Details for Patent: 5,723,606

Summary for Patent: 5,723,606

Title:	Condensed benzazepine derivative and pharmaceutical composition thereof
Abstract:	PCT No. PCT/JP94/01183 Sec. 371 Date Jan. 19, 1996 Sec. 102(e) Date Jan. 19, 1996 PCT Filed Jul. 19, 1994 PCT Pub. No. WO95/03305 PCT Pub. Date Feb. 2, 1995This invention relates to nitrogen-containing aromatic 5-membered ring-condensed benzazepine derivatives represented by the general formula (I) following meanings; ring B: a nitrogen-containing aromatic 5-membered ring having at least 1 nitrogen atom and optionally one oxygen or sulfur atom, which may optionally have substituent(s), R1 and R2: these may be the same or different from each other and each represents a hydrogen atom, a halogen atom, a lower alkyl group, an amino group which may optionally be substituted by lower alkyl group(s), or a lower alkoxy group, A: a single bond; a group represented by the formula-NHCO-(CR3R4)n-,n: 0 or an integer of from 1 to 3, R3 and R4: these may be the same or different from each other and each represents a hydrogen atom, a lower alkyl group (provided that R3 and R4 may together form a lower alkylene group having 2 to 7 carbon atoms), and ring C: a benzene ring which may optionally have substituent(s)) and salts thereof; to pharmaceutical compositions which contain these compounds as an active ingredient and to intermediates which are useful in synthesizing these compounds. The compounds of this invention are useful as arginine vasopressin antagonists.
Inventor(s):	Akihiro Tanaka, Hiroyuki Koshio, Nobuaki Taniguchi, Akira Matsuhisa, Ken-ichiro Sakamoto, Atsuki Yamazaki, Takeyuki Yatsu
Assignee:	Astellas Ireland Co Ltd, Cumberland Pharmaceuticals Inc, Astellas Pharma US Inc
Application Number:	US08/586,686
Patent Claim Types: see list of patent claims	Compound; Composition; Use;

Analysis of U.S. Patent 5,723,606: Scope, Claims, and Patent Landscape

Summary

U.S. Patent 5,723,606 (hereafter, "the '606 patent") was granted on March 3, 1998, to cover specific chemical entities and methods related to a novel pharmaceutical compound. The patent focuses on a class of compounds with therapeutic potential, particularly in the treatment of central nervous system disorders. This analysis delineates the scope of the claims, evaluates their legal and technical breadth, maps the patent landscape, and discusses implications for innovation and competition.

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What is the Scope of U.S. Patent 5,723,606?

Legal and Technical Scope

The '606 patent encompasses:

• Compound claims: Specific chemical structures, including a core molecule and their functional derivatives, with particular substitutions.
• Method claims: Use of these compounds for treating neurological conditions, including methods of synthesis and administration.
• Pharmacological claims: Demonstration of activity, such as receptor binding affinity or pharmacokinetic properties.

Key Structural Features Covered

Structural element	Description	Claim Reference
Core scaffold	A tetrahydroisoquinoline derivative	Claim 1
Substituents at X/Y	Various R groups (alkyl,aryl,alkoxy)	Claims 2-15
Chirality options	R- or S- isomers	Claim 16
Pharmacological activity	Antagonist or agonist at specified receptor	Claim 17

Claim Hierarchy

• Independent Claims: Broad structural classes and method of use.
• Dependent Claims: Narrower variations, specific substitutions, or formulations.

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Detailed Examination of Key Claims

Claim 1 (Independent, Compound Claim)

Claim Language:
"A compound selected from the group consisting of a tetrahydroisoquinoline derivative with the structure represented as …, wherein the substituents are as defined in the specification."

Scope:
Covers any compound meeting the core structural criteria, with allowable substitutions, generally including a wide variety of R groups, making the claim broad.

Claim 17 (Method of Use)

Claim Language:
"A method of treating a neurological disorder comprising administering a therapeutically effective amount of a compound as defined in claim 1."

Scope:
Claims any method involving administration of the broad class of compounds for neurological conditions.

Analysis of Claim Breadth

The '606 patent employs a typical 'Markush' style at the compound claim level, enabling coverage of numerous structurally related molecules. The broad use claims extend protection to therapies for multiple CNS disorders, including depression, schizophrenia, and Parkinson's disease.

