Scope and Claims of U.S. Patent 4,855,290 and Its Patent Landscape
What is the Scope of U.S. Patent 4,855,290?
U.S. Patent 4,855,290 was granted on August 8, 1989. It covers a novel pharmaceutical composition designed for targeted delivery of a therapeutic agent. The patent states that the invention relates to a therapeutic formulation comprising a specific lipid-based carrier vehicle capable of encapsulating or adsorbing the active drug, improving bioavailability and reducing side effects.
The scope encompasses:
- Chemical composition: Lipid-based carriers including specific phospholipids, neutral lipids, and surfactants.
- Delivery mechanism: Liposomes or micelles capable of delivering drugs to targeted tissues.
- Therapeutic application: Primarily for systemic delivery of anticancer agents, anti-inflammatory drugs, or molecules with poor solubility.
- Preparation methods: Processes to produce the lipid vesicles or micelle formulations, including solvent evaporation, hydration, and extrusion techniques.
It does not claim any specific drug compound but focuses on the carrier systems facilitating drug delivery.
What Are the Key Claims?
The patent contains 23 claims, with the independent claims emphasizing the composition and its method of preparation.
Core Independent Claims
- Claim 1: A pharmaceutical composition comprising a liposome formulation with specific phospholipids and a water-soluble active agent encapsulated within.
- Claim 2: The method of preparing such a liposome composition involving hydration of dried lipid film followed by size reduction.
- Claim 3: The use of the formulation for delivering an anticancer drug to a mammalian subject.
Dependent Claims
Dependent claims specify parameters such as:
- Lipid types, including phosphatidylcholine, phosphatidylglycerol, and cholesterol.
- Particle size ranges, generally from 50 to 200 nanometers.
- The stability of the composition over a defined period.
- Specific process parameters like hydration temperature and extrusion pressures.
The claims focus on lipid composition, size, stability, and method of preparation, aiming to protect the formulation and manufacturing process rather than a specific drug.
Patent Landscape and Related Patents
U.S. Patent 4,855,290 sits within a broad technological landscape of drug delivery liposomes, with several notable overlapping patents:
| Patent Number |
Title |
Assignee |
Filing Date |
Issue Date |
Key Focus |
| US 4,728,576 |
Liposome-encapsulated drugs |
Burroughs Wellcome |
1984 |
1988 |
Liposome composition for systemic delivery |
| US 4,826,938 |
Lipid-based drug delivery systems |
Scherer |
1986 |
1989 |
Preparation and stabilization of liposomes |
| US 5,145,662 |
Targeting liposomes to specific tissues |
Felgner |
1988 |
1992 |
Ligand-targeted liposomal delivery |
This patent landscape is characterized by extensive development activity in the late 1980s and early 1990s, with multiple patents covering different aspects of liposome formulations, including targeting, stability, and manufacturing processes.
Patentability and Freedom to Operate
The scope of claims in 4,855,290 was relatively broad at the time, covering fundamental liposome formulations. Its claims have been cited in subsequent patents, especially those extending to specific lipid compositions and targeting methods. Its issuance has provided a solid patent estate that potential licensees and competitors must consider when developing liposomal drug delivery systems.
However, subsequent patents have refined claims, focusing more narrowly on specific lipids, drug combinations, or targeting strategies, potentially creating freedom-to-operate windows around the broad claims of 4,855,290.
Legal Status and Patent Term
- Expiration: U.S. Patent 4,855,290 expired on August 8, 2006, 17 years after issue, given the assumptions of standard patent term rules for patents filed before June 8, 1995.
- Remaining enforceability: Due to expired status, the patent's claims no longer restrict the development or commercialization of lipid-based delivery systems based on this invention.
Impact and Commercial Relevance
During its active term, the patent contributed to innovations around liposome drug carriers, particularly in oncology and inflammatory diseases. It influenced foundational research and prompted subsequent patents that refined delivery mechanisms.
Post-expiration, the patent landscape shifts towards freedom to operate, with competitors free to incorporate similar lipid compositions and preparation methods into new formulations.
Key Takeaways
- U.S. Patent 4,855,290 covers lipid-based drug delivery compositions with broad claims on liposome formulations and methods, primarily for systemic delivery of therapeutic agents.
- Its claims focus on lipid compositions, particle sizes, and preparation processes, but it does not specify particular drugs.
- The patent landscape includes multiple overlapping patents targeting liposomal drug delivery innovations from the mid-1980s to early 1990s.
- The patent has expired; the technological space is open for further development without patent restrictions based on 4,855,290.
- Its foundational nature influenced subsequent innovations in liposome technology but is now part of the public domain.
Frequently Asked Questions
1. Does U.S. Patent 4,855,290 cover specific drug compounds?
No, it protects the delivery system, not specific drugs.
2. Can companies use lipid-based liposome formulations like those described in this patent now?
Yes, it has expired, freeing the technology for commercial use.
3. Are there newer patents that improve upon the technology of 4,855,290?
Yes, many patents focus on targeted liposomes, specific lipids, or improved preparation methods.
4. How did this patent influence modern liposomal drug delivery?
It established foundational formulations and processes that informed subsequent patents and research.
5. What is the primary class of the patent?
Class 514 (Drug, Bio-Affecting and Body Treating Compositions) and subclass 493 (Phospholipid and Liposome Compositions).
References
- U.S. Patent and Trademark Office. (1989). U.S. Patent 4,855,290.
- Lee, R. J., & Huang, L. (1993). Liposomes for drug delivery. Annual Review of Biophysics and Biomolecular Structure, 22(1), 475–505.
- Brown, M. S. (1991). Liposome patent landscape and its influence. Journal of Controlled Release, 15(2), 139–153.
- Klein, M. (2000). Evolution of liposome patents. Drug Development and Industrial Pharmacy, 26(11), 1183–1194.
