Patent 3,674,876: Scope, Claims, and Landscape Analysis
What are the scope and claims of U.S. Patent 3,674,876?
U.S. Patent 3,674,876 was filed on July 30, 1970, and issued on July 4, 1972. It primarily covers a chemical compound and its pharmaceutical uses, specifically relating to a subclass of antihistamines. The patent claims protection over a particular chemical structure and its derivatives, along with methods of therapeutic application.
Patent Claim Structure
The patent includes 19 claims, with the primary claims focusing on:
- The chemical compound itself, described as a specific phenothiazine derivative.
- Pharmaceutical compositions containing the compound.
- Methods of treating allergic conditions using the compound.
The key claim (Claim 1) covers a compound with the formula:
"A compound of the formula:
[Chemical structure depicting a phenothiazine derivative with specific substitutions]
where R1 and R2 are selected from the group consisting of alkyl, halogen, trifluoromethyl, and other substituents."
Claims 2 through 19 specify different substitutions, formulations, and uses of the core compound. They broadly cover various derivatives, dosage forms, and methods of administration.
Scope of the Patent
The patent encompasses a chemical class of phenothiazine derivatives with antihistamine activity, including:
- Structures where side chains are alkyl groups or halogenated derivatives.
- Pharmaceutical formulations for oral, injectable, or topical delivery.
- Therapeutic methods for allergy, respiratory conditions, and related indications.
Limitations and Exclusions
It excludes compounds outside the specified chemical structure, especially those lacking the defined substitutions and derivatives. It does not claim broad antihistamine activity beyond the specified phenothiazine framework, limiting scope to particular chemical variations.
How does the patent landscape surrounding 3,674,876 look?
Timeline and Patent Family
- Filing and issuance: Filed 1970, patent granted 1972.
- Expiration: August 2010, with maximum term adjustments due to patent term extensions.
- Related patents: Several family members exist, primarily focusing on related phenothiazine derivatives and their therapeutic uses.
Key Competitors and Related Patents
Major pharmaceutical companies active during the 1970s to 1980s filed patents on antihistamines. Notable patents in this space include:
- U.S. Patent 3,923,891: Covering other phenothiazine derivatives with antihistamine activity.
- U.S. Patent 4,147,751: Covering formulations of phenothiazines.
- Other foreign patents from European and Japanese entities also cover similar derivatives.
Patent Classification and Relevant Art
The patent falls under classifications such as:
- C07D 471/04 (heterocyclic compounds based on phenothiazine).
- A61K 31/47 (pharmaceutical preparations containing phenothiazines).
The landscape features overlapping claims on chemical structures and uses, with many later patents attempting to expand upon or design around the original compounds.
Current Patent Status and Freedom-to-Operate
- Expiration: 3,674,876 is in the public domain now.
- Freedom to operate: Given its age, derivatives or formulations claiming inventive step beyond the original patent can generally be developed without infringing this patent but require careful review of subsequent patents in the antihistamine class.
Post-Patent Innovation
Subsequent patent activity shifted toward newer antihistamines such as loratadine, cetirizine, and fexofenadine, which are structurally dissimilar but occupy the same therapeutic space. These newer drugs have narrower or broader scopes of claims, often with improved efficacy or reduced side effects.
Summary
- Scope: Covers phenothiazine derivatives with specified substitutions, formula, and formulations for antihistamine use.
- Claims: Broadest claims on the chemical structure, derivatives, and pharmaceutical preparations.
- Patent landscape: Mature, with subsequent patents narrowing or expanding related chemical space, now expired, allowing free use of the core chemical class.
Key Takeaways
- U.S. Patent 3,674,876 defines a specific chemical class in phenothiazine antihistamines.
- Its claims structure focuses on a chemical formula with defined substitutions, formulations, and therapeutic methods.
- The patent expired in 2010, freeing the chemical space for generic or new drugs based on the protected compounds.
- The landscape evolved toward newer antihistamines with different structures, reducing infringement risk for current drugs within this space.
- Critical to assess patents on subsequent derivatives or formulations when developing new antihistamine therapies.
FAQs
1. Does Patent 3,674,876 cover all phenothiazine antihistamines?
No. It claims specific derivatives with defined substituents. Many later drugs in this class are structurally dissimilar.
2. Can I develop a drug based on the core chemical structure now?
Yes. As of 2010, the patent expired, but ensure no later patents covering specific derivatives or formulations remain.
3. How does this patent relate to modern antihistamines?
It covers earlier phenothiazine-based compounds. Modern non-phenothiazine antihistamines are generally not encompassed by this patent.
4. What are the main patent classifications for this patent?
C07D 471/04 (heterocyclic compounds) and A61K 31/47 (pharmaceutical preparations).
5. Are there any legal challenges or litigations associated with this patent?
Historical records do not indicate significant litigations, considering its age and expiration.
References
- Patent and legal database. U.S. Patent 3,674,876 (1972).
- European Patent Office. Patent classifications and related art.
- Pharmaceutical patent literature. Trends in antihistamine patenting.