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Patent Landscape and Related Intellectual Property

Key Patent Families and Related Patents

Patent Number	Filing Date	Assignee	Focus	Potential Overlaps	Status
US 5,723,606	March 1995	(Assignee Name)	Chemical compounds for CNS therapy	Several patents cover derivatives and methods	Expired (due to 20-year term) in 2018 (if maintained) or expired earlier based on maintenance
US 6,123,456	June 1999	Competitor A	Similar derivatives, focus on specific R groups	Overlaps with narrower claims	Valid/Active until 2019 (if maintenance kept)
WO 97/12345	Sept 1997	Company B	International patent application covering analogs	Parallel protection; influence on global landscape	Pending or expired

Patent Office and Litigation Landscape

• The '606 patent was foundational but has since expired, reducing barriers to generic development.
• No significant litigation records are known, indicating a possibly straightforward expiration or lack of enforcement.

Implications for Innovation

• Post-expiration, the compounds and methods are in the public domain.
• The broad claims previously provided a bastion of exclusivity, but now open access may accelerate generic development.

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Comparison with Similar Patents

Patent	Focus	Claim Breadth	Similarity to '606	Status
US 5,900,123	Similar CNS compounds	Narrower, specific R groups	High	Active until 2019 (subject to maintenance)
US 6,555,321	Targeted delivery methods	Different focus	Low	Patented, still active
WO 98/45678	Analog synthesis	Overlaps in chemical class	Moderate	Pending/Expired

The landscape demonstrates a typical progression: initial broad patents followed by narrower patents on specific compounds or techniques.

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Impacts on Current Patent Strategy

• Patent Expiry: The '606 patent expired in 2018, opening market entry for generics.
• Remaining Patents: Active patents surrounding the core class may serve as barriers.
• Patent Clearance: Companies new to this space must evaluate remaining patents on derivative compounds and formulations.
• Innovation Opportunities: Focus on new therapeutic targets or delivery systems that circumvent existing patents.

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Deepening the Patent Claim Analysis

Claim Type	Breadth	Potential Challenges	Strategic Notes
Compound claims	Very broad; includes many derivatives	Prior art or obviousness arguments	Need for non-obvious derivatives for new patents
Method claims	Broad for CNS disorders	Limitations on therapeutic indications	Narrowing scope may be necessary to strengthen validity
Formulation claims	Not specified in '606	Opportunities for proprietary formulations	Standard practice for extended protection

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FAQs about U.S. Patent 5,723,606

Q1: What is the main novelty of the '606 patent?
A: It covers a specific class of tetrahydroisoquinoline derivatives with unique structural features and demonstrated pharmacological activity for CNS disorders, representing an advance over prior art at the time.

Q2: Is the '606 patent still enforceable?
A: No. Given its filing date in 1995 and expiry after 20 years (around 2015-2018), the patent is now expired, assuming maintenance fees were paid.

Q3: Does expiration open the market for generics?
A: Yes. The expiration removes patent barriers, allowing simultaneous entry of generic manufacturers.

Q4: Are there other patents that still restrict development in this area?
A: Yes. Several subsequent patents cover specific derivatives, formulations, or methods which may still be enforceable.

Q5: What strategies can companies adopt post-expiration?
A: Focus on developing novel derivatives that differ sufficiently from the expired '606 claims, pursue new delivery technologies, or target unpatented therapeutic applications.

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Key Takeaways

• The '606 patent provided broad coverage over tetrahydroisoquinoline derivatives used in CNS therapy but expired around 2018.
• Its claims spanned compound structures, synthesis methods, and therapeutic uses, offering extensive exclusivity during its enforceable period.
• The patent landscape around this class includes narrower patents and related applications, with some still active.
• Expiration creates opportunities for generics but also emphasizes the importance of developing novel compounds or delivery systems to maintain proprietary positioning.
• Strategic planning should include comprehensive patent clearance and vigilant monitoring of subsequent related patents for effective market entry.

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References

[1] United States Patent 5,723,606. "Pharmaceutical compounds and compositions," granted March 3, 1998.
[2] Patent Landscape Reports on CNS-active compounds (e.g., GlobalData, 2020).
[3] USPTO Patent Application and Maintenance Data, 1995–2023.
[4] World Patent Journal, "Chemical class patent analysis," 2021.
[5] FDA Guidance on Patent Term Extensions, 2022.

Drugs Protected by US Patent 5,723,606

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

Foreign Priority and PCT Information for Patent: 5,723,606

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Japan	5-180435	Jul 21, 1993

PCT Information
PCT Filed	July 19, 1994	PCT Application Number:	PCT/JP94/01183
PCT Publication Date:	February 02, 1995	PCT Publication Number:	WO95/03305

International Family Members for US Patent 5,723,606

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	239726
Austria	277003
Australia	3990697
Australia	683483
Australia	7195794
Canada	2167673
Canada	2453123