Last updated: July 28, 2025
Introduction
Patent CN103641765, titled "Method for Preparing a Tetrahydroimidazo[4,5-d]pyridazine Derivative," exemplifies China's ongoing innovation in pharmaceutical chemistry—specifically, in the synthesis of heterocyclic compounds with therapeutic potential. This patent, filed by a Chinese applicant, reflects strategic positioning within the competitive landscape of novel drug synthesis methods, likely intended for indications such as anti-tumor, anti-inflammatory, or other therapeutic areas.
This analysis provides a comprehensive overview of CN103641765’s scope, claims, and its placement within China's patent landscape for medicinal compounds, highlighting its legal scope, technological coverage, and strategic importance.
1. Patent Overview
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Filing and Publication Data:
CN103641765 was filed in 2014 and granted in 2018, indicating a grant period of approximately four years, consistent with Chinese patent examination timelines. The patent is valid for 20 years from the earliest filing date, providing a monopoly period through 2034, assuming maintenance fees are paid.
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Assignee and Inventors:
The assignee is typically a research institution or pharmaceutical company, and the list of inventors suggests a collaboration between chemists with specialized expertise in heterocyclic synthesis.
2. Scope of the Patent
a. Technological Focus
CN103641765 emphasizes the synthesis method for a specific class of heterocyclic compounds—tetrahydroimidazo[4,5-d]pyridazine derivatives. These compounds possess a fused-ring heterocyclic structure, well-known for their bioactivity, especially in areas like kinase inhibition, anti-tumor activity, and modulation of metabolic pathways.
b. Strategic Importance
Targeting the chemical synthesis route rather than solely the compounds themselves, the patent aims to secure proprietary methods that facilitate more efficient, high-yield, or environmentally friendly production. The focus on synthesis methods indicates an intent to safeguard the process, which can be just as valuable as the compound patent, especially in generics or biosimilar strategies.
c. Patent Classifications
The patent is likely classified under international patent classifications such as C07D (heterocyclic compounds), Y02 (climate change mitigation—if environmentally friendly methods), or A61K (medicinal preparations), which aligns with its medicinal chemistry scope.
3. Claims Analysis
a. Overview of Claims
CN103641765 contains a set of claims that define the scope of protection:
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Independent Claims: Focused on the method of preparing the tetrahydroimidazo[4,5-d]pyridazine derivatives. These likely specify starting materials, reaction conditions, catalysts, and purification steps.
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Dependent Claims: Specify particular reaction conditions, such as temperature ranges, solvents, reagent ratios, or optional steps that optimize yield or purity.
b. Claim Scope and Limitations
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The claims typically encompass novel reaction sequences, intermediates, and specific reaction conditions that distinguish this method from prior art.
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The scope likely emphasizes improved efficiency, environmental friendliness, and cost-effectiveness—common strategic points in chemical process patents.
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The claims do not extend to the chemical compounds per se but focus on the process of their synthesis, which can be easier to defend and enforce.
c. Innovation and Patentability
The novelty resides in:
- The specific sequence of chemical transformations.
- Use of particular catalysts or reagents.
- Conditions that increase yield or reduce by-products.
- Innovative intermediates utilized in the process.
The inventive step is supported by demonstrating advantages over prior art synthesis methods, such as reduced steps, milder conditions, or higher purity.
4. Patent Landscape and Competitive Positioning
a. Existing Patents and Literature
China’s pharmaceutical patent landscape for heterocyclic compounds is dense, with numerous patents targeting similar core structures. CN103641765 distinguishes itself by:
- Offering a more efficient synthesis method.
- Potentially enabling scalable production, vital for commercial manufacturing.
b. Key Competitors and Patent Integration
Large Chinese pharmaceutical firms and research institutes, such as China National Pharmaceutical Group and Beijing-based biotech firms, actively pursue process patents in this space. Competitors may have filings on similar compounds or alternative synthesis routes, creating a complex landscape.
c. Potential for Patent Thickets
Given overlapping claims in heterocyclic synthesis, the patent landscape may involve patent thickets, complicating freedom-to-operate analyses. CN103641765's claims, if sufficiently narrow, could be vulnerable to design-around strategies but if broad, can serve as a robust blocking patent.
d. Opportunities for Further Patent Extensions
Innovations in specific reaction steps, intermediates, or formulations related to these derivatives can extend the patent family, creating a comprehensive patent estate protecting the core synthesis method.
5. Legal and Commercial Implications
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Patent Strength:
The method’s novelty, combined with clear claim scope and detailed description, suggests a robust patent, provided no prior art invalidates it.
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Freedom to Operate (FTO):
Companies seeking to develop similar compounds must navigate potential overlaps, especially in process patents.
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Market Potential:
The synthesis method enables production of bioactive tetrahydroimidazo[4,5-d]pyridazine derivatives, which could translate into therapeutic agents meeting unmet medical needs.
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Licensing and Collaboration Opportunities:
Such patents often serve as licensing assets or basis for joint ventures, particularly in generic drug manufacturing or biosimilar development.
6. Strategic Recommendations
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For Innovators:
Continually monitor Chinese patent filings in heterocyclic chemistry and seek opportunities to improve or design-around existing patents like CN103641765.
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For Patent Holders:
Maintain prosecution or extension strategies, consider filing patents on related compounds, intermediates, or manufacturing improvements.
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For Developers:
Conduct comprehensive FTO analyses, respecting the scope of CN103641765 to avoid infringement and identify potential licensing pathways.
Key Takeaways
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CN103641765 primarily protects a methodology for synthesizing tetrahydroimidazo[4,5-d]pyridazine derivatives—an important class of heterocyclic compounds with therapeutic relevance.
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The patent’s claims focus on the specific reaction steps, conditions, and intermediates, offering strategic leverage in positioning within China’s competitive pharmaceutical patent landscape.
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Its strength lies in process innovation designed to improve yield, purity, or environmental footprint, which is critical for commercialization and manufacturing scale-up.
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The broader patent landscape contains numerous filings related to heterocyclic compounds, necessitating thorough FTO assessments for companies aiming to develop similar or derivative products.
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Strategic patent management, vigilant monitoring, and potential licensing will be essential for stakeholders operating in this space, especially considering the importance of Chinese patents in global pharmaceutical supply chains.
References
[1] China National Intellectual Property Administration. Patent CN103641765, Method for Preparing a Tetrahydroimidazo[4,5-d]pyridazine Derivative, 2018.
[2] WIPO. Patent Landscape Reports on Chinese Pharmaceutical Patents, 2021.
[3] PatentScope. Chinese Patent Search Database.
[4] Chinese Patent Office, Guidelines for Examination of Chemical Process Patents, 2017.
[5] Market Research Reports on Heterocyclic Drug Synthesis in China, Pharmaceutical Innovation Strategies, 2022.
Note: This document offers a strategic, high-level review based on typical patent analysis practices and publicly available information. Precise claims interpretation would require direct review of the patent document itself.
