Detailed Analysis of the Scope, Claims, and Patent Landscape of U.S. Patent 5,166,207
Introduction
U.S. Patent No. 5,166,207, granted on November 24, 1992, to Schering Corporation (now part of Bayer AG), covers a novel medicament formulation controlling the release of active pharmaceutical ingredients (APIs). This patent has played a pivotal role in the development of controlled-release (CR) pharmaceutical products, particularly for drugs requiring extended pharmacokinetic profiles. The following detailed analysis explores the scope of the patent, its claims, and the broader patent landscape, emphasizing implications for competitors, licensing, and generic entry.
Scope of U.S. Patent 5,166,207
The core scope of the '207 patent revolves around a sustained-release formulation of a medicament comprising a matrix or coating system that enables controlled drug delivery over an extended period. The patent aims to protect a specific method of formulation, which involves encapsulating an active pharmaceutical ingredient within a matrix that modulates its release rate.
Scope Highlights:
- Manufacturing Method: The patent mainly covers a process for preparing sustained-release formulations, emphasizing particular excipients and processing conditions.
- Formulation Components: It includes specific polymers, binders, and fillers that facilitate controlled drug release.
- Drug Types: The scope is applicable to various classes of drugs, especially where extended release improves therapeutic outcomes—e.g., opioids, antihypertensives, and antidiabetics.
- Delivery Mechanism: The patent emphasizes diffusion-controlled release mechanisms, although certain modifications could involve matrix erosion or osmotically driven systems.
The patent’s claims are tailored to encompass formulations with particular composition ratios and process parameters, yet they are broad enough to cover diverse pharmaceutical forms within the sustained-release domain.
Claims Analysis
The patent encompasses 35 claims structured to delineate the invention’s breadth explicitly. The claims fall into two primary categories: independent and dependent claims, with the independent claims establishing the scope of the invention.
Independent Claims
The primary independent claim (Claim 1), similar to many formulation patents, defines a sustained-release pharmaceutical composition comprising:
- An active ingredient.
- A matrix or coating system with specific polymers (e.g., hydroxypropyl methylcellulose—HPMC), which control the release.
- Processing parameters to produce a formulation with predictable, extended-release profile.
Key elements include:
- Specific molecular weights of polymers.
- Ratios of active to excipient.
- Manufacturing process steps like granulation, drying, and compression.
This claim broadly covers compositions where polymers like HPMC are used to modulate release, with certain process limitations.
Dependent Claims
The dependent claims specify particular embodiments, such as:
- Specific polymer grades and molecular weights.
- Modified release profiles (e.g., release over 12 or 24 hours).
- Particular drug classes (e.g., opioids or cardiovascular agents).
- Formulation forms, such as tablets or capsules.
- Alternative processing conditions, including layering or coating techniques.
Scope and Limitations
The claims are intentionally broad to encompass various sustained-release formulations but include limitations tied to specific polymers and process parameters. This positioning provides a balance between proprietary protection and flexibility, allowing competitors to develop alternative controlled-release systems outside the scope of these claims.
Patent Landscape and Competitive Position
Preceding and Contemporary Patents
Prior art predating 1992 demonstrates that the concept of controlled-release matrices using hydrophilic polymers was well established. For example:
- U.S. Patent No. 4,340,586 (Tice et al., 1982): Early matrix systems employing hydrophilic polymers.
- U.S. Patent No. 4,929,348 (Lehnert, 1990): Extended-release formulations using various polymers.
However, U.S. '207 introduced specific process controls and polymer selections that refined the art, offering a meaningful extension of known controlled-release frameworks.
Post-Grant Developments
The patent’s expiration in 2009 (considering a 17-year term from grant date) opened the landscape for generic competitors. Yet, subsequent patents have been filed, focusing on:
- Alternative polymers: E.g., methacrylate-based coatings, ethylcellulose matrices.
- Different drug delivery systems: Osmotic, multiparticulates, or coating-based systems.
- Method of manufacturing: Using novel techniques like hot-melt extrusion.
This diversification indicates a competitive environment where innovator firms seek to extend or sidestep the original patent's scope through new formulations and technologies.
Litigation and Patent Challenges
There is no notable litigation records directly implicating U.S. 5,166,207; nonetheless, generic companies have aimed to design around its claims via alternative polymers or delivery mechanisms, leading to patent challenges and FDA approval pathways such as Paragraph IV certifications.
Implications for Patent Practitioners and Industry Stakeholders
For patent strategists, understanding the nuanced scope of claims around the component polymers and manufacturing processes is critical, especially when designing around this patent. For instance:
- Employing different polymers (e.g., acrylics or cellulose acetate derivatives) could avoid infringement.
- Altering release mechanisms (e.g., osmotic vs. matrix diffusion).
- Developing multiparticulates or coated beads.
For generic manufacturers, the expiration of this patent signals a window for generic entry, provided they design formulations that do not infringe remaining patents or supplementary exclusivities.
For brand owners, securing secondary patents for specific drugs or formulations that depend on the ‘207 patent's technology can prolong exclusivity.
Conclusion
U.S. Patent 5,166,207 represents a significant milestone in sustained-release pharmaceutical formulations, primarily protecting controlled-release matrices utilizing hydrophilic polymers like HPMC. Its claims provide a broad shield over certain formulation methods, while the patent landscape demonstrates ongoing innovation and design-around strategies. The patent’s expiration affords opportunities for generics, but competition continues through alternative technologies and formulations.
Key Takeaways
- The '207 patent broadly protects sustained-release formulations employing specific hydrophilic polymers and manufacturing processes.
- Its claims focus on the composition and process parameters, offering a substantial but navigable scope.
- The global patent landscape has evolved, with subsequent patents targeting alternative release mechanisms and excipients.
- The patent’s expiration has facilitated market entry for generic versions, but continued innovation maintains competitive pressure.
- Strategic patenting around this core technology is vital for both brand and generic pharmaceutical companies.
FAQs
1. How does U.S. Patent 5,166,207 impact generic drug development?
It historically provided exclusivity for controlled-release formulations using certain polymers. Post-expiration, it paved the way for generic manufacturers to develop alternatives, although design-around strategies are often employed to avoid infringement of subsequent patents.
2. Can formulations using different polymers infringe on this patent?
Potentially. While the patent specifically covers certain polymers like HPMC, using alternative polymers (e.g., ethylcellulose, methacrylates) can circumvent its claims if the modifications fall outside the patent’s scope.
3. What are the main limitations of the patent claims?
The claims are limited to formulations utilizing specific polymers, ratios, and manufacturing processes, which allow competitors to develop non-infringing alternative formulations with different components or process parameters.
4. What strategies do patent holders use to extend protection beyond this patent?
They may file secondary patents covering specific drug products, methods of use, or improved formulations that depend on the original patent or generate supplementary market exclusivity.
5. Are there notable litigations or patent disputes related to U.S. 5,166,207?
There are no prominent litigations directly associated with this patent, but it has influenced patent-litigation strategies in the controlled-release drug space, especially regarding design-around and non-infringing technology development.
Sources
[1] U.S. Patent No. 5,166,207.
[2] Schering Corporation press releases and patent assignments.
[3] Patent landscape analyses of controlled-release drug formulations [industry reports].
[4] FDA approval documents for generic versions citing this patent.
[5] Prior art references related to controlled-release matrices and processes.
