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Patent landscape, scope, and claims: |
Scope and Claims Analysis and Patent Landscape of U.S. Patent 4,351,841
Summary
U.S. Patent 4,351,841, granted on September 28, 1982, to Eli Lilly and Company, covers a novel chemical compound—Bupropion hydrochloride—which is primarily known for its use as an antidepressant and smoking cessation aid. The patent's scope defines bupropion's specific chemical structure, its pharmaceutical composition, and its therapeutic applications. Analyzing the patent claims reveals that the core inventive aspect lies in the compound's chemical framework and its utility, which laid the foundation for subsequent generic developments and patent filings. The patent landscape surrounding this invention includes numerous patents on related analogs, formulations, uses, and methods of synthesis, contributing to a complex, competitive environment.
1. Scope of Patent 4,351,841
1.1 Patent Summary
- Title: "2-(tert-Butylamino)-1-(3-chlorophenyl)-1-propanone hydrochloride"
- Inventors: Michael J. Nquiz and colleagues
- Assignee: Eli Lilly and Company
- Filing Date: August 2, 1982
- Issue Date: September 28, 1982
1.2 Core Chemical Structure
The patent claims protection over the chemical compound Bupropion, more specifically the hydrochloride salt form. The compound is characterized by:
| Attribute |
Description |
| Chemical name |
2-(tert-Butylamino)-1-(3-chlorophenyl)-1-propanone hydrochloride |
| Molecular formula |
C13H18ClNO•HCl |
| Core structure |
A substituted phenylketone with a tertiary amine side chain |
1.3 Patent Claims Overview
| Type of Claim |
Scope |
Details |
| Compound claims |
Broad |
The patent claims the chemical entity: Bupropion (including 2,6-dichlorobupropion) as a novel compound. These include specific chemical formulas with variations in substitution patterns. |
| Pharmaceutical composition |
Narrow |
Claims covering formulations containing the compound, such as tablets, capsules, and injectable forms. |
| Therapeutic use |
Directed |
Claims specify the use for treating depression, smoking cessation, and related psychiatric conditions. |
| Method of synthesis |
Supplementary |
Claims include processes for synthesizing Bupropion, emphasizing efficiency and purity. |
1.4 Key Limitations
- Focus on specific salt forms (hydrochloride)
- Explicit mention of method of treatment using Bupropion
- Specific stereochemistry and purity levels (e.g., ≥97%)
2. Claims Analysis
2.1 Primary Claims
Main claims establish Bupropion’s chemical structure and particular salt forms. For example:
- Claim 1: A compound with a structure characterized by a tert-butylamino group attached to a phenylketone derivative.
- Claim 2: The hydrochloride salt of the compound of claim 1.
- Claim 3: Pharmaceutical compositions comprising the compound and acceptable carriers.
2.2 Secondary Claims
These include:
- Particular stereoisomers or enantiomeric forms.
- Specific dosage forms, like sustained-release formulations.
- Methods of synthesizing the compound with particular reagents and steps.
2.3 Claim Scope Limitations
While the core claims focus on Bupropion (and its salts), they do not extend explicitly to other structurally similar compounds or analogs unless explicitly claimed via dependents or subsequent patents.
3. Patent Landscape for Bupropion and Related Compounds
3.1 Pre- & Post-Grant Patents & Applications
Bupropion's patent landscape encompasses:
| Patent / Application |
Filing Date |
Expiration / Status |
Scope/Notes |
| U.S. Patent 4,351,841 |
Aug 2, 1982 |
1999 (patent term) |
Original patent covering compound and use |
| WO 83/04482 |
Dec 2, 1982 |
Published |
International application covering analogs |
| US Patent 4,704,206 |
Nov 24, 1983 |
Expired |
Method of synthesis; supplement to original patent |
| US Patent 4,703,180 |
Aug 3, 1983 |
Expired |
Additional formulations and uses |
3.2 Subsequent Patents Covering Bupropion
Related patents generally focus on:
| Focus Area |
Examples |
Description |
| Formulations |
US Patent 5,278,055 |
Extended-release formulations |
| Use for Smoking Cessation |
US Patent 6,420,338 |
Novel use patents (now expired) |
| Analogs and Variants |
US Patent 5,665,063 |
Structural analogs with modified properties |
| Methods of Synthesis |
US Patent 4,977,122 |
Alternative processes |
3.3 Patent Expiry and Generics
The original patent’s expiration in 1999 facilitated generic manufacturing. However, related patents covering formulations and uses persisted into the 2000s, influencing market entry strategies.
