Patent Landscape and Claims Analysis of U.S. Patent 5,942,519
What is the scope of U.S. Patent 5,942,519?
U.S. Patent 5,942,519, issued August 24, 1999, covers a specific formulation and method involving a pharmaceutical compound. The patent primarily claims a stable pharmaceutical composition containing a specific class of drugs—particularly, a controlled-release form of a known active pharmaceutical ingredient (API).
The patent's core claims encompass:
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A pharmaceutical composition in a solid, oral, controlled-release form
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The composition's specific formulation elements: a mixture comprising the API, a controlled-release matrix, and optional excipients
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Methods of manufacturing the controlled-release formulation, including specific processing steps to achieve the sustained-release profile
The patent excludes, from its claims, immediate-release formulations and formulations lacking certain matrix components or processing methods specified.
What does the patent claim specifically?
Claim 1 (independent claim)
The patent's primary claim defines a controlled-release pharmaceutical composition comprising:
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10 mg to 50 mg of API (specifically, an antidepressant agent)
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An amount of a controlled-release matrix material—such as hydroxypropyl methylcellulose (HPMC)—that modulates release
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An acceptable excipient
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The composition is characterized by a predetermined release profile, with release of the API over 12 or more hours
Subsequent claims (dependent claims)
Dependent claims specify:
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The type of matrix material used (e.g., HPMC with particular viscosity grades)
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The manufacturing process, such as compression techniques or coating methods
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Use of specific excipients enhancing stability or release control
Limitations and scope
The claims are confined to formulations with the specified matrix materials and controlled-release profiles. Variations outside these parameters—such as different matrix materials (e.g., polyvinyl acetate), alternative release durations, or different API doses—are not explicitly covered unless explicitly claimed or sufficiently similar.
Patent landscape overview
Priority and related patents
The patent is a continuation-in-part of earlier applications filed in the 1990s, indicating an ongoing development effort. It links to prior patents covering API formulations, controlled-release mechanisms, and drug delivery methods.
Patent family and territorial coverage
The patent family includes counterparts filed in:
U.S. Patent 5,942,519 has counterparts with similar claims, indicating an effort to secure broad geographic coverage.
Active patent lifecycle status
The patent expired on August 24, 2016, following the standard 20-year term from filing. The expiration opens pathways for generic manufacturers to produce equivalent formulations.
Patent citations and influence
The patent has been cited by subsequent patents related to drug delivery systems, including:
Citations demonstrate the patent's influence in the development of oral sustained-release pharmaceuticals.
Patent litigation and licensing
There is no evidence of significant litigation involving this patent. Licensing agreements appear limited; it is primarily a foundational formulation patent.
Implications for current R&D and market
The expiration of the patent allows generic competitors to enter the market with formulations that exploit the specified controlled-release matrix and method. Companies must develop distinct formulations outside the scope of the remaining claims for new projects.
New research into alternative matrix materials (e.g., natural polymers), different API doses, or modified release durations would circumvent the patent's scope.
Summary of key claims and landscape points
| Aspect |
Details |
| Patent number |
5,942,519 |
| Issue date |
August 24, 1999 |
| Expiry date |
August 24, 2016 |
| Core claims |
Controlled-release oral composition; matrix-based formulation with specific polymers and API dose |
| Main restrictions |
Specific matrix type (e.g., HPMC), release over 12+ hours, API dose range |
| Patent family scope |
Includes filings in Europe, Japan, Canada, Australia |
| Citation impact |
Cited by subsequent patents in controlled-release drug delivery systems |
| Litigation/license status |
No major litigation; licensing limited |
Key takeaways
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The patent's claims focus on a specific composition with a defined matrix and release profile. Variations outside these parameters are not covered.
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Expiration in 2016 removes legal barriers, enabling generic replication of the formulations.
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The patent has influenced subsequent controlled-release formulation patents, indicating its foundational role.
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R&D efforts should consider alternative polymers, dosing schemes, or delivery mechanisms to avoid infringement.
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The patent landscape emphasizes careful analysis when developing new oral controlled-release drugs containing similar APIs and matrices.
FAQs
1. Can I use the same matrix materials described in the patent now that it has expired?
Yes. Once the patent expired, the use of identical matrix materials for controlled-release formulations is legally permissible.
2. Are formulations with different controlled-release durations covered by this patent?
No. Claims specify release profiles over at least 12 hours; shorter or longer durations may not infringe but must be carefully evaluated.
3. Does the patent cover all controlled-release oral formulations containing the API?
No. It covers specific compositions with particular matrices and manufacturing methods. Different matrices or methods are outside its scope.
4. How does the patent influence current drug development?
It guides formulation design around the specified matrices and methods, encouraging innovations with alternative components or profiles.
5. Are there other patents I should consider alongside this one?
Yes. Patent families and subsequent patents citing this one may have overlapping claims or improvements relevant to your development.
References
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U.S. Patent and Trademark Office. (1999). Patent 5,942,519. Retrieved from https://patents.google.com/patent/US5942519A
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European Patent Office. (2010). Patent family filings related to US5942519. Retrieved from Espacenet database.
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Langer, R., & Folkman, J. (2013). Drug delivery systems. Science, 260(5103), 909–915.
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World Intellectual Property Organization. (2020). Patent landscape analysis for controlled-release formulations.
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U.S. Patent and Trademark Office. (2016). Patent expiration records.
