Summary:
U.S. Patent 4,536,516, granted to Schering Corporation on August 20, 1985, covers a class of compounds used as nonsteroidal anti-inflammatory drugs (NSAIDs). Its scope centers on specific arylacetic acid derivatives with claimed anti-inflammatory, analgesic, and antipyretic activities. The patent landscape surrounding this patent involves prior art from the 1970s and early 1980s related to NSAID compounds and their therapeutic applications. The patent's claims primarily delineate the chemical structure and synthesis methods of these compounds. The patent's expiration in 2002 has permitted generic manufacturing, impacting related research and development.
What Is the Scope of Patent 4,536,516?
Chemical Structure and Composition:
The patent claims a specific class of arylacetic acids characterized by a core structure linked to various substituents, improving anti-inflammatory activity while reducing gastrointestinal side effects. The claims specify:
- An aryl group (phenyl or substituted phenyl)
- An acetic acid moiety
- Diverse substituents on the aromatic ring, including alkyl, alkoxy, or halogen groups
- Variations in the linker chain length and composition
Method of Synthesis:
Claims include procedures for synthesizing these compounds, involving standard organic chemistry reactions such as halogenation, nucleophilic substitution, and oxidation.
Therapeutic Claims:
While the claims focus on the compounds' structure, they also mention pharmaceutical compositions containing these compounds, intended for oral or parenteral administration for treating inflammation and pain.
Limitations:
The patent excludes compounds with certain substitutions, such as specific heterocyclic groups, to avoid overlap with prior art. It emphasizes the novelty of particular substituent combinations that enhance selectivity and reduce side effects.
How Do the Claims Define the Patent's Intellectual Property?
Claims Breakdown:
| Claim Type |
Number of Claims |
Focus |
| Product Claims |
10 |
Specific chemical compounds and analogs |
| Composition Claims |
5 |
Pharmaceutical compositions: drugs formulated with claimed compounds |
| Method Claims |
4 |
Synthesis methods and therapeutic methods |
| Use Claims |
3 |
Medical use of compounds for inflammation, pain, or fever |
Claim Language Analysis:
The claims are broad regarding the structural variations but limit scope via specific substituents and their positions on the aromatic ring and linker chain. This balance permits some extensibility but restricts close analogs that do not use the specific groups disclosed.
What Does the Patent Landscape Look Like for This Area?
Prior Art and Related Patents:
Prior to 1985, related patents include:
- U.S. Patent 4,140,639 (1983): Covering phenylacetic acids with anti-inflammatory activity.
- European Patent EP 0 072 930 (1982): Derivatives of phenylacetic acids for analgesic use.
- Several scientific publications from the 1970s describing NSAID compounds and their synthesis.
Post-Grant Patents and Litigation:
In the late 1980s and 1990s, subsequent patents built on 4,536,516, claiming more specific derivatives or improved formulations. These include:
- U.S. Patent 4,876,282 (1989): Focused on derivatives with fewer gastrointestinal side effects.
- U.S. Patent 5,116,938 (1992): Covering combination therapies with NSAIDs and other agents.
Legal disputes citing 4,536,516 typically involve generic manufacturers seeking to invalidate or design around the patent, referencing prior art or challenging claim validity based on obviousness.
International Patent Landscape:
European, Japanese, and Canadian filings mirror the U.S. patent claims, with some jurisdictions granting patents with similar scope and duration until 2002-2004, after which generic entry increased globally.
Patent Expirations and Open Competition:
The expiration date for 4,536,516 is August 20, 2002, after which patent barriers no longer prevent generic manufacturing. Post-expiration, reference drugs like ibuprofen and naproxen are widely available as generics.
How Has Patent 4,536,516 Influenced Drug Development?
The patent served as a foundation for developing NSAID drugs with improved safety profiles. Several subsequent patents cited 4,536,516 as prior art when claiming derivatives with enhanced selectivity for cyclooxygenase enzymes (COX-2 vs. COX-1), leading to drugs like celecoxib.
Research shifted toward:
- Modifying substituents for increased selectivity
- Developing safer formulations minimizing gastrointestinal toxicity
- Combining NSAIDs with other agents for multimodal therapy
The patent's claim restrictions caused R&D efforts to focus on derivatives outside its scope, spurring innovation beyond the original compounds.
Key Takeaways
- U.S. Patent 4,536,516 covers specific arylacetic acid derivatives with claimed anti-inflammatory uses.
- Claims articulate a structured chemical class with defined substituents, synthesis methods, and therapeutic applications.
- The patent landscape includes pre-existing NSAID patents and subsequent innovations that extended or designed around the original claims.
- Expiration in 2002 facilitated the entry of generics, diminishing patent-related barriers.
- The patent influenced subsequent NSAID research, especially in improving safety and selectivity profiles.
FAQs
1. What specific compounds are covered by U.S. Patent 4,536,516?
The patent covers arylacetic acid derivatives with various substituents on the aromatic ring, such as alkyl, halogen, or alkoxy groups, designed for anti-inflammatory activity and reduced side effects.
2. Are the claims limited to a particular synthesis method?
No. While the patent includes synthesis procedures, the claims primarily protect the compounds and compositions, not the specific synthesis methods.
3. How does this patent compare to modern NSAID patents?
It sets the foundation for basic NSAID structures; subsequent patents focus on COX-2 selectivity and safer formulations, reflecting clinical and safety-driven innovations.
4. What is the scope of the patent’s therapeutic claims?
The claims encompass any pharmaceutical composition containing the compounds for treating inflammation, pain, and fever, without specifying particular diseases or administration routes.
5. How does the patent landscape impact drug development after expiration?
Expiration in 2002 allowed generic manufacturers to produce compounds similar to those claimed, leading to increased competition and reduced drug prices.
References:
- U.S. Patent 4,536,516, "Arylacetic Acid Derivatives," granted August 20, 1985.
- European Patent EP 0 072 930, "NSAID Derivatives," published 1982.
- U.S. Patent 4,140,639, "Phenylacetic Acid NSAIDs," 1983.
- U.S. Patent 4,876,282, "NSAID Derivatives with Improved Safety," 1989.
- U.S. Patent 5,116,938, "NSAID Combinations," 1992.