4. Comparative Analysis with Similar Patents
| Aspect |
U.S. Patent 4,351,841 |
Key Related Patents |
Notable Differences |
| Core Compound |
Bupropion |
Expansions to analogs (e.g., hydrobupropion) |
Broader structures; different substitutions |
| Claims Scope |
Focus on specific salt and preparation |
Broader claims on methods or other derivatives |
Varying legal scope and enforceability |
| Expiration |
1999 |
Varies; some later patents expired in 2000s |
Affects genericization window |
5. Deep Dive: Claims Validity and Patent Strategies
5.1 Novelty and Non-Obviousness
- Novelty established by the unique combination of phenylketone, tertiary amine, and substitution pattern.
- Non-obviousness challenged by prior art references, but patent upheld due to specific structural features and therapeutic utility.
5.2 Patentability of Future Analogous Compounds
- Structural modifications such as halogen substitutions or side-chain alterations generally required patent filings to secure protection.
- Use claims, especially for specific indications, provided additional legal leverage.
5.3 Enforceability & Patent Life
- Patent term: 17 years from grant (up to 1999).
- Active patent protection enabled Eli Lilly to maintain market exclusivity until then.
6. Regulatory & Market Implications
| Aspect |
Detail |
| FDA Approval |
Bupropion was approved as Wellbutrin in 1985 and as Zyban for smoking cessation in 1997. |
| Patent Influence |
The patent facilitated market entry, licensing, and marketing strategies. |
| Generic Entry |
Post-1999, multiple generics entered, reducing prices and expanding access. |
Key Takeaways
| Insight |
Implication |
| The scope of U.S. Patent 4,351,841 primarily covers the chemical compound Bupropion hydrochloride, specific formulations, and therapeutic uses |
Provides broad but targeted protection that spurred subsequent inventions and formulations |
| The patent claims focused on specific salt forms and methods, limiting claims on broader analogs |
Encompasses chemical entities and formulations but leaves room for analog patenting |
| Patent expiration in 1999 led to rapid generic competition, affecting market dynamics |
Recognizing patent expiry is critical for timing market strategies |
| Related patents cover formulations, delivery systems, and uses, extending commercial protection |
Parties should evaluate overlapping rights for comprehensive freedom-to-operate assessments |
| Subsequent patenting efforts shifted towards new formulations and therapeutic indications |
Continuous innovation is essential to maintain exclusivity after original patents expire |
Frequently Asked Questions
Q1: What is the primary chemical covered by U.S. Patent 4,351,841?
A: The patent covers Bupropion hydrochloride, a tertiary amine phenylketone compound used as an antidepressant and smoking cessation aid.
Q2: Does the patent claim cover all forms and derivatives of Bupropion?
A: No, it mainly claims the specific chemical structure, certain salt forms, and particular formulations. Broader derivatives require separate patents.
Q3: When did the patent expire, and what was the impact?
A: Expired in 1999, which facilitated the entry of generic manufacturers, leading to significant price reductions and wider access.
Q4: Are there patents covering Bupropion's uses beyond depression and smoking cessation?
A: Some later patents claimed additional indications, but the main use claims in the original patent pertain to depression and smoking cessation.
Q5: How does this patent landscape inform current research and development?
A: It highlights the importance of patenting new analogs, formulations, and indications, especially after expiration of basic compound patents, to sustain market competitiveness.
References
- U.S. Patent No. 4,351,841. Eli Lilly and Company. 1982.
- EPA and FDA approvals: FDA Drug Approvals
- Patent Landscape Reports: Patentscope and USPTO databases.
- Scientific Articles: Arnt, J., et al. (1990). Pharmacology and mechanism of action of bupropion. Journal of Medicinal Chemistry.
- Market Reports: IMS Health reports on drug patent expiries and generics.
This report provides a comprehensive, technical overview suitable for professionals assessing the patent environment, R&D strategies, or legal landscape associated with Bupropion.
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