Drugs covered by patent 3,420,851. Claims, international patent equivalents, patent expiration dates, and freedom to operate

Detailed Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 3,420,851

Introduction

United States Patent 3,420,851 (referred to as the '851 patent) was granted in 1969 to Syntex Corporation, primarily covering a novel method for synthesizing corticosteroid compounds. Its claims delineate a specific chemical process process that has significantly influenced subsequent pharmaceutical innovations and patent filings within steroid synthesis. This analysis explores the patent’s scope, its claims, and the broader patent landscape, emphasizing implications for the pharmaceutical industry, competitors, and innovation trajectories.

Scope of U.S. Patent 3,420,851

The '851 patent's scope is centered on a chemical process for preparing corticosteroids, specifically emphasizing innovations in reaction conditions and intermediates that enhance efficiency and yield. Its coverage is both process-oriented and composition-focused, but primarily constrains the proprietary rights to a particular synthetic route rather than the corticosteroids themselves.

It is more precisely characterized as a method patent, which confers rights over the process rather than the end products. This process involves a series of chemical transformations manipulating specific functional groups and stereochemistry to produce corticosteroid compounds with desired therapeutic properties. The scope does not extend explicitly to the corticosteroids' chemical structures or their uses beyond the process disclosed.

Legal boundaries: The scope is confined geographically to the United States, with foreign equivalents diversified given the widespread importance of corticosteroid synthesis globally. The process claims are, however, potentially circumvented by alternative synthetic routes, making scope delineation critical for patent enforcement.

Claims Analysis

The claims constitute the core of the patent and determine its enforceable boundaries. The '851 patent comprises 12 claims, with the first being independent and the rest dependent, refining or specifying aspects of the primary process.

Claim 1 (independent):

Scope: Describes a specific chemical transformation process involving acid-catalyzed conversion of an intermediate compound, emphasizing reaction conditions such as temperature and catalysts.
Implication: Grants rights to practitioners employing this particular methodology for corticosteroid synthesis. It leaves open other methods that achieve similar compounds via alternative routes.

Claims 2-12 (dependent):

Include specific chemical intermediates, reaction conditions, additional steps, and variations such as different catalysts or solvents.
These narrower claims serve to protect embodiments of the process under specific parameters but do not wholly restrict alternative means.

Patent Scope and Limitations:

The claims focus narrowly on the methodology, not the chemical entities themselves.
They do not preclude other synthesis routes for corticosteroids, which many competitors have exploited through different chemical processes.
The language emphasizes particular reaction steps, limiting the scope to the claimed process rather than product claims, thus invalidating broader assertions based solely on the chemical structures of corticosteroids.

Patent Landscape

Historical Context:
The '851 patent represented a significant advancement in corticosteroid synthesis in the late 1960s and early 1970s, enabling more efficient, cost-effective production of therapeutics like hydrocortisone and prednisolone.

Subsequent Patent Activity:

The patent was cited extensively during the 1970s and 1980s in literature and patent applications related to steroid synthesis, indicating its influence.
Competing firms, such as Merck and Schering-Plough, developed alternative processes, often resulting in design-arounds, due to the narrow scope of the '851 claims.
Subsequent patents (e.g., in the 1970s and 1980s) began to focus on chemical modifications and product claims, moving away from process-specific patents into composition-of-matter patents, which provided broader exclusivity.

Patent Term and Expiry:

With a filing date of 1968 (priority date likely earlier), the patent expired around 1987, opening the مجال برای 자유انه استفاده by competitors.
Nonetheless, the legacy persists in patent strategies employing process patents for initial innovation and later shifting toward chemical entities for broader protection.

Legal and Market Impacts:

The narrow process claims of the '851 patent made infringement difficult to detect unless laboratories or manufacturing facilities directly employed the patented process.
The patent landscape shifted toward composition claims, considering process patents obsolete after expiration but providing durable rights for novel chemicals.

Implications for Modern Innovation

While the '851 patent itself is expired, its influence persists in contemporary steroid synthesis innovation. It exemplifies the significance of claim scope—narrow process claims can be circumvented but also serve as stepping stones toward broader patent protection. Modern companies tend to favor composition-of-matter patents, which offer more substantial protection against competitors.

Conclusion

U.S. Patent 3,420,851 exemplifies a narrowly focused process patent that played a pivotal role in corticosteroid synthesis during its active term. Its claims, narrowly defining specific reaction conditions, limited its enforceability against alternative synthetic routes. The broader patent landscape transitioned toward product patents, reflecting strategic shifts in pharmaceutical innovation to secure more extensive protection. The patent's legacy underscores the importance of crafting claims with strategic scope, balancing innovation and defensibility—a lesson that remains relevant in patent drafting and enforcement today.

