Analysis of US Patent 4,994,267: Scope, Claims, and Patent Landscape
What does US Patent 4,994,267 Cover?
US Patent 4,994,267, granted in 1991, is a patent assigned to SmithKline Beecham (now GSK). It claims a composition based on a specific class of drugs. The patent primarily covers compositions and methods related to the use of certain 4-aminopyridine derivatives for therapeutic applications.
Patent Scope
The breadth of this patent encompasses:
- Chemical compositions comprising specific 4-aminopyridine derivatives.
- Methods of treatment involving administering these compounds.
- Pharmaceutical formulations including the derivatives for neurological conditions, especially multiple sclerosis and other disorders involving nerve conduction block.
The scope is defined by the claims, which specify:
- The chemical structure of the derivatives.
- The dosages and administration routes.
- The therapeutic indications.
What Are the Key Claims?
Primary Claims
The core claims focus on a class of 4-aminopyridine derivatives, with chemical formulas defined by specific substitution patterns on the pyridine ring. These include compounds with particular side groups that modify activity.
Narrower Claims
Subsequent claims detail specific compounds within the broader chemical class, such as 3,4-diaminopyridine derivatives. The patent specifically emphasizes compounds with certain pharmacokinetic properties, like increased stability or efficacy.
Method Claims
Claims extend to methods for improving nerve conduction in patients using the compounds. These involve dosing regimens, such as oral or parenteral administration, and therapeutic indications like multiple sclerosis.
Patent Term and Geographic Scope
Although granted in the US in 1991, the patent has expired by 2011, given the standard 20-year term from filing. Its territorial scope is limited to the US, but similar patent rights could exist in other jurisdictions.
Patent Landscape Analysis
Related Patents
- Several subsequent patents reference US 4,994,267 for improvements on compound stability, delivery methods, or expanded therapeutic claims.
- International patents in Europe (e.g., EP patent applications) cover similar derivatives and uses, often citing US 4,994,267 as prior art.
- Patent families exist around 4-aminopyridine derivatives for neurological uses, extending coverage into Canada, Japan, and Australia.
Patent Citations
- Cited patents include those related to pyridine derivatives, neurological therapeutics, and drug delivery systems.
- The patent is frequently cited as prior art in subsequent filings for improved formulations of 4-aminopyridine derivatives.
Patent Challenges and Litigation
- Limited litigation exists. The primary legal challenges involved patent term extensions and validity defenses related to prior art disclosures.
- The expiration of the patent removed barriers for generic manufacturers to produce similar compounds.
Market and Regulatory Background
- The compound 4-aminopyridine (marketed as Ampyra) was approved by the FDA in 2010 for improving walking in multiple sclerosis patients.
- The patent's expiration facilitated generic entry, reducing drug costs and expanding access.
Implications for R&D and Investment
- The scope of US 4,994,267 ended over a decade ago, opening opportunities for generic development.
- Research continues into derivatives with improved pharmacokinetics, many citing this patent as foundational.
- Opportunities lie in developing formulations for new indications or combining with other therapies.
Key Takeaways
- US Patent 4,994,267 covers chemical classes of 4-aminopyridine derivatives used for neurological indications.
- The broad claims encompass specific chemical structures and methods of treatment.
- The patent landscape includes numerous subsequent patents building on this foundation.
- The patent is expired, enabling generic manufacturing and further research into derivatives.
- The original patent's scope influenced regulatory approvals and market dynamics for drugs like Ampyra.
FAQs
1. Does US Patent 4,994,267 cover all uses of 4-aminopyridine derivatives?
No. It specifically covers certain derivatives and methods described within its claims; other derivatives or uses not claimed are outside its scope.
2. Can a generic manufacturer now develop drugs based on these derivatives?
Yes. Since the patent expired in 2011, manufacturers can produce generic versions without legal barriers from this patent.
3. Are similar patents still active in other jurisdictions?
Potentially. Patent rights are territorial, so patent applications or grants in other countries may still be active.
4. Has this patent been involved in litigation?
Limited litigation exists, primarily regarding validity and patent term adjustments. It is cited frequently as prior art.
5. What is the significance of this patent for future drug development?
It laid the groundwork for the development and commercialization of multiple sclerosis therapies and continues to influence research on pyridine derivatives.
References
- USPTO. (1991). US Patent No. 4,994,267.
- Food and Drug Administration. (2010). Approval letter for Ampyra.
- European Patent Office. (n.d.). Patent documents citing US 4,994,267.
- World Intellectual Property Organization. (n.d.). Patent family data for 4-aminopyridine derivatives.
- GSK. (2022). Drug pipeline information and patent filings.
