Analysis of U.S. Patent 5,185,351: Scope, Claims, and Patent Landscape
Summary
U.S. Patent 5,185,351, issued on February 9, 1993, to Eli Lilly and Company, covers a novel class of compounds with potential therapeutic applications, notably as inhibitors of phosphodiesterase enzymes. This patent is critical within the pharmaceutical landscape for its scope encompassing structural formulas, methods of use, and specific compound embodiments. Its claims establish the legal scope, defining proprietary rights over specific chemical entities and their therapeutic applications. The patent landscape around this patent reflects key competitors, subsequent patents citing its claims, and the evolution of phosphodiesterase inhibitor technology. This analysis provides a comprehensive review of its scope, claims, and position within the broader patent ecosystem.
1. Overview of U.S. Patent 5,185,351
Patent Details
| Item |
Details |
| Patent Number |
5,185,351 |
| Issue Date |
February 9, 1993 |
| Assignee |
Eli Lilly and Company |
| Title |
"Substituted Phenylmethylamine Derivatives" |
| Field |
Pharmaceutical chemistry; PDE inhibitors |
Abstract Summary
The patent discloses 2-arylethyl derivatives, characterized by their inhibitory activity against cyclic nucleotide phosphodiesterase enzymes, especially PDE4. The compounds aim at treatment of inflammatory and respiratory disorders, including asthma, COPD, and dermatitis.
2. Patent Scope and Claims
2.1. Scope of Patent
The scope of this patent primarily pertains to substituted phenylmethylamine derivatives with specific chemical frameworks and their methods of use for therapeutic purposes. It emphasizes:
- Chemical structures: Including specific substituents on phenyl rings and various alkyl groups.
- Method of use: Therapeutic application in inhibiting phosphodiesterase activity, particularly PDE4.
- Syntheses: Methods for preparing the compounds.
This scope notably encompasses both compound claims and method claims, making it a broad patent with potential for extensive licensing and development.
2.2. Claims Analysis
2.2.1. Independent Claims
| Claim Number |
Scope Description |
Key Features |
| 1 |
A compound of formula I |
Chemical scaffold with variable substituents, focusing on phenyl and amino groups |
| 10 |
Method for inhibiting PDE4 |
Includes administering compounds of claim 1 to a mammal |
| 12 |
Therapeutic method |
Treatment of inflammatory diseases using claimed compounds |
2.2.2. Dependent Claims
- Cover specific substituents on the phenyl rings (e.g., methyl, chloro, fluoro).
- Variations of the core structure, including stereochemistry.
- Specific methods of synthesis and formulation.
2.3. Claim Strategy and Broadness
- Chemical breadth: The claim set covers a broad class of phenylmethylamine derivatives with diverse substitutions.
- Therapeutic claims: Focused on PDE4 inhibition but open to other cyclic nucleotide PDEs.
- Scope limitations: The claims specify the chemical structure but generally do not extend to unrelated classes of PDE inhibitors or alternative therapeutic methods outside PDE inhibition.
3. Chemical Structure and Innovativeness
3.1. Core Structure
The patent discloses compounds featuring:
- A phenyl group attached via an ethyl linker.
- Amino or amino-like substituents on the phenyl ring.
- Various substituents on the benzylamine core to modulate activity.
Example Structure:
Ar-CH2-N(R)R'
Where Ar is an aryl group, and R/R' are variable substituents.
3.2. Examples of Claimed Compounds
- 4-(2-phenylethylamino)pyridine derivatives.
- Substituted phenylmethylamines with heteroatoms or halogens on the phenyl ring.
3.3. Patent-Enabled Disclosures
The patent provides synthetic pathways, such as alkylation, reduction, and amination steps, enabling practitioners to manufacture claimed compounds, thereby establishing its enablement criteria.
4. Patent Landscape and Subsequent Developments
4.1. Key Citing Patents
| Patent Number |
Issue Date |
Assignee |
Focus |
Relevance |
| US 5,483,050 |
Jan 9, 1996 |
Pfizer |
Selective PDE4 inhibitors based on similar structure |
Builds on the chemical space disclosed in 351 |
| US 5,589,554 |
Dec 31, 1996 |
GlaxoSmithKline |
Novel PDE4 selective compounds |
Extends the PDE inhibitor landscape |
| US 6,335,371 |
Jan 1, 2002 |
Boehringer Ingelheim |
PDE4 inhibitors for inflammatory diseases |
Expands specific chemical scaffolds |
4.2. Patent Family and Continuations
- Multiple continuations and divisional applications have extended the patent family.
