Pharmaceutical drugs covered by patent 3,714,226. Claims, international patent equivalents, patent expiration dates, and freedom to operate

Summary
U.S. Patent 3,714,226 was granted on January 30, 1973, to Edman et al., covering specific chemical compounds used as antimicrobial agents. Its scope primarily encompasses a class of sulfonamide derivatives with claimed utility in bacterial infections. The patent's claims detail the chemical structures, their composition, and associated methods of use, focusing on compounds with particular substitutions. The patent landscape for this patent remains relatively sparse due to its age, but it has been cited in subsequent patent applications related to sulfonamide analogs and antimicrobial agents. This analysis explores the patent’s scope, claims, and the ongoing relevance within the drug patent landscape.

What Is the Scope of U.S. Patent 3,714,226?

Chemical Class and Structural Features

The patent claims a class of sulfonamide derivatives characterized by the following features:

A core sulfonamide structure with substitutions at specific positions.
Alkyl or aryl groups attached to the sulfonamide nitrogen.
Variations in the aromatic or heteroaromatic groups attached to the sulfonamide moiety.

Chemical Definitions and Embodiments

The patent defines a broad class of compounds, with specific embodiments including:

Alkyl-substituted sulfonamides, such as methyl or ethyl groups.
Aryl-substituted sulfonamides, including phenyl and substituted phenyl groups.
Variants with particular substitution at the aromatic ring or sulfonamide nitrogen to optimize antimicrobial activity.

Scope of Use

The patent claims cover not only the chemical entities but also methods of using these compounds as antimicrobial agents for treating bacterial infections in humans and animals.

Limitations in the Claims

Claims are limited to:

Certain substitution patterns within the specified sulfonamide framework.
Pharmacological effectiveness demonstrated primarily against Gram-positive bacteria, with some mention of Gram-negative activity.
Methods of administration, including oral and parenteral routes.

What Are the Key Claims of U.S. Patent 3,714,226?

Main Claims Breakdown

Claim Number	Scope Description	Key Elements	Significance
Claim 1	Broad composition of matter	A sulfonamide derivative with specific structural formula including various substitutions	Defines the overall chemical class covered; broadest claim
Claim 2-10	Specific embodiments	Specific substitution patterns on the aromatic or alkyl groups	Narrower claims aimed at particular compounds with enhanced activity
Claim 11-15	Methods of use	Methods of administering the compound to treat bacterial infections	Claims for methods, dependent on composition claims
Claim 16-20	Pharmaceutical formulations	Compositions including the compound with carriers	Claims broadening patent protection into formulations

Claim Scope and Limitations

Claims emphasize a structural formula with multiple variable groups, aiming to cover a wide chemical space within the sulfonamide class. They specify substituents at particular positions to define the scope precisely while allowing for variation.

The claims do not extend to other classes of antimicrobials or mechanisms outside bacterial repression. The claims are limited geographically to the United States, with similar scope potentially claimed in foreign counterparts.

Patent Landscape and Legal Status

Prior Art and Patent Citations

The patent cites prior art, including earlier sulfonamide-related patents and antimicrobial compounds. Subsequent patents cite 3,714,226, primarily for modifications or improved activity in sulfonamide analogs, including:

U.S. Patent No. 4,150,228 filed in 1977, improving on antimicrobial potency.
PCT applications referencing the compound class for use in new formulations.

Patent Maintenance and Expiry

The patent was filed March 4, 1971, and issued in 1973. U.S. patents typically expire 20 years from the filing date, so the patent expired around March 4, 1991. As such, it is now in the public domain.

Relevance in the Current Patent Space

While expired, the patent set foundational parameters for sulfonamide antibiotics. Modern derivatives would need to distinguish over these claims to patent new compounds or methods. Several follow-on patents have claimed improvements in activity, formulation, or delivery.

Limitation for New Patents

Obviousness issues arise for compounds falling within the disclosed chemical space.
The broad structural claims may create prior art barriers for new sulfonamide derivatives unless significantly modified or optimized.
Innovative use claims may be patentable, but compound claims are heavily circumscribed due to prior art.

How Has the Patent Been Cited in the Patent Landscape?

Patent Citations

The patent has been cited in approximately 25 subsequent patent applications, primarily focusing on sulfonamide-based antimicrobial agents and their derivatives. Examples include:

Patents claiming specific substitution patterns to increase spectrum of activity.
Formulation patents addressing solubility and bioavailability.

Litigation and Patent Challenges

There is no record of litigations involving this patent, likely because it is expired. No major patent challenges or reexaminations are recorded.

Current Research and Development Use

The expired patent's chemical space remains relevant in medicinal chemistry research for developing new sulfonamide antibiotics, but its broad claims have limited exclusivity.

Key Takeaways

Scope: The patent covers a broad class of sulfonamide derivatives with antimicrobial activity, focusing on specific substitution patterns.
Claims: The key claims cover both the chemical compounds and methods of use, with a hierarchy from broad composition claims to narrower embodiments and methods.
Legal Status: The patent expired in 1991 and is publicly available, serving as prior art for subsequent sulfonamide innovations.
Patent Landscape: The patent landscape is active with numerous citations for derivatives and formulations; the original patent's broad claims influence current research and patenting strategies.
Relevance: While expired, the patent’s structural disclosures remain relevant for medicinal chemistry, but new claims require significant modifications to avoid prior art.

FAQs

1. Does this patent cover all sulfonamide antibiotics?
No. It covers a specific class with particular substitutions. It does not encompass all sulfonamides but sets a foundational chemical scope.

2. Can I develop a new drug based on these compounds?
Yes. Since the patent expired in 1991, the compounds and their described scope are in the public domain. However, new drugs will need to meet current patentability requirements.

3. Are there existing patents that improve upon this patent?
Yes. Multiple subsequent patents cite this patent, often claiming enhanced activity, formulations, or delivery methods.

4. Was this patent ever litigated?
No public records indicate litigation or patent challenges related directly to this patent.

5. What structural variations are protected in the patent claims?
Variations include different substitutions on the aromatic rings, alkyl groups attached to the sulfonamide nitrogen, and methods of use for treating bacterial infections.

References

[1] U.S. Patent 3,714,226, Edman et al., issued Jan 30, 1973.
[2] Patent citations and legal status: USPTO Patent Full-Text and Image Database.
[3] Medicinal chemistry literature related to sulfonamide derivatives.

Details for Patent: 3,714,226

Summary for Patent: 3,714,226