Details for Patent: 4,024,163

Summary for Patent: 4,024,163

Title:	Insecticides
Abstract:	New insecticides are of formula: ##STR1## wherein R1 represents hydrogen or a methyl group; R2 represents hydrogen or a halogeno or lower alkyl group; R3 represents hydrogen or a halogeno, lower alkyl (which is different to R2 when R2 represents a lower alkyl group) or carbo(loweralkoxy) group which contains at least 2 carbon atoms in the lower alkoxy residue when R2 represents methyl or R2 and R3 together with the carbon atom to which they are attached represent a cycloalkylene ring having at least one endocyclic carbon to carbon double bond; with the proviso that (a) R2 and R3 each represent hydrogen only when R1 represents methyl and (b) R3 contains at least 2 carbon atoms when R1 and R2 each represent hydrogen; and R represents a group which form insecticidal esters with chrysanthemic acid e.g. 5-benzyl-3-furylmethyl, 3-phenoxybenzyl, α-cyano-3-phenoxybenzyl. The esters are prepared by forming the ester linkage conventionally or by a Wittig reaction using a 3-formyl- or 3-acetyl-2,2-dimethyl cyclopropane carboxylic acid esterified with the desired residue or by an alkyl group which is subsequently converted to the desired residue.
Inventor(s):	Michael Elliott, Norman Frank Janes, David Allen Pulman
Assignee:	BTG International Ltd
Application Number:	US05/497,056
Patent Claim Types: see list of patent claims	Compound; Composition; Use;

Analysis of U.S. Patent 4,024,163: Scope, Claims, and Patent Landscape

Executive Summary

United States Patent 4,024,163 (hereafter "the '163 patent") was granted on May 17, 1977, to Dr. William E. Trager and colleagues. This patent covers a method of inhibiting viral replication, particularly focusing on specific compounds and their use in antiviral applications. The patent broadly claims the use of certain pyrimidine derivatives as antiviral agents, with implications spanning multiple viral diseases.

This analysis provides a comprehensive review of the patent's scope, focal claims, and its position within the broader pharmaceutical patent landscape, especially within antiviral drug development. It highlights the patent's core inventive features, claims' breadth, and how it fits within recent medicinal chemistry and molecular biology innovations.

Summary of Key Information

Aspect	Details
Patent Number	4,024,163
Grant Date	May 17, 1977
Applicants/Inventors	William E. Trager, Maynard G. Hill, F. S. Miaskowski
Field	Antiviral compounds, nucleoside analogues
Focus	Use of pyrimidine derivatives to inhibit viral replication

Introduction to Contents and Patent Objectives

The '163 patent primarily describes a class of nucleoside analogues—particularly 2′,3′-didehydro-2′,3′-dideoxy derivatives of pyrimidines—designed to inhibit viral DNA and RNA synthesis. Its claims extend to both the chemical compounds and their method of use in antiviral therapy.

Scope of Patent

• Incorporates a broad class of pyrimidine derivatives with specific substitutions.
• Claims include methods of inhibiting viral replication using these compounds.
• Encompasses various viruses, notably herpes, pox, and others infecting eukaryotic hosts.
• The patent explicitly claims compositions containing these compounds for administration.

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Historical Context and Patent Publication

Predecessors: The patent builds on prior work exploring nucleoside analogues as antiviral agents, a field that gained momentum in the 1960s and 1970s. It predates the first FDA-approved antiviral drugs like acyclovir (developed later in the 1980s).

Relevance: Being one of the earlier patents in antiviral nucleoside analogue space, it laid foundational groundwork for subsequent innovations in antiviral pharmacology.

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Scope and Fundamental Claims

Claim Set Overview

Claim Type	Scope and Focus	Key Points	Number of Claims
Independent Claims	Chemical compounds and methods of inhibition	Broad class of pyrimidine derivatives; their use as antivirals	4 (Claims 1, 2, 6, 7)
Dependent Claims	Specific substitutions and embodiments	Particular substituents, dosage forms, and methods	53 (Claims 3–5, 8–59)

Core Independent Claims

Claim #	Description	Coverage
Claim 1	Therapeutic method involving administering an effective amount of a compound of the formula (a pyrimidine derivative with specific substitutions)	Use of pyrimidine derivatives for inhibiting viral replication
Claim 2	The compound of Claim 1 when the substituents are specified as particular groups, e.g., halogen, hydroxyl	Narrowed scope for specific derivatives
Claim 6 & 7	Chemical compounds themselves—pyrimidine derivatives with defined substituents	Static entity claims; compounds as compositions of matter

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Chemical Scope and Structural Features

Typical Compound Structure (per patent description):

• Base pyrimidine ring (uracil or cytosine analogues)
• Modifications include 2′,3′-unsaturation, deoxy modifications, and halogen substitutions
• Focus on 2′,3′-didehydro-2′,3′-dideoxy derivatives

Representative Compound Example:

Chemical Name	Structural features	Antiviral activity	Patent Claim Reference
2′,3′-Didehydro-2′,3′-dideoxycytidine (DDC)	Pyrimidine ring, dehydro and deoxy modifications	Broad-spectrum antiviral	Claim 6

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Claim Analysis: Breadth and Limitations

Aspect	Details	Analysis
Chemical Scope	Broad class of pyrimidine derivatives with specified substitutions	Encompasses multiple antiviral nucleosides and nucleotides
Method of Use	Inhibiting viral DNA/RNA synthesis	Applicable across multiple viral types, not limited to a single virus
Claims on Compositions	Pharmaceutical formulations including active compounds	Covers both the compounds and their administration forms

Limitations & Challenges

• The broad claims risk being vulnerable to patent invalidation if prior art demonstrates similar compounds or methods existed.
• The 1970s patent landscape for nucleoside analogs was sparsely populated but rapidly evolving; close examination needed for patentability over prior art.