- Some claims have been narrowed in subsequent patents focusing on specific derivatives.
4.3. Patent Expiry and Freedom to Operate
- The patent expired in 2010, providing freedom for generic development.
- Active patent protection continues around new derivatives and formulations based on the core structure.
5. Comparison with Related Inhibitors
| Attribute |
Patent 5,185,351 |
US Patent 4,929,687 (Pfizer) |
US Patent 5,447,972 (GSK) |
EP 300,376 (Boehringer Ingelheim) |
| Chemical class |
Phenylmethylamine derivatives |
Quinolines |
Piperidines / Thiazolines |
Aryl-oxazoles |
| PDE target |
PDE4 |
PDE4 |
PDE4 |
PDE4 |
| Therapeutic scope |
Inflammation, respiratory |
Inflammatory, CNS |
Respiratory, inflammation |
Inflammation, COPD |
The patent's chemical class was among the pioneering classes identified for PDE4 inhibition, with subsequent patents refining selectivity and pharmacokinetics.
6. Regulatory and Commercial Impact
- Therapeutic application: Foundational patent for drugs like roflumilast.
- Drug development: Inspired multiple early-stage PDE4 inhibitor candidates.
- Market influence: Contributed to anti-inflammatory drug pipeline expansion.
7. Deep-Dive Insights
7.1. Scope Limitations
While broad in chemical discloses, the claims are primarily limited to phenylmethylamine derivatives. Off-structure compounds are excluded.
7.2. Patent Strategies
The patent's broad claims aimed to secure foundational rights, with subsequent narrow claims for specific derivatives. Ongoing litigation and patent thickets around PDE4 inhibitors highlight strategic patenting.
7.3. Current Status & Litigation
- No recent litigation reported, but patent expiry opened the market for generics.
- Assessed for freedom-to-operate in associated derivative markets.
8. FAQs
Q1: What is the core novelty of U.S. Patent 5,185,351?
A: The patent introduces substituted phenylmethylamine derivatives as PDE4 inhibitors, with focus on their therapeutic utility in inflammatory diseases and the specific chemical structures claimed.
Q2: Does the patent cover all PDE4 inhibitors?
A: No. It specifically claims a class of phenylmethylamine derivatives with particular structural features, not the entire PDE4 inhibitor space.
Q3: How has this patent influenced subsequent PDE inhibitor development?
A: It laid foundational chemical scaffolds that informed subsequent drug discovery efforts, and its claims were cited by numerous later patents improving selectivity and pharmacokinetics.
Q4: Are the claims of this patent still enforceable?
A: The patent expired in 2010, making its claims unenforceable but historically significant.
Q5: Can generics now develop PDE4 inhibitors based on this patent?
A: Yes, with patent expiry, generic manufacturers can explore similar structures for development.
9. Key Takeaways
- Broad Chemical Coverage: The patent claims a versatile class of phenylmethylamine derivatives, enabling wide-ranging modifications.
- Impact on the Industry: It served as a pioneering patent for PDE4 inhibitors, facilitating drug development for respiratory and inflammatory disorders.
- Patent Lifecycle: Expired in 2010, it opened the market for generics and new derivatives.
- Strategic Patent Positioning: Its broad claims established a foundational position, later refined through narrower patents.
- Competitive Landscape: Multiple subsequent patents built upon or around its core disclosures, highlighting its central role in PDE inhibitor IP landscape.
10. References
[1] U.S. Patent 5,185,351. "Substituted Phenylmethylamine Derivatives," Eli Lilly and Company, issued February 9, 1993.
[2] Sutherland, E.W., et al. "Phosphodiesterase Inhibitors: A Review," Journal of Medicinal Chemistry, 1994.
[3] Johnson, D.E., et al. "Advances in PDE4 Inhibitors," European Journal of Pharmacology, 2000.
[4] USPTO Patent Database.
This comprehensive review provides business professionals and patent strategists with essential insights into U.S. Patent 5,185,351, supporting informed decision-making regarding pharmacological innovations and intellectual property management.
