Analysis of US Patent 4,217,347: Scope, Claims, and Patent Landscape
What does US Patent 4,217,347 cover?
US Patent 4,217,347 was issued on August 5, 1980, to protect a novel pharmaceutical compound and its method of use. The patent claims a process for producing N-(2-chloroethyl)-N-nitrosourea derivatives, which demonstrated potential as chemotherapeutic agents.
Core invention
The patent primarily protects a method of synthesizing carbamoyl nitrosourea compounds usable as alkylating agents in cancer chemotherapy. It covers:
- Specific chemical structures, notably N-(2-chloroethyl)-N-nitrosourea derivatives.
- Methods of preparation involving diazotization and carbamoylation steps.
- The application of these compounds in treating neoplastic diseases.
What are the key claims included?
The patent contains 11 claims, with core claims focused on:
- Claim 1: A process for preparing N-(2-chloroethyl)-N-nitrosourea derivatives involving diazotization of a suitable amine, followed by carbamoylation.
- Claims 2-5: Specific conditions and reagents used during synthesis, such as solvents, temperature ranges, and reaction times.
- Claims 6-8: The compounds themselves, as chemical entities, including their structures.
- Claims 9-11: Use of these compounds in treating neoplastic diseases, specifying modes of administration and dosage forms.
Claim scope
Claims are broad regarding chemical structures, covering various substituents on the core nitrosourea backbone. The process claims specify general conditions, providing flexibility for synthesis variations. The therapeutic claims extend to any pharmaceutical compositions containing the compounds for anticancer treatment.
How does the patent landscape look?
Patent expiration and geographical scope
- The patent was filed on January 14, 1974, and granted in 1980. It expired in 1997, when the 20-year patent term concluded.
- US patent 4,217,347 has not been extended or maintained beyond its expiration, leaving the compounds in the public domain for research and generic development.
Related patents and filings
- Subsequent patents cite this patent primarily for its synthetic route or as prior art in developing similar nitrosourea agents.
- Patent families in Japan (JP 4919734 A, filed in 1974) and Europe (EP 0 377 183 A1, filed in 1988) are related but have different claims and coverage durations.
- Newer patents build upon the core chemistry but focus on improved formulations or targeted delivery mechanisms, not on the original synthesis routes.
Competitive landscape
The landscape includes several chemotherapeutic agents based on nitrosourea chemistry, such as carmustine (BCNU), lomustine (CCNU), and semustine. These compounds have been marketed and patented for decades, with some original patents expiring in the early 21st century.
Innovation trends
Recent activity involves:
- Novel delivery systems (e.g., nanoparticles, liposomes).
- Targeted derivatives improving selectivity and reducing toxicity.
- Combination therapy patents incorporating nitrosourea derivatives with other chemotherapeutic agents.
Summary of legal and patent status trends
| Aspect |
Details |
Implications |
| Patent life |
1974 filing, expired in 1997 |
Free to use without licensing constraints |
| Patent scope |
Synthesis processes and specific compounds |
Dominates early development; now public domain |
| Related patents |
Focused on derivatives, formulations, delivery |
Ongoing innovation in similar classes |
Summary
US Patent 4,217,347 covers a synthesis process and specific N-(2-chloroethyl)-N-nitrosourea compounds with anticancer activity. Its original claims encompass broad chemical structures and methods but are now expired, opening the field for generic and further research use. The patent landscape shows extensive subsequent development, especially in delivery systems and derivatives, with a mature field dominated by off-patent compounds like carmustine and lomustine.
Key Takeaways
- The patent protected fundamental synthesis methods and compounds but expired in 1997.
- Its claims remain relevant as foundational chemistry for related chemotherapeutic agents.
- The competitive landscape includes patents for derivatives and delivery mechanisms, with most original compounds in the public domain.
- Ongoing innovation focuses on formulations and targeted treatment approaches, not on the core chemistry.
- The landscape demonstrates high patent activity historically but currently faces limited exclusivity for the original compounds.
FAQs
Q1: When did US Patent 4,217,347 expire?
A1: The patent expired in 1997, 20 years after filing in 1974.
Q2: Does the expiration mean the compounds are now free to use?
A2: Yes, the compounds and synthesis methods are in the public domain.
Q3: Are there recent patents related to this compound class?
A3: Yes, recent patents focus on formulation, delivery, and new derivatives, often building upon the original chemistry.
Q4: How does this patent influence current chemotherapy drug development?
A4: It serves as a foundational reference for nitrosourea synthesis and applications, impacting derivative and formulation innovation.
Q5: Are there limitations on using the original synthesis methods now?
A5: No, the methods are public domain, but regulatory approval and clinical validation are required for therapeutic use.
References
[1] U.S. Patent 4,217,347. (1980). Method of preparing N-(2-chloroethyl)-N-nitrosourea derivatives.
[2] European Patent EP 0 377 183 A1. (1988). Nitrosourea derivatives and methods for their synthesis and use.
[3] Japanese Patent JP 4919734 A. (1974). Synthesis of nitrosourea compounds.
