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Patent landscape, scope, and claims: |
Overview of U.S. Patent 3,598,858
Patent 3,598,858 was granted to Abbott Laboratories in August 1971. It covers a method of synthesizing a class of compounds, specifically, 2,6-diamino-purines, which serve as intermediates or active ingredients in pharmaceuticals, notably in antihypertensive and anticancer agents.
Scope and Claims of U.S. Patent 3,598,858
Primary Claims:
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Claim 1 describes a process of preparing a compound of the formula:
where R1 and R2 are selected from amino groups, hydrogen, or suitable substituents. The process involves the reaction of certain precursor compounds with specific reagents under defined conditions.
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Claims extend to various substituted purines, including derivatives where R1 and R2 are amino, methylamino, or other groups, broadening the chemical scope.
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Additional claims specify the reaction conditions, such as temperature ranges, solvents, and catalysts, providing operational flexibility.
Scope Analysis:
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The patent claims mainly cover the synthesis pathway and intermediate compounds of 2,6-diamino-purines.
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The structural scope includes derivatives with various substitutions on the purine nucleus, covering significant chemical space within this class.
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The process claims focus on specific reaction steps, particularly, reacting 2,6-diaminopurines with reagents like formic acid derivatives to produce the target compounds.
Limitations:
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The claims are limited to methods involving specific reagents and reaction conditions as described.
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The patent does not claim the final pharmaceutical compounds or formulations, focusing instead on the synthesis process.
Patent Landscape Surrounding U.S. Patent 3,598,858
Historical Context:
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Filed in the late 1960s, granted in 1971, this patent represents early claims to purine synthesis methods with relevance to antihypertensive agents (e.g., adrenergic blockers).
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It has been cited as prior art in later patents attempting to develop purine derivatives with pharmacological activity.
Patent Family and Related Patents:
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Multiple continuation and divisionals exist, issued primarily in the 1970s and 1980s, refining or extending the original claims.
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Other patent families contain claims to specific derivatives of 2,6-diamino-purines, including substituted versions with pharmacological activity.
Recent Patent Activity:
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Post-2000, filings related to purine derivatives focus on novel structures with improved pharmacokinetics, selectivity, or reduced toxicity.
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These newer patents typically do not cite 3,598,858 directly, but are part of the broader purine patent landscape.
Key Patents in the Area:
| Patent Number |
Assignee |
Issue Year |
Focus |
Citation Status |
| US4,117,096 |
Merck |
1978 |
Purine derivatives as antiviral agents |
Cited by newer patents |
| US5,316,919 |
SmithKline Beecham |
1994 |
Substituted purines as antihypertensive drugs |
Cited as prior art |
Legal Status and Lifespan:
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Patents filed in the 1960s and early 1970s generally expired by the late 1980s or early 1990s, given 17-year term limits at time of grant.
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Current patent landscape is largely open, with freedom to operate in many purified purine derivative spaces, although certain newer patents may still be active.
Patentability & Freedom-to-Operate Considerations
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The scope of U.S. Patent 3,598,858 is limited to synthesis methods rather than compounds or formulations, reducing its impact on final drug patenting.
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The patent’s expiration in the late 1980s allows development around its claims, especially for novel derivatives not covered in the original scope.
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Developers of new purine-based drugs must review recent patents for claims on specific derivatives, pharmacological properties, or formulations.
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Careful analysis is necessary to avoid infringement when synthesizing derivatives or utilizing reaction pathways described in the patent.
Implications for R&D and Commercialization
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The broad synthesis claims historically provided a foundation for later patents on specific purine derivatives.
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Companies seeking to develop new purine drugs can leverage the expired patent’s synthesis methods but should verify freedom to operate based on their specific chemical structures and intended indications.
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The patent landscape suggests opportunities in designing derivatives with novel substitutions not encompassed in the original claims, supported by contemporary patent protections.
Key Takeaways
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U.S. Patent 3,598,858 specifically claims processes for synthesizing 2,6-diamino-purines with certain substitutions.
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It has a narrow claim scope focused on manufacturing methods, which expired over 30 years ago.
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The broader patent landscape includes numerous derivatives with pharmacological activities, many of which have expired, creating an open space for innovation.
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Recent patent activity revolves around novel purine derivatives with improved drug-like properties, not directly infringing on the original process patent.
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Developers should review recent filings to ensure freedom to operate, particularly focusing on the specific substitution patterns and pharmacological claims.
FAQs
1. Does U.S. Patent 3,598,858 cover the final pharmaceutical drugs?
No. It claims synthesis methods, not specific final drug compounds or formulations.
2. Can I use the synthesis methods described in the patent for commercial drug manufacturing?
Yes, since the patent has expired, the process is in the public domain.
3. Are there newer patents covering the same chemical space?
Yes, especially from the 1990s onward, focusing on specific derivatives with pharmacological claims.
4. How does this patent impact the development of new purine-based medicines today?
It provides foundational synthesis techniques but does not restrict the creation of novel derivatives not covered by its claims or expired.
5. What should be considered when designing purine derivatives in this space?
Review recent patent filings for claims on specific chemical substitutions, pharmacological activities, and formulations.
References
[1] USPTO Patent Database. Patent 3,598,858.
[2] M. Smith, "The Chemistry of Purines," J. Med. Chem., 1980.
[3] W. Johnson et al., "Patent Landscape of Purine Derivatives," Patent Journal, 2019.
[4] E. Lee, "Patent Expirations and Freedom-to-Operate," Intellectual Property Insights, 2020.
[5] G. Turner, "Historical Patent Filing Trends," Pharmaceutical Patent Review, 2021.
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