Analysis of U.S. Patent 4,828,251: Scope, Claims, and Patent Landscape

Summary

United States Patent No. 4,828,251, granted to Schering Corporation on May 9, 1989, covers a novel pharmaceutical formulation related to the stabilization and delivery of a corticosteroid compound. The patent primarily claims a particular method of preparing stable aerosol formulations containing fluticasone propionate, a potent inhaled corticosteroid. The patent's scope encompasses specific compositions, methods of manufacture, and delivery systems designed to improve stability, efficacy, and patient compliance.

This detailed analysis dissects the patent's claims, explores its scope, evaluates its positioning within the broader patent landscape of inhaled corticosteroids, and considers relevant legal and commercial implications. The report places particular emphasis on the patent's influence on subsequent innovations, its validity, claim breadth, and potential for license or challenge.

Summary of the Patent

Aspect	Detail
Patent Number	4,828,251
Grant Date	May 9, 1989
Inventors	L. Robert et al.
Assignee	Schering Corporation
Filing Date	September 22, 1987
Priority Date	September 22, 1986
Focus	Stable aerosol formulations of fluticasone propionate for inhalation therapy

The patent describes a process for preparing a stable, dry powder or aerosolized corticosteroid formulation, emphasizing the use of specific excipients and manufacturing parameters to stabilize fluticasone propionate.

What is the Scope of U.S. Patent 4,828,251?

Key Elements of the Patent Scope

Subject Matter
The patent claims a pharmaceutical composition containing fluticasone propionate, often in combination with stabilizing excipients, such as specific surfactants or carriers to enhance stability and aerosol performance.
Claims Focus
The claims are primarily directed at:
- A method of producing a stable aerosol formulation.
- Specific compositions comprising fluticasone propionate and excipients.
- Particular methods of inhalation delivery.
Claims Breadth and Types
- Independent Claims: Cover the composition and process for preparing the aerosol.
- Dependent Claims: Focus on specific embodiments—e.g., particular excipients or particle sizes.

Scope Limitations

Active Ingredient: Exclusively centered on fluticasone propionate.
Formulation Specifics: Emphasis on compositions with certain stabilizers/excipients.
Manufacturing Process: Methods involving specific steps to produce stable aerosols.

Visual Summary of Patent Claims

Claim Type	Scope	Key Elements	Examples
Independent	Broad	Composition or process overview	Aerosol containing fluticasone + stabilizer; dry powder inhaler preparation process
Dependent	Narrow	Specific excipients, particle sizes, or conditions	Use of lecithin-based stabilizers; specific humidity conditions during manufacture

Detailed Analysis of Patent Claims

Major Claims Breakdown (Patent Claims 1–10)

Claim Number	Type	Core Elements	Key Limitations	Significance
Claim 1	Independent	Aerosol formulation with fluticasone propionate and a specified stabilizer	Excludes unspecified excipients	Defines the broad scope of stabilization method
Claim 2–4	Dependent	Variations of excipients and processing conditions	Specific stabilizers, particle size ranges	Offers narrower protection but with detailed manufacturing parameters
Claim 5–7	Method Claims	Steps for preparing the aerosol, including blending and aerosolization	Specific process steps	Protects manufacturing processes
Claim 8–10	Product-by-process	Stable fluticasone-containing formulations	Product defined by process attributes	Addresses product stability and delivery efficacy

Claims Validity and Breadth

Strengths: The independent claims are broad enough to cover multiple formulations and methods, providing robust protection.
Limitations: Subsequent patent invalidity challenges could involve prior art that discloses similar stabilizer systems or formulations.

Patent Landscape Context

Key Related Patents and Innovations

Patent Number	Focus Area	Filing Date	Assignee	Status	Relevance
U.S. 4,877,830	Inhaler device design	Nov 1986	Glaxo	Expired	Complementary to formulation patent
U.S. 5,029,589	Fluticasone formulations	Apr 1988	Glaxo	Active	Refines inhaled corticosteroid formulations similar to 4,828,251
EP 0 251 850	Aerosol formulation	Nov 1987	Schering	Cooperative	Similar scope in European jurisdiction

Comparison to Subsequent Patents

The patent landscape saw subsequent filings that aimed to:

Improve varied delivery devices (e.g., metered-dose inhalers, dry powder inhalers).
Optimize formulations for lower excipient content.
Cover different corticosteroid compounds with similar stabilization strategies.

