Detailed Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 4,761,418
Introduction
U.S. Patent 4,761,418, granted on August 2, 1988, to Boehringer Mannheim GmbH (now part of Roche), represents a pivotal patent in the pharmaceutical domain. It primarily pertains to methods and compositions related to the detection of specific analytes in biological samples, notably bilirubin. An understanding of this patent's scope, claims, and broader patent landscape offers valuable insight into its influence on diagnostic assay development and subsequent patenting activities.
Scope and Purpose of U.S. Patent 4,761,418
The patent discloses a novel method for detecting bilirubin in biological fluids, employing a specific reagent system that involves diazonium salts reacting with bilirubin to produce a quantifiable colorimetric change. Its scope encompasses both the reagent compositions and the methodological procedures aimed at enhancing sensitivity, specificity, and simplicity in bilirubin detection.
Key aspects of the scope include:
- Reagent Composition: The patent claims a reagent system comprising diazonium salts linked to certain coupling components, designed to react selectively with bilirubin.
- Analytical Method: The patent delineates procedures for mixing biological samples with the reagent, incubating under specified conditions, and measuring resulting color changes via spectrophotometry.
- Application Breadth: It broadly covers assays for bilirubin in clinical diagnostics, with implications extending to other conjugated or unconjugated bilirubin forms, provided they react within the described system.
The patent’s scope emphasizes improved simplicity and increased accuracy over prior art, providing a foundation for many subsequent bilirubin assay innovations.
Claims Analysis
U.S. Patent 4,761,418 contains 10 claims, with Claim 1 being the broadest and independent. Below, the key claims are summarized:
Claim 1 (Independent Claim):
Describes a reagent composition for bilirubin detection comprising a diazonium salt coupled with a specific coupling component, characterized by its ability to react with bilirubin to produce a discernible chromogen. It also encompasses the method of employing this reagent to measure bilirubin in biological samples.
Claims 2-10 (Dependent Claims):
Refine and specify the claims by elaborating on chemical specifics, such as:
- The precise structure of diazonium salts suitable for the reagent.
- The nature of the coupling components (e.g., phenolic compounds, aromatic amines).
- Conditions such as pH, temperature, and incubation time.
- Variations in sample preparation or detection methods.
Claim Scope Analysis:
- The independent claim's broad wording covers a wide range of diazonium salts and coupling components, allowing for various formulations within the scope.
- Dependent claims narrow this scope, emphasizing particular chemical structures and procedural parameters, often to establish patentability over prior art or to protect specific commercial embodiments.
Legal and Patent Scope Implications:
- The broad claims enable the patent holder to assert rights over a wide spectrum of bilirubin assay reagents and methods.
- The claims, however, are likely constrained by prior art references focusing on azo dyes and bilirubin detection, which could impact enforceability.
Patent Landscape and Subsequent Developments
The patent landscape surrounding U.S. 4,761,418 has evolved with various patents covering innovations in bilirubin detection, reagent compositions, and clinical assay systems.
Key milestones in the patent landscape:
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Pre-1990s Innovations: The patent built upon earlier azo dye chemistry and colorimetric detection, with several prior arts describing azo dye formation with bilirubin.
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Post-Patent Developments: Widely cited in subsequent patents, including those focusing on:
- Enhanced specificity: Use of alternative coupling agents to improve assay selectivity (e.g., U.S. Patent 5,308,677).
- Automated analyzers: Integration into automated clinical chemistry systems (e.g., U.S. Patent 5,385,963).
- Novel reagents: Antibody-based bilirubin detection and other fluorescence methods inspired by the foundational azo dye approach.
Legal landscape:
The original patent's expiration in 2005 has led to broader commercialization and adaptation of bilirubin detection methods. However, patent rights associated with specific reagent formulations or improved methods remain in force via subsequent patents.
Impact on Clinical Diagnostics and Market
The patent revolutionized bilirubin testing by enabling more reliable, straightforward colorimetric assays, leading to widespread clinical application. It helped standardize bilirubin measurement, critical for diagnosing jaundice, hemolytic conditions, and liver function assessments. Its influence persists as a foundational technological platform, even as newer detection techniques emerge.
Conclusion
U.S. Patent 4,761,418's broad scope, defining both reagent compositions and methodologies for bilirubin detection, has significantly influenced diagnostic assay development. Its claims' breadth facilitated widespread adoption but also prompted a landscape of subsequent innovations. Recognizing its scope and the surrounding patent ecosystem aids in strategic development and IP management within the diagnostics industry.
Key Takeaways
- The patent covers a versatile bilirubin reagent system centered on diazonium chemistry, enabling simple, accurate colorimetric detection.
- Its broad claims underpin many subsequent innovations but are bounded by prior azo dye chemistry.
- The patent's expiration has opened opportunities for generic assay systems, while derivative patents continue to refine and enhance bilirubin detection technologies.
- Understanding this patent’s scope is critical for companies developing diagnostic reagents or automated analyzers targeting bilirubin and related analytes.
- Navigating the evolving patent landscape ensures compliance, freedom-to-operate, and strategic advantage in bilirubin diagnostics.
FAQs
1. What specific chemical components are covered by U.S. Patent 4,761,418?
The patent claims reagent compositions comprising diazonium salts linked to specific coupling components capable of reacting with bilirubin to produce a color change, including a variety of azo dye-forming chemicals.
2. How does this patent differ from earlier bilirubin detection methods?
It introduces specific diazonium-based reagents and procedures that enhance sensitivity, specificity, and simplicity compared to prior azo dye and colorimetric assays, streamlining clinical diagnosis.
3. Has this patent been cited in subsequent innovations?
Yes. It has been cited in numerous later patents related to improved bilirubin assays, automated diagnostics, and alternative detection methods, indicating its foundational role.
4. Is the patent still enforceable?
No. U.S. Patent 4,761,418 expired in 2005 after its 17-year patent term, opening the field for generic and alternative bilirubin detection systems.
5. Are there newer patents that infringe on the original patent’s scope?
While the original patent has expired, ongoing patents related to bilirubin assays often build upon or modify its foundational chemistry. Companies should conduct thorough freedom-to-operate analyses to avoid infringement on current active patents.
Sources
[1] U.S. Patent 4,761,418, "Method and reagent system for determining bilirubin."
[2] Existing literature on azo dye chemistry and diagnostic assays.
[3] Patent citations and subsequent patent family filings related to bilirubin detection.
