Last updated: July 28, 2025
Introduction
China Patent CN101835473, filed by Baiyunshan Pharmaceutical Holdings Co., Ltd., centers on a method of producing a pharmaceutical composition containing a specific antifungal agent. As an essential piece of intellectual property within China's expanding pharmaceutical patent landscape, the patent warrants a comprehensive review of its scope, claims, and positioning within the broader patent environment related to antifungal therapies.
Patent Overview
CN101835473 was granted on February 26, 2014, with priority from an earlier application filed in 2012, indicating a strategic innovation aimed at improving formulations of antifungal drugs. The patent primarily emphasizes a unique process for preparing a stable, bioavailable pharmaceutical composition containing terbinafine hydrochloride—an allylamine antifungal agent indicated for dermatophyte infections, onychomycosis, and similar fungal conditions.
Scope and Core Claims
The patent encompasses both a method of preparation and the pharmaceutical composition itself. The claims focus on enhancing bioavailability, stability, and ease of administration through specific formulation techniques.
Main Claims
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Claim 1 (Method of Preparation):
Describes a process involving dissolving terbinafine hydrochloride in a suitable solvent, then incorporating specific auxiliary agents (such as stabilizers, surfactants, or carriers) under controlled temperature and pH conditions to produce a stable, uniform solution or suspension conducive for further formulation into oral or topical forms.
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Claim 2 (Pharmaceutical Composition):
Focuses on the resulting composition, characterized by a particular ratio of terbinafine hydrochloride to excipients that improve solubility and bioavailability. It explicitly claims an oral tablet, capsule, or topical cream containing the processed compound as described in claim 1.
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Claim 3 (Stability and Bioavailability):
Asserts that the composition exhibits enhanced stability under standard storage conditions and improved absorption in vivo, backed by experimental data included in the patent description.
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Dependent Claims (4-10):
Elaborate on specific excipient types, processing conditions (e.g., crystallization parameters), and application methods, providing detailed embodiments of the core invention.
Legal & Technical Scope
The patent’s claims demonstrate a focus on formulation technology—specifically, a novel preparation process that yields a stable, bioavailable form of terbinafine hydrochloride suitable for various administration routes. The scope extends to both the composition and the method of manufacturing, offering broad protection over specific formulation techniques and ingredient ratios. While the claims are centered on terbinafine hydrochloride, their breadth could encompass similar allylamine antifungal agents if evidence suggests functional equivalence, subject to patent examination standards in China.
Innovation and Patentability
Given that terbinafine is well-known (marketed since the early 1990s), the novelty hinges on the specific formulation process and resultant composition. The patent emphasizes stability and bioavailability improvements, aligning with typical patent strategies in pharmaceutical formulation. They serve to solve common issues such as poor solubility and shelf-life stability—common hurdles in antifungal drug development.
Patent Landscape Context
1. Global Patent Environment for Terbinafine Formulations
Globally, terbinafine has extensive patent protection, with early patents covering the compound itself and later patents addressing formulations, delivery methods, and specific uses. Notably, the original compound patent expired in numerous jurisdictions before 2012, prompting generic manufacturers to develop alternative formulations, often advancing stability or bioavailability.
In China, local inventive activity is prominent owing to the rise of domestic pharmaceutical firms innovating on formulations and manufacturing processes to extend patent life and market exclusivity. CN101835473 exemplifies this trend, focusing on formulation enhancements rather than the active ingredient itself.
2. Competitor Patents and Formulation Patents
Within China’s patent landscape, formulations based on terbinafine are highly competitive, with multiple patents targeting:
- Novel excipients or carriers to increase solubility or control release.
- Processes for microsphere or nanoparticle production.
- Combination formulations with other antifungal agents.
In particular, patent CN102348560 (filed by Zhejiang Huankang Pharmaceutical Co., Ltd.) claims a microsphere formulation of terbinafine with improved dissolution properties, illustrating the emphasis on advanced delivery systems in this field.
Comparison and Positioning
Compared to other Chinese patents, CN101835473 claims a relatively straightforward process, but its strategic value lies in protecting specific manufacturing steps and formulations that can be licensed or exclusively marketed.
3. Patent Term and Market Implications
Given its grant date in 2014, CN101835473 provides patent protection until at least 2034, assuming maintenance fees are paid. This window secures a significant period for Baiyunshan to commercialize and defend its formulation innovations, particularly in China's expanding antifungal market.
Current Challenges and Opportunities
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Challenges:
The rapid evolution of formulation technologies may lead to challenges via obviousness or prior art, especially as other firms develop nanoparticle or liposomal formulations. Patent examiners may scrutinize claims on process novelty versus obvious adaptations.
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Opportunities:
The patent provides a basis for licensing, strategic expansion in antifungal products, and potentially cross-licensing with competitors. It also complements patent portfolios targeting combination drugs or new delivery devices.
Conclusion
The scope of CN101835473 centers on a proprietary method to produce a stable and bioavailable terbinafine hydrochloride formulation, protected through method and composition claims. The patent landscape reflects intense innovation around improving antifungal drug delivery, with this patent occupying a strategic niche focused on formulation stability. Its protection consolidates Baiyunshan’s position in China's antifungal pharmaceutical market, offering a platform for further innovation and commercialization.
Key Takeaways
- CN101835473 protects a specific formulation process for terbinafine hydrochloride with an emphasis on stability and bioavailability enhancement.
- Its broad claims include both the process and the resulting composition, offering robust protection within China’s pharmaceutical formulation space.
- The patent’s strategic value stems from its longevity—effective until 2034—and its role in maintaining market exclusivity.
- The patent landscape for antifungal formulations indicates ongoing innovation, especially in nanoparticle and targeted delivery systems, which could pose either challenges or opportunities for CN101835473's holders.
- Firms should monitor competitor filings and technological advances to navigate potential patent overlaps or carve out new innovation pathways.
FAQs
1. How does CN101835473 differentiate from prior terbinafine formulations?
It emphasizes a specific preparation process that improves the chemical stability and bioavailability of terbinafine hydrochloride, addressing common issues such as poor solubility and shelf life—differentiating it from traditional formulations.
2. Can the claims in CN101835473 be extended to other antifungal agents?
While the claims are specific to terbinafine hydrochloride, the underlying formulation techniques may be adaptable to similar lipophilic antifungal compounds, contingent on patent examiners’ interpretations and further patent filings.
3. How does this patent impact generic manufacturers in China?
It may limit generic companies from producing similar stable formulations unless they develop alternative methods or wait until the patent expires, ensuring market exclusivity for Baiyunshan.
4. What are the main challenges in defending this patent?
Challenges include demonstrating the novelty of the process amid prior art and proving the claimed stability and bioavailability improvements constitute non-obvious inventive steps under Chinese patent law.
5. Are there opportunities for licensing or developing derivative works based on CN101835473?
Yes, firms can license the formulation technology or develop derivative formulations that bypass specific claims, especially if they employ different excipients, processes, or delivery systems not covered by the current patent.
References
[1] Chinese Patent CN101835473. "Preparation method and pharmaceutical composition containing terbinafine hydrochloride."
[2] Chinese Patent CN102348560. "Terbinafine microsphere formulation."
[3] Global patent databases and literature on terbinafine formulation patents.
