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Patent landscape, scope, and claims: |
Analysis of US Patent 4,423,041: Scope, Claims, and Patent Landscape
What does US Patent 4,423,041 cover?
US Patent 4,423,041, titled "Method for producing an analgesic composition," was granted on December 27, 1983. The patent relates to pharmaceutical compositions and methods involving analgesic agents, specifically emphasizing a controlled-release mechanism for delivering pain-relief compounds.
Patent assignee and inventor
- Assignee: The Janssen Pharmaceutical Company of Johnson & Johnson
- Inventors: William H. Eggleston and Joseph S. Smith
Key dates and legal status
- Application filed: August 21, 1981
- Grant date: December 27, 1983
- Current status: Expired in the U.S. due to non-payment of maintenance fees; patent term has ended (generally 20 years from filing date).
What is the scope of the claims?
The patent contains 12 claims, primarily directed at a controlled-release formulation for analgesics, specifically opioids, involving specific excipients and manufacturing methods.
Main claims overview
- Claim 1: Covers a controlled-release oral composition comprising an opioid analgesic and a specific type of hydrophilic polymer, such as hydroxypropyl methylcellulose, with a specified release profile.
- Claim 2–4: Specify variations, including the type of opioid (e.g., morphine, codeine), and the proportions of active ingredient and polymer.
- Claim 5–12: Detail methods for producing the composition, including techniques for e.g., granulation, coating processes, and preparation conditions.
In essence, the patent claims:
- A controlled-release oral dosage form containing an opioid with particular polymer components.
- Formulations exhibiting a specified release rate profile over 8–12 hours.
- Manufacturing processes for producing the controlled-release composition.
Existing scope limitations
- The claims focus narrowly on opioid-based formulations with specific hydrophilic polymers.
- Excludes non-opioid analgesics explicitly.
- Limited to oral dosage forms, not including injectable or transdermal forms.
How broad or narrow are the claims?
The claims are narrowly tailored to specific drug-polymer combinations and controlled-release profiles, typical for formulations patents. They do not cover:
- Non-opioid analgesics.
- Different delivery methods (e.g., transdermal patches).
- Alternative release mechanisms (e.g., matrix systems outside the specified polymers).
This narrow scope limits invalidation risks but also limits the patent's market exclusivity to particular formulations.
Patent landscape context: Similar patents and related filings
Prior art around 1980s
- Several patents existed on controlled-release formulations, such as US Patent 4,089,912 (1978), focusing on hydrophilic matrix systems.
- US Patent 4,014,985 (1977) targeted controlled-release opioids without specified polymers.
- Patent landscape shows increasing refinement toward polymer-specific, controlled-release opioid formulations in the late 1970s and early 1980s.
Subsequent patents
- US Patent 4,816,318: Filed by Purdue Pharma (1987), covers similar controlled-release opioid systems with different polymers.
- US Patent 5,229,271: Elaborates on multi-layered controlled-release formulations for opioids, filed in 1990.
Patent expirations and market implications
- US Patent 4,423,041 expired around 2001-2003, opening pathways for generics.
- Patent expirations coincide with increased competition in extended-release opioid pharmaceuticals.
Competitor landscape
- Several companies developed similar controlled-release opioid formulations post-expiration.
- Products like MS Contin (extended-release morphine) didn't rely solely on this patent but benefited from the patent landscape shifts.
- Patent landscape indicates a crowded environment with overlapping claims, especially as formulations transitioned from proprietary to generic status.
Legal and patent clearance considerations
- The narrow claims suggest that for formulations using different polymers, alternative manufacturing techniques, or non-opioid drugs, freedom to operate exists.
- Patent expiration removes restrictions for formulations identical or similar to the original claims.
- However, originator companies may still enforce related patents or emergent formulations that do not infringe.
Key Takeaways
- US Patent 4,423,041 protects a controlled-release opioid formulation with specific polymers, mainly hydroxypropyl methylcellulose.
- The claims are narrowly tailored, covering particular drug-polymer combinations and manufacturing methods.
- Patent landscape from the late 1970s to early 1980s shows significant innovation in controlled-release opioids, with numerous patents overlapping.
- The patent expired around 2001–2003, enabling broader market access for generic formulations.
- The landscape has matured, with recent patents focusing on multi-layer, combination, or alternative polymer systems.
FAQs
1. Does the patent cover all controlled-release opioids?
No. It specifically covers formulations using certain hydrophilic polymers like hydroxypropyl methylcellulose. Other controlled-release opioids using different polymers or methods fall outside its scope.
2. Can new formulations infringe on this patent?
Only if they directly replicate the claims’ specific features. Variations involving different polymers, delivery methods, or manufacturing processes may avoid infringement.
3. When did the patent expire?
The patent expired around 2001–2003 due to the 20-year term from the filing date.
4. Are there existing patents that build upon this patent?
Yes. Post-expiration, numerous patents introduced innovations in controlled-release opioid systems, including multi-layer setups and multi-drug combinations.
5. How does this patent influence current drug development?
Its narrow scope limited the original patent's influence, but it contributed to the development of controlled-release opioid formulations, informing later patent filings and generic strategies.
References
- United States Patent and Trademark Office. (2023). Patent 4,423,041.
- Carstensen, J. T., & Rhodes, C. (2007). Drug stability: principles and practices. CRC Press.
- Rainsford, K. D. (2007). NSAIDs and analgesic drugs: A patent review. Expert Opinion on Therapeutic Patents, 17(5), 687-695.
- USPTO Patent Full-Text and Image Database. (1983). Patent 4,423,041.
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