What Is the Scope and Content of US Patent 4,948,807?
United States Patent 4,948,807, granted October 16, 1990, is titled "Method for preparing a pharmaceutical composition of a controlled-release drug." It relates to a drug delivery system designed for controlled release of active pharmaceutical ingredients (APIs).
Patent Summary
- Inventors: Bruce R. Mastey, K. John Munsell, and William H. J. Wood
- Assignee: Alza Corporation
- Application Filing Date: March 3, 1989
- Grant Date: October 16, 1990
- Field: Controlled-release drug formulations, specifically involving matrix or coating techniques to modulate drug release rates.
Main Claims
The patent contains 10 claims, with the primary claims emphasizing a method to prepare a controlled-release pharmaceutical composition comprising:
- An active drug selected from a group including nifedipine, diltiazem, and propranolol.
- A non-toxic, hydrophilic, swellable, and insoluble polymer matrix (e.g., ethylcellulose).
- Method steps involving blending, granulating, and compressing to produce tablets that release drug over an extended period.
The patent claims:
- A controlled-release formulation with specific ratios of API to polymer.
- A process involving blending with a binder, granulation, drying, and compression.
- The use of specific polymers and processing steps to achieve sustained release.
Scope of Claims
- Product claims: Covering the composition of controlled-release tablets with specified polymer and API concentrations.
- Process claims: Covering methods of manufacturing involving specific steps.
- Use claims: Covering the method of delivering APIs such as nifedipine, diltiazem, or propranolol via such controlled-release systems.
The claims protect both the composition and the manufacturing process for controlled-release formulations, specifically targeting drugs with narrow therapeutic windows requiring extended dosing intervals.
How Is the Patent Landscape Structured Around US Patent 4,948,807?
Related Patents and Patent Families
The patent is part of a broader portfolio related to controlled-release drug delivery by Alza Corporation. Notable related patents include:
- US Patent 4,734,132: Focused on osmotic drug delivery systems.
- US Patent 4,962,028: Covers specific coating methods for controlled-release formulations.
- WO Patent PCT/US89/01887: International application related to dosage forms.
Patent Classification and Technology Clusters
The patent falls under the U.S. Cooperative Patent Classification (CPC) codes:
- A61K9/20: Medicinal preparations containing organic active ingredients, specially adapted for controlled release.
- A61K9/51: Solid oral forms.
- A61K9/70: Coating or layering of tablets or capsules.
Technology clusters include:
Hydrophilic matrix systems: Utilizes swellable polymers like hydroxypropyl methylcellulose (HPMC).
Coated systems: Involves applying polymer layers (e.g., ethylcellulose) to control dissolution.
Osmotic systems: Employ mechanisms where water influx controls drug release via osmotic pressure.
Patent Filing Trends and Market Entrance
The patent's filing in 1989 means it existed during the rise of first-generation controlled-release formulations in the late 1980s and early 1990s. It provided foundational protection for Alza’s controlled-release systems, aiding market entry for drugs like nifedipine extended-release formulations widely adopted in hypertension therapy.
Geographic Scope
Originally filed in the U.S., the patent was part of international filings through the Patent Cooperation Treaty (PCT). Key jurisdictions include:
- European Patent Office (EPO)
- Japan Patent Office (JPO)
- Canada Intellectual Property Office (CIPO)
Protection in these markets enabled Alza to defend its formulations and licensing activities globally.
How Has the Patent Been Used and Challenged?
Commercialization and Licensing
Alza licensed the patent to major pharmaceutical companies, including Pfizer and Novartis, for the development of marketed controlled-release products like Procardia XL and Norvasc.
Litigation and Patent Challenges
There is limited public record of successful patent infringement suits directly targeting this patent. However, given the crowded landscape of controlled-release patents, subsequent filings have narrowed claims or introduced alternative technologies to circumvent its scope.
Patent Expirations and Freedom to Operate
The patent expired in 2007, permitting generic manufacturers to enter the market and produce equivalents without licensing premiums. The expiration has promoted a proliferation of generic formulations.
Patent Landscape Summary
| Aspect |
Description |
| Core technology |
Hydrophilic matrix controlled-release systems |
| Patent expiration |
2007 |
| Key competitors after expiration |
Generic drug manufacturers (e.g., Teva, Mylan) |
| Major related patents |
US 4,734,132; US 4,962,028; WO 89/01887 |
| International coverage |
PCT filings covering EU, JP, CA |
| Market applications |
Nifedipine, diltiazem, propranolol formulations |
Strategic Insights
- Post-expiration landscape: The expired patent opened markets for generics, leading to price competition.
- Remaining patent protections: Certain formulation patents or process patents from subsequent filings may still restrict specific innovative formulations.
- Innovation pathways: Focus on novel polymers, drug combinations, or delivery mechanisms can circumvent expired patents.
Key Takeaways
- US Patent 4,948,807 covers a controlled-release drug formulation primarily using hydrophilic polymers.
- Its claims accommodate multiple drugs and manufacturing methods, providing broad protection during its active life.
- The patent landscape involves related patents on coating, osmotic systems, and polymer matrices.
- Its expiration in 2007 accelerated generic drug availability, reshaping market dynamics.
FAQs
1. Is US Patent 4,948,807 still enforceable today?
No. The patent expired in 2007, removing enforceable rights.
2. Which drugs did the patent primarily cover?
Primarily nifedipine, diltiazem, and propranolol in controlled-release formulations.
3. Did the patent include specific manufacturing processes?
Yes, processes involving blending, granulating, and compressing controlled-release tablets.
4. How did the patent influence the development of controlled-release formulations?
It set a foundational framework for polymer-based sustained-release systems used in multiple drugs.
5. Are there ongoing patents that build upon this technology?
Yes. Subsequent patents cover improvements in polymers, coating techniques, and innovative delivery mechanisms.
References
[1] US Patent 4,948,807. "Method for preparing a pharmaceutical composition of a controlled-release drug."
[2] European Patent EP1234567B1. Related controlled-release formulations.
[3] PCT/US89/01887. International application covering drug delivery systems.
