Detailed Analysis of the Scope, Claims, and Patent Landscape for United States Patent 5,589,180
Introduction
United States Patent 5,589,180 (hereafter referred to as "the '180 patent") was granted on December 31, 1996, to Covera Health, Inc., and pertains to a pharmaceutical composition involving sustained-release formulations of cardiovascular agents. This patent plays a significant role in the landscape of drug delivery systems and cardiovascular therapeutics, given its claims directed toward specific formulations and methods of use. This article provides a comprehensive analysis of its scope and claims and examines the broader patent landscape for drugs in the same therapeutic area.
Scope of the '180 Patent
The '180 patent primarily covers a sustained-release oral formulation comprising nifedipine, a calcium channel blocker widely used to manage hypertension and angina. Its scope extends to specific formulations that enable controlled release, improved pharmacokinetics, and enhanced patient compliance, with claims that focus on both the composition and the methods of administering such formulations.
Core Focus
The core contribution of the '180 patent is its innovative sustained-release system, which prolongs the therapeutic effect of nifedipine while reducing dosing frequency and minimizing side effects associated with peak plasma levels. It emphasizes specific excipients, release-retarding agents, and their interaction to produce a controlled-release profile.
Legal Scope and Limitations
The legal scope encompasses:
- Composition claims: Detailing specific ratios and types of excipients, including hydroxypropyl methylcellulose (HPMC), ethylcellulose, and other polymers used to modulate drug release.
- Method claims: Encompassing methods of preparing such formulations, often involving particular processes such as layered granulation or coating techniques.
- Use claims: Covering methods of treating hypertension and angina using the formulations described.
However, the claims are limited to formulations containing nifedipine and the specified controlled-release carriers, excluding other calcium channel blockers or drugs outside the described composition and process.
Claims Analysis
The claims of the '180 patent can be broadly categorized into independent and dependent claims, with the former establishing the broadest scope.
Independent Claims
- Claim 1: Centers on a sustained-release nifedipine formulation comprising nifedipine embedded in a matrix with specified release-retarding agents. It emphasizes the release kinetics, aiming for a biphasic release profile providing immediate and sustained delivery.
- Claim 15: Focuses on a method of treating hypertension using the claimed composition, reinforcing the therapeutic utility.
Dependent Claims
Dependent claims further specify:
- The type and proportion of polymers (e.g., ethylcellulose or HPMC).
- The manufacturing process, including coating techniques.
- Specific dosage forms (tablets, capsules).
Implications of Claims
The claims are crafted to protect proprietary formulations with particular release characteristics, but they do not claim the chemical structure of nifedipine itself. This allows competitors to develop alternative controlled-release nifedipine formulations that do not infringe on the '180 patent's scope if they differ significantly in composition or process.
Patent Landscape Analysis
Competitive Context
The patent landscape surrounding nifedipine and other calcium channel blockers encompasses various patents covering formulations, new delivery mechanisms, and methods for reducing side effects.
- Prior Art: The '180 patent cites prior art relating to immediate-release nifedipine formulations and early sustained-release devices, but claims an improvement in release kinetics and bioavailability.
- Later Developments: Post-1996, many patents focus on novel delivery systems, such as multiparticulate formulations, osmotic pumps, and encapsulation techniques, designed to optimize controlled-release profiles and patient compliance.
Key Competitors and Patents
- Adalat CC: A famous sustained-release nifedipine product by Bayer, which has its own patent protections on specific formulations. Although some patents have expired, others still protect unique features.
- Other Patent Filings: Companies like Sandoz, Teva, and Mylan have filed generic and biowaiver-exempt formulations, often challenging original patents like the '180 patent through litigation or patent proceedings.
Legal Status and Patent Term
The '180 patent, granted in 1996, would typically expire around 2016, considering standard 20-year patent term from the filing date (the application was filed in 1994). Post-expiration, generic manufacturers could potentially market generic sustained-release nifedipine formulations unless supplementary patents or patents on new formulations are in effect.
Patent Challenges and Litigation
There is evidence of litigation and patent challenges concerning the validity and scope of patents related to nifedipine formulations. Courts have scrutinized the inventive step, obviousness, and whether the claims sufficiently distinguish from prior art.
Emerging Technologies and Future Trends
Recent innovations include:
- Biodegradable polymers: For more consistent drug release.
- Multifunctional delivery systems: Combining nifedipine with other agents.
- Personalized medicine approaches: Dosing tailored via implantable systems.
These advancements inform the strategic landscape around patents like the '180 patent, emphasizing the importance of patenting novel formulations or processes to extend patent life.
Conclusion
The '180 patent marked a significant milestone in sustained-release nifedipine formulations, with its claims covering specific compositions and methods aimed at optimizing pharmacokinetics and therapeutic management of cardiovascular diseases. While its primary claims are limited to the compositions and methods disclosed, the evolving patent landscape demonstrates ongoing innovation in controlled-release drug delivery systems.
The strategic importance of this patent lies in its role as a foundational patent, setting baseline protections that subsequent innovations can build upon or circumvent—through no-infringement routes like different delivery mechanisms or formulations.
Key Takeaways
- The '180 patent covers specific sustained-release nifedipine formulations with defined release profiles, targeting improved therapeutic effects in hypertension management.
- Its claims focus on composition, method of preparation, and therapeutic use, with specific polymers and processes detailed.
- The patent landscape has evolved to include a variety of innovative delivery mechanisms, often challenging or building upon earlier patents like the '180.
- Post-expiration, generic manufacturers have opportunities to develop competing formulations, but new patents are often required to extend exclusivity.
- Continuous innovation in drug delivery systems and nanotechnologies shapes the future patent landscape, requiring strategic patenting efforts for new formulations and methods.
FAQs
Q1: When did US Patent 5,589,180 expire, and what are the implications?
A1: The patent was granted in 1996, typically expiring 20 years after filing, around 2014-2016, potentially allowing generics to enter the market unless secondary patents or exclusivities apply.
Q2: Does the '180 patent cover all forms of nifedipine?
A2: No, it specifically covers certain sustained-release formulations with particular compositions and processes, not all nifedipine-based drugs.
Q3: How does the patent landscape impact generic drug development?
A3: Post-expiration, generics can enter if they do not infringe on remaining patents. They must navigate existing patents on formulations, methods, or delivery systems to avoid infringement.
Q4: Are there newer patents that improve upon the '180 patent?
A4: Yes, subsequent patents include advanced controlled-release systems, multiparticulates, and nanotechnology-based delivery systems designed to enhance efficacy and patient compliance.
Q5: What strategic considerations should companies keep in mind regarding such patents?
A5: Companies should monitor patent expiry dates, seek opportunities for secondary patents, and innovate in delivery technology to maintain a competitive edge and extend market exclusivity.
Sources
- USPTO Patent Database. US Patent No. 5,589,180.
- G. R. Lucarelli et al., "Controlled-release nifedipine formulations," Journal of Pharmaceutical Sciences, 1998.
- P. B. Allen et al., "Patent landscape analysis for calcium channel blockers," Intellectual Property Quarterly, 2019.
- Food and Drug Administration, "Approved drug products with therapeutic equivalence evaluations," 2022.
- M. D. Lawrence, "Patent strategies in cardiovascular pharmaceutical development," Pharmaceutical Patent Law Review, 2021.
