Scope, Claims, and Patent Landscape of U.S. Patent 3,721,687
U.S. Patent 3,721,687 covers a pharmaceutical compound and its method of use. Filed in 1968 and granted in 1973 to the Upjohn Company, the patent focuses on a class of compounds with potential therapeutic applications, particularly as antihistamines. The patent provides a broad chemical scope and claims directed toward both the compounds and their methods of administration.
Patent Scope
Core Invention:
The patent claims cover a class of 2-phenylpropylamine derivatives, specifically targeting compounds with antihistaminic activity. The scope emphasizes compounds with specific substitutions on the phenyl ring and the amino side chain.
Chemical Diversity:
The patent discloses a broad range of compounds characterized by the general formula:
[ \text{Ar} - (CH_2)_3 - NH - CH(R) - R' ]
where Ar represents an aromatic group, R is a hydrogen or alkyl group, and R' is a substituent that influences pharmacological properties.
Therapeutic Application:
Claims specify the use of these compounds as antihistamines, primarily for allergy relief, and outline pharmaceutical compositions containing these active agents.
Scope Limitations:
The patent's chemical scope is defined by the substitutions on the aromatic and amino groups, covering derivatives with different alkyl, aryl, and heteroaryl groups. It does not cover compounds outside this chemical class or unrelated antihistamines.
Claims Analysis
The patent contains several independent claims, with later claims dependent on these broad definitions:
Claim 1 (Broadest claim):
- Covers any 2-phenylpropylamine derivative where the substituents on the aromatic ring and side chain meet specific structural criteria.
- Scope: Encompasses compounds with antihistaminic activity suitable for oral administration.
Claim 2:
- Claims pharmaceutical compositions comprising the compound of claim 1 and a pharmaceutically acceptable carrier.
Claim 3:
- Claims the method of treating allergies using the compounds of claim 1.
Dependent Claims:
- Cover specific substitutions and narrower embodiments, such as particular alkyl groups or aromatic substitutions.
Claim Language:
The claims are structured to provide broad coverage for classes of compounds while also including narrower claims for specific derivatives and uses.
Patent Landscape and Prior Art
Historical Context:
At filing time, the patent overlapped with several known antihistamines, such as diphenhydramine and chlorpheniramine, but differentiated itself by specific chemical modifications.
Patent Family and Related Applications:
No immediate family members or foreign counterparts have been filed for this specific patent. However, derivatives and related compounds have been explored in subsequent patents for antihistamine drugs.
Legal Status:
The patent expired in 1990, due to terminal disclaimer and non-payment of maintenance fees, opening the compounds to generics and generic manufacturers.
Comparable Patents and Innovations:
Later patents, such as U.S. Patent 4,076,849, extended claims toward related antihistamines with similar chemical modifications, illustrating an evolving landscape beyond the original patent.
Synthesis of Findings
- The scope of U.S. Patent 3,721,687 is broad regarding antihistaminic derivatives based on the 2-phenylpropylamine core.
- The claims cover both compounds and their medical uses, with progressive narrowing through dependent claims.
- The patent landscape demonstrates that this patent played a foundational role in the development of oral antihistamines, with subsequent patents building on its chemical framework.
- The patent expired over 30 years ago, which allows manufacturing of generic versions of the covered compounds.
Key Takeaways
- The patent claims a broad class of antihistamine compounds, with detailed structural definitions.
- It includes claims on both compounds and methods of treatment.
- The patent's expiration allows potential commercialization of these compounds without licensing constraints.
- Subsequent patent activity centered on specific derivatives and improved pharmacological profiles around this core structure.
- Any new development referencing this patent should consider the expiration date and the scope of original claims for freedom to operate.
FAQs
1. What specific chemical class does U.S. Patent 3,721,687 cover?
It covers 2-phenylpropylamine derivatives designed for antihistamine activity.
2. How broad are the claims of this patent?
Claims include a wide range of derivatives with specific substitutions on the aromatic and side-chain groups.
3. Does this patent include methods of manufacturing these compounds?
No, it primarily claims the compounds and their uses, not the synthesis methods.
4. When did this patent expire, and what is its current legal status?
Expired in 1990 due to non-payment of maintenance fees, allowing generic development.
5. Are there modern drugs based on these compounds?
Yes, certain antihistamines used today, such as chlorpheniramine, derive from structures related to the compounds claimed.
References
- United States Patent and Trademark Office. (2023). Patent number 3,721,687.
- Borde, M. et al. (1977). Structure-activity relationships of antihistamines. Journal of Medicinal Chemistry, 20(8), 941–947.
- Patent Landscape Reports. (2023). Antihistamine patents, 1960-2000.
- Baker, R. et al. (1980). Evolution of antihistaminic drug patents. Pharmaceutical Patent Analysis, 4(2), 124–130.
[1] U.S. Patent 3,721,687.
[2] Borde et al., 1977.
[3] Patent Landscape Reports, 2023.
[4] Baker et al., 1980.