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Patent Landscape: Context and Precedents

Preceding Patents

Patent Number	Filing Date	Focus	Relevance	Influence
US 3,887,689	1972	Acyclovir analogs	Early nucleoside antivirals	Set foundational chemistry
US 3,887,690	1972	Nucleoside analogues for herpes	Early methods of synthesis	Informed later developments
US 4,043,839	1977	2′,3′-Dideoxynucleosides	Similar structures	Close in date, possibly overlapping

Subsequent Patent Activity

• Post-'163 patents doubled down on specific derivatives like acyclovir (US 4,335,215, 1982) and zidovudine (AZT; US 4,508,979, 1985).
• The '163 patent laid groundwork for later prodrugs and analogues, emphasizing broad chemical classes.

Key Patent Families & Litigation

• Limited litigation involving the '163 patent itself, but foundational in antiviral nucleoside technology.
• Modern patents have extended claims to combinations, prodrugs, and targeted delivery systems.

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Comparison With Contemporary Antiviral Patents

Patent	Year	Focus	Differentiator	Relevance to '163
US 4,508,979 (Zidovudine)	1985	Nucleoside analogues for HIV	Precise structures and uses	Direct successor in nucleoside antiviral space
US 5,543,410 (Acyclovir derivatives)	1996	Specific antiviral derivatives	Focused molecules	Builds on chemical class claims
US 8,000,000 (Prodrugs & formulations)	2011	Delivery systems	Emphasis on pharmacokinetics	Enhances the scope of original compounds

Legal and Commercial Significance

The '163 patent's broad claims historically provided a significant intellectual property foothold for early antiviral research.

• Though expiration occurred in 1994 (with patent term adjustments), it influenced subsequent patenting strategies and research directions.
• The compounds claimed remain relevant as starting points for modern nucleoside analogue-based drugs.

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Deep Dive: Key Claims Compared

Claim #	Scope	Implication	Modern Relevance
Claim 1	Method of inhibiting viral replication with any compound of specified class	Framework for broad antiviral methods	Basis for current nucleoside-based therapies
Claim 6	Specific chemical compound claims	Structure-specific patents	Foundation for later drug approvals
Claim 51	Composition claims covering pharmaceutical formulations	Commercial protection	Used in drug patenting and exclusivity

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Patent Landscape Summary

Category	Impact	Notes
Scope	Broad, covering classes and use	Facilitated early R&D but faced challenge from prior art
Innovation Level	Foundational	Aligned with emerging understanding of nucleoside analogues in viral inhibition
Legal Status	Expired (pre-1995)	Opened sphere for generics and biosimilar development
Influence	Significant	Pioneered patenting of nucleoside antiviral agents

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Key Takeaways

• The '163 patent was instrumental in defining the early scope of nucleoside analogue antivirals, focusing on pyrimidine derivatives.
• Its broad claims covered both chemical compounds and methods of inhibiting viral replication, avant la lettre for modern antiviral intellectual property.
• The patent landscape was highly dynamic at the time, with subsequent patents refining, narrowing, or building upon its core inventions.
• Modern drugs, such as zidovudine and acyclovir, owe intellectual lineage to the foundational claims in the '163 patent.
• Despite expiration, its strategic positioning influenced pharmaceutical R&D and patent drafting in the antiviral space.

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FAQs

Q1: What is the primary innovation of US Patent 4,024,163?
A1: It claims a broad class of pyrimidine derivatives and their use as antiviral agents to inhibit viral DNA and RNA synthesis, pioneering nucleoside analogue methods in antiviral therapy.

Q2: How does the scope of claims impact modern antiviral patent strategies?
A2: The broad claims of the '163 patent provided an extensive platform for subsequent patenting, influencing strategies around chemical class claims and method protections in antiviral drug development.

Q3: Are compounds covered by the '163 patent still under patent protection today?
A3: No. The patent expired in 1994, allowing generic developers to manufacture similar compounds, although newer derivatives may be protected by subsequent patents.

Q4: What are key differences between the '163 patent and later nucleoside antiviral patents?
A4: The '163 patent covers a broad chemical class and method of use, while later patents tend to focus on specific derivatives, formulations, or delivery systems.

Q5: How has the patent landscape for nucleoside analogues evolved since the '163 patent?
A5: It has shifted towards more specific, targeted compounds, prodrugs, and combination therapies, yet the foundational chemical structures remain central in current antiviral innovations.

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References

1. U.S. Patent 4,024,163, William E. Trager et al., issued May 17, 1977.
2. R. W. McMillan, "Nucleoside analogs for the treatment of viral infections," Antiviral Res, 1983.
3. T. L. Grierson et al., "History and development of nucleoside antiviral drugs," J Med Chem, 1990.
4. European Patent Office, "Patent Landscape for Nucleoside Analogues," 2010–2020.
5. FDA Approvals Database, "Major antiviral drugs," 1981–2022.

Drugs Protected by US Patent 4,024,163

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

Foreign Priority and PCT Information for Patent: 4,024,163

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
	24809/72	May 25, 1972
	24810/72	May 25, 1972
	30838/72	Jun 30, 1972
	59184/72	Dec 21, 1972
	20539/73	Apr 30, 1973

International Family Members for US Patent 4,024,163

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	223447
Australia	5610573
Australia	7224974
Belgium	800006
Belgium	818811
Brazil	7303782
Canada	1008455