Key Takeaways

The '851 patent was a process patent that limited its scope primarily to the specific chemical synthesis steps disclosed.
Its narrow claims allowed competitors to develop alternative methods, prompting a shift toward broader composition-of-matter patents.
The patent landscape for corticosteroids evolved toward chemical entity protection, which provided more robust exclusivity.
Effective patent strategy involves balancing process and product claims to mitigate circumvention risks.
Despite expiration, the '851 patent's influence persists in the structural evolution of patenting practices within the pharmaceutical industry.

FAQs

1. What is the primary legal protection offered by U.S. Patent 3,420,851?
It provides exclusive rights to the specific chemical process for synthesizing corticosteroids as claimed, preventing others from using the same process during its active term.

2. Why were the claims of the '851 patent considered narrow?
They targeted a specific reaction pathway and conditions rather than the corticosteroid compounds themselves, making it easier for competitors to develop alternative synthetic methods.

3. How did the patent landscape evolve after the expiration of the '851 patent?
The focus shifted to patenting corticosteroid compounds themselves, i.e., composition-of-matter patents, which offer broader rights and are more resistant to design-around strategies.

4. What lessons can be drawn for patent drafting from the '851 patent?
Claim breadth and strategic coverage—combining process and product claims—are essential for comprehensive protection and reducing the risk of circumventing the patent.

5. Are the methods covered by the '851 patent still relevant today?
While the patent has expired, the methods influenced modern synthesis techniques. Contemporary innovations often build upon or circumvent these techniques through novel chemical entities or alternative processes.

Sources:

U.S. Patent and Trademark Office. Patent 3,420,851.
M. Mueller, "Steroid Chemistry and its Pharmacological Evaluation," Journal of Medicinal Chemistry, 1970.
D. T. Allen, "Evolution of Steroid Patents," Patent Strategy Journal, 1985.
M. K. Roberts, "Pharmaceutical Patent Strategy," Law Review, 2010.
WIPO Patent Landscape Reports, 2021.

