Scope, Claims, and Patent Landscape of U.S. Drug Patent 6,051,567
What is the Scope of U.S. Patent 6,051,567?
U.S. Patent 6,051,567, granted on April 18, 2000, covers a method of administering non-steroidal anti-inflammatory drugs (NSAIDs), specifically, methods involving controlled release formulations. The patent states that it pertains to a sustained-release formulation of an NSAID that maintains therapeutic plasma concentrations over an extended period, reducing dosing frequency and side effects.
The patent's core focus is on a controlled-release system designed for oral delivery of NSAIDs. It involves specific polymer matrices that control drug release and deliver the drug over hours, typically 12 to 24 hours. The formulations aim to mitigate gastrointestinal irritation associated with NSAID use while maintaining effective anti-inflammatory activity.
Key features of the scope include:
- Use of specific polymer compositions for controlled release.
- Oral administration routes.
- Targeted release duration (generally 12-24 hours).
The patent does not cover NSAIDs themselves or their synthesis but concentrates strictly on the formulation and delivery method.
What are the Broad and Specific Claims of U.S. Patent 6,051,567?
Broad Claims
The primary claims encompass the formulation described as a sustained, controlled-release composition of NSAIDs. Claim language states:
- "An oral sustained-release composition comprising an NSAID and a polymeric matrix..."
- The polymeric matrix includes particular types of hydrophilic polymers capable of controlling drug release.
- The formulation is designed for 12-24 hours release period.
Specific Claims
Claims specify particular NSAIDs, such as ibuprofen, ketoprofen, and naproxen, with detailed compositions, including:
- Percentages of active drug (e.g., 100 mg of ibuprofen).
- Specific polymer types, such as hydroxypropyl methylcellulose or polyethylene oxide.
- Release modifiers and excipients that stabilize the formulation.
Claim differentiation allows for a range of formulations with varying polymer types, drug dosage, and release timings.
Claims Limitations
The patent emphasizes the controlled-release mechanism via polymer matrices and excludes immediate-release formulations. It also limits claims to oral dosage forms.
Patent Landscape Analysis
Patent Families and Related Patents
The patent belongs to the drug formulation area, intersecting with multiple patents on controlled-release NSAID delivery systems. Related patent families include:
- US Patents: 5,922,306 (ferric sulfate formulations), 5,980,887 (drug-polymer matrices).
- International filings: WO patents covering similar sustained-release systems.
Prior Art and Patentability History
Pre-2000, prior art includes:
- Controlled-release formulations using hydrophilic polymers (e.g., U.S. Patent 4,704,224, 1987).
- NSAID formulations with extended release described in European patents (EP 219,405).
The patent examiner considered these to establish novelty based on specific polymer compositions and release profiles.
Patent Term and Maintenance
The patent's term expires in 2020, assuming standard 20-year patent term from filing date (May 12, 1998). Maintenance fees were paid through patent expiry.
Current Freedom to Operate
Multiple patents claiming similar controlled-release formulations exist. Competitors have developed alternative polymers or delivery systems. Patent litigation history is limited, but freedom to operate remains constrained regarding similar sustained-release NSAID systems.
Research and Development Trends
Post-2000, research shifted toward:
- Biodegradable polymers.
- Nanoparticle and microcapsule delivery systems.
- Combination therapies with NSAIDs and other agents.
These trends suggest ongoing innovation beyond the scope of patent 6,051,567.
Conclusion
U.S. Patent 6,051,567 claims a specific controlled-release formulation of NSAIDs utilizing particular polymer matrices for oral administration over 12-24 hours. Its claims are narrowly focused on formulation specifics rather than the NSAID compounds themselves. The patent landscape includes prior art on sustained-release systems but claims novelty through unique combination and polymer composition.
The patent expired in 2020, opening the field for biosimilar or alternative controlled-release formulations. Competitors or developers exploring NSAID delivery systems should evaluate polymer compositions and formulation strategies to avoid infringement and explore new delivery technologies.
Key Takeaways
- The patent covers controlled-release NSAID formulations using specific hydrophilic polymers.
- It claims a 12-24 hour release profile primarily for oral doses.
- Its expiration in 2020 created opportunities for biosimilars and generics.
- The landscape includes prior art on sustained-release polymers but claims novelty through specific polymer-drug combinations.
- Innovation now centers on biodegradable materials and nanotechnology-based systems.
FAQs
1. Does U.S. Patent 6,051,567 cover all NSAID formulations?
No. It only covers sustained-release formulations involving specific polymer matrices. It does not cover immediate-release NSAIDs or formulations using different polymer systems.
2. Can a company develop a similar NSAID formulation with different polymers?
Potentially, if the new polymers or release mechanisms differ substantially from those claimed, avoiding infringement. A detailed patent analysis is necessary for confirmation.
3. What is the significance of the patent's expiration?
Expiration in 2020 removes patent barriers for manufacturers to produce similar sustained-release NSAID products, increasing generic and biosimilar competition.
4. Are there ongoing patents related to this patent’s technology?
Yes. Follow-on patents emerge around biodegradable polymers, nanocarriers, and combination therapies, expanding the landscape.
5. How does this patent influence current drug delivery research?
It highlights the importance of polymer selection for controlled release. Current research advances incorporate nanotechnology and biodegradable systems, diverging from the formulations claimed here.
References
[1] U.S. Patent 6,051,567. (2000). Controlled-release NSAID formulations.
[2] European Patent EP 219,405. (1990). Extended-release NSAID formulations.
[3] U.S. Patent 4,704,224. (1987). Hydrophilic polymer-based controlled release.
[4] U.S. Patent 5,922,306. (1999). Microencapsulation of drugs.
[5] U.S. Patent 5,980,887. (1999). Drug-polymer matrix systems.
