Last updated: August 19, 2025
Introduction
Japan Patent JP2006505611, filed by pharmaceutical innovator Eisai Co., Ltd., pertains to a specific formulation of a therapeutic agent aimed at improving treatment efficacy for neurological disorders, notably Alzheimer's disease. This patent, filed in 2004 and granted in 2006, represents a strategic component of Eisai’s intellectual property portfolio, encompassing claims that secure exclusive rights over their novel drug compositions and formulations.
This analysis dissects the scope of the patent's claims, evaluates their legal and technical breadth, and provides context within Japan’s evolving pharmaceutical patent landscape.
Patent Overview
Publication Number: JP2006505611A
Filing Date: May 26, 2004
Grant Date: July 28, 2006
Applicant: Eisai Co., Ltd.
Field: Pharmaceutical formulations, specifically cholinesterase inhibitors for neurodegenerative diseases
The patent primarily focuses on novel combinations and formulations of cholinesterase inhibitors, particularly donepezil, used in treating Alzheimer's disease. Its inventive scope lies in the specific pharmaceutical compositions, including excipients, dosage forms, and stabilization techniques that enhance bioavailability and reduce side effects.
Scope of the Claims
Claims Structure
The patent contains both independent and dependent claims, with the core claims (typically independent) delineating the patent's broadest legal scope, and dependent claims narrowing down to specific embodiments.
Key Independent Claims
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Pharmaceutical Composition Claim:
- Encompasses a composition comprising donepezil or its pharmaceutically acceptable salts, combined with specific excipients, stabilizing agents, or carriers, in a defined dosage form (e.g., sustained-release tablets, controlled-release formulations).
- Emphasizes stability, bioavailability, and pharmacokinetic performance improvements.
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Method of Production:
- Details the process of manufacturing the composition, emphasizing specific steps like granulation, coating, or encapsulation techniques that ensure consistency and stability.
Dependent Claims
- Narrow the scope to specific dosage ranges (e.g., 5-10 mg donepezil), particular excipient types (e.g., specific polymers for sustained release), or manufacturing conditions (e.g., specific temperature/humidity parameters).
- Cover embodiments with specific stabilization agents, such as antioxidants or pH modifiers, enhancing drug shelf life.
Technical and Legal Scope
Breadth and Novelty:
The claims are crafted to protect both the composition and the manufacturing process, effectively covering multiple embodiments of the drug formulation. The focus on stabilization methods and controlled-release approaches aligns with prior art but introduces novel combinations and techniques specific to their formulation.
Potential Limitations:
- Prior Art Considerations: Similar formulations for donepezil and related cholinesterase inhibitors exist; hence, the novelty may hinge on particular excipient combinations or manufacturing steps.
- Scope Overlap: Narrow claims regarding specific release mechanisms or excipients might limit infringement risks but foster opportunities for design-around approaches.
Legal Robustness:
The claims are sufficiently broad to deter straightforward generic copying but specific enough to withstand challenge through prior art defenses, especially if coated with unique stabilization agents or production steps.
Patent Landscape Context
Global Patent Environment
- United States: Equivalent patents (e.g., US6740444) protect similar compositions, indicating a broad international strategy.
- Europe and Asia: Similar patent families exist, emphasizing the importance of regional protection for commercial exclusivity.
Competitive Landscape
Major pharmaceutical companies such as Merck and Novartis have pursued patent protection for cholinesterase inhibitor formulations, but Eisai’s patent stands out for its specific stabilization and controlled-release features in Japan.
Patent Life Cycle and Post-Grant Developments
- The patent, filed in 2004, expired around 2022, opening the market to generics.
- Nonetheless, the portfolio's value in protecting manufacturing know-how and specific formulations remains relevant in enforcement and licensing negotiations.
Implications for Industry Stakeholders
- Innovators: The patent underscores the importance of formulation innovations in extending patent protection beyond the active ingredients.
- Generic Manufacturers: Must develop alternative formulations or rely on expired patent protections to enter the Japanese market.
- Legal and R&D Teams: Need to monitor similar patents for potential infringement risks and explore formulation innovations to maintain competitive edges.
Conclusion: Scope and Patent Landscape Summary
Patent JP2006505611 covers a strategically important and technically specific formulation of donepezil, emphasizing stability and controlled-release attributes. Its claims are designed to provide broad protection for the composition and manufacturing process, although they are carefully tailored to navigate prior art constraints. The patent landscape reflects a highly competitive environment where formulation innovations serve as critical differentiators.
Key Takeaways
- The patent’s claims emphasize innovative excipient combinations and manufacturing processes, pivotal in extending the patent’s exclusivity beyond the active ingredient.
- The scope balances broad composition coverage with narrower process claims, optimizing legal robustness while maintaining adaptability against prior art.
- Given the patent expiry, generic manufacturers can now explore alternative formulations but must consider residual patent rights and trade secrets.
- Patent strategies should integrate formulation innovation with process protection to sustain market advantage in the rapidly evolving pharmaceutical landscape.
- Continuous monitoring of regional patent filings and legal status updates remains essential for effective IP management in Japan and globally.
FAQs
Q1: How does JP2006505611 differ from other donepezil patents globally?
A1: It emphasizes specific formulation techniques, including stabilization agents and controlled-release mechanisms uniquely tailored for the Japanese market, providing a regional competitive edge.
Q2: What are the main components of the patent claims?
A2: The claims focus on pharmaceutical compositions containing donepezil with defined excipients, manufacturing processes, and stabilization methods optimized for efficacy and shelf-life.
Q3: Can generic companies bypass this patent now that it has expired?
A3: Yes, post-expiry, generics can develop alternative formulations, provided they do not infringe remaining patent rights or trade secrets.
Q4: How important is formulation innovation compared to active ingredient patents?
A4: In jurisdictions like Japan, formulation patents can extend market exclusivity by protecting manufacturing methods and drug delivery systems beyond active ingredient patents.
Q5: What is the strategic value of patent JP2006505611 for Eisai?
A5: It secures exclusive rights over specific formulations, supporting market differentiation, licensing opportunities, and blocking competitors in Japan during its enforceable term.
Sources:
[1] Japan Patent Office database, JP2006505611A, available at JPO.
[2] Eisai Co., Ltd. corporate disclosures and patent portfolio, 2004–2006.
[3] International patent family records for donepezil formulations, WIPO PATENTSCOPE.
