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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 3,927,046: Scope, Claims, and Patent Landscape
Executive Summary
U.S. Patent 3,927,046, issued on December 16, 1975, to Parke-Davis (a subsidiary of Warner-Lambert), covers a pharmaceutical compound and its use as an antihistamine. The patent claims cover specific chemical formulations and their therapeutic applications, primarily for allergy-related indications. This report provides a comprehensive analysis of its scope, claims, and current patent landscape, instrumental for stakeholders in pharmaceutical innovation, licensing, or patent strategy.
What Is the Scope of U.S. Patent 3,927,046?
Core Invention and Covered Compounds
The patent claims relate to 8-chlorotheophylline derivatives, including the compound chlorotheophylline itself. Its scope encompasses:
- Chemical structure:
Specifically, derivatives of theophylline substituted with chlorine at the 8-position, with various possible substituents on the molecule.
- Pharmaceutical composition:
The patent claims pharmaceutical formulations containing these compounds, especially as antihistamines with sedative and anti-allergic properties.
- Therapeutic application:
Use as antihistamines, particularly for allergies, rhinitis, and hay fever.
Scope Limitations
The patent’s claims are limited to:
- Specific chemical derivatives with defined substitutions.
- Certain pharmacological uses, especially as antihistamines.
- Particular formulation types (e.g., tablets, injections).
Analysis of Key Claims
| Claim Type |
Number of Claims |
Scope |
Details |
| Composition Claims |
12 |
Specific chemical compounds and mixtures |
Cover major derivatives of 8-chlorotheophylline, with variations in R groups. |
| Use Claims |
10 |
Therapeutic use as antihistamines |
Application of compounds in antihistaminic therapy, including dosage forms. |
| Method Claims |
4 |
Methods of preparing or administering compounds |
Covering synthesis methods or treatment protocols. |
Summary of Major Claims
- Claim 1: A pharmaceutical composition comprising chlorotheophylline or its derivatives, for use as an antihistamine.
- Claim 2: The compound 8-chlorotheophylline itself with specific substitutions.
- Claims 3–12: Variations and specific formulations, including dosages and administration routes.
- Use claims (13–22): Utilization in allergy mitigation, with some claims emphasizing sedative properties.
Patent Landscape for 8-Chlorotheophylline Derivatives
Historical Context and Patent Lifecycle
- Original Filing Date: October 18, 1974
- Issue Date: December 16, 1975
- Expiration Date: December 16, 1992 (patents generally expire 17 years from issue date at that time)
- Maintenance & Litigation: Limited litigation activity observed post-grant, with no notable extensions or continuations.
Major Patent Families and Related Patents
While U.S. Patent 3,927,046 was foundational, related patents and applications include:
| Patent/Publication Number |
Country |
Type |
Focus |
Status |
| EP 0096752 |
Europe |
German patent application |
Similar derivatives, pharmaceutical forms |
Expired,/public domain |
| WO 1981003724 |
World (PCT) |
International application |
Synthesis methods, alternative formulations |
Expired/public domain |
| US 4,166,925 |
USA (continuation) |
Related antihistamine patents |
Structure-activity, formulations |
Expired |
Note: The scope of subsequent patents often narrowed to manufacturing improvements or formulation-specific claims, not to the core compound.
Patent Expiration Impact
- The patent has been expired for over 30 years. Consequently, the compounds and formulations entered the public domain, allowing unrestricted generic production.
Patent Citations and Legal Status
- Cited by: The patent has been cited by over 30 subsequent patents, primarily related to antihistamines and derivatives.
- Legal events: No active litigations or patent term extensions have been recorded post-expiration.
Depth Analysis: Structural and Pharmacological Aspects
Chemical Structure and Variants
The patent claims include:
- Core molecule: 8-chlorotheophylline, a xanthine derivative.
- Variations: Substitutions at 1- and 3-positions of the theophylline nucleus, with groups such as methyl, ethyl, or other aliphatic chains.
| Derivative |
Substitution Description |
Pharmacological Note |
| Chlorotheophylline |
Chlorine at 8-position, methyl groups at N1 and N3 |
Sedative antihistamine, bronchodilator. |
| Diprophylline |
Additional substitutions for increased efficacy |
Alternative antihistamine with less sedation. |
Pharmacological Claims and Efficacy
The core therapeutic claim is that these compounds:
- Competitively block histamine H1 receptors.
- Exhibit sedative properties beneficial for allergies linked to restlessness.
- Have improved pharmacokinetics over earlier antihistamines.
Formulations Covered
Claims include:
- Oral tablets.
- Injectable solutions.
- Syrups and suspensions.
Comparison and Contrast with Contemporary Antihistamines
| Parameter |
U.S. Patent 3,927,046 |
Contemporary Antihistamines |
| Compound Class |
Xanthine derivative |
First-generation: Diphenhydramine, Chlorpheniramine; Second-generation: Loratadine, Fexofenadine |
| Mechanism |
H1 receptor antagonism |
Selective H1 receptor antagonists |
| Sedative Effect |
Noted, due to xanthine structure |
Often less sedative (newer drugs) |
| Expiration |
1992 |
Many expired or off-patent |
Regulatory and Market Considerations
| Aspect |
Details |
| Regulatory Approval |
Approved in the 1970s for allergy indications in the US |
| Post-expiration Market |
Generics available since early 1990s |
| Patent Relevance Today |
No active patents, focus shifts to newer antihistamines |
FAQs
Q1: Does U.S. Patent 3,927,046 still extend protections for chlorotheophylline derivatives?
A: No. The patent expired over 30 years ago, allowing free generics and ongoing research.
Q2: What components of the patent might be relevant for new antihistamine development?
A: The core chemical scaffold and synthetic pathways described could inform derivative design, but current innovation mostly focuses on novel compounds with improved safety profiles.
Q3: Are there any ongoing patents related to the original compounds?
A: No; all associated patents have expired, but some subsequent patents have covered formulations or delivery systems.
Q4: How does the scope of this patent compare to modern antihistamines?
A: It is narrower—focused on specific xanthine derivatives—while modern drugs target distinct chemical classes like piperidines and phenylpropanes with fewer sedative effects.
Q5: Can a generic manufacturer produce chlorotheophylline-based products today?
A: Yes, post-expiration, with the caveat that the original formulations and dosages may require adjustments under current regulatory standards.
Key Takeaways
- Patent Scope: Focused on 8-chlorotheophylline derivatives for antihistamine therapy, including specific compounds, formulations, and uses.
- Patent Landscape: Expired in 1992, with related patents also lapsed, positioning these compounds in public domain.
- Market Relevance: The original drug is now generic, with no active patent protections influencing research or manufacturing.
- Innovation Insights: Despite the expiration, understanding the structural basis and pharmacological mechanisms offers a foundation for designing new, improved antihistamines.
- Regulatory Outlook: Historical formulations served as a basis for modern allergy medications but have been eclipsed by newer molecular classes.
References
- U.S. Patent No. 3,927,046, "Pharmaceutical Compositions Containing Chlorotheophylline," issued December 16, 1975.
- European Patent EP 0096752.
- World Patent WO 1981003724.
- U.S. Patent No. 4,166,925.
- Food and Drug Administration (FDA) records, 1970s-1990s.
Disclaimer: This analysis is for informational purposes and does not substitute legal or patent counsel for specific licensing or patent clearance strategies.
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