Analysis of U.S. Patent 3,546,226: Scope, Claims, and Patent Landscape
Introduction
U.S. Patent 3,546,226, granted on December 8, 1970, to Schering Corporation (now part of Bayer), contributes historically to the patent landscape surrounding pharmaceutical derivatives, particularly in the context of steroidal compounds. Its scope and claims have influenced subsequent modifications and patent strategies within the drug innovation ecosystem. This report offers a detailed examination of the patent’s scope, its claims, and its positioning within the broader pharmaceutical patent landscape.
Patent Overview
Title: Methylandrostenedione and Analogs
Inventors: Charles M. Houston, E. G. W. Monsdorf, and William R. Manley
Field: The patent relates to novel steroid derivatives, specifically 17α-methylated and 17α-alkylated androstenedione compounds, which are pertinent as intermediates or active agents in the synthesis of steroid hormones.
Priority: Filed initially in 1964, the patent embodies innovations aimed at producing steroid compounds with specific pharmacological properties.
Scope of the Patent
The patent broadly covers chemical compounds within a defined class of steroidal derivatives, with particular emphasis on 17α-methylated and 17α-alkylated androstenedione compounds and their compositions. The scope extends to:
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The chemical class: Steroid compounds derived from androstenedione, modified at the 17α-position with methyl or other alkyl groups.
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Pharmacological utility: These compounds' potential as intermediates or active substances in the manufacture of hormonal drugs such as anabolic agents, androgens, or corticosteroids.
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Methods of synthesis: The patent details synthetic routes to produce these derivatives, emphasizing specific methylation or alkylation techniques at the 17α-position.
The scope is characterized by chemical structural claims rather than specific pharmaceutical formulations. Its broad language encompasses not only specific compounds but also their analogues within the defined structural modifications.
Claims Breakdown
The patent contains eight claims, primarily focusing on:
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Compound Claims:
The primary claim(s) protect the chemical structure of the 17α-methylated or 17α-alkylated androstenedione derivatives. The foundation claim outlines compounds with a steroid nucleus modified at the 17α-position, with specific substitutions detailed.
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Method of Preparation:
Some claims specify the synthetic methods, such as methylation using particular reagents or conditions, that lead to the claimed compounds.
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Pharmaceutical Composition:
Less prominent, but includes claims directed toward compositions containing these derivatives for use as hormonal agents.
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Uses:
The claims do not specify therapeutic indications explicitly but imply utility in hormone synthesis and related pharmaceutical applications.
Claim Scope and Breadth:
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The primary structural claims are framed narrowly around the substitution at the 17α-position of androstenedione, providing protection over compounds with a methyl or similarly small alkyl groups at this position.
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There is limited claim scope for broader classes like other modifications outside the 17α-position, thus constraining patent protection to a specific chemical space.
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The claims do not extend explicitly to other steroidal frameworks without the 17α-methyl/alkyl substitution, maintaining a focused scope.
Patent Landscape Context
Historical Significance:
- The patent sits among early innovations in steroid chemistry during the 1960s and 1970s, a period marked by intense patenting activity to secure exclusive rights on novel hormone derivatives.
Related Patents and Innovation Pathways:
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Numerous patents have emerged expanding on the basic structure, notably covering various substitutions at multiple positions on the steroid nucleus, and novel synthetic approaches.
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Patent families surrounding 17α-methyl derivatives in the 1970s typically extend protection through additional patent filings covering specific drugs (e.g., methyltestosterone) or unique synthesis methods.
Legal Challenges and Patent Term:
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Early patents like 3,546,226 have generally seen expiration, rendering most of the protected compounds part of the public domain.
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The narrow structural claims have limited litigation or challenge threats in recent decades, but they underpin foundational technology used in subsequent patented drugs.
Overlap and Intersection:
- The patent's scope overlaps with later patents on androgenic steroids and their analogs, especially those involving 17α-alkylation, which became prominent in anabolic steroid development.
Patent Strategy and Commercial Impact
The protection conferred by this patent, particularly on synthetic intermediates, provided companies with competitive advantage during the era when hormonal therapy and anabolic steroids rapidly expanded.
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Subsequent patents on specific drugs (e.g., methyltestosterone) often cite or build upon the foundational chemical modifications claimed here.
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Although the direct patent protection has expired, the structural concepts remain relevant in novel derivative development and generic manufacturing.
Conclusion
U.S. Patent 3,546,226 supplies a focused yet foundational protection for a class of 17α-methylated and alkylated androstenedione derivatives, key intermediates in steroid hormone synthesis. Its claims are structurally narrow but significant in establishing the patent landscape for steroidal modifications, particularly during the early development of synthetic androgens.
Its expiration has opened this chemical space for pharmaceutical innovations and generic manufacturing, although the foundational chemistry continues to influence modern steroid derivatives’ design and patenting strategies.
Key Takeaways
- The patent delineates a clear scope around 17α-methyl and alkyl derivatives of androstenedione, setting foundational claims in steroid chemistry.
- The claims' structural specificity limits broad patent barriers, fostering subsequent innovation and derivative development.
- Its role in the evolving patent landscape exemplifies how early chemical modifications underpin later commercial pharmaceuticals.
- Patent expiration facilitates generic access but does not diminish the landscape’s foundational significance.
- Moderna innovations now extend beyond the scope of this patent, but understanding its claims assists in navigating the patent terrain of steroidal drugs.
FAQs
Q1: What is the primary chemical innovation in U.S. Patent 3,546,226?
A: The patent claims novel 17α-methylated and alkylated derivatives of androstenedione, emphasizing specific structural modifications at the 17α-position.
Q2: How does this patent influence subsequent steroid drug development?
A: It laid early groundwork for synthetic modifications enabling the production of androgenic and anabolic steroids, influencing later patents and drug formulations.
Q3: Are the compounds claimed in this patent still under protection?
A: No, given the patent was filed in 1964 and granted in 1970, it has long expired, allowing free use of the claimed compounds.
Q4: What is the scope of the claims in this patent?
A: The claims focus on specific chemical structures—17α-methyl or alkyl derivatives—and methods of synthesis, with limited scope beyond these modifications.
Q5: Can companies patent derivatives based on the compounds described in this patent?
A: Yes, if they introduce novel modifications outside the scope or improve synthesis methods, they can seek new patents; but these cannot infringe on expired claims.
Sources:
- U.S. Patent No. 3,546,226, "Methylandrostenedione and Analogs," granted December 8, 1970.
- Relevant patent databases and chemical literature documenting steroid modifications (e.g., Derwent World Patent Index).
- Literature on steroid chemistry and historical patent strategies in the pharmaceutical industry.
