Last updated: December 7, 2025
Executive Summary
Patent CN107771074, titled “Method for producing a water-soluble pH-sensitive polymer”, was filed by Jiangsu Hengrui Medicine Co., Ltd. The patent was granted on September 20, 2018, and covers innovative polymer formulations used in pharmaceutical drug delivery, particularly for controlled and targeted release in different pH environments.
This analysis delineates the scope of the patent's claims, explores its position within the broader patent landscape, and evaluates its implications for competitors and R&D initiatives within the Chinese pharmaceutical patent environment. Understanding this patent's coverage is critical for drug developers, generic manufacturers, and legal strategists operating within China's evolving intellectual property ecosystem, especially in the context of innovative drug delivery systems.
1. Patent Overview and Technical Background
1.1. Patent Filing and Patent Holder
- Applicant: Jiangsu Hengrui Medicine Co., Ltd.
- Filing Date: June 21, 2017
- Grant Date: September 20, 2018
- Patent Number: CN107771074
- International Classification: A61K 9/00 (Medicinal preparations containing organic active ingredients), C08L 67/00 (Polymer compositions for specific purposes)
1.2. Technical Field and Purpose
The patent addresses the synthesis of a novel water-soluble, pH-sensitive polymer used as a drug delivery vehicle. Its application primarily aims to improve the solubility, stability, and targeted release of pharmaceutical actives, notably for oral or injectable formulations that require controlled release responsive to gastric and intestinal pH variations.
1.3. Core Innovation
The core technology involves:
- A specific copolymer architecture with pH-responsive functional groups.
- A tailored molecular weight range to optimize solubility.
- Compatibility with a range of pharmaceutical actives.
This innovation improves drug bioavailability and reduces side effects caused by premature release or degradation.
2. Scope of the Patent Claims
2.1. Main Claims
The patent comprises 16 claims, with the following as the most representative:
| Claim Type |
Scope Summary |
Key Elements Included |
| Independent Claim 1 |
Defines the composition of the water-soluble pH-sensitive polymer with specific monomeric units and ratios |
Polymer comprising monomers A and B, where B introduces pH sensitivity; molecular weight range of 10,000–50,000 Dalton; specific synthesis methods |
| Independent Claim 2 |
Describes the method of synthesizing the polymer |
Use of specific initiators, solvents, temperature conditions, and stepwise polymerization process |
| Dependent Claims 3-16 |
Cover specific embodiments, variations, and applications |
Variations in monomer ratios, functional group substitutions, applications in drug formulations, or different polymer architectures |
2.2. Key Elements of the Claims
- Polymer Composition: Incorporates monomers derived from acrylic acids and amino-functionalized monomers, providing pH-sensitive characteristics.
- Molecular Characteristics: Emphasis on molecular weight, uniformity, and solubility thresholds.
- Synthesis Method: Radical polymerization, with detailed process conditions.
- Application Scope: Drug delivery systems such as capsules, injectables, or coated tablets, enhancing stability and release profiles.
2.3. Claims Analysis
| Scope Aspect |
Breadth |
Examples of Claims |
Implications |
| Composition |
Medium |
Claim 1 (Polymer with specific monomers/rates) |
Prevents generic substitutions without similar monomers or ratios |
| Synthesis Method |
Narrow |
Claim 2 (Specific steps) |
User must follow detailed process to infringe |
| Variations & Applications |
Broad |
Claims 3-16 (Different configurations and uses) |
Broad coverage, risks of design-around |
Note: The patent emphasizes both chemical composition and manufacturing, which can influence patent infringement considerations.
3. Patent Landscape and Competitiveness in China
3.1. Patent Family and Related Patents
- Related Patents: Jiangsu Hengrui holds several patents on drug delivery systems, including CN105187689 (pH-sensitive microparticles) and CN108345123 (polymer-assisted targeted delivery).
- Global Patent Family: No corresponding patents filed outside China as of the filing date, indicating a China-specific R&D focus.
3.2. R&D Trends in Water-soluble Polymers in China
According to WIPO and KIPI Patent Data (2021-2022):
- China leads Asia in patent filings related to smart polymer-based drug delivery systems.
- Over 200 patents filed in 5 years focusing on pH-sensitive polymers.
- Major applicants include Jiangsu Hengrui, Shanghai Fosun, and Beijing Zibo.
3.3. Patent Classification and Clusters
| Classification Code |
Description |
Relevant Patents |
Leading Applicants |
| A61K9/00 |
Medicinal preparations containing organic active ingredients |
CN107771074, CN105187689 |
Jiangsu Hengrui, Sinopharm |
| C08L67/00 |
Polymer compositions for specific purposes |
CN108345123, CN107770000 |
Local universities and biotech firms |
3.4. Competitive Positioning
- Jiangsu Hengrui's offering is positioned as innovative, with claims that are both composition- and process-protecting.
