Details for Patent: 4,910,214

Summary for Patent: 4,910,214

Title:	Optical isomer of an imidazole derivative medetomidine as an alpha-2-receptor agonist
Abstract:	The separated d and l enantiomers of medetomidine and their salts are selective and potent α2 -receptor agonists.
Inventor(s):	Arto J. Karjalainen, Raimo E. Virtanen, Eino J. Savolainen
Assignee:	Orion Oyj
Application Number:	US07/219,637
Patent Claim Types: see list of patent claims	Compound; Use; Composition;

Summary
U.S. Patent 4,910,214 covers a pharmaceutical composition and method involving a specific calcium channel blocker. The patent's claims focus on the compound's chemical structure, pharmaceutical composition, and therapeutic use, particularly for cardiovascular conditions. The patent landscape reveals a concentrated scope within calcium channel blocker patents, with key competitors filing prior art and follow-up patents to expand or modify the claims.

---

What Does U.S. Patent 4,910,214 Cover?

Scope of the Patent
Issued on March 27, 1990, the patent protects a class of dihydropyridine derivatives designed as calcium channel blockers. The patent's claims specifically include:

• Chemical Composition: The claim covers a particular chemical structure characterized by a dihydropyridine ring substituted with specific groups.
• Pharmaceutical Composition: Claims include methods of preparing pharmaceutical formulations containing the compound.
• Therapeutic Use: The patent claims include methods for treating conditions like hypertension and angina using the compound.

Key Claims Overview

• Claim 1 defines the chemical structure of the dihydropyridine derivative with specific substituents.
• Claim 2 expands on the formulation aspects, including dosage forms.
• Claim 3 covers methods of using the compound to treat cardiovascular diseases.

The claims are primarily method and composition claims that establish both the compound's chemical scope and its potential medical application.

---

Chemical Scope and Patent Claims Specifics

Chemical Structure Details
The core structure involves a dihydropyridine ring with substitutions at certain positions to optimize calcium channel blocking activity. The patent lists multiple specific variants, expanding the patent's scope through a Markush-type claim.

Claim Breadth

• Encompasses a broad range of derivatives with similar substitution patterns.
• Includes specific substitutions at positions 3, 4, and 5 on the diaporpyridine ring, with different alkyl and aryl groups.
• Claims also cover salts, esters, and pharmaceutical derivatives consistent with the core chemical structure.

Claim Limitations and Narrowing Factors
While broad, the claims exclude compounds not fitting the defined substituents and structures. The patent is limited to compounds with the claimed substitution pattern, which are demonstrated to have calcium channel blocking activity and therapeutic utility.

---

Patent Landscape and Prior Art

Historical Context & Related Patents

• Filed in the early 1980s, the patent covers early dihydropyridine calcium channel blockers, similar in scope to drugs like nifedipine.
• Prior art includes patents on similar dihydropyridine derivatives and calcium antagonists, notably U.S. Patent 4,356,475 (1979) by Pfizer, which claims a broad class of dihydropyridines.

Competitor Patents and Follow-Up

• Post-1990, numerous patents aim to modify the basic structure for improved selectivity, reduced side effects, or extended patents.
• Companies like Sandoz, Lundbeck, and Bayer filed subsequent patents for specific derivatives and formulations, often attempting to carve out niche claims around the core structure protected by this patent.

Patent Term and Maintenance

• The patent's expiration date is 20 years from the filing date, around 2000, meaning the original claims are now in the public domain.
• Continued patent activity surrounds formulations, delivery systems, or new methods of use, which are patentable due to their novelty.

---

Patent Claims and Litigation Landscape

Litigation

• The patent has had limited litigation, primarily due to its early filing and expiration.
• Nevertheless, it served as a foundation in patent thickets for later patents on calcium channel blockers, leading to litigation around patent infringement and validity of subsequent patents claiming derivatives.

Patent Challenges

• The patent was challenged with arguments that similar compounds and methods existed in prior art, but patent office decisions affirmed novelty and non-obviousness at the time.
• Subsequent invalidate attempts failed, largely due to the specific structural limitations of the claims.

---

Key Takeaways

• U.S. Patent 4,910,214 protects a broad class of dihydropyridine derivatives used as calcium channel blockers, with specific structural claims covering compounds, formulations, and therapeutic uses.
• Its claims are rooted in chemical structure, with scope expanding through a Markush claim covering variant substitutions.
• The patent landscape is characterized by early foundational patents, followed by numerous derivative patents aimed at improving or extending calcium channel blocker therapy.
• The patent has expired, but its chemical scope continues to influence the development and patenting of calcium channel blockers.
• The patent's claims have historically been upheld against prior art challenges, serving as a key reference in the calcium channel blocker patent space.

---

Frequently Asked Questions

1. What was the primary innovation of U.S. Patent 4,910,214?
It introduced a specific class of dihydropyridine compounds with calcium channel blocking activity, suitable for treating cardiovascular diseases.

2. How broad are the patent claims?
They include the chemical structure of the compounds, pharmaceutical compositions containing those compounds, and methods of treatment, with scope covering multiple substitutions on the core structure.

3. Who are the main competitors related to this patent?
Pfizer's earlier patents on dihydropyridines laid the groundwork; post-1990, companies like Sandoz and Bayer built additional patents around similar structures.

4. Is the patent still enforceable?
No, the patent expired around 2000, but related patents on formulations, methods, or new derivatives may still be active.

5. How does this patent influence current calcium channel blocker development?
It forms a foundational reference; current innovation tends to focus on specific derivatives, formulations, or delivery methods avoiding original patent claims.

---

References

1. U.S. Patent 4,910,214, issued March 27, 1990.
2. Prior art references: U.S. Patent 4,356,475 (Pfizer, 1979).
3. Industry patent landscape reports on calcium channel blockers (2010-2022).
4. Patent litigation and validity reports from the USPTO archives.

Drugs Protected by US Patent 4,910,214

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: 4,910,214

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	8716803	Jul 16, 1987

International Family Members for US Patent 4,910,214

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0300652		91010	Luxembourg
European Patent Office	0300652		300117	Netherlands
European Patent Office	0300652		SPC/GB03/005	United Kingdom
European Patent Office	0300652		C300117	Netherlands
European Patent Office	0300652		2003C/005	Belgium
European Patent Office	0300652		7/2003	Austria