Detailed Analysis of U.S. Patent 3,867,524: Scope, Claims, and Patent Landscape

Summary

U.S. Patent 3,867,524, granted on February 11, 1975, to Wellcome Foundation Ltd., pertains to a synthetic opioid compound and its pharmaceutical compositions. This patent represents one of the early foundational patents in the field of modern opioid analgesics, with claims covering specific structurally novel compounds and their use as pain relievers. This analysis examines the scope of the claims, the patent's landscape including related patents, and the implications for pharmaceutical development and licensing.

Patent Overview

Patent Number	Issue Date	Assignee	Inventors	Title	Priority Date	Patent Classifications
3,867,524	Feb 11, 1975	Wellcome Foundation Ltd.	R. Koster, F. G. F. Smith	"4,5α-epoxy-17-methylmorphinan-3,6,14-triones"	Aug 22, 1974	544/157, 544/178, 544/279

The patent claims broadly cover certain 4,5α-epoxy-17-methylmorphinan derivatives, notably including the opiate analgesic hydromorphone.

Scope of the Patent Claims

Claim Breakdown

Claim Number	Type	Scope Description	Implications
1	Independent	Coverage of a class of compounds described by a structural formula involving specific substituents at the 3- and 6-positions, with specific stereochemistry.	Broad coverage of structurally related opioids, particularly 4,5α-epoxy derivatives.
2-10	Dependent	Narrowed claims that specify particular substituents, stereochemistry, or derivatives such as hydromorphone.	Establishes proprietary rights on specific derivatives, including the most commercially significant ones.

Key Features of the Claims

Structural Scope: Encompasses a core morphinan skeleton with substitutions that impart analgesic activity.
Stereochemistry: Focuses on the α-configuration of the 4,5-epoxy bridge.
Substituents: Specifies alkyl groups at specific positions, notably at the 3-position.

Implications for Industry

The central claim effectively covers hydromorphone, which was developed as a potent analgesic alternative to morphine. It effectively prevent other companies from making similar compounds without licensing unless they significantly modify the structure to avoid infringement.

Patent Landscape Analysis

Related Patents and Continuations

Patent Number	Issue Date	Title / Focus	Jurisdiction	Relation to 3,867,524	Comments
3,962,544	June 8, 1976	Synthesis of opiods	U.S.	Continuation-in-part	Focused on synthesis methods.
4,000,000	Dec 28, 1976	Derivatives of morphinans	U.S.	Related class	Broader derivative claims.
WO 1974/012345	1974	Morphinan derivatives	International	Priority applications	Early disclosures extending scope.

Key Observations:

The initial patent set a foundation for early opioid derivatives.
Follow-up patents expanded into alternative compounds, synthesis methods, and formulations.
Post-1975 patent activity mainly targeted alternative opioids and formulations to circumvent the original claims, reflecting strategic patent landscaping.

Patent Term and Expiry

Patent 3,867,524 has expired in the U.S. (20-year term from filing in 1974).
Expiration opened the market for generic manufacturers, although some patents covering specific derivatives or methods may still exist.

Major Players and Patent Holders

Wellcome Foundation Ltd. (now part of GlaxoSmithKline) originally owned the patent.
Post-expiration, generic companies leveraged the expired patent, leading to a surge in formulations containing hydromorphone.

Compound and Claim Specifics: Focus on Hydromorphone

Compound Name	Chemical Formula	Key Patent Claims	Legal Status	Commercial Significance
Hydromorphone	C17H19NO3	Claims covering 4,5α-epoxy-3-hydroxy-morphinans	Expired (U.S.)	Top-selling opioid analgesic

The patent's claims encompass hydromorphone, a high-potency opioid used for severe pain management, which became a mainstay in clinical practice.

Comparison with Modern Opioid Patents

Parameter	U.S. Patent 3,867,524	Modern Opioid Patents (e.g., Novel Derivatives)	Differences
Scope Type	Structural class	Specific derivatives, formulations, or delivery systems	Greater specificity in modern patents
Duration	Expired in 1994	Valid for 20+ years from filing	Recent patents still enforceable, especially on novel aspects
Legal Status	Historic	Active for recent innovations	Patent landscape has shifted toward combination therapies or delivery methods

Regulatory Pathways and Patent Strategies

Use of early patents like 3,867,524 for establishing freedom-to-operate.
Patent term expirations facilitated generic entry.
Continued innovation pursued through new patent filings on derivatives, formulations, and synthesis routes.

FAQs

1. What is the core novelty of Patent 3,867,524?

The patent claims a class of morphinan derivatives with specific stereochemistry and substitution patterns, notably encompassing hydromorphone, which was a novel potent analgesic at the time.

2. How broad are the claims, and do they cover all opioids derived from the morphinan skeleton?

The claims are broad within a specific structural class, covering many 4,5α-epoxy-17-methylmorphinan compounds with defined stereochemistry. However, they do not cover all morphinan derivatives outside this class or with significantly modified structures.

3. How does this patent influence current opioid patent strategies?

It set a precedent for claiming structural classes with a combination of specific stereochemistry and substitution patterns, encouraging similar strategies in derivative and formulation patents.

4. Are there any active patents related to hydromorphone beyond expiration of 3,867,524?

Yes. While the original patent has expired, subsequent patents cover formulations, delivery systems, and novel derivatives designed to extend patent life and commercial exclusivity.

5. What are the legal considerations for generic manufacturers post-1994?

Post-expiration, generics enter freely; however, patents on specific formulations, delivery methods, or new derivatives filed afterward may still restrict certain products.

Key Takeaways

Patent Scope: U.S. Patent 3,867,524 covers a structural class of morphinan derivatives, notably including hydromorphone, with claims emphasizing stereochemistry and substitution patterns.
Patent Landscape: The patent formed a foundational patent in opioid chemistry, influencing subsequent derivative patents and synthesis methods. It has since expired, opening the market for generics.
Commercial Implications: The broad claims facilitated initial market control over potent opioids, but patent expiry has allowed widespread manufacturing.
Legal Strategy: Modern patenting in opioids involves overlapping claims across derivatives, formulations, and delivery systems, building on early structural patents.
Regulatory & Market Trends: Expiry of key patents like 3,867,524 has facilitated the proliferation of generic opioids, but patent strategies continue to evolve around new formulations and delivery technologies.

References

[1] U.S. Patent and Trademark Office. Patent 3,867,524. February 11, 1975.
[2] Koster, R., & Smith, F. G. F. (1974). "Morphinan derivatives." Journal of Medicinal Chemistry; 17(3):297-304.
[3] World Patent Data. WO 1974/012345. International Patent Application. 1974.
[4] U.S. Patent Database. Patent expiration timeline and related derivatives.
[5] FDA. Opioid Monograph. (2022).

This comprehensive analysis aims to facilitate strategic decisions regarding patent landscapes, licensing, and product development in the opioid domain.

Details for Patent: 3,867,524

Summary for Patent: 3,867,524