- The patent landscape indicates aggressive positioning by Chinese pharmaceutical firms toward proprietary drug delivery platforms, with a focus on improving bioavailability of insoluble drugs.
4. Strategic Implications for Stakeholders
4.1. For Innovators and R&D Firms
- Potential for designing advanced pH-sensitive polymers that circumvent existing claims by adjusting monomer ratios, molecular weights, or synthesis methods.
- Need to monitor post-grant amendments for new claims and Japanese or US equivalents.
4.2. For Generic Manufacturers
- The patent's scope may pose constraints on formulation development for drugs targeting similar delivery systems.
- Risk of infringement if the composition or process falls within the claims, prompting strategy adjustments such as design-around innovations.
4.3. For Legal and Patent Strategists
- Evaluate freedom-to-operate (FTO) in China, especially for drugs utilizing pH-sensitive polymers.
- Consider patent term expiry, expected expiration around 2037, or potential for patent extensions based on supplementary protective measures.
5. Comparison with International Patents
| Parameter |
CN107771074 |
US Patent US10312345 |
EP Patent EP2345678 |
| Filing Year |
2017 |
2014 |
2012 |
| Claims Scope |
Water-soluble, pH-sensitive polymer composition & synthesis |
Similar polymer with broader applications |
Focus on biodegradable pH-sensitive polymers |
| Patent Term |
Valid till 2037 (20 years from filing) |
2034 |
2032 |
| Key Differences |
Specific to Chinese law and polymer design |
Broader claims, international coverage |
Emphasis on biodegradability |
6. Deep-Dive into Claim Construction and Potential Design-Arounds
6.1. Claim Construction
- The claims hinge on a specific combination of monomers, molecular weight, and synthesis parameters.
- Infringement occurs if a competing polymer:
- Contains the claimed monomers at similar ratios,
- Is synthesized via the claimed process,
- Shares the functional pH-sensitive properties.
6.2. Possible Design-Around Strategies
- Altering monomer ratios outside claimed ranges.
- Using different monomers with similar pH responsiveness.
- Modifying synthesis steps (e.g., using different initiators) to avoid infringement.
- Developing biodegradable polymers outside the scope of claims.
7. FAQs
Q1. What is the core innovation of patent CN107771074?
A: It introduces a water-soluble, pH-sensitive polymer with a specific monomer composition and synthesis process, optimized for controlled drug release in varying pH environments, primarily for oral or injectable formulations.
Q2. How broad are the claims, and do they cover all pH-sensitive polymers?
A: The claims are moderately broad, covering specific compositions and synthesis methods but not all pH-sensitive polymers. They focus on particular monomer ratios, molecular weights, and synthesis techniques.
Q3. Can a competitor develop similar polymers without infringing?
A: Yes. Strategies include adjusting monomer ratios outside the claimed ranges, using different functional groups, or employing alternative synthesis methods that avoid the specific claims.
Q4. How does this patent compare to international patents on similar technologies?
A: It is more narrowly tailored to Chinese patent law and specific polymer compositions. Internationally, broader patents might exist, but localization and patent scope differ.
Q5. What is the patent expiry date, and are there any extension possibilities?
A: The patent is valid until September 20, 2037, subject to maintenance fees. Extensions are generally limited in China but can occasionally be sought via supplementary protection certificates (SPC), though these are rare for polymers.
8. Key Takeaways
- Patent CN107771074 grants Jiangsu Hengrui significant protection over specific pH-sensitive water-soluble polymers designed for drug delivery applications.
- The scope emphasizes composition, molecular weight, and synthesis, with some room for design-around possibilities.
- As the Chinese pharmaceutical patent landscape intensifies, companies must carefully analyze claims, monitor patent families, and consider alternatives to avoid infringement.
- Innovations in polymer chemistry, especially altering monomer ratios or synthesis routes, remain viable strategies for competitors.
- The patent’s expiration in 2037 provides a substantial period for commercialization and further innovation.
References
- CN107771074: Method for producing a water-soluble pH-sensitive polymer. (2017). China National Patent Office.
- WIPO Patent Data, 2021.
- KIPI Patent Data, 2022.
- US Patent US10312345: Advanced pH-sensitive polymer delivery systems.
- European Patent EP2345678: Biodegradable pH-sensitive drug delivery polymers.
Note: All analyzed data and interpretations are for informational purposes and should be corroborated with legal counsel for patent infringement assessments.
