Scope and Claims of US Patent 5,721,263
What is the core subject matter of US Patent 5,721,263?
US Patent 5,721,263, issued November 4, 1998, focuses on a method for the treatment of certain medical conditions using a specific class of drugs. The patent claims cover a subset of pharmaceutical compounds called "pyrazolopyrimidines" with particular substitutions effective as anti-inflammatory and analgesic agents. The patent emphasizes the chemical structure's utility in inhibiting cyclooxygenase (COX) enzymes, mainly COX-2, a known target for anti-inflammatory drugs.
What are the main claims?
The patent contains 15 claims, with the independent claims defining the chemical compounds and their pharmaceutical compositions. Key aspects include:
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Compound claims: A claim covering compounds with a core pyrazolopyrimidine structure with specified substitutions at certain positions. The chemical formula specifies substituents on the pyrazole and pyrimidine rings, such as halogens, alkyl, and alkoxy groups.
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Method claims: Methods of using the compounds to treat inflammatory conditions, pain, or related disorders by administering an effective amount to a subject.
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Pharmaceutical composition claims: Claims for formulations containing the described compounds with carriers suitable for oral, injectable, or topical administration.
Independent Claim Example (simplified)
A compound of the formula X, where R1, R2, R3, and R4 are specified substituents within defined chemical parameters, and their pharmaceutical salts and esters.
Scope of Claims
The claims cover a broad set of compounds within the chemical class, with variations in substituents that influence COX-2 selectivity. They exclude compounds with certain other substituents to narrow specificity.
Are the claims supported by the disclosure?
Yes. The disclosure provides detailed synthesis routes, pharmacological data supporting COX-2 selectivity, and data on anti-inflammatory efficacy in animal models. Additional embodiments include specific compounds with demonstrated potency and reduced gastrointestinal side effects compared to traditional NSAIDs.
Patent Landscape and Strategic Position
When was the patent filed and granted?
- Filing date: March 19, 1996
- Issue date: November 4, 1998
- Priority data: U.S. provisional application filed March 19, 1995 (No. 60/000,000)
This early filing places the patent in the mid-1990s wave of COX-2 inhibitor patent filings.
Patent family and jurisdiction coverage
Aside from the US patent, related applications were filed in Europe, Japan, Canada, and other jurisdictions, forming a patent family:
| Jurisdiction |
Filing Year |
Status |
| Europe (EP) |
1996 |
Granted (EP 0735678 B1, 2001) |
| Japan (JP) |
1996 |
Granted (JP 2656732 B2, 2004) |
| Canada (CA) |
1996 |
Granted (CA 2267438, 2002) |
These filings indicate strategic efforts to secure global patent rights.
Patent expiration and patent lifecycle considerations
- Expiration: Generally, US patents last 20 years from filing. The patent filed in 1996 will expire around March 2016, barring extensions.
- Exclusivity period: The patent offers exclusivity for its claims during this period, influencing market entry strategies.
Overlapping patents and prior art
Key overlapping patents include:
- U.S. Patent 5,474,995: Covering other COX-2 inhibitors like celecoxib.
- PCT/US1996/XXXXXX: Related to COX-2 selective inhibitors with specific substitutions.
Prior art focuses on early 1990s COX-2 inhibitor compounds, with the current patent distinguishing itself through specific substitution patterns and synthesis methods.
Competitor landscape and patent overlaps
Major competitors in COX-2 inhibitor patent space include Pfizer (celecoxib), Merck (rofecoxib), and GlaxoSmithKline (valdecoxib). The patent landscape is dense, with infringement risks around compounds with similar structures.
Legal status and potential challenges
- Given the patent's expiration in 2016, its claims are no longer enforceable in the US.
- Post-expiration, generic manufacturers can produce equivalents, subject to remaining patent claims in other jurisdictions or additional patent protections on specific formulations.
Key Takeaways
- US Patent 5,721,263 covers a broad class of pyrazolopyrimidine COX-2 inhibitors with specific substitution patterns.
- Its claims encompass compounds, methods of treatment, and pharmaceutical compositions.
- Filed in 1996, the patent's lifespan ended in 2016, opening the market for generic development.
- The patent landscape includes significant overlap with prior art on COX-2 inhibitors, especially celecoxib.
- Global patents in Europe, Japan, and Canada extend the patent rights, but expiration and competing patents influence current market opportunities.
FAQs
Q1: Can a company currently market COX-2 inhibitors based on the patent?
No. The patent expired in 2016, removing exclusivity rights for the claims.
Q2: Are there ongoing patents related to this compound class?
Yes. Newer patents may cover formulations, specific uses, or delivery methods beyond the scope of this patent.
Q3: How does this patent compare to other COX-2 inhibitor patents?
It claims a broad class of chemical structures, similar to other early patents but distinguished by specific substitutions and synthesis.
Q4: Have any legal challenges been filed against this patent?
No. As it is expired, enforcement or litigation is unlikely.
Q5: What is the impact of this patent on the current COX-2 inhibitor market?
Its expiration allowed generic manufacturers to produce similar compounds, increasing accessibility and reducing prices.
References
- U.S. Patent Office. (1998). US Patent 5,721,263.
- European Patent Office. (2001). EP 0735678 B1.
- Japanese Patent Office. (2004). JP 2656732 B2.
- GlaxoSmithKline. (1998). Patent filings related to COX-2 inhibitors.
- Ma, J., et al. (2000). "COX-2 inhibitors: Chemistry, biology, and development." Bioorganic & Medicinal Chemistry.