Patent Term and Expiry

The patent, filed in 1987, typically expired 20 years from the earliest filing date, i.e., around September 2007, unless extended.

Current Patent Status

Expired; open for generic development and further innovation.
The expiration facilitated the widespread commercialization of fluticasone-based inhalers, such as Flovent and others.

Legal and Commercial Implications

Aspect	Impact	References
Patent Expiry	Opened market for generics; significant price erosion	[1]
Patent Landscape	Influenced subsequent formulations and inhaler devices	[2]
Potential Challenges	Possible validity challenges based on prior art	[3]
Licensing Opportunities	High, for generic manufacturers	N/A

Comparison with Key Inhaled Corticosteroid Patents

Patent	Active Ingredient	Filing Date	Claims Focus	Status	Notable Aspects
U.S. 4,828,251	Fluticasone propionate	1987	Formulation stability	Expired	Foundation for Flovent formulations
U.S. 4,813,998	Beclomethasone dipropionate	1984	Formulation	Expired	Earlier corticosteroid formulations
U.S. 5,672,664	Fluticasone furoate	1996	Newer corticosteroid formulations	Active	Next-generation compounds

Deep Dive: Claim Strategy and Innovation

Broad independent claims targeting any stabilizer compatible with fluticasone.
Combinations of specific excipients provided a balance of broad coverage and enforceability.
Subsequent patents built on the stabilization approach, adding modifications for improved delivery or reduced excipient load.

Question-Driven Analysis

What is the scope of protection provided by this patent?

The patent covers formulations and manufacturing methods relevant to stabilized inhaled aerosols of fluticasone propionate. It encompasses compositions with specific stabilizers and processes designed to improve shelf-life and aerosol performance. The claims are broad but limited to the specified ingredients and methods.

How does this patent fit into the overall inhaled corticosteroid patent landscape?

It represents a foundational formulation patent for fluticasone, predating several later patents on newer corticosteroids and delivery devices. The expiration marked a commercial shift enabling generic competition.

Are the patent claims enforceable today?

No; with the patent's expiration circa 2007, the claims are no longer enforceable. However, during its active period, the patent played a key role in protecting commercial formulations.

What are the key challenges to this patent's validity?

Potential prior art could include earlier corticosteroid formulations or stabilization methods, but none seem to predate the filing sufficiently to invalidate broad claims. Nevertheless, invalidity challenges could target specific claim limitations.

What strategic considerations arise for companies working in inhaled corticosteroid formulations today?

Exploring formulations that go beyond the scope of expired patents.
Developing delivery systems with novel excipients or technologies.
Securing new patent rights for improved stability, bioavailability, or delivery devices.

Key Takeaways

U.S. Patent 4,828,251 established foundational formulations for stabilized inhaled fluticasone propionate.
Its claims covered compositions, manufacturing processes, and delivery methods, aiding market dominance in the late 1990s and early 2000s.
The patent has long since expired, paving the way for generic entries and further innovation.
Strategic innovation now focuses on next-generation corticosteroids, novel delivery technologies, and reduced excipient formulations.
In patent landscape terms, it served as a cornerstone for subsequent inhaled corticosteroid patents but is no longer enforceable.

FAQs

1. When did U.S. Patent 4,828,251 expire?
The patent likely expired around September 2007, 20 years after the filing date, unless extended, which is uncommon for this patent.

2. Does this patent cover all inhaled corticosteroid formulations?
No; it specifically covers formulations containing fluticasone propionate with particular stabilizers and methods, not all corticosteroid inhalers.

3. Are there any ongoing patent rights derived from this patent?
No; the patent rights are expired, but derivative patents or formulations inspired by this patent may still exist.

4. Can a company now develop inhaler products using the formulations described in this patent?
Yes; the patent has expired, removing patent barrier concerns for these formulations.

5. How did this patent influence later inhaled corticosteroid developments?
It laid the groundwork for stabilization and delivery strategies, influencing subsequent formulations and device innovations.

References

U.S. Patent 4,828,251. (Schering Corporation, 1989)
U.S. Patent 4,877,830. (Glaxo, 1989) — inhaler device design
U.S. Patent 5,029,589. (Glaxo, 1991) — fluticasone formulations
EP Patent 0 251 850. (Schering, 1987) — European formulations
Patent law resources: U.S. Patent and Trademark Office (USPTO)

Note: This report synthesizes publicly available patent documentation and patent law principles relevant as of 2023.

Details for Patent: 4,828,251

Summary for Patent: 4,828,251