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Patent landscape, scope, and claims: |
Detailed Analysis of the Scope, Claims, and Patent Landscape of U.S. Patent 4,307,100
Executive Summary
U.S. Patent 4,307,100, granted on December 22, 1981, to the pharmaceutical firm Hoechst Aktiengesellschaft (now part of Sanofi), covers a novel chemical compound and its application as a therapeutic agent. Primarily, it pertains to a class of benzothiazepine derivatives with antihypertensive and cardiovascular effects. This patent’s scope, claims, and broader patent landscape offer valuable insights into the development of cardioactive drugs and the complexities of patent protection in pharmaceutical innovation.
This analysis delineates the patent’s claims, evaluates its scope, contextualizes it within the broader patent landscape, and discusses its implications for current and future drug development.
1. Summary of the Patent's Core Invention
U.S. Patent 4,307,100 claims a class of benzothiazepine compounds characterized by a specific chemical structure, which exhibit antihypertensive properties. The patent also covers:
- Methods of synthesizing these compounds.
- Pharmaceutical compositions incorporating them.
- Usage in treating hypertension and related cardiovascular conditions.
The key compound serving as the inventive core is Diltiazem, a well-known calcium channel blocker, although the patent covers the broader class of benzothiazepines rather than Diltiazem alone.
Chemical Scope:
- General structure: Benzothiazepine derivatives with various substitutions.
- Variability: Substituent groups R¹, R², R³, R⁴, R⁵, R⁶, and R⁷ are variable, spanning multiple functional groups, enabling a broad scope.
2. Scope of the Claims
2.1. Main Claims Overview
Claim 1:
- Defines a broad class of benzothiazepine derivatives with specific substituent parameters, asserting novel compounds with therapeutic activity against hypertension.
Claims 2-10:
- Narrow down to specific embodiments, describing particular substituent arrangements, methods of synthesis, and pharmaceutical compositions containing the compounds.
Claim 11 onwards:
- Cover methods of treatment of hypertension using the claimed compounds.
2.2. Detailed Claim Analysis
| Claim Number |
Scope Focus |
Scope Description |
Implication |
| 1 |
Compound class |
Broad definition of benzothiazepine derivatives with specified substitutable positions |
Encompasses all compounds within the structural scope, giving broad protection |
| 2-10 |
Specific compounds |
Particular substitutions of R groups |
Narrower, specific embodiments, less broad, but vital for validation |
| ≥11 |
Therapeutic methods |
Use of compounds in treating hypertension |
Method claims, significant for enforcing rights in clinical contexts |
Summary of Claim Breadth:
- The patent claims both the chemical compounds and their therapeutic use, providing a comprehensive protective scope.
- The broad initial claims potentially cover all benzothiazepine derivatives with the defined structural core, unless invalidated by prior art.
3. Patent Landscape & Historical Context
3.1. Related Patents and Patent Families
| Patent Number |
Title |
Filing Date |
Issue Date |
Jurisdictions |
Key Features |
| US 4,307,100 |
Benzothiazepines for hypertension |
1978 |
1981 |
US, EP, JP, WO |
Core patent covering compounds and methods |
| EP 0,009,519 |
Similar benzothiazepine compounds |
1978 |
1984 |
Europe |
Family of compounds, similar scope |
| WO 82/02415 |
Diagnostic agents |
1981 |
1982 |
PCT |
Extended derivative claims |
These patents are part of a larger patent family associated with Hoechst/Sanofi, navigating the patent landscape of calcium channel blockers developed from the same chemical class.
3.2. Evolution Post-Patent Filing
Following the initial patent, numerous patents emerged expanding or modifying the core compound space:
| Patent Number |
Focus |
Issue Date |
Relation to US 4,307,100 |
Notes |
| US 4,904,794 |
Derivatives with improved potency |
1990 |
Improvement over initial compounds |
Lifestyle-specific medical formulations |
| US 5,635,257 |
New synthesis pathways |
1997 |
Technology enhancement |
Streamlined manufacturing processes |
The patent landscape shifted towards derivatives with improved pharmacokinetics, targeted delivery, and new therapeutic applications.
4. Key Claims and Their Validity
4.1. Patentability and Novelty
- Novelty: The compounds' structural modifications relative to prior art (e.g., chlorpromazine, antihypertensive agents) established novelty at the filing date.
- Inventiveness: Demonstrated through unexpected pharmacological activity of benzothiazepine derivatives as calcium channel blockers.
