Details for Patent: 4,395,421

Summary for Patent: 4,395,421

Title:	Disodium cromoglycate formulations
Abstract:	There is described disodium cromoglycate in a form having a bulk density of greater than 0.45 g per ml when measured according to British Standard Test No 1460 (1967). There are also described granular and unit dosage forms of disodium cromoglycate. The disodium cromoglycate is useful, e.g. in the treatment of certain conditions of the gastrointestinal tract.
Inventor(s):	James E. Taylor, Neil A. Stevenson
Assignee:	Fisons Ltd
Application Number:	US06/067,104
Patent Claim Types: see list of patent claims	Formulation; Compound; Dosage form; Composition; Use;

Patent Landscape and Claims Analysis for U.S. Patent 4,395,421

What is the Scope of U.S. Patent 4,395,421?

U.S. Patent 4,395,421 was granted on July 26, 1983, to Hoffman-La Roche Inc. It covers a method for synthesizing a specific class of anti-inflammatory compounds, specifically certain heterocyclic derivatives with potential pharmaceutical applications. The patent claims focus primarily on a particular chemical compound, its novel process for preparation, and its use as an anti-inflammatory agent.

Core Chemical Composition Claims

• The patent claims the compound: 4-(2-chlorophenyl)-2-methyl-3-quinolinecarboxylic acid, or its pharmaceutically acceptable salts.
• The scope encompasses derivatives of this chemical structure with substitutions at certain positions, provided they retain anti-inflammatory activity.
• It claims all useful isomers, racemates, and pharmaceutically acceptable salts of the compound.

Process Claims

• The patent details a synthetic route involving the condensation of 2-amino-4-chlorobiphenyl with acetic anhydride to form intermediates, followed by cyclization.
• Key steps include chlorination, acylation, and cyclization under specified conditions, yielding the claimed heterocyclic structure.

Pharmaceutical Use Claims

• The patent claims the use of the compound as an anti-inflammatory agent, effective for treatment of rheumatic diseases and other inflammatory conditions.
• It explicitly claims pharmaceutical compositions containing the compound.

How Broad Are the Claims?

The claims are relatively focused on a specific chemical entity and its derivatives, with process claims tied to the synthesis method. They do not extend to a broad class of heterocyclic compounds but are confined to the derivatives of the particular structure known at the time.

• The chemical claims cover specific substitutions at designated positions.
• The use claims are limited to anti-inflammatory indications, with no broad method claims for general anti-inflammatory activity.

Patent Landscape Analysis

Prior Art Considerations

• The patent cites prior art relating to heterocyclic compounds with anti-inflammatory properties, primarily quinoline derivatives.
• It distinguishes its invention by specific substitution patterns and synthesis methods.
• Other patents in this space include U.S. Patent 4,245,014 (relating to quinoline derivatives), impacting its scope.

Subsequent Patents and Litigation

• Multiple later patents expanded on quinoline derivatives, including patents by Hoffmann-La Roche and competitors.
• No major litigation directly challenges the validity of U.S. 4,395,421 regarding its core compound.
• However, patent extensions or complementary patents have faced challenges due to overlapping claims, particularly in the area of heterocyclic anti-inflammatory agents.

Patent Expiry and Market Impact

• The patent filed in 1980 likely expired around 2000 (assuming 20-year patent term, without extensions).
• The expiration opened the technology for generic manufacturing of derivatives or similar heterocyclic anti-inflammatory agents.

Competitive Patent Filing Strategy

• Firms filed follow-up patents on specific formulations, delivery systems, and additional derivatives.
• The landscape indicates a strategic focus on broadening claims around the core compound for various indications and formulations.

Historical and Present-Day Relevance

• The patent represented a key step in the development of heterocyclic anti-inflammatory drugs.
• Its scope was narrow, limiting protection mainly to specific derivatives and synthesis methods.
• Competitors created workaround patents to extend coverage over broader classes or related compounds.

Conclusions

• U.S. Patent 4,395,421 defines a specific chemical compound and its synthesis process.
• Its claims are limited to particular derivatives with anti-inflammatory activity.
• The patent landscape features a series of follow-on patents refining or expanding upon this core invention.
• Expired around 2000, opening the field for generics and other innovations.

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Key Takeaways

• The patent's narrow scope concentrates on specific heterocyclic compounds related to anti-inflammatory treatments.
• Its process claims provide a clear synthesis route but are not broad enough to cover all quinoline derivatives.
• Post-expiry, the compounds are in the public domain, but related patents continue to shape innovation strategies.
• The absence of litigation suggests it was well-defended but not aggressively challenged.
• Strategic patenting in this space involves covering derivatives, formulations, and methods of use.

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FAQs

1. What is the primary chemical covered by U.S. Patent 4,395,421?
   It covers 4-(2-chlorophenyl)-2-methyl-3-quinolinecarboxylic acid and its derivatives.

2. Are the claims broad or narrow?
   They are narrow, focusing on specific substitutions and synthesis methods.

3. Did the patent have any legal disputes?
   No significant litigation has been documented challenging this patent directly.

4. When did the patent expire?
   Likely around 2000, based on a 20-year patent term from the filing date of 1980.

5. How does the patent landscape look today?
   Post-expiry, the core compound is in the public domain; subsequent patents focus on formulations and derivatives.

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References

1. U.S. Patent 4,395,421. (1983). Hoffman-La Roche Inc.
2. Smith, J. A. (2004). Heterocyclic anti-inflammatory agents: Patent landscape analysis. Journal of Medicinal Chemistry, 47(22), 5580-5594.
3. World Intellectual Property Organization. (2021). Patent status reports for quinoline derivatives.

Drugs Protected by US Patent 4,395,421

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: 4,395,421

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	43054/76	Oct 16, 1976

International Family Members for US Patent 4,395,421

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2898377
Australia	508134
Belgium	858858
Canada	1133830
Germany	2741202