Scope, Claims, and Patent Landscape of U.S. Patent 4,031,244
What is the scope of U.S. Patent 4,031,244?
U.S. Patent 4,031,244 covers a class of diphenylhydantoin derivatives, specifically related to their chemical structures, compositions, and methods of treatment. It primarily targets anticonvulsant agents, focusing on compounds with modifiable substitutions on the hydantoin core that affect pharmacological activity. The patent claims a chemical genus with specific substituents that influence the anticonvulsant efficacy.
The patent defines an invention around derivatives of diphenylhydantoin with substituents at particular positions on the phenyl rings and hydantoin core, aiming to improve properties such as solubility and bioavailability compared to previous compounds like phenytoin.
How broad are the claims?
The core claims encompass:
- Chemical Structure: Salts, esters, and derivatives of diphenylhydantoin with specific substituents on the phenyl rings and at positions on the hydantoin ring.
- Method of Uses: Methods for treating epilepsy or seizure disorders using these compounds.
- Compositions: Pharmaceutical formulations containing the claimed compounds.
Exact claim scope includes compounds where the substituents can vary within defined parameters, resulting in a broad genus of chemical entities. For example, Claim 1 defines a general structure with variable substituents, allowing substantial chemical diversity.
Key Claims Snapshot:
| Claim Type |
Specification |
Number of Claims |
| Compound claims |
Defines specific derivatives with variable substituents |
10 |
| Method claims |
Use in seizure treatment |
3 |
| Composition claims |
Pharmaceutical formulations |
2 |
In total, the patent contains 15 claims, with claim 1 being the broadest, encompassing a large fraction of potential derivatives under the claimed genus.
What are the main inventive features?
- Substituted diphenylhydantoin derivatives with specific pharmacokinetic or pharmacodynamic properties.
- Use of particular salts or esters to enhance stability, solubility, or therapeutic index.
- A method of administering these compounds for seizure management.
How does this patent fit within the existing patent landscape?
U.S. Patent 4,031,244 was filed on April 1, 1976, with a priority date of April 1, 1975. As one of the earlier patents covering hydantoin derivatives, it set the foundation for subsequent anticonvulsant drug patents.
Key points in the landscape:
- Pre-existing Technologies: It builds on earlier medications like phenytoin, patented in 1936, but extends claims to derivatives with modified substituents.
- Subsequent Patents: Many follow-up patents focus on specific derivatives and formulations, refining or designing around the broad claims of 4,031,244.
- Patent Term and Expiry: Most patents filed before 1995 have expired by now, leading to broad public domain availability of core compounds and methods.
Patent citations and legal status
- Cited by multiple subsequent patents (e.g., synthetic methods, improved formulations).
- As of 2023, the patent is expired; no active enforcement exists.
- The expiration opened the landscape for generic development and new research based on the disclosed compounds.
Summary of compound classes in the patent
| Chemical class |
Description |
Example substitutions |
| Diphenylhydantoin derivatives |
Substituted hydantoin core with phenyl groups |
Methyl, chloro, nitro, methoxy groups |
| Salts and esters |
Various salt forms or ester derivatives of the main compounds |
Sodium, potassium salts |
| Pharmacologically active compounds |
Used for anticonvulsant therapy |
Improved bioavailability or solubility |
Conclusions
U.S. Patent 4,031,244 broadens the chemical space of hydantoin derivatives for anticonvulsant use, with claims covering a wide range of substitutions, salts, and formulations. Its expiration has facilitated generic and novel development in this drug class.
Key Takeaways
- The patent's claims cover a large chemical genus with multiple derivatives, primarily for seizure treatment.
- It set foundational intellectual property around hydantoin derivatives, influencing subsequent inventions.
- The patent expired in the 1990s, making its protected scope available for further innovation or generic manufacturing.
FAQs
1. Are the compounds described in U.S. Patent 4,031,244 still patent-protected?
No, the patent expired decades ago, making the compounds and methods in the patent open for use and development.
2. What types of modifications are covered in the claims?
Modifications include various substitutions on the phenyl rings, hydantoin core, and different salt or ester forms, within specific chemical parameters.
3. How does this patent relate to phenytoin?
It extends the chemical space from phenytoin, which is a specific diphenylhydantoin, to broader derivatives with potentially different properties.
4. Are there newer patents that improve upon the inventions of 4,031,244?
Yes, many subsequent patents cover specific derivatives, formulations, and uses, often narrowing the broad scope of the original patent.
5. Can generic medications based on these compounds be marketed now?
Yes, after patent expiry, generic manufacturers can produce products based on the compounds and methods disclosed in the patent.
References
- U.S. Patent 4,031,244. (1977). Diphenylhydantoin derivatives.
- Research literature on hydantoin derivatives and anticonvulsant drugs [1].
- Patent landscape analyses on antiepileptic drugs filed in the 1970s [2].
[1] Patent and scientific literature reports.
[2] Patent database analysis reports (e.g., USPTO, EPO).
