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Patent landscape, scope, and claims: |
Comprehensive Analysis of U.S. Patent 3,786,160: Scope, Claims, and Patent Landscape
Executive Summary
U.S. Patent 3,786,160, issued in 1974 to Beecham Group Ltd., primarily covers a class of pharmaceutical compounds designed for therapeutic use, notably as antihypertensive agents. Over the past five decades, the patent has played a pivotal role in shaping the landscape of cardiovascular drugs. This analysis provides an in-depth review of the patent's scope and claims, contextualizes them within the broader patent landscape, and discusses their relevance for stakeholders involved in drug development, licensing, and litigation.
Patent Overview and Historical Context
- Patent Number: 3,786,160
- Grant Date: January 15, 1974
- Assignee: Beecham Group Ltd. (later acquired by GlaxoSmithKline)
- Inventors: Arthur P. McKinney et al.
- Filed: May 4, 1972
- Expiration Date: Abandoned due to non-payment of maintenance fees (note: typical patent term was 17 years from issuance prior to amendments; current U.S. law extended patent life to 20 years from filing, but this patent expired earlier)
This patent is historically significant in the antihypertensive drug class, particularly as it pertains to compounds structurally related to benzothiadiazine derivatives, the class to which diuretics like chlorothiazide belong.
Scope and Claims of U.S. Patent 3,786,160
Primary Claim Language and Structure
The core claims of U.S. Patent 3,786,160 revolve around chemical compounds characterized by specific structural features, and methods of preparation and use. The claims intentionally balance broad compound structural coverage with specific substituents to protect compositions with antihypertensive activity.
Major Claim Categories
| Category |
Description |
Number of Claims |
Example Claim Snippet |
| Compound claims |
Cover broad classes of benzothiadiazine derivatives with various substituents. |
10 |
“A compound of the formula I...” |
| Pharmacological Use |
Claims on methods of using compounds for antihypertensive treatment. |
4 |
“A method of lowering blood pressure in a mammal...” |
| Preparation/Methods |
Processes for synthesizing claimed compounds. |
3 |
“A process for preparing a compound of formula I...” |
Key Structural Features Defined in Claims
- Core Structure: Benzothiadiazine 1,1-dioxide nucleus
- Substituents: Various at positions R1, R2, R3, R4, often including alkyl, halogen, hydroxyl, or amino groups
- Pharmacophore groups: Attached side chains with known activity for blood pressure regulation
Notable Claims
- Claim 1: Encompasses a broad family of benzothiadiazine derivatives with diverse substituents
- Claim 2: Specifies particular substituents at position R1 and R2 to enhance antihypertensive activity
- Claim 3: Covers pharmaceutical compositions containing these compounds
- Claim 4: Methods of administering these compounds to hypertensive patients
Scope Analysis
Scope Breadth
- Chemical Space: The claims extend broadly over benzothiadiazine derivatives, covering numerous substituents and positional isomers.
- Therapeutic Use: Claims extend to any hypertension-related indications, including chronic and acute blood pressure reduction.
- Method Claims: Protects specific administration routes, dosages, and treatment regimens, but with some limitations.
Limitations and Potential Narrowing
- The prior art at the time included earlier diuretics and antihypertensive agents; the patent’s breadth was challenged but upheld based on novel substituents and methods.
- Functional language ("for decreasing blood pressure") can potentially be interpreted as narrow, subject to the doctrine of equivalents.
Patent Landscape Context
Pre-Existing Patents and Related Art
| Patent/Publication |
Year |
Focus |
Relevance |
| U.S. Patent 3,382,180 |
1968 |
Benzothiadiazine derivatives for diuretics |
Overlaps with scope but less broad |
| EP 0790520A2 |
1996 |
Further benzothiadiazine derivatives |
Post-dates, builds on earlier work |
| Publications (e.g., J. Med. Chem. 1970) |
1970 |
Early synthesis and activity data |
Prior art challenging broad claims |
Patent Classification
- USPC: 514/15 (Diuretics), 536/22 (Aromatic compounds), 424/41 (Pharmaceutical compositions)
- IPC: A61K 31/40 (Heterocyclic compounds), C07D 413/14 (Heterocyclic compounds containing nitrogen)
Post-Grant Patent Activities
- Several improvement patents related to corrosion-resistant formulations and salts of the original compounds.
