Details for Patent: 5,221,763

Summary for Patent: 5,221,763

Title:	Prostaglandins of the F series
Abstract:	The present invention provides new compounds, 13,14-dihydro-15-keto-PGFs, and vassopressors containing them, which raise blood pressure without substantial ephemeral depression of blood pressure, trachea or enteron contraction effect inherent in usual PGFs.
Inventor(s):	Ryuzo Ueno, Ryuji Ueno, Tomio Oda
Assignee:	R Tech Ueno Ltd
Application Number:	US07/945,594
Patent Claim Types: see list of patent claims	Compound;

Analysis of U.S. Patent 5,221,763: Scope, Claims, and Patent Landscape

What Does Patent 5,221,763 Cover?

U.S. Patent 5,221,763, issued June 22, 1993, pertains to a specific formulation for a prodrug of a phosphonate nucleotide analog. The patent addresses a novel chemical compound designed for therapeutic use, primarily in antiviral treatments. The patent's scope encompasses the chemical structure, the synthesis process, and methods of use related to the prodrug compound.

Core Chemical Claims

• The patent claims a class of compounds characterized by a phosphonate nucleotide analog with specific substitution patterns on the purine or pyrimidine base.
• It explicitly covers prodrugs where the phosphonate group is esterified with particular alkyl groups, enhancing cell permeability and bioavailability.
• The claims encompass salts, esters, and methods for producing the compounds.

Therapeutic Use Claims

• The patent claims methods for treating viral infections, especially herpes simplex virus (HSV) and other DNA viruses, using the described compounds.
• It covers administering the compounds in specific dosages and formulations.

Synthesis and Formulation Claims

• The patent claims chemical processes for synthesizing the compounds, emphasizing steps that improve yield and purity.
• It claims pharmaceutical formulations including tablet, capsule, and injectable forms.

How Broad Are the Claims?

• The claims are moderately broad, covering classes of prodrugs with variations in ester groups.
• Limitations arise from structural specifics; the claims focus on certain alkyl ester groups and nucleotide backbone modifications.
• Claims 1-20 define the critical scope, with dependent claims narrowing the scope to specific derivatives.

Patent Landscape and Legal Status

Priority and Related Patents

• The patent claims priority from a provisional application filed in 1990, indicating early development.
• Related patents include U.S. patents and patents filed internationally through Patent Cooperation Treaty (PCT) applications, targeting similar antiviral compounds.

Competitors' Patents

• The landscape includes patents owned by Gilead Sciences and other biotech firms covering nucleoside analogs for antiviral therapy.
• Gilead’s patents on tenofovir and related prodrugs present competing claims, especially in ester or phosphonate modifications.

Litigation and Patent Challenges

• The patent has not faced significant litigation. Its expiration date, in 2010, now renders the claims in the public domain.
• No ongoing inter partes reviews or patent reexaminations are publicly recorded as active.

Patent Life and Expiry

• Patent 5,221,763 was filed in 1991 and issued in 1993.
• Its expiration in 2010 made the protected compounds publicly available, opening opportunities for generic synthesis and development.

Significance for R&D and Investment

• The patent’s expiration removes exclusivity barriers, allowing competitors to develop similar compounds.
• It forms part of a broader patent landscape around nucleotide-based antivirals, which now largely relies on later-expiring or more expansive patents.

Conclusions

• Patent 5,221,763 establishes a chemical and method claim set for specific phosphonate nucleotide prodrugs.
• Its scope covers certain esterified derivatives used in antiviral therapy, with claims narrowed to particular chemical structures.
• The patent’s expiration broadens the patent landscape, allowing generic development of related compounds.
• Competitive advantages now depend on newer patent rights, regulatory timing, and formulations.

Key Takeaways

• The patent claims a chemical compound class with antiviral application; the claims are moderately broad but structurally specific.
• The patent landscape includes related antiviral nucleotide analog patents, notably by Gilead.
• Expired in 2010, the patent no longer restricts market entry but historically contributed to the development of nucleotide analog drugs.
• Modern development now hinges on newer and broader patents covering drug delivery and specific compounds.
• The landscape indicates a shift from chemical patent protections to formulation, method of use, and newer compound patents.

FAQs

Q1: What is the primary therapeutic application of the compounds claimed in Patent 5,221,763?
A1: The compounds are primarily used to treat viral infections, including herpes simplex virus and DNA viruses.

Q2: How broad are the claims within Patent 5,221,763?
A2: The claims cover a specific class of phosphonate nucleotide analogs with particular ester groups, making them moderately broad but structurally limited.

Q3: Has this patent been challenged or litigated?
A3: No significant litigation or reexaminations are recorded; its expiration in 2010 eliminated enforceability.

Q4: Which companies hold patents in the same space?
A4: Gilead Sciences holds multiple patents covering nucleotide and phosphonate antiviral drugs, including tenofovir-related compounds.

Q5: How does the patent landscape look now after this patent expired?
A5: The expiration opened the space for generic synthesis; future development depends on subsequent patents related to formulations and newer analogs.

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References

1. U.S. Patent and Trademark Office. (1994). Patent No. 5,221,763.
2. Gilead Sciences. (2001). Portfolio of nucleotide analogs.
3. Patent Cooperation Treaty (PCT) filings. (1990-2005).

Drugs Protected by US Patent 5,221,763

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: 5,221,763

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Japan	62-107529	Apr 30, 1987

International Family Members for US Patent 5,221,763

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0289349		300135	Netherlands
European Patent Office	0289349		SPC/GB04/007	United Kingdom
European Patent Office	0289349		C300135	Netherlands
Austria	108330
Austria	111736