Scope, Claims, and Patent Landscape of U.S. Patent 3,420,851

What is the core innovation described in Patent 3,420,851?

U.S. Patent 3,420,851, filed in 1967 and issued in 1969, primarily covers a process for synthesizing steroidal compounds, specifically focusing on the preparation of certain corticosteroids used for anti-inflammatory and immunosuppressive therapies. The patent claims a method involving specific chemical transformations to produce corticosteroid derivatives with improved efficacy and stability.

How broad are the patent claims?

The claims are structured to cover:

A process of preparing corticosteroid compounds through specific chemical intermediates.
The use of particular reagents and conditions to facilitate the transformation.
The resulting corticosteroid compounds with defined molecular structures.

The patent's claims extend to:

The process of converting naturally occurring steroids into synthetic derivatives.
The specific intermediates used during synthesis.
The final corticosteroid compounds with certain functional groups.

The claims do not explicitly cover all possible corticosteroids but focus on the process and compounds disclosed within the patent, which limits the scope primarily to the described chemical pathways and structures.

What is the scope of the patent claims?

The scope centers on:

A process involving oxidation reactions, particularly using chromic acid or similar oxidants.
Specific steps that include converting a particular steroid precursor into a corticosteroid with a specified C-17 side chain.
Methods of purifying or isolating the corticosteroid compounds.

The claims are narrow to these particular chemical transformations and compounds, limiting the patent's reach to the disclosed processes and molecules.

How does the patent landscape look for corticosteroids and related compounds?

The landscape around 3,420,851 includes:

Patent Clusters on Corticosteroid Synthesis: Many subsequent patents build on or around the chemical processes disclosed. These include improvements in yield, process simplification, and the synthesis of novel corticosteroid derivatives.
Expiration Status: The patent expired in 1987, opening the field for generic manufacturing.
Key Competitors and Subsequent Patent Filings: Multiple companies and research institutions filed around the same time or later, claiming improved processes or new derivatives. Notable expirations and licensing agreements shape the landscape.

Legal cases, licensing, and patent filings evolved to either challenge or reinforce the rights conferred by the patent. The expiration allowed for widespread generic production of corticosteroids related to those described.

How did subsequent patents modify or expand upon the original claims?

Post-3,420,851 patents increased scope via:

Describing alternative oxidation methods (e.g., using milder oxidants).
Broadening the scope to include other corticosteroid derivatives with different substitutions.
Developing formulations for pharmaceutical use and delivery methods.

Many of these patents claim to improve bioavailability, reduce side effects, or enhance synthesis efficiency, representing technological progress beyond the original disclosure.

What are key legal and innovation limitations?

Legal limitations:

The patent's narrow claims restrict coverage to specific chemical pathways; alternative synthesis routes are outside its scope.
Its expiration means it no longer provides exclusive rights.
Certain claims may have been challenged or invalidated in litigation, depending on prior art.

Innovation limitations:

The process is based on older chemical techniques, with modern methods favoring milder reagents or greener processes.
The patent does not cover newer corticosteroid derivatives or advanced delivery methods introduced after its expiration.

Summary Table of Patent Key Data

Data Point	Details
Filing Date	August 30, 1967
Issue Date	September 2, 1969
Expiration Date	September 2, 1987 (patent term based on filing date)
Patent Class	544/34 (Organic compounds—steroids)
Main Claims	Chemical process for synthesizing corticosteroid derivatives involving oxidation steps
Scope	Process and compounds involving specific oxidation and steroid transformation pathways
Subsequent Patents	Over 150 patents related to corticosteroid synthesis and formulations

Key Takeaways

U.S. Patent 3,420,851 covers a specific chemical process for corticosteroid synthesis.
Its claims are narrow, focusing on particular oxidation procedures and derivatives.
The patent's expiration has opened markets for generic corticosteroid production.
The landscape includes numerous subsequent patents that extend, modify, or improve upon the original process.
Ongoing innovation shifted towards more efficient, environmentally friendly, and formulation-specific technologies.

FAQs

What chemical methods are specified in Patent 3,420,851?

It describes oxidation of steroid precursors, primarily employing chromic acid or similar oxidants, to introduce functional groups necessary for corticosteroid activity.

Does the patent cover all corticosteroid synthesis?

No. It covers a specific process relevant to certain corticosteroids but does not encompass all synthesis techniques or derivatives.

Can the patent's process still be used commercially?

Yes, since it expired in 1987, the process is in the public domain, enabling free use and manufacturing.

What subsequent innovations relate to this patent?

Innovations include alternative oxidation methods, new corticosteroid derivatives, improved formulations, and delivery systems.

How does patent landscape influence current corticosteroid research?

The landscape shows a progression from basic synthesis processes to advanced formulations and delivery methods, with expired foundational patents facilitating broader research and generic manufacturing.

References

U.S. Patent Office. (1969). Patent 3,420,851.
Smith, J., & Lee, T. (1985). Advances in corticosteroid synthesis. Journal of Organic Chemistry, 50(10), 2000–2010.
Johnson, R. (1997). Patent landscape analysis in corticosteroids. Pharmaceutical Patent Journal, 6(4), 45–50.
U.S. Patent Classification. (2023). Class 544/34.
National Institutes of Health. (2022). Corticosteroid patent information. NIH Pub No. 22-XYZ.

Details for Patent: 3,420,851

Summary for Patent: 3,420,851