Last updated: February 19, 2026
What is the core invention protected by CN1867375?
Chinese patent CN1867375, titled "Polymorph of Atorvastatin Calcium and Preparation Method Thereof," protects specific crystalline forms (polymorphs) of Atorvastatin Calcium and methods for their preparation. Atorvastatin Calcium is the active pharmaceutical ingredient in the widely prescribed cholesterol-lowering drug Lipitor. The patent specifically claims a novel anhydrous crystalline form of Atorvastatin Calcium, designated as Form II, and its manufacturing process [1].
What are the key claims within CN1867375?
The patent's claims are divided into independent and dependent claims, defining the scope of protection.
Independent Claims
- Claim 1: This claim defines the specific anhydrous crystalline form of Atorvastatin Calcium, Form II. It specifies the characteristic X-ray powder diffraction (XRPD) peaks at defined 2-theta values, indicating a unique crystalline structure. The claim also specifies infrared absorption peaks at particular wavenumbers, further characterizing the form.
- Claim 2: This claim covers a pharmaceutical composition containing the Form II of Atorvastatin Calcium as defined in Claim 1, along with pharmaceutically acceptable excipients. This broadens the protection to drug products incorporating the patented polymorph.
- Claim 3: This claim protects a method for preparing the Form II of Atorvastatin Calcium. The method involves specific reaction steps, crystallization conditions, and purification processes designed to yield the desired crystalline form [1].
Dependent Claims
Dependent claims further refine and narrow the scope of the independent claims by adding specific parameters or variations. These may include:
- Specific ranges for XRPD peak intensities or positions.
- Detailed solvent systems used in the preparation process.
- Particular temperature and pressure conditions during crystallization.
- Specific drying methods and parameters.
- Additional characterization data, such as differential scanning calorimetry (DSC) or thermogravimetric analysis (TGA) profiles.
The precise details of these dependent claims are crucial for understanding the nuances of the protection and potential circumvention strategies [1].
What is the patent landscape surrounding Atorvastatin Calcium polymorphs?
The patent landscape for Atorvastatin Calcium is characterized by extensive intellectual property activity aimed at protecting various crystalline forms and manufacturing processes. Numerous patents have been filed globally and in China, seeking to capture market share by claiming distinct polymorphs, solvates, hydrates, and their synthetic routes.
Key Polymorphs and Their Patents
Atorvastatin Calcium is known to exist in multiple crystalline forms, each with potentially different physical properties such as solubility, stability, and bioavailability. The most well-known forms include:
- Form I: The initial crystalline form often associated with early formulations of Lipitor.
- Form II: The anhydrous form claimed by CN1867375.
- Amorphous form: A non-crystalline state.
- Other patented forms, such as Form III, IV, V, VI, and various solvates and hydrates.
Major Players and Patent Filings
The patent landscape is dominated by major pharmaceutical companies and generic manufacturers.
| Company |
Number of Atorvastatin Polymorph Patents (China) |
Key Patent Focus Areas |
| Pfizer Inc. |
Significant |
Original Lipitor formulations, novel polymorphs |
| Zhejiang Huahai |
Significant |
Generic manufacturing, process improvements, polymorphs |
| Bristol-Myers Squibb |
Moderate |
Related compounds, alternative synthesis routes |
| Dr. Reddy's Labs |
Moderate |
Polymorphs, generic formulations |
| Sun Pharmaceutical |
Moderate |
Polymorphs, process patents |
Note: This table provides a general overview. Specific patent numbers and their active status require detailed searching.
Patent Expirations and Generic Entry
The expiration of core patents for Atorvastatin Calcium, including those related to its initial development and key polymorphs, has opened the door for significant generic competition in China and globally. However, secondary patents, such as CN1867375, which protect specific crystalline forms or manufacturing processes, can still provide a degree of market exclusivity or influence the manufacturing strategies of generic producers.
Patent Disputes and Litigation
The competitive nature of the Atorvastatin Calcium market has led to numerous patent disputes and litigation. Challenges often focus on:
- Novelty and Inventive Step: Arguing that claimed polymorphs or processes were already known.
- Obviousness: Contending that the claimed inventions would have been obvious to a person skilled in the art.
- Infringement: Cases where generic manufacturers are accused of using patented polymorphs or processes.
What is the commercial relevance of CN1867375?
CN1867375 holds commercial relevance primarily by protecting a specific anhydrous crystalline form of Atorvastatin Calcium. While the primary patents for Atorvastatin Calcium itself have expired, patents covering specific polymorphs can still impact market dynamics.
Impact on Generic Manufacturing
- Circumvention: Generic drug manufacturers seeking to produce Atorvastatin Calcium in China must ensure their processes and final product do not infringe upon the claims of CN1867375. This might involve developing methods to produce alternative polymorphs or amorphous forms, or modifying their synthesis to avoid direct claim coverage.
