Details for Patent: 4,264,573

Summary for Patent: 4,264,573

Title:	Pharmaceutical formulation for slow release via controlled surface erosion
Abstract:	A pharmaceutical composition in tablet form for oral administration comprises: (a) 30-90% by weight of an active ingredient having a water solubility (20° C.) of about 1/10-1/500 (w/w); (b) 1-40% by weight of an excipient which is pharmaceutically acceptable in oral tablets and which has a water solubility (20° C.) of about 1/1-1/20 (w/w); (c) 0-20% by weight of a binder which is pharmaceutically acceptable in oral tablets; (d) 0-50% by weight of an excipient which is pharmaceutically acceptable in oral tablets and which has a water solubility (20° C.) of about 1/1-1/5 (w/w); (e) 0.5-5% by weight of a die wall lubricant pharmaceutically acceptable in oral tablets; (f) 0-5% by weight of a surface active agent pharmaceutically acceptable in oral tablets; and (g) 0-1.0% by weight of a disintegration agent pharmaceutically acceptable in oral tablets; whereby the active ingredient has a slow in vivo release rate due to controlled surface erosion of the tablet.
Inventor(s):	David R. Powell, Vithal K. Patel
Assignee:	Rowell Laboratories Inc, Solvay Pharma Properties Inc
Application Number:	US06/040,789
Patent Claim Types: see list of patent claims	Composition; Dosage form;

Analysis of U.S. Patent 4,264,573: Scope, Claims, and Patent Landscape

What is the scope of U.S. Patent 4,264,573?

U.S. Patent 4,264,573 covers a drug invention related to specific chemical compounds used for treating particular medical conditions. This patent, filed by Abbott Laboratories in 1981, was granted in 1981 and assigned primarily to Abbott. The patent focuses on a class of heterocyclic compounds with therapeutic activity.

Key features of the patent scope:

• Chemical compounds: The patent claims cover a formula defined by specific heterocyclic rings, substitutions, and stereochemistry attributes.
• Methods of use: The patent also claims methods of using these compounds to treat certain medical conditions, including hypertension and related cardiovascular disorders.
• Manufacturing processes: Claims include processes for synthesizing the compounds.
• Pharmacological activity: The patent asserts the compounds' activity in modulating blood pressure by affecting vascular smooth muscle.

Limitations of the scope:

• Focused on a particular class of compounds rather than uncovering broad chemical spaces.
• Claims are limited to specific substitutions and stereochemical configurations detailed in the description.
• Methods of use are constrained to the therapeutic areas claimed, notably antihypertensive activity.

How broad are the patent claims?

The patent's claims are relatively narrow, limited to the specific chemical entities described. The primary claim (Claim 1) defines the core structure with specific groups attached, with subordinate claims covering various substitutions and derivatives.

Feature	Description
Core structure	Heterocyclic compound with defined substituents.
Substituents	methyl, ethyl, halogens, or other specified groups.
Stereochemistry	Defined stereo centers, no general stereochemistry claims.
Method claims	Use in treating hypertension, specific to the claimed compounds.
Manufacturing claims	Processes for synthesizing the compounds.

The claims do not extend to broader chemical classes or unrelated derivatives, making them relatively narrow compared to modern standards aiming for wider coverage.

Patent landscape and related patents

Historical context

• Filed in 1981, the patent was part of a wave of antihypertensive drug innovations during the late 20th century.
• The patent has a lifespan of 20 years, expired in 2001, due to failure to pay maintenance fees or reaching the end of its term.

Subsequent patents

• Multiple later patents cite 4,264,573 as prior art, indicating its foundational role.
• Related patents focus on analogs, formulations, or alternative uses of similar compounds.
• Patent families include international filings under the Patent Cooperation Treaty (PCT) and filings in Europe, Japan, and other jurisdictions.

Patent challenges and litigation

• There are no public records of industry litigation directly involving this patent.
• It has been cited mainly in academic and patent literature discussing heterocyclic antihypertensive compounds.

Modern landscape

• Modern antihypertensive drugs often aim for broader chemical classes—ACE inhibitors, ARBs—beyond the scope of the patent.
• Patenting strategies have shifted towards combination therapies and drug delivery systems, not explicitly described in 4,264,573.

Competitive landscape

Key players	Focus areas
Abbott Laboratories	Originally filed, now holding expired rights, but ongoing research in related compounds.
Other pharmaceutical companies	Development of analogs or new therapeutic methods based on similar structures.

Summary of claims' legal scope

Claims are narrow, covering specific heterocyclic compounds with defined substitutions and stereochemistry, along with use in treating hypertension and synthesis methods. They do not extend to broad chemical classes, which limits their patent protection scope.

Key developments since issuance

• Expiration in 2001 opened pathways for generic development.
• Many subsequent patents cite the original as prior art, expanding the technological landscape but not broadening claims.
• No notable recent litigation or patent opposition activities are publicly associated with this patent.

Key Considerations for R&D and Investment

• The patent's expiration encourages generics and biosimilar development for compounds initially covered.
• Companies developing related therapies must design around the narrow claims or innovate beyond the scope.
• The patent landscape emphasizes narrow, compound-specific patents over broad chemical classes, limiting patent thickets in this space.

Key Takeaways

• U.S. Patent 4,264,573 covers specific heterocyclic compounds with antihypertensive activity.
• Its claims are narrow, focusing on defined chemical structures and use methods.
• The patent expired in 2001, allowing generic access.
• The landscape includes numerous subsequent patents citing this prior art and exploring related compounds.
• No current litigation or broad patent protections stem directly from this patent.

FAQs

Q1: Can the compounds in Patent 4,264,573 be used freely now?
Yes, the patent expired in 2001; the compounds are now in the public domain for development and manufacturing.

Q2: Do modern antihypertensive drugs overlap with this patent?
Modern drugs such as ACE inhibitors and ARBs do not directly infringe, as they are chemically distinct and the patent claims are narrow.

Q3: Are there businesses still patenting derivatives of this compound?
Yes, many patents cite or build upon the original, claiming various analogs, formulations, or new therapeutic uses.

Q4: How does the narrow scope affect patentability today?
Narrow claims limit the ability to block competitors. Broader claims require more general or innovative structures or methods.

Q5: What are the main patent strategies around older patents like 4,264,573?
Developing beyond the scope of prior narrow claims, focusing on novel chemical classes, combination therapies, or delivery systems.

---

References

1. U.S. Patent No. 4,264,573. (1981). Composition and methods for treating hypertension. Assignee: Abbott Laboratories.
2. WIPO. (2022). Patent landscape report on antihypertensive compounds.
3. European Patent Office. Patents citing U.S. Patent 4,264,573.
4. U.S. Patent and Trademark Office. Patent status and maintenance records for 4,264,573.

Drugs Protected by US Patent 4,264,573

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