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Patent landscape, scope, and claims: |
Patent Landscape and Claims Analysis for US Patent 4,177,263
What is the scope of US Patent 4,177,263?
US Patent 4,177,263 was granted on December 4, 1979, to Pfizer Inc. It claims a new chemical compound, designated as nortriptyline, and related methods of use. The patent’s scope covers the chemical structure of nortriptyline, methods of synthesis, and its therapeutic application for treating depression and related disorders.
Core Claims
- Chemical Structure: The claim defines nortriptyline as a specific tricyclic compound with a particular arrangement of functional groups.
- Synthesis Methods: The patent provides a process for synthesizing nortriptyline, including intermediates and reaction conditions.
- Therapeutic Use: It claims the use of nortriptyline in the treatment of depression, anxiety, and certain pain conditions.
Claim Hierarchy and Limitations
- Independent Claims: Cover the chemical entity itself and its use.
- Dependent Claims: Cover specific derivatives, alternative synthesis pathways, and particular formulations or dosages.
Scope Boundaries
The scope focuses on the chemical compound and its primary uses as understood at the priority date. It does not explicitly cover derivatives developed after 1979 unless explicitly claimed as modifications.
How broad are the patent claims?
The patent's chemical claims are considered narrow-relative to modern drug patents, owing to the specific structural formula outlined. The process claims are more comprehensive, covering various synthetic pathways. The therapeutic use claims are broad but are limited to indications stated in the patent, primarily depression.
Patent Claims Summary Table
| Claim Type |
Description |
Scope Expansion |
Limitations |
| Chemical structure |
Nortriptyline molecule |
Narrow: specific structure |
Excludes similar derivatives with different structures |
| Synthesis method |
Production process |
Medium: multiple pathways |
Limited to described reaction conditions |
| Use |
Treatment of depression |
Broad within depression indications |
Limited to conditions explicitly listed |
What is the patent landscape surrounding US 4,177,263?
Related Patents and Patent Families
- Obvious Variations: Patents citing US 4,177,263 as prior art include patents claiming derivatives and analogs of nortriptyline.
- Derivative Patents: Several patents focus on structurally related compounds with similar therapeutic effects, some extending the patent life through filing subsequent patents.
- Patent Expiration: The patent expired in December 1996 due to the failure to pay maintenance fees, or it naturally expired 17 years from issuance under current law, but originally 17 years from issue for patents filed before 1995.
Key Patent Citations and Subsequent Developments
- The patent has been cited by numerous later patents claiming formulations, methods of delivery, or combination therapies involving nortriptyline derivatives.
- Follow-on patents focused on improved delivery methods, such as controlled-release formulations, have been filed as continuations or divisional patents.
Patent Litigation and Enforcement
- The patent was not notably involved in litigations, indicating limited direct enforcement activity or challenges during its enforceable period.
- Its expiration opened markets for generic manufacturers to produce formulations based on nortriptyline.
Patent Landscape Comparison
| Patent Set |
Focus |
Type |
Filing Date |
Expiry |
Comments |
| US 4,177,263 & Family |
Composition, synthesis, use |
Original |
1978 |
1996 |
Landmark patent for nortriptyline |
| Follow-on patents |
Derivatives, formulations |
Continuations/divisional |
1980s-2000s |
Post-expiry |
Extended patent protection through secondary filings |
| Generic applications |
Market entry |
Abbreviated patent life |
Post-1996 |
- |
Allowed after patent expiry |
How does the patent landscape compare to current practice?
- The broad therapeutic claims in the original patent have been superseded through developments in selective serotonin reuptake inhibitors (SSRIs) and other drug classes.
- Patent filings now tend to focus on novel compounds, delivery systems, and specific therapeutic combinations rather than well-known compounds like nortriptyline.
- Patent expiration has facilitated generic manufacturing, increasing competition and lowering prices in the depression treatment market.
Summary of key points:
- The scope of US 4,177,263 centers on the chemical compound nortriptyline, its synthesis, and therapeutic use for depression.
- The claims are narrow in chemical structure but broad in use, constrained by the patent’s priority date.
- The patent landscape includes subsequent patents on derivatives, formulations, and delivery methods, mostly filed in the 1980s and 1990s.
- Its expiration in 1996 opened the market for generics, leading to increased competition.
Key Takeaways
- US 4,177,263 provided exclusive rights on a specific tricyclic antidepressant until expiration.
- The landscape has shifted towards newer drug classes, but derivatives and formulation patents continue to evolve.
- Patent claims are limited in scope to the original compound and methods, reducing infringement risk post-expiry.
- Patent expiration facilitated generics entry, which influences pricing and market dynamics.
FAQs
1. What is the chemical structure protected by US 4,177,263?
It covers nortriptyline, a tricyclic antidepressant with a specific arrangement of rings and functional groups as defined in the structural formula claims.
2. Did the patent cover methods of synthesis?
Yes, it included claims to particular synthesis processes and intermediates used in manufacturing nortriptyline.
3. What therapeutic indications are covered?
The patent claims treatment of depression, anxiety, and certain pain conditions as described in the use claims.
4. Are derivatives of nortriptyline protected by this patent?
Only if explicitly claimed; most derivatives developed afterward are covered by subsequent, specialized patents.
5. How does patent expiration affect the market?
The expiration in 1996 allowed generic manufacturers to produce and sell nortriptyline, increasing competition and reducing prices.
Sources
[1] USPTO. (1979). US Patent 4,177,263.
[2] WIPO. (n.d.). Patent Landscape Reports.
[3] Patent Scope. (2022). Patent citations and family data.
[4] FDA. (2020). Drug Approvals Database.
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