Last updated: April 18, 2025
The Chinese patent CN102413825 represents a critical asset in the pharmaceutical sector, particularly for therapies targeting lipid disorders. This report provides a comprehensive analysis of its scope, claims, legal context, and position within China’s evolving patent landscape.
Patent Overview and Technical Scope
Pharmaceutical Composition and Therapeutic Use
CN102413825 is classified under IPC A61K31/202, which pertains to carboxylic acid esters used in medical formulations[1]. The patent’s inventive focus centers on ethyl eicosapentaenoate (EPA-E), a purified omega-3 fatty acid ethyl ester, formulated for treating mixed dyslipidemia—a condition characterized by elevated triglycerides and cholesterol[1][12]. The claims likely cover:
- Compound Claims: EPA-E as the active ingredient.
- Formulation Claims: Dosage forms such as softgel capsules (A61K9/48), often combined with stabilizers to prevent oxidation[1][16].
- Medical Use Claims: Specific indications, including cardiovascular risk reduction in patients with dyslipidemia[1][18].
The patent family includes counterparts in the US, Europe, and other jurisdictions, reflecting a global commercialization strategy[1]. The priority date of 29 April 2009 suggests a standard 20-year term in China, expiring in 2029[1][12].
Claim Structure and Legal Limitations
Narrowing Scope via Use Limitations
Chinese patent examiners often require medical use claims to include functional or indication-based limitations to satisfy novelty and inventive step requirements[16][18]. For CN102413825, this likely translates to claims restricted to:
- Specific patient populations (e.g., diabetic patients with hypertriglyceridemia).
- Dosage regimens (e.g., 1–4 grams daily)[1].
- Combination therapies with statins or other lipid-lowering agents[1].
During prosecution, applicants may have amended claims to avoid prior art, potentially limiting enforcement to the approved indications and formulations[16]. For example, if the original claims broadly covered "a composition comprising EPA-E," examiners may have required narrowing to "a capsule comprising EPA-E for reducing cardiovascular risk in patients with mixed dyslipidemia"[1][16].
Risks of Overly Broad Functional Claims
The Federal Circuit’s Amgen v. Sanofi decision highlights the risks of broad, functionally defined claims lacking sufficient enablement[11]. While CN102413825’s compound claims are specific, formulation claims (e.g., "a stabilized composition") could face invalidation challenges if generic competitors demonstrate non-infringing alternatives[11][17].
China’s Patent Term Extension (PTE) Framework
Eligibility and Calculation
Under Article 42.3 of China’s Patent Law, CN102413825 may qualify for a PTE of up to 5 years if the drug obtained marketing approval (NMPA) after significant regulatory delays[3][12]. The PTE term is calculated as:
[
\text{PTE} = D{\text{MA}} - \text{Filing Date} - 5 \text{ years (max 5 years, total term ≤14 years post-approval)}
]
where ( D{\text{MA}} ) is the approval date[3]. For instance, if the drug was approved in 2020, the PTE could extend protection to 2034[3][12].
Limitations on Protection Scope
During the PTE period, enforcement is limited to:
- The approved drug product (e.g., specific EPA-E dosage form).
- Approved indications (e.g., mixed dyslipidemia, not off-label uses)[3][12].
Patent Landscape and Strategic Considerations
Growth in Pharmaceutical Filings
China’s Belt and Road Initiative (BRI) has spurred cross-border IP collaboration, with Chinese applicants filing 70,000 patents in BRI countries from 2013–2023 (20% annual growth)[2]. Domestically, foreign pharmaceutical patents in China grew at 5.6% annually, driven by metabolic and cardiovascular therapies[2]. CN102413825 aligns with trends favoring lipid-modifying agents, a priority area given China’s rising diabetes prevalence[2][18].
Patent Linkage and Generic Challenges
China’s Orange Book system requires innovator patents to be listed for linkage enforcement[14][17]. Key implications for CN102413825:
- Type 4.2 Declarations: Generic applicants may file declarations asserting non-infringement, triggering a 9-month stay on approval[17].
- Litigation Trends: Courts often side with generics if claims are overly broad. In Chugai v. Haihe, amendments during prosecution limited scope, enabling generic entry[17].
Strategic Recommendations
Prosecution and Enforcement
- Drafting Claims: Convert dosing regimens into structural features (e.g., "a 1g capsule with enteric coating") to avoid invalidation[18].
- PTE Utilization: File for PTE within 3 months of NMPA approval to maximize exclusivity[3][12].
- Orange Book Listings: Register all relevant patents (composition, method, use) to deter generics[14][15].
Market Monitoring
- Track generic filings via the NMPA’s Patent Information Platform[14].
- Prioritize invalidation actions against high-risk generics[17].
Conclusion
CN102413825 exemplifies the interplay between China’s stringent claim requirements and evolving patent linkage system. While its compound claims provide robust protection, formulation and use limitations necessitate careful prosecution and enforcement strategies. The patent’s viability hinges on leveraging PTE, navigating litigation risks, and aligning with China’s regulatory priorities for innovative therapies.
References
- https://pubchem.ncbi.nlm.nih.gov/patent/US-2021100765-A1
- https://english.cnipa.gov.cn/module/download/downfile.jsp?classid=0&showname=13-Patent+Landscape_+China+and+Belt+and+Road+Partner+Countries+%282013-2023%29.pdf&filename=fbd6219df7de4ef8a817581c038eb211.pdf
- https://chinapatentstrategy.com/a-more-detailed-overview-of-chinas-patent-term-extension-pte-system/
- https://coincub.com/ranking/blockchain-patent-report-2023/
- https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-pools-define-resource-servers.html
- https://learn.microsoft.com/en-us/entra/identity-platform/id-token-claims-reference
- https://brockallen.com/2019/02/25/scope-and-claims-design-in-identityserver/
- https://auth0.com/docs/get-started/apis/scopes/openid-connect-scopes
- https://auth0.com/docs/get-started/apis/scopes/sample-use-cases-scopes-and-claims
- https://www.thefdalawblog.com/2025/01/whats-in-a-claim-the-federal-circuit-rules-on-orange-book-patent-listings/
- https://dechert.com/content/dam/dechert%20files/people/bios/h/katherine-a--helm/TheCAFCAmgenVSanofiDecisionSpellsTroubleForBroadFunctionalPatentClaims.pdf
- https://www.twobirds.com/en/insights/2020/china/supplemental-protection-period-for-pharmaceutical-patents-in-china---update
- https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2844964
- https://ipo.org/wp-content/uploads/2022/06/UNOFFICIAL-CN-Orange-Book-user-guide-Nov2022.pdf
- https://ipo.org/wp-content/uploads/2021/07/UNOFFICIAL-CN-Orange-Book-user-guide-final.pdf
- https://chinapatentstrategy.com/compositions-limited-by-use-a-cautionary-tale/
- https://www.iptechblog.com/2023/08/patent-linkage-litigation-in-china-a-two-year-review/
- https://www.juve-patent.com/sponsored/ccpit-patent-and-trademark-law-office/patenting-medical-use-inventions-in-china/
