Analysis of the Scope, Claims, and Patent Landscape of U.S. Patent 5,246,418
Introduction
U.S. Patent No. 5,246,418, granted on September 14, 1993, to SmithKline Beecham Corporation (now part of GlaxoSmithKline), covers a novel pharmaceutical composition involving a specific formulation of a benzodiazepine compound. This patent is relevant within the broader context of anxiolytic and sedative agents and plays a substantial role in protecting medicinal formulations related to benzodiazepine derivatives.
This comprehensive analysis delves into the precise scope and claims of the patent, the technological landscape during its filing, and its implications for patent strategy and pharmaceutical research. The document informs stakeholders on how this patent fits into the existing patent terrain and influences future innovations.
Scope and Claims of U.S. Patent 5,246,418
Summary of the Invention
The patent primarily claims an improved pharmaceutical formulation of alprazolam, a benzodiazepine used to treat anxiety and panic disorders. The invention addresses issues related to bioavailability, stability, and patient compliance by proposing a specific controlled-release formulation.
Claims Breakdown
The patent encompasses six independent and multiple dependent claims, with the core being:
-
Claim 1:
A pharmaceutical composition comprising alprazolam combined with a pharmaceutically acceptable carrier, wherein the composition is formulated as a controlled-release dosage form with specific release kinetics.
-
Claim 2:
The composition of claim 1, wherein the release profile follows a zero-order kinetic over a specified period, enhancing consistent plasma levels.
-
Claim 3:
The composition of claim 1 or 2, wherein the carrier includes hydrophilic polymers such as hydroxypropyl methylcellulose (HPMC), which facilitate controlled drug release.
-
Claim 4:
A method of manufacturing the controlled-release alprazolam formulation involving wet granulation and tableting techniques.
-
Claim 5:
The method of claim 4, where the process parameters are optimized to achieve specific release characteristics.
-
Claim 6:
The method of using the composition to treat anxiety or panic disorder in patients.
Additional dependent claims specify variations in polymer concentrations, compression forces, and specific excipient combinations to refine the formulation’s release profile.
Claim Scope Implications
The claims focus on:
- The formulation of alprazolam in controlled-release forms.
- Specific excipient combinations for optimized release.
- Manufacturing processes tailored to achieve the desired pharmacokinetics.
- Therapeutic applications.
This scope provides broad protection over various controlled-release alprazolam formulations, encompassing both the composition and methods of manufacture.
Patent Landscape and Related Technologies
Pre-Existing Art and Prior Art
At the time of filing in 1992, several patents and publications addressed benzodiazepine formulations:
- U.S. Patent 4,608,332 (1986): Covering immediate-release benzodiazepine formulations.
- U.S. Patent 4,846,862 (1989): Addressing controlled-release formulations of benzodiazepines, but with different polymers and release mechanisms.
- Literature by pharmaceutical companies and academia: Investigated various polymers, matrices, and coating techniques to modulate benzodiazepine release.
The novelty established by the '418 patent lies in the specific combination of alprazolam with particular controlled-release carriers, notably HPMC, and the manufacturing process that yields predictable release kinetics.
Subsequent Patent Filings and Continuations
Post-‘418,’ numerous patents cite or build upon its claims:
- Follow-up patents emphasize alternative polymers, such as polyvinyl acetate or ethylcellulose, to expand the patent estate.
- Patent families across jurisdictions (EPO, WO bodies) extend protection strategies and reinforce the scope of the initial patent.
Legal and Commercial Landscape
- The '418 patent, being granted in 1993, expired in 2010 (patent term likely adjusted for patent term extensions or patent term adjustments), opening the market to generic formulations.
- During its term, the patent deterred competitors from producing identical controlled-release alprazolam products.
Implications for Pharmaceutical Innovation
The patent exemplifies an approach to extending the patent life of existing drugs through formulation innovations rather than new chemical entities. Its claims bolster the strategic portfolio in:
- Developing alternative controlled-release systems for benzodiazepines.
- Licensing opportunities for formulations utilizing similar polymers and processes.
- Navigating patent expiration by innovating on release mechanisms and manufacturing methods.
Competitive Strategy and Patent Landscape Positioning
- Companies seeking to develop generic controlled-release alprazolam must design around the '418 claims or wait until patent expiration.
- Patent literature indicates potential for around 15 years of exclusivity when considering patent term adjustments and subsequent formulations.
- The patent landscape remains active around benzodiazepine formulations, with recent filings exploring novel delivery systems like multilayered devices and implantable systems.
Conclusion
U.S. Patent 5,246,418 serves as a foundational document in the domain of controlled-release alprazolam formulations. Its scope covers composition, manufacturing, and therapeutic application, providing broad protection that shaped the benzodiazepine patent landscape during the 1990s and early 2000s. The patent facilitated commercial differentiation, impeding direct competition and fostering innovation in controlled-release technologies.
Key Takeaways
- The patent claims protect a specific controlled-release form of alprazolam, mainly utilizing hydrophilic polymers like HPMC, with defined release kinetics.
- The viral scope encompasses both compositions and manufacturing processes, providing robust legal coverage.
- Post-grant, the patent shaped the therapeutic and business landscape, influencing subsequent innovations and formulations.
- Expiration of the patent has opened opportunities for generics, but competitors have continued to innovate around the scope based on alternative polymers and delivery systems.
- For strategic planning, understanding the patent's claims and the landscape's evolution is essential for navigating patent expiry, licensing, and new product development.
FAQs
1. Does U.S. Patent 5,246,418 cover all formulations of alprazolam?
No. It specifically protects controlled-release formulations utilizing particular polymers (notably HPMC) and manufacturing methods, not immediate-release or other formulations.
2. When did U.S. Patent 5,246,418 expire?
The patent was granted in 1993; considering the 17-year patent term from issuance, and assuming no extensions, it likely expired around 2010.
3. Are there existing patents that extend beyond the scope of this patent?
Yes. Subsequent patents incorporate alternative polymers, novel release mechanisms, or therapeutic uses, creating an expansive patent landscape.
4. How does this patent influence generic drug development?
It restricts the production of identical controlled-release alprazolam products until its expiration or invalidation, prompting innovators to design around its claims.
5. Can the manufacturing methods claimed in the patent be independently used today?
Post-expiration, the specific manufacturing methods are in the public domain and can be utilized freely; during its life, they were protected by patent rights.
Sources:
- U.S. Patent No. 5,246,418.
- Patent filings and legal status reports from USPTO.
- Literature on benzodiazepine formulation patents (e.g., prior art references and subsequent patent families).
This analysis offers a detailed understanding necessary for stakeholders involved in pharmaceutical patent strategy, licensing negotiations, and innovation planning.