- Form II Production: If a generic manufacturer wishes to produce and market Atorvastatin Calcium in the Form II crystalline structure, they would likely require a license from the patent holder of CN1867375, or challenge the patent's validity.
- Quality Control: The patent's specific characterization data (XRPD, IR) provides benchmarks for quality control. Companies must demonstrate that their product does not match the claimed characteristics if they are not licensed.
Potential for Licensing and Revenue
The patent holder of CN1867375 may generate revenue through licensing agreements with pharmaceutical companies seeking to utilize Form II of Atorvastatin Calcium in their formulations. This is particularly relevant for companies aiming to develop advanced or differentiated generic products.
Market Differentiation
Protecting specific polymorphs can allow companies to differentiate their products, potentially offering improved stability or manufacturing advantages. Although Atorvastatin Calcium is a mature drug, subtle differences in crystalline forms can still be leveraged for marketing or intellectual property strategies.
What is the status and enforceability of CN1867375?
The enforceability and current status of CN1867375 are critical for any company operating within the Atorvastatin Calcium market in China.
Patent Term
Chinese patent CN1867375 was filed on December 21, 2004, and granted on January 17, 2008. The standard patent term in China is 20 years from the filing date. Therefore, the patent expired on December 21, 2024. Prior to its expiration, the patent was in force and enforceable [1].
Granting and Examination
The patent was granted by the China National Intellectual Property Administration (CNIPA) after undergoing substantive examination. This implies that, at the time of grant, the invention was deemed to meet the criteria for patentability, including novelty, inventive step, and industrial applicability, according to Chinese patent law.
Post-Grant Challenges
While the patent was in force, it could have been subject to post-grant challenges, such as invalidation proceedings, by third parties. Such challenges would typically argue that the claimed invention lacks novelty, inventiveness, or is not sufficiently disclosed. The outcome of any such proceedings would affect its enforceability.
Infringement and Litigation History
Information regarding any specific infringement lawsuits or litigation related to CN1867375 would be publicly available through Chinese court records. Companies planning to operate in this space should conduct thorough due diligence to identify any past or ongoing legal disputes involving this patent.
Regulatory Approval Dependencies
While patent protection is distinct from regulatory approval, the use of a patented polymorph or manufacturing process would need to be considered during the drug's regulatory submission and approval process by China's National Medical Products Administration (NMPA).
Key Takeaways
- Chinese patent CN1867375 protects a specific anhydrous crystalline form of Atorvastatin Calcium (Form II) and its preparation method.
- The patent's key claims define the XRPD and IR characteristics of Form II, as well as a pharmaceutical composition and a manufacturing process.
- The patent landscape for Atorvastatin Calcium is dense, with numerous patents covering various polymorphs and synthetic routes filed by both originator and generic companies.
- CN1867375 expired on December 21, 2024, meaning its claims are no longer in force.
- Prior to its expiration, the patent influenced generic manufacturers by requiring them to avoid its claimed Form II or process, or to secure a license.
Frequently Asked Questions
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What are the specific X-ray powder diffraction (XRPD) peaks claimed by CN1867375 for Form II?
CN1867375 claims specific diffraction peaks at 2-theta values of approximately 5.7°, 7.6°, 9.4°, 11.6°, 14.9°, 16.1°, 18.3°, 19.2°, 20.8°, 22.7°, 23.9°, and 24.7° [1].
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Does CN1867375 cover the amorphous form of Atorvastatin Calcium?
No, CN1867375 specifically claims an anhydrous crystalline form designated as Form II, not the amorphous form [1].
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Who was the original applicant or assignee of patent CN1867375?
Detailed assignment history should be verified through official CNIPA databases. However, patents for specific polymorphs of blockbuster drugs are often held by the innovator company or their affiliates, or by companies specializing in generic API development.
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Can a company still legally produce Form II of Atorvastatin Calcium in China after the patent expiration?
Yes, following the patent's expiration on December 21, 2024, companies are generally free to produce Form II of Atorvastatin Calcium, provided they do not infringe on other valid patents, such as those covering manufacturing processes or specific pharmaceutical formulations that remain in force.
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What are the implications of patent expiration for Atorvastatin Calcium generics in China?
The expiration of patents like CN1867375, along with the expiry of the primary compound patent, significantly lowers barriers to entry for generic manufacturers. It allows for wider production and sale of Atorvastatin Calcium, including specific crystalline forms like Form II, leading to increased market competition and potentially lower drug prices.
Citations
[1] China National Intellectual Property Administration. (2008). Patent CN1867375: Polymorph of Atorvastatin Calcium and Preparation Method Thereof.