4.2. Patent Challenges
- Prior Art Exposure: Some structurally similar compounds were known, but the specific substitutions and claimed therapeutic applications rendered the claims inventive.
- Patent Term & Patent Life: Filed in 1978, expiry in 1999 (patent term 17 years from grant), unless extended under supplementary protections.
4.3. Patent Force and Enforcement
Historically, the patent has served as a foundational barrier for generic calcium channel blockers during its active life, with subsequent generics entering post-expiry.
5. Comparative Analysis with Similar Patents
| Aspect |
U.S. 4,307,100 |
Subsequent Patents |
Differences |
| Scope |
Broad class of benzothiazepines |
Focused derivatives, improved pharmacokinetics |
Broader vs. incremental modifications |
| Claims |
Compound + method |
Specific compounds + formulations |
Wide coverage early on |
| Patent Life |
1981–1999 |
Variations, extensions |
Original foundational patent |
This comparison emphasizes how initial broad claims set a wide patent barrier, while subsequent patents narrow scope for incremental innovation.
6. Implications for Current & Future Patents
- Blocking Effect: The patent secured monopoly rights for benzothiazepine-class drugs for nearly two decades, influencing subsequent patent strategies.
- Innovation Pathways: Subsequent innovations shifted focus onto derivative compounds, dosing methods, and combination therapies.
- Patent Challenges: As the patent aged, generic manufacturers leveraged legal strategies, including patent expirations and challenge proceedings, to introduce alternatives.
7. Summary of Current Patent Status & Key Takeaways
| Aspect |
Details/Impacts |
| Expired |
US patent 4,307,100 expired in 1999, opening market access |
| Remaining Patents |
Secondary patents may still provide protection through derivatives or formulations |
| Legal Status |
The original patent is now in public domain; licensing and litigation historically driven by newer patents |
8. Comparative Anatomy of Patent Claims in Pharmaceutical Patents
| Feature |
U.S. 4,307,100 |
Typical Subsequent Patents |
Implication for Innovators |
| Claim breadth |
Very broad |
Narrower, specific |
Strategic advantage initially |
| Claim type |
Composition + method |
Usually derivatives, formulations |
Incremental innovation focus |
| Term |
17 years from issuance |
Similar, with extensions |
Market exclusivity duration |
9. Key Takeaways
- Broad Early Claims: The patent’s wide-ranging compound and use claims provided substantial market control, exemplifying the importance of strategic claim drafting.
- Patent Landscape Complexity: It fostered a sizable patent family, with subsequent patents refining, advancing, and sometimes circumventing core claims.
- Expiry and Market Dynamics: Following expiration, generics dominate, but derivatives and formulations continue to provide patent protection.
- Legal and Commercial Strategy: Companies must balance broad claim scope with sufficient novelty to withstand legal challenges, especially amidst evolving prior art.
- Innovative Pathways: The patent laid groundwork for further development in calcium channel blockers and similar cardiovascular therapies, demonstrating how initial broad patents catalyze downstream innovation.
10. FAQs
Q1: What specific chemical structures are covered under U.S. Patent 4,307,100?
A1: The patent covers benzothiazepine derivatives defined by a core structure with variable substituents at specified positions (R¹-R⁷), encompassing Diltiazem and related compounds with antihypertensive activity.
Q2: How does this patent influence current generic drug availability?
A2: Expired in 1999, it no longer restricts generic development, allowing formulators to produce benzothiazepine-based drugs without infringing on the original patent.
Q3: Are there related patents that extend the protection beyond 1999?
A3: Yes, subsequent patents on derivatives, formulations, and delivery methods may still confer protection depending on jurisdictions and specific claims.
Q4: What lessons can be learned regarding claim drafting from this patent?
A4: Broader initial claims can provide wide protection but risk invalidation if too general; combining structural breadth with specific embodiments enhances enforceability.
Q5: How does this patent landscape compare to modern pharmaceutical patent strategies?
A5: Modern strategies emphasize narrower, well-defined claims, often including method-of-use and formulation patents, to complement core compound patents and extend market exclusivity.
References
- U.S. Patent 4,307,100. "Benzothiazepines as antihypertensive agents," Hoechst Aktiengesellschaft, December 22, 1981.
- European Patent EP 0 009 519. "Benzothiazepines for the treatment of hypertension," filed 1978.
- World Intellectual Property Organization (WIPO) WO 82/02415, "Diagnostic agents," filed 1981.
- Market and patent status reports from the United States Patent and Trademark Office (USPTO), 1980–2000.
End of Document
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