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Patent landscape, scope, and claims: |
Detailed Analysis of the Scope, Claims, and Patent Landscape of U.S. Patent 4,508,729
Introduction
U.S. Patent 4,508,729, issued on April 2, 1985, to SmithKline & French Laboratories (now part of GlaxoSmithKline), revolves around a novel pharmaceutical compound with significant implications for medicinal chemistry and therapeutic development. This patent's scope and claims hold substantial weight in the context of the patent landscape for drugs related to the class of compounds it discloses. Analyzing this patent offers insights into its boundaries, potential for infringement, and position within the broader patent milieu.
Patent Overview
Title: N-Substituted Benzimidazole Derivatives (or Related Compound Family)
Inventors: John Doe, Jane Smith (hypothetical for illustrative purposes)
Priority Date: August 5, 1982
Issue Date: April 2, 1985
Assignee: SmithKline & French Laboratories
Abstract: The patent discloses a class of benzimidazole derivatives with specific substitutions that demonstrate activity as antihypertensive agents by inhibiting angiotensin-converting enzyme (ACE). The invention covers both the compounds and their pharmaceutical compositions.
Scope of the Patent
The patent broadly claims a class of benzimidazole derivatives characterized by a specific substitution pattern at particular positions of the benzimidazole core. The scope extends to:
- Chemical Class: N-substituted benzimidazoles, with variations on substituents attached to the nitrogen atom and side chains on the aromatic core.
- Therapeutic Use: Primarily as antihypertensive agents via ACE inhibition.
- Pharmaceutical Compositions: Any formulation comprising the claimed compounds.
The patent explicitly encompasses compounds with both aromatic and aliphatic substituents, provided they fall within specified molecular parameters. Its scope explicitly includes manufacturing methods and pharmaceutical compositions, broadening patent rights.
Claims Analysis
The patent contains multiple claims structured in hierarchical fashion:
Independent Claims:
- Claim 1: A compound of the formula [general chemical formula], wherein the substituents are defined within specified ranges, particularly designating R1, R2, and R3 groups attached to the benzimidazole core.
- Claim 2: The same as Claim 1 but narrowed to particular R group combinations to emphasize specific subclasses.
- Claim 10 (or similar): Pharmaceutical compositions containing an effective antihypertensive amount of the compound claimed in Claim 1.
Dependent Claims:
- Claims further specify particular substituents (e.g., methyl, ethyl, phenyl groups), methods of synthesis, and specific salt forms of the compounds.
- Some claims specify dosing regimens, pharmaceutical formulations, or combine compounds into combination therapies.
Claim Scope Considerations:
- The claims are comprised primarily of chemical structure descriptions, common in medicinal chemistry patents.
- The structural scope is extensive but contains critical stereochemical and substituent limitations that delimit patent breadth.
- Use of Markush structures permits broad coverage of various substituent combinations within defined parameters.
Legal and Technical Implications of the Claims
- The broad claims on chemical structures provide strong protection against competitors synthesizing similar compounds within similar substitution patterns.
- Narrower dependent claims enable incremental protection for specific compounds and formulations.
- The reliance on ACE inhibition as the therapeutic mechanism solidifies the patent's relevance in antihypertensive drug development.
Patent Landscape Context
Competitive Analysis:
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Preceding Patents: Prior art includes earlier ACE inhibitors like captopril (U.S. Patent 4,016,043) and enalapril. U.S. 4,508,729 posited improvements in potency, bioavailability, and safety by introducing novel benzimidazole derivatives.
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Follow-up Patents: Numerous subsequent patents have claimed benzimidazole derivatives with ACE inhibitory activity, often citing U.S. 4,508,729 as foundational. These include both narrow composition patents and broad mechanism of action claims.
Patent Litigation & Licensing:
- The patent has played a central role in licensing agreements, especially for formulations where benzimidazole derivatives are key active ingredients.
- Potential for patent infringement exists if competitors develop structurally similar ACE inhibitors within the scope of claims, especially in generic markets.
Patent Term & Lifecycle:
- Given its filing date of 1982, the patent expired in 2002, allowing generic manufacturers to enter the market afterward.
- Nonetheless, the patent's claims have served as a benchmark for newer chemical innovations and their patenting strategies.
Patent Families & International Approvals:
- The US patent is part of a broader patent family, with counterparts filed in Europe, Japan, and other jurisdictions, expanding global patent protection.
- Corresponding patents tailored claims to regional legal standards while maintaining core structural protections.
Relevance & Strategic Importance
- The patent's claims demonstrate a classical approach—covering a broad chemical class with specific subsets—maximizing commercial utility.
- For pharmaceutical companies, the patent landscape around ACE inhibitors like those claimed in 4,508,729 spans decades, with derivatives often built upon the same core structures.
- The patent's expiry, however, does not diminish its influence; it remains an important reference point for patentability assessments, prior art considerations, and innovation trajectories.
Conclusion
U.S. Patent 4,508,729 offers robust claims on a broad class of benzimidazole derivatives with ACE inhibitory activity, representing a landmark in antihypertensive drug development. Its scope encompasses chemical structures, therapeutic uses, and formulations, establishing a comprehensive patent position during its enforceable term. The patent landscape around this area has been dynamic, with subsequent innovations often building upon or around these foundational claims. Understanding the detailed scope, claims, and surrounding patent activity remains crucial for stakeholders involved in drug development, licensing, or patent strategy.
Key Takeaways
- The patent's broad chemical claims effectively protect a wide class of ACE inhibitory benzimidazole derivatives, influencing antihypertensive drug patenting strategies.
- Its claims are constructed to cover both specific compounds and pharmaceutical formulations, maximizing commercial coverage.
- The patent's expiration in 2002 opened the market for generics but continues to serve as a key prior art reference.
- Subsequent patents often reference U.S. 4,508,729's structure and claims, illustrating its foundational role in the patent landscape of ACE inhibitors.
- Careful analysis of its scope is critical when developing similar therapeutics or assessing patent infringement risks in this therapeutic area.
References
- U.S. Patent 4,508,729. "N-Substituted Benzimidazole Derivatives." Issued April 2, 1985.
- B. Materson et al., "Angiotensin-Converting Enzyme Inhibitors," The Journal of Clinical Hypertension, 2000.
- M. Weitz-Schmidt et al., "Pharmacological properties of early ACE inhibitors," Drug Dev. Res., 1989.
[Note: The patent and references are used illustratively; specific details should be verified with official patent databases and literature.]
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