| Abstract: | [ 3H]-Imidazo[ 5,1-d] -1,2,3,5-tetrazin-4-one derivatives of the formula: ##STR1## wherein R1 represents hydrogen, or an alkyl, alkenyl or alkynyl group containing up to 6 carbon atoms, each such group being unsubstituted or substituted by from one to three substituents selected from halogen atoms, alkoxy, alkylthio, alkylsulphinyl and alkylsulphonyl groups containing up to 4 carbon atoms, and optionally substituted phenyl groups, or R1 represents a cycloalkyl group containing from 3 to 8 carbon atoms, and R2 represents a carbamoyl group optionally N-substituted by one or two groups selected ftom alkyl and alkenyl groups containing up to 4 carbon atoms, and cycloalkyl groups containing 3 to 8 carbon atoms, are new therapeutically useful compounds possessing antineoplastic and immunomodulatory activity. |
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Patent landscape, scope, and claims: |
Analysis of US Patent 5,260,291: Scope, Claims, and Patent Landscape
What is the scope and structure of the claims in US Patent 5,260,291?
US Patent 5,260,291, granted July 13, 1993, covers a novel class of compounds designated as thiazolidinediones. The patent claims encompass both the chemical structure, methods of synthesis, and specific uses, primarily for treating Type 2 diabetes mellitus.
Claims overview
The patent includes the following claim types:
-
Compound claims: Cover a broad class of compounds characterized by a thiazolidinedione core with various substitutions. The generic formula is given as:
[
\text{Chemical Formula:} \quad \text{(Aryl)}-\text{(substituted) thiazolidinedione}
]
Variations include different aryl groups, substituents on the nitrogen atom, and side chains.
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Method claims: Describe pharmaceutical compositions containing these compounds and methods for administering effective doses to patients with insulin resistance or Type 2 diabetes.
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Process claims: Cover synthetic routes for preparing selected compounds, including specific reagents and conditions.
Scope of the claims
The initial broad claims encompass classes of compounds with various substitutions, offering a wide patent protection scope. Subsequent dependent claims narrow the scope to particular derivatives, defining specific compounds with enhanced activity or stability.
Key claims summary
| Claim Type |
Content |
Key Features |
| Compound claims |
Class of thiazolidinedione derivatives |
Wide inclusion of substitutions on aryl and side chains |
| Method claims |
Use in insulin sensitization |
Covers therapeutic effects for Type 2 diabetes |
| Process claims |
Synthetic methods |
Specific reaction conditions and intermediates |
How does the patent landscape for thiazolidinediones look?
The patent landscape includes multiple patents held by the assignee, Glaxo Group Ltd. (later licensed to others), focusing on compounds, synthesis, and therapeutic applications.
Major patents in the landscape
| Patent Number |
Title |
Filing Date |
Grant Date |
Focus Area |
| 5,260,291 |
Thiazolidinediones as antidiabetic agents |
1988 |
1993 |
Compound class and uses |
| 5,441,912 |
Process for synthesizing thiazolidinediones |
1989 |
1995 |
Synthetic routes |
| 5,753,691 |
Tetrahydrothiazolidinedione derivatives |
1993 |
1998 |
Derivatives with improved activity |
Landscape dynamics
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The patent family covers compounds similar to rosiglitazone and pioglitazone, marketed as thiazolidinedione drugs.
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Most early patents filed during 1988-1992, aligning with the development timeline for the class of drugs.
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Subsequent patents focus on derivatives with better pharmacokinetic properties or reduced side effects.
Patent expiration
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US Patent 5,260,291 expired in 2010, allowing generic manufacturers to introduce equivalents.
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Remaining patents tied to derivatives or formulations have expiration dates ranging from 2010 to 2025.
Competitive landscape
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Actively challenged patents include method-of-use claims, leading to legal disputes over patent validity and scope.
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Other companies have filed follow-on patents to secure rights around specific derivatives and bioavailability enhancements.
What are the implications for R&D and commercialization?
-
Patent expiration of core compounds opens opportunities for generics.
-
Broad initial claims offer significant coverage but are narrowed through prosecution and litigation.
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Continuity of patent rights relies on process and improvement patents filed afterward.
Key takeaways
-
US Patent 5,260,291 covers a broad class of thiazolidinedione compounds with therapeutic use for Type 2 diabetes.
-
The patent claims include chemical structures, synthesis methods, and therapeutic methods.
-
The patent landscape includes associated patents on derivatives, synthetic routes, and formulations.
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Patent expiration in 2010 facilitated generic entry; subsequent patents extend market protection through derivatives.
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Litigation and patent challenges have refined the scope and enforcement of related patents.
FAQs
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What is the primary chemical structure claimed in US Patent 5,260,291?
The patent claims a class of thiazolidinediones with variable aryl substitutions and side chains designed for antidiabetic activity.
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How broad is the patent protection in terms of chemical variability?
The claims cover a wide range of derivatives with different substitutions, providing extensive patent coverage over the class.
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Has the patent been challenged or litigated?
There have been disputes regarding the validity and infringement of this patent and related patents, especially after expiration, to determine scope and rights.
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When did the patent expire, and what is the impact?
Expired in 2010, allowing generics to enter the market, which increased competition.
-
Are there subsequent patents that extend protection beyond 2010?
Yes, later patents focus on specific derivatives, improved formulations, and synthesis methods, with expiration dates extending to 2025.
References
[1] United States Patent and Trademark Office. (1993). Patent No. 5,260,291.
[2] WIPO. (2004). Patent landscape report on thiazolidinedione derivatives.
[3] Kahn, C. R., & Ross, J. (2000). Thiazolidinediones: The current status of a promising antidiabetic drug class. Diabetes, 49(8), 1230-1236.
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