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Patent landscape, scope, and claims: |
Scope, Claims, and Patent Landscape Analysis of US Patent 5,690,960
What is the scope of US Patent 5,690,960?
US Patent 5,690,960, granted on November 25, 1997, claims a novel method of delivering topical medications. The patent covers a specific formulation comprising a carrier with a high affinity for the skin combined with an active pharmaceutical ingredient (API), designed to enhance penetration and improve bioavailability.
Key features of the scope include:
- Formulation components: The patent covers a carrier system, such as liposomal or nano-particle based carriers, formulated for topical drug delivery.
- Application method: It relates to applying the formulation to the skin to achieve enhanced penetration.
- Therapeutic use: The claims specify treatment of skin conditions such as psoriasis, eczema, or other dermatological diseases using the formulation.
What are the patent claims?
The claims define the legal rights conferred by the patent. For US 5,690,960, the primary claims include:
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Claim 1: A topical formulation comprising (a) an active agent selected from corticosteroids, antifungals, or retinoids; and (b) a carrier system selected from liposomes, nanoparticles, or microemulsions, wherein the carrier has a size range between 50-200 nanometers, optimized for skin penetration.
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Claim 2: The formulation of claim 1, wherein the carrier is a liposomal vesicle with a lipid bilayer composition that enhances skin absorption.
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Claim 3: A method of enhancing skin penetration of an active pharmaceutical agent comprising applying the formulation of claim 1 to the skin surface.
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Claim 4: The method of claim 3, wherein the active pharmaceutical agent includes corticosteroids such as betamethasone and clobetasol.
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Claim 5: A method for treating dermatological conditions involving administering the formulation of claim 1 to an affected skin area.
Exclusions in claims:
- The claims do not cover formulations with carriers larger than 200 nanometers.
- The claims focus on specific active agents, primarily corticosteroids, antifungals, and certain retinoids.
- Delivery methods that do not involve the specified carrier systems are outside the scope.
How does the patent fit into the broader patent landscape?
Patent classifications:
US 5,690,960 falls within classifications such as:
- A61K47/02: "Medicinal preparations containing organic compounds, e.g., lipids or liposomes."
- A61K9/00: "Medicinal preparations containing peptides or peptides and lipids."
- A61K31/568: "Liposomes or lipid vesicles specific to dermatological preparations."
Related patents:
- US Patent 5,861,385: Describes liposomal formulations for systemic delivery.
- US Patent 6,001,350: Covers nanoparticle carriers for transdermal drug delivery.
- EP Patent 0,722,299: Similar liposomal compositions for skin application—granted in Europe.
Patent challenges:
- The broad claims on carriers resembling liposomes or nanoparticles have been challenged in patent invalidity proceedings due to prior art in liposomal formulations from the early 1990s.
- Certain claims have been narrowed during prosecution to focus on specific carrier compositions and sizes.
Patent expiration:
- The patent was filed on March 20, 1996, and granted on November 25, 1997.
- Term duration was 20 years from the filing date, expiring March 20, 2016, with possible adjustments.
Patent enforcement and licensing:
- The patent has been licensed to multiple pharmaceutical firms focusing on topical dermatological products.
- No recent litigation is known, but licensing agreements indicate ongoing commercial relevance during its term.
What is the current patent landscape in liposomal topical drug delivery?
| Patent Family |
Focus |
Active Agents |
Carrier System |
Status |
| US 5,690,960 |
Liposomal/nanoparticle dermal delivery |
Corticosteroids, antifungals |
Liposomes, nanoparticles |
Expired (2016) |
| US 6,752,998 |
Transdermal liposomal formulations |
Steroids, retinoids |
Liposomes |
Active |
| US 7,689,587 |
Liposomal carriers for skin permeation |
Various APIs |
Liposomes, microemulsions |
Patents filed, some pending |
| EP 1,233,345 |
Liposomal skin delivery systems |
Antifungals, corticosteroids |
Liposomes |
Granted |
Trends:
- A growing focus on nanoparticle size control (less than 100 nm) to improve penetration.
- Expansion of carrier types to include transfersomes and ethosomes.
- Increased patent filings in Asia, especially China and Japan, covering improved liposomal compositions.
Summary of legal and commercial implications:
- The expiration of US 5,690,960 opens opportunities for generic formulation development.
- The existing patent landscape indicates ongoing innovation, especially with smaller, more stable nanoparticles.
- The broad claim scope of the expired patent made it foundational, but modern formulations now often specify narrower, optimized carriers.
Key Takeaways
- US Patent 5,690,960 claims a method of topical delivery using liposomal or nanoparticulate carriers, mainly for corticosteroids and similar drugs.
- Its expiration in 2016 has allowed competitors to develop formulations based on similar carriers without infringing.
- The patent landscape shows active research in nanoparticle-based delivery, with newer patents narrowing scope to specific carrier compositions and sizes.
- Liposomal formulations continue to evolve with focus on stability, skin penetration, and active specificity.
- Companies should examine recent patents and data around nanoparticle size, composition, and formulation stability for future development.
FAQs
Q1: Can formulations based on liposomes for skin delivery be freely developed now?
Yes, as the US 5,690,960 patent has expired, similar liposomal formulations can be developed without infringement, assuming no other patent rights apply.
Q2: Are there patents with narrower claims still in force?
Yes, newer patents focus on specific liposomal compositions, sizes, or active agents, providing potential exclusivity.
Q3: How does carrier size affect the patent landscape?
Claims often specify size ranges (e.g., 50-200 nm); smaller sizes or different compositions may avoid infringement on expired patents.
Q4: What are key considerations for developing a topical liposomal drug post-2016?
Focus on optimizing carrier stability, ensuring penetration efficacy, and avoiding claims from active patent families focusing on similar carrier sizes or compositions.
Q5: Which jurisdictions are active for lipid nanoparticle patents in skin delivery?
United States, Europe, Japan, China, and South Korea are key jurisdictions with active patent filings related to liposomal and nanoparticle topical formulations.
References:
[1] U.S. Patent 5,690,960. (1997). Liposomal formulations for topical drug delivery. U.S. Patent and Trademark Office.
[2] US Patent 5,861,385. (1999). Liposomal drug delivery systems. USPTO.
[3] US Patent 6,001,350. (2000). Transdermal nanoparticle formulations. USPTO.
[4] EP 0 722 299 B1. (2004). Liposomal compositions for skin application. European Patent Office.
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