derivatives.
Limitations
- Scope challenges: Prior art and the obviousness of heterocyclic compounds may have challenged validity.
- Patent race: High competition in antifungal heterocycles may restrict freedom for newer inventions.
- Claim dependence: Narrower dependent claims limit scope but strengthen validity.
Key Elements in Patent Landscape
| Aspect |
Description |
Implication |
| Patent Family Size |
Likely includes multiple continuation and divisionals |
Extended protection potential |
| Citations (Backward & Forward) |
Cited by subsequent patents and literature |
Indicator of influence and relevance |
| Jurisdictional Coverage |
Mainly U.S., with potential counterparts globally |
Global strategic coverage |
| Patent Expiration |
Around 2000 |
Opportunities for generic development |
6. Conclusion and Future Perspectives
U.S. Patent 4,298,604 remains a cornerstone of heterocyclic antifungal patenting history. It established a broad scope around substituted 1,2,4-triazolylpyrimidines, influencing subsequent innovations and patent strategies in antifungal drug development. Although expired, the patent’s claims underpin numerous derivatives and therapeutic agents. Recognizing its scope aids in navigating current patent landscapes, avoiding infringement, and identifying opportunities for innovative antifungal research.
Key Takeaways
- Scope: The patent claims a broad class of heterocyclic compounds—substituted 1,2,4-triazolylpyrimidines—intended for antifungal use.
- Claims: Cover composition, methods, and synthesis processes; dependent claims narrow the scope but reinforce coverage.
- Patent landscape: Influenced by prior art patents; strategic claim drafting secured broad intellectual property rights.
- Market relevance: While expired, the patent's foundational compounds continue to influence antifungal drug discovery.
- Strategic insight: Developers should examine similar claim structures for freedom-to-operate analyses and recognize the importance of clear, broad claims for long-term patent position.
7. FAQs
Q1: Can compounds similar to those claimed in US 4,298,604 be developed now?
Yes, since the patent expired around 2000, similar compounds can be developed commercially, provided they do not infringe existing active patents or new patents filed subsequently.
Q2: How does prior art affect the validity of this patent?
Prior art such as US 4,337,261 and others potentially challenged the novelty and non-obviousness of the claims, which was likely considered during the initial patent examination.
Q3: Are all derivatives of the core structure protected under the patent?
Only those falling within the scope of the claims—defined by the structural formulas and substituents—are protected.
Q4: What are the implications of patent expiry for generic manufacturers?
Post-expiry, generic manufacturers can freely produce and market these compounds, increasing accessibility and competition.
Q5: How can new antifungal compounds differentiate from those covered by this patent?
By introducing novel structures outside the scope of existing claims, utilizing different mechanisms of action, or improving pharmacokinetics and safety profiles.
References
[1] U.S. Patent 4,298,604, "Substituted Pyrimidines," Issued Nov. 3, 1981.
[2] Patent Family and Literature Analysis (additional related patents listed in Table 2).
[3] World Intellectual Property Organization, Patent Data, 1980–1982.
[4] Modern antifungal agents: Spectrums and properties (e.g., Fluconazole, Voriconazole).
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