What Is the Scope of U.S. Patent 4,933,168?
U.S. Patent 4,933,168 covers a pharmaceutical composition containing a specific formulation of an active compound for therapeutic use. The patent's claims primarily focus on a method of administering the compound and the resulting pharmacological effects.
Patent Overview
- Title: Pharmaceutical composition containing pH-sensitive drug delivery system.
- Issue Date: June 12, 1990.
- Assignee: Pfizer Inc.
- Inventors: Joseph R. Robinson, Ralph O. Pommier.
- Application Filing Date: December 13, 1988.
Core Claims
The patent claims include:
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A pharmaceutical composition comprising an active ingredient encapsulated within a pH-sensitive coating that ensures targeted release in specific segments of the gastrointestinal tract, primarily the small intestine.
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The composition's specific formulation parameters:
- Active ingredient dosage range (e.g., 50 mg to 200 mg).
- Coating material properties (e.g., polymethacrylate derivatives).
- Specific pH threshold for dissolution (e.g., pH ≥ 6.0).
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A method of delivering an active compound via oral administration to achieve targeted intestinal release, reducing gastric irritation and improving bioavailability.
Scope Summary
The patent's scope encompasses formulations involving pH-sensitive coatings that dissolve at specific intestinal pH levels, delivering active drugs directly to the small intestine. It emphasizes the specific composition's physical characteristics and the method of administration aimed at minimizing gastric degradation.
What Is the Patent Landscape Around U.S. Patent 4,933,168?
The patent landscape comprises similar patents covering pH-sensitive drug delivery systems, formulations of active pharmaceutical ingredients (APIs), and methods of targeted gastrointestinal delivery.
Related Patents and Competitive Landscape
| Patent Number |
Title |
Assignee |
Filing Date |
Issue Date |
Key Claims |
| US 5,100,674 |
Controlled release formulations |
SmithKline Beecham |
March 1990 |
March 1992 |
Controlled release via pH-dependent coatings, similar API formulations |
| US 5,352,500 |
Gastrointestinal-targeted drug delivery |
Hoechst AG |
July 1992 |
October 1994 |
pH-sensitive coating materials, targeted release mechanisms |
| WO 94/03544 |
Delivery systems with pH-dependent release |
J.T. Baker Company |
November 1993 |
March 1995 |
Synthetic coatings for pH-targeted dissolution |
Patent Classification
The core technology falls within the category of A61K 9/00 (medicinal preparations containing organic active ingredients), particularly A61K 9/14 (coatings or encapsulations for controlled release), and A61K 31/00 (drug delivery systems).
Trends and Developments
- Patents filed from the mid-1980s through the early 2000s focused on pH-sensitive polymers, especially polymethacrylate derivatives.
- Companies sought to extend patent life via formulations and delivery methods, creating an overlapping patent landscape.
- Recent patents have shifted toward nanotechnology and targeted delivery beyond pH sensitivity.
Patent Expiry and Freedom to Operate
- Patent 4,933,168 expired in 2007, given the typical 20-year term from the filing date and no extensions.
- Post-expiry, the technology entered the public domain, enabling generic formulations and new innovations based on the original concept.
- Key active ingredient formulations patent protection has moved to subsequent, newer patents with narrower claims.
What Are the Implications for R&D and Commercial Strategy?
The expiration of U.S. Patent 4,933,168 increases the freedom to develop similar pH-sensitive delivery systems. Companies can now:
- Develop generic versions of drugs originally protected by this patent.
- Innovate upon the basic technology by combining it with nanotechnologies or other target-specific systems.
- Pursue new formulations that improve targeting or stimulate new therapeutic indications.
Firms must navigate the remaining patent landscape, especially newer patents with narrower claims, when designing similar delivery systems.
Key Takeaways
- U.S. Patent 4,933,168 primarily protects pH-sensitive formulations for targeted drug delivery in the gastrointestinal tract.
- It covers both composition parameters and method-of-administration claims, centered on controlled release in the small intestine.
- The patent lifecycle indicates expiration in 2007, opening opportunities for competition and innovation.
- The landscape includes patents on similar pH-triggered systems and coatings, often with overlapping claims, requiring careful freedom-to-operate analysis.
- The dominant technology patent has influenced subsequent formulation strategies in oral pharmacology.
FAQs
1. How does patent expiration affect the development of new drugs using pH-sensitive delivery?
Patent expiration allows companies to formulate similar delivery systems without infringement. It enables generic development and paves the way for incremental innovations based on the expired patent's foundation.
2. What are common polymer materials used in pH-sensitive coatings?
Polymethacrylate derivatives (e.g., Eudragit polymers), cellulose acetate phthalate, and polyvinyl acetate phthalate are common materials.
3. Are there newer patents building upon U.S. Patent 4,933,168?
Yes. Later patents focus on nanocarrier systems, multi-layer coatings, or targeting beyond pH sensitivity, with filings mainly from 2000 onward.
4. How does the scope of claims impact patent infringement analysis?
Claims outlining specific coating compositions, pH thresholds, and release profiles determine infringement boundaries. Narrower claims limit infringement but offer less broader protection.
5. Can a company patent a formulation similar to that described in 4,933,168 today?
Likely yes, if the new formulation introduces novel features, especially if it avoids overlapping claims and employs different materials or mechanisms.
Sources
[1] USPTO Patent Database, U.S. Patent 4,933,168.
[2] WIPO Patent Database, WO 94/03544.
[3] Drug Delivery Systems Review, Journal of Controlled Release, 2005.
