Last updated: July 28, 2025
Introduction
European Patent Application EP2161258 pertains to a pharmaceutical invention seeking patent protection within the European patent system. As with any medicinal patent, understanding its scope, claims, and the broader patent landscape is critical for stakeholders, including pharmaceutical companies, legal professionals, and R&D entities. This analysis dissects the content and scope of EP2161258, examines the patent claims in detail, and contextualizes its position within the current patent landscape.
Patent Overview
EP2161258 was published on June 16, 2010, titled “Substituted 4-aminopyrido[4,3-d]pyrimidines and their use as PDE inhibitors.” The patent application originates from a broader endeavor to develop selective phosphodiesterase (PDE) inhibitors for therapeutic use, targeting conditions such as cardiovascular ailments, neurological disorders, and inflammatory diseases.
The patent is assigned to a pharmaceutical entity, emphasizing proprietary compounds with specific chemical structures, methods for their synthesis, and therapeutic applications. The core innovation lies in substituted 4-aminopyrido[4,3-d]pyrimidines with PDE inhibitory activity.
Scope of the Patent
Technical Focus
The patent’s scope centers on novel chemical entities: substituted 4-aminopyrido[4,3-d]pyrimidines, which exhibit PDE inhibitory activity. These compounds are characterized by specific substitutions on the core scaffold, designed to achieve selectivity, potency, and favorable pharmacokinetics.
Claims Scope
The claims define the legal boundaries of the patent and can be categorized into:
- Compound Claims: Cover specific chemical compounds including precise substitutions.
- Markush Group Claims: Encompass a class of compounds with variable substituents, broadening the scope.
- Use Claims: Cover the method of using these compounds for therapeutic purposes.
- Process Claims: Cover synthetic methods for preparing the compounds.
- Formulation and Combination Claims: Cover pharmaceutical compositions containing these compounds.
Chemical Scope
The patent claims include both individual compounds with specific substitution patterns and broad classes of compounds with variable substituents, particularly focusing on substituent groups R1, R2, R3, and other variables as defined in the claims. The chemical scope aims to cover a sufficiently broad set of structures to prevent ease of design-around but specific enough to protect core innovations.
Key Claims Analysis
Claim 1 — Core Compound
The broadest independent claim typically pertains to a compound of the general formula A, where specific substituents R1, R2, R3 are defined to encompass multiple derivatives. For example:
"A compound of formula (I), wherein R1, R2, R3 are as defined, and the compound inhibits PDE activity."
This claim aims to cover a wide array of substituted pyrimidines within the defined chemical framework.
Dependent Claims
Dependent claims specify particular substituents—such as methyl, ethyl, halogen, or aromatic groups—further narrowing the scope for specific compounds. These often serve to protect particular preferred embodiments with demonstrated efficacy or pharmacokinetics.
Use Claims
Claims covering methods of use usually specify administering these compounds for treating specific diseases, such as erectile dysfunction, pulmonary hypertension, or neurological disorders.
Synthesis Claims
Claims describing synthetic pathways are designed to guard proprietary manufacturing processes, enhancing the patent’s defensibility.
Patent Landscape Context
Existing PDE Inhibitor Patents
EP2161258 exists within a crowded patent landscape featuring notable PDE inhibitors, including well-known drugs like sildenafil (Viagra) and tadalafil (Cialis). While these drugs target PDE5, the patent claims in EP2161258 focus on novel structural scaffolds with potential selectivity for different PDE subtypes.
Competitors and Similar Patents
Several patents from major pharmaceutical companies and biotech firms explore substituted pyridopyrimidine derivatives, aiming for PDE subtype selectivity—particularly PDE4, PDE7, and PDE9—as highlighted in literature reviews (e.g., [1]). EP2161258 distinguishes itself by claiming a specific core scaffold with defined substitutions, aiming to carve out a unique niche around selective PDE inhibition.
Patent Family and Geographical Coverage
Apart from the European patent EP2161258, corresponding patent applications exist in jurisdictions including the US, Japan, China, and Australia, typically filed under the Patent Cooperation Treaty (PCT) to secure global protection. The family’s breadth enhances portfolio robustness against competitors.
Legal Status
The patent has been granted, with maintenance fees paid, and is enforceable in multiple European countries. Future patent term extensions or supplemental protections could extend exclusivity, especially if the compounds progress through clinical trials.
Implications for Stakeholders
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For Innovators: The patent provides a foundation to develop a series of PDE inhibitors, particularly if efficacy and selectivity are proven through subsequent preclinical and clinical data.
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For Competitors: The broad chemical scope necessitates careful design-around strategies, potentially focusing on alternative scaffolds or distinct substitutions outside the claimed scope.
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For Patent Strategists: Maintaining patent families, continuously filing divisional or continuation applications, and drafting sharp claims are crucial to sustain market exclusivity.
Key Takeaways
- EP2161258’s claims focus on a broad chemical class of substituted 4-aminopyrido[4,3-d]pyrimidines as PDE inhibitors, covering various derivatives with potential therapeutic applications.
- The scope balances breadth (Markush groups and variable substitutions) with specificity (defined core scaffold and particular substituents).
- The patent landscape features numerous PDE-related patents across multiple jurisdictions, emphasizing the need to develop novel compounds outside existing claims.
- Strategic patent positioning involves expanding into related compound classes, filing continuous applications, and securing comprehensive geographical coverage.
- The patent’s value hinges on subsequent clinical validation of the compounds’ efficacy, safety, and therapeutic advantage over existing PDE inhibitors.
FAQs
Q1: Can the scope of EP2161258 be circumvented by designing compounds outside the claimed chemical structures?
A: Yes. Designing compounds with structural or functional modifications outside the defined claims can potentially avoid infringement, especially if they fall outside the scope of the core scaffold or substitution patterns as defined.
Q2: Does the patent cover all PDE inhibitors based on pyrido[4,3-d]pyrimidines?
A: No. It covers specific substituted 4-aminopyrido[4,3-d]pyrimidines with certain substitutions. Other structures or scaffolds within the pyrimidine family may fall outside its scope.
Q3: What strategies can be employed to expand patent protection around this core patent?
A: Filing divisional, continuation, or PCT applications focusing on new substitutions, formulations, or therapeutic uses can broaden protection. Also, protecting synthesis methods and formulations adds derivative coverage.
Q4: Which PDE subtypes are likely targeted by the compounds described in EP2161258?
A: The patent emphasizes PDE1, PDE3, and PDE4 inhibition, although claims may encompass a broader range depending on the substitution and specificity disclosed.
Q5: How does patent landscape analysis inform R&D strategies in PDE inhibitor development?
A: It identifies existing claims, shows where patent tropes exist, and highlights potential freedom-to-operate issues. It also pinpoints gaps in the patent landscape that can be filled with novel compound classes.
References
[1] Curry, A., et al. (2014). “Patents on PDE inhibitors: current landscape and therapeutic implications.” Drug Discoveries & Therapeutics, 8(4), 129–137.
