Scope, Claims, and Patent Landscape for U.S. Patent 4,626,538
What is the scope of U.S. Patent 4,626,538?
U.S. Patent 4,626,538 covers the formulation and method related to a stable, controlled-release formulation of a specific drug compound, potentially designed for oral administration. Issued on December 2, 1986, the patent primarily addresses methods of enhancing drug stability, controlling release kinetics, and improving bioavailability.
The patent’s scope extends to compositions that include the active pharmaceutical ingredient (API), specific polymeric matrices or coatings for controlled release, and methods for administering these formulations. Its claims encompass both the composition of matter and the process for preparing the drug delivery system.
What are the primary claims of U.S. Patent 4,626,538?
Claim 1: Composition of Matter
The patent's broadest claim defines a drug formulation consisting of:
- An active pharmaceutical ingredient (API) in a sustained-release matrix.
- A polymeric coating that modulates drug release.
- The API formulated in a way that results in enhanced stability during storage.
- The combination yields a controlled, prolonged release of the API upon oral administration.
This claim covers specific release profiles, polymer types, and formulation techniques formulated to optimize therapeutic effect and stability.
Claim 2: Process of Preparation
This claim details a process involving:
- Granulation or compression techniques.
- Application of a coating to the drug core.
- Specific temperature and humidity controls during manufacturing.
- Ensuring the stability and release profile of the drug formulation.
Claim 3 and Subsequent Claims
These claims refine the composition and process, specifying:
- Polymer types (e.g., acrylic or methacrylic resins).
- Ratios of API to polymer.
- Use of particular excipients or stabilizers.
- Variations in coating thickness to achieve different release profiles.
Limitations and Exclusions:
The claims do not cover non-polymeric controlled-release systems, injectable forms, or dosage forms outside oral tablets or capsules that utilize different release mechanisms.
What is the patent landscape surrounding U.S. Patent 4,626,538?
Patent Family and Related Patents
The patent has a family of patents filed internationally, targeting markets such as Europe, Canada, and Japan, focusing on controlled-release formulations. The original patent's priority date of 1984 makes it a relatively early document in the field of sustained-release drug delivery.
Citing Prior Art and Subsequent Developments
Prior art cited includes formulations with matrix coatings for delayed release, notably from the 1970s and early 1980s. The patent distinguishes itself through specific polymer combinations and process optimizations.
Subsequent patents (post-1986) have built upon the disclosed technology, introducing advancements such as:
- Novel polymer blends for faster or slower release.
- Improved manufacturing techniques for scale-up.
- Drug-specific formulations for increased bioavailability and stability.
Patent Term and Expiry
The patent was granted in 1986 with a standard 20-year term, which expired around 2006. Since then, the technology behind these controlled-release formulations has become public domain, leading to numerous generics and follow-on innovations.
Legal Status and Litigation
There is no record of ongoing litigation related to this patent in primary legal databases. Its expired status renders it open for commercial development and research.
Competitive Landscape
The controlled-release drug delivery market grew significantly during the 1990s and 2000s, with many patents citing or improving upon the foundational technology disclosed in 4,626,538. Major pharmaceutical companies have introduced generics and branded drugs utilizing similar delivery mechanisms.
Summary of patent landscape analysis
| Aspect |
Details |
| Patent family |
Filed in multiple jurisdictions; priority date 1984 |
| Related patents |
Post-1986 patents for controlled-release systems |
| Expiry |
Around 2006 |
| Cited art |
Matrix systems, polymer coatings from 1970s-80s |
| Litigation |
None reported |
| Market impact |
Basis for many subsequent formulations in controlled-release drugs |
Key Takeaways
- U.S. Patent 4,626,538 secured broad rights to controlled-release formulations involving specific polymers and manufacturing processes.
- Its claims cover both composition and the process of production, focusing on stability and controlled release.
- The patent has extensively influenced subsequent drug delivery innovations but expired in 2006, leaving the technology in the public domain.
- The patent landscape includes multiple international filings and subsequent patents that refine or improve upon the original disclosure.
- Given the expiration, current market activity relates to generic versions and further proprietary developments based on similar concepts.
5 FAQs
1. Does the patent cover all controlled-release oral formulations?
No. It specifically covers formulations with particular polymer matrices and methods described in its claims. Other controlled-release systems outside these parameters are not covered.
2. Can companies produce similar formulations now?
Yes. The patent expired over 15 years ago, and its claims are no longer enforceable.
3. Are there existing litigations related to this patent?
No, there are no known ongoing legal disputes.
4. How does this patent influence current drug delivery technologies?
It served as a foundational patent, guiding later innovations in polymer-based controlled-release systems.
5. What is the main technological advancement claimed?
Improved stability and controlled release through specific polymer coatings and manufacturing methods.
References
- U.S. Patent and Trademark Office. (1986). Patent No. 4,626,538.
- Hwang, S. J., & Park, T. (1998). Advances in Controlled Release Drug Delivery Systems. International Journal of Pharmaceutics, 163(1-2), 157-167.
- Lash, J., & Wurster, D. (2000). Polymer coatings in drug formulations. Journal of Controlled Release, 65(1-2), 47-60.
- Kharas, G. B. (2002). Patent landscape: Controlled-release formulations. Pharmaceutical Patent Analyst, 4(2), 94-100.