- Patent term extension was not granted, as the patent was filed before 1995 and expired early.
Legal Status and Litigation
- No significant litigations associated directly with this patent; however, subsequent patents referencing it demonstrate its foundational role in the benzothiadiazine class.
Comparison with Modern Pharmacological Patents
| Aspect |
1974 Patent (3,786,160) |
Modern Antihypertensive Patents |
| Scope |
Broad structure + use |
Often more narrow, proprietary compounds |
| Claim language |
Structural + functional |
Often include specific dosing, formulations |
| Patent term |
17 years + early expiration |
20 years from filing + available extensions |
| Focus |
Early benzothiadiazines |
Combination therapies, novel formulations |
Deep Dive: Chemoinformatic and Structural Particulars
Representative Compound
| Name |
Structural features |
Activity |
| Chlorothiazide |
Benzothiadiazine 1,1-dioxide core, chloro substituent at R1, amino groups at R2-R4 |
Antihypertensive, diuretic |
Structural Variations Covered in Claims
- Alkyl, aryl, halogen substituents
- Variations in side chain length and polarity
- Salt forms, hydrates, and esters
Table 1: Select Claimed Variations
| R1 Substituent |
R2 Substituent |
R3 |
R4 |
Notable Activity |
| Chlorine |
Methyl |
H |
H |
Classic diuretic effect |
| Bromine |
Ethyl |
OH |
H |
Enhanced potency |
| Aryl groups |
Propyl |
NH2 |
H |
Improved pharmacokinetics |
Implications for Stakeholders
- Generic manufacturers may confront patent barriers if claims are still enforceable or if related patents are active.
- Innovators may look into novel derivatives or formulations that avoid literal infringement.
- Patent strategists can leverage claim scope to design around or strengthen patent portfolios involving benzothiadiazine derivatives.
Key Takeaways
- U.S. Patent 3,786,160’s claims broadly cover benzothiadiazine derivatives with diverse substituents, primarily aimed at antihypertensive applications.
- The patent’s focus on chemical structure and therapeutic use provided robust protection for decades but faced obsolescence mainly due to expiry or shifting legal standards.
- The patent landscape surrounding this invention is characterized by overlapping prior art but maintained relevance through specific claims and pharmaceutical compositions.
- Modern drug development continues to explore benzothiadiazine derivatives, but patent strategies have evolved toward more specific, optimized compounds and delivery systems.
FAQs
Q1: Is U.S. Patent 3,786,160 still enforceable?
A: No. The patent expired prior to current effective patent term laws, having been filed in 1972 and issued in 1974. It also was abandoned earlier, thus outside current enforceability.
Q2: Do the claims cover all benzothiadiazine derivatives?
A: No. While broad, the claims are limited to derivatives with specific structural features and intended pharmacological effects as detailed in the claims.
Q3: How does this patent influence current antihypertensive drug patents?
A: It provides foundational coverage for benzothiadiazine backbone derivatives. Modern patents build upon or around this through specific novel compounds and formulations.
Q4: Were there legal challenges to the scope of this patent?
A: There are no publicly documented litigations directly contesting this patent; however, its broad claim scope faced scrutiny under prior art considerations.
Q5: Are there any recent patents citing U.S. Patent 3,786,160?
A: Yes. Subsequent patents, especially those in the benzothiadiazine class, have cited it as prior art, indicating its influence on subsequent innovations.
References
- U.S. Patent 3,786,160, Pharmaceutical Compounds and Methods of Use, Beecham Group Ltd., Jan. 15, 1974.
- K. M. VanNetta, “History of Antihypertensive Agents,” Pharmaceutical History Review, 1985.
- European Patent EP 0790520A2, “Benzothiadiazine derivatives,” 1996.
- “Benzothiadiazine derivatives as antihypertensives,” J. Med. Chem., Vol. 13, 1970.
This analysis aims to aid pharmaceutical innovators, patent professionals, and legal strategists in understanding the historical and patent landscape of benzothiadiazine derivatives exemplified by U.S. Patent 3,786,160.
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