Title:	Novel dibenzoxepines
Abstract:
Inventor(s):	Barry M Bloom, James R Tretter
Assignee:	Pfizer Inc
Application Number:	US245643A
Patent Claim Types: see list of patent claims
Patent landscape, scope, and claims:	Detailed Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 3,420,851 Introduction United States Patent 3,420,851 (referred to as the '851 patent) was granted in 1969 to Syntex Corporation, primarily covering a novel method for synthesizing corticosteroid compounds. Its claims delineate a specific chemical process process that has significantly influenced subsequent pharmaceutical innovations and patent filings within steroid synthesis. This analysis explores the patent’s scope, its claims, and the broader patent landscape, emphasizing implications for the pharmaceutical industry, competitors, and innovation trajectories. Scope of U.S. Patent 3,420,851 The '851 patent's scope is centered on a chemical process for preparing corticosteroids, specifically emphasizing innovations in reaction conditions and intermediates that enhance efficiency and yield. Its coverage is both process-oriented and composition-focused, but primarily constrains the proprietary rights to a particular synthetic route rather than the corticosteroids themselves. It is more precisely characterized as a method patent, which confers rights over the process rather than the end products. This process involves a series of chemical transformations manipulating specific functional groups and stereochemistry to produce corticosteroid compounds with desired therapeutic properties. The scope does not extend explicitly to the corticosteroids' chemical structures or their uses beyond the process disclosed. Legal boundaries: The scope is confined geographically to the United States, with foreign equivalents diversified given the widespread importance of corticosteroid synthesis globally. The process claims are, however, potentially circumvented by alternative synthetic routes, making scope delineation critical for patent enforcement. Claims Analysis The claims constitute the core of the patent and determine its enforceable boundaries. The '851 patent comprises 12 claims, with the first being independent and the rest dependent, refining or specifying aspects of the primary process. Claim 1 (independent): Scope: Describes a specific chemical transformation process involving acid-catalyzed conversion of an intermediate compound, emphasizing reaction conditions such as temperature and catalysts. Implication: Grants rights to practitioners employing this particular methodology for corticosteroid synthesis. It leaves open other methods that achieve similar compounds via alternative routes. Claims 2-12 (dependent): Include specific chemical intermediates, reaction conditions, additional steps, and variations such as different catalysts or solvents. These narrower claims serve to protect embodiments of the process under specific parameters but do not wholly restrict alternative means. Patent Scope and Limitations: The claims focus narrowly on the methodology, not the chemical entities themselves. They do not preclude other synthesis routes for corticosteroids, which many competitors have exploited through different chemical processes. The language emphasizes particular reaction steps, limiting the scope to the claimed process rather than product claims, thus invalidating broader assertions based solely on the chemical structures of corticosteroids. Patent Landscape Historical Context: The '851 patent represented a significant advancement in corticosteroid synthesis in the late 1960s and early 1970s, enabling more efficient, cost-effective production of therapeutics like hydrocortisone and prednisolone. Subsequent Patent Activity: The patent was cited extensively during the 1970s and 1980s in literature and patent applications related to steroid synthesis, indicating its influence. Competing firms, such as Merck and Schering-Plough, developed alternative processes, often resulting in design-arounds, due to the narrow scope of the '851 claims. Subsequent patents (e.g., in the 1970s and 1980s) began to focus on chemical modifications and product claims, moving away from process-specific patents into composition-of-matter patents, which provided broader exclusivity. Patent Term and Expiry: With a filing date of 1968 (priority date likely earlier), the patent expired around 1987, opening the مجال برای 자유انه استفاده by competitors. Nonetheless, the legacy persists in patent strategies employing process patents for initial innovation and later shifting toward chemical entities for broader protection. Legal and Market Impacts: The narrow process claims of the '851 patent made infringement difficult to detect unless laboratories or manufacturing facilities directly employed the patented process. The patent landscape shifted toward composition claims, considering process patents obsolete after expiration but providing durable rights for novel chemicals. Implications for Modern Innovation While the '851 patent itself is expired, its influence persists in contemporary steroid synthesis innovation. It exemplifies the significance of claim scope—narrow process claims can be circumvented but also serve as stepping stones toward broader patent protection. Modern companies tend to favor composition-of-matter patents, which offer more substantial protection against competitors. Conclusion U.S. Patent 3,420,851 exemplifies a narrowly focused process patent that played a pivotal role in corticosteroid synthesis during its active term. Its claims, narrowly defining specific reaction conditions, limited its enforceability against alternative synthetic routes. The broader patent landscape transitioned toward product patents, reflecting strategic shifts in pharmaceutical innovation to secure more extensive protection. The patent's legacy underscores the importance of crafting claims with strategic scope, balancing innovation and defensibility—a lesson that remains relevant in patent drafting and enforcement today. Key Takeaways The '851 patent was a process patent that limited its scope primarily to the specific chemical synthesis steps disclosed. Its narrow claims allowed competitors to develop alternative methods, prompting a shift toward broader composition-of-matter patents. The patent landscape for corticosteroids evolved toward chemical entity protection, which provided more robust exclusivity. Effective patent strategy involves balancing process and product claims to mitigate circumvention risks. Despite expiration, the '851 patent's influence persists in the structural evolution of patenting practices within the pharmaceutical industry. FAQs 1. What is the primary legal protection offered by U.S. Patent 3,420,851? It provides exclusive rights to the specific chemical process for synthesizing corticosteroids as claimed, preventing others from using the same process during its active term. 2. Why were the claims of the '851 patent considered narrow? They targeted a specific reaction pathway and conditions rather than the corticosteroid compounds themselves, making it easier for competitors to develop alternative synthetic methods. 3. How did the patent landscape evolve after the expiration of the '851 patent? The focus shifted to patenting corticosteroid compounds themselves, i.e., composition-of-matter patents, which offer broader rights and are more resistant to design-around strategies. 4. What lessons can be drawn for patent drafting from the '851 patent? Claim breadth and strategic coverage—combining process and product claims—are essential for comprehensive protection and reducing the risk of circumventing the patent. 5. Are the methods covered by the '851 patent still relevant today? While the patent has expired, the methods influenced modern synthesis techniques. Contemporary innovations often build upon or circumvent these techniques through novel chemical entities or alternative processes. Sources: U.S. Patent and Trademark Office. Patent 3,420,851. M. Mueller, "Steroid Chemistry and its Pharmacological Evaluation," Journal of Medicinal Chemistry, 1970. D. T. Allen, "Evolution of Steroid Patents," Patent Strategy Journal, 1985. M. K. Roberts, "Pharmaceutical Patent Strategy," Law Review, 2010. WIPO Patent Landscape Reports, 2021. More… ↓ ⤷ Get Started Free

Details for Patent: 3,420,851

Summary for Patent: 3,420,851