How to Make Hard-to-Absorb Medicines Easier for the Body to Use
A method for mixing specific chemical compounds with surfactants to help the body absorb them more effectively.
Original patent title: “Readily absorbed pharmaceutical composition”
A method for mixing specific chemical compounds with surfactants to help the body absorb them more effectively. Granted to Green Cross Corp Japan in 1991 with 14 claims and 16 forward citations.
Key facts
Coverage
What does this patent actually cover?
This patent describes a way to improve how the body absorbs a class of chemicals called benzoyl urea compounds. These compounds are often difficult for the body to process because they do not dissolve well in water. By mixing these compounds with specific nonionic surfactants—substances that help bridge the gap between water and oil—and grinding them into tiny particles (0.2 to 10 micrometers), the inventors created a formula that is much easier for the body to take up. The process involves wet-milling the mixture, often using glass beads, to ensure the particles are small enough to be effective.
The gap
What does this patent NOT cover?
- Does not cover benzoyl urea compounds outside the specific chemical structure defined in claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1.
- Does not cover the use of ionic surfactants, which have a different chemical charge profile.
- Does not cover methods of administration that do not rely on this specific particle-size reduction process.
- Does not cover the synthesis of the benzoyl urea compound itself, only the composition and its preparation.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation lies in the combination of mechanical wet-milling with specific nonionic surfactants to stabilize the resulting micro-particles, preventing them from clumping back together and ensuring consistent absorption.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Formulations for agricultural pesticides
Experimental drug delivery systems for poorly soluble compounds
Why it matters
The bigger picture
Many potent drugs fail in clinical trials simply because the body cannot absorb them efficiently. This patent addresses the 'bioavailability' problem, which is a major hurdle in pharmaceutical development. By providing a standardized way to formulate these compounds, it allows researchers to turn promising chemical candidates into viable, usable medicines.
Filed
July 27, 1989
Granted
March 26, 1991
Market context
Who's building on this
Companies in this space
Pharmaceutical and agrochemical companies continue to refine drug delivery systems using similar wet-milling and surfactant-stabilization techniques. The principles of particle size reduction and solubility enhancement remain foundational to modern drug formulation science.
Market impact
This patent contributed to the body of knowledge regarding solubility enhancement for hydrophobic drugs. It helped standardize methods for processing difficult-to-dissolve compounds, which is a critical step in the development of many modern oral medications and specialized chemical treatments.
Claim 1 — Plain English
What this patent covers
This patent describes a way to improve how the body absorbs a class of chemicals called benzoyl urea compounds. These compounds are often difficult for the body to process because they do not dissolve well in water. By mixing these compounds with specific nonionic surfactants—substances that help bridge the gap between water and oil—and grinding them into tiny particles (0.2 to 10 micrometers), the inventors created a formula that is much easier for the body to take up. The process involves wet-milling the mixture, often using glass beads, to ensure the particles are small enough to be effective.
The clever bit
The innovation lies in the combination of mechanical wet-milling with specific nonionic surfactants to stabilize the resulting micro-particles, preventing them from clumping back together and ensuring consistent absorption.
What it does not cover
- Does not cover benzoyl urea compounds outside the specific chemical structure defined in claim 1.
- Does not cover the use of ionic surfactants, which have a different chemical charge profile.
- Does not cover methods of administration that do not rely on this specific particle-size reduction process.
- Does not cover the synthesis of the benzoyl urea compound itself, only the composition and its preparation.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
25/40
Moderately cited
Claim breadth
9/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$41K – $130K
Midpoint $81K · expired or expiring · industry ×3.0
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
14 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Kondo, N., Yokoyama, K., Yamada, N., Nakajima, T., Watanabe, M., Sugi, H., Haga, T., & Koyanagi, T. (1991). How to Make Hard-to-Absorb Medicines Easier for the Body to Use (U.S. Patent No. 5,002,952). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/5002952/duragesic-fentanyl-patch
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How to Make Hard-to-Absorb Medicines Easier for the Body to Use cover?
A method for mixing specific chemical compounds with surfactants to help the body absorb them more effectively.
Who owns patent US 5002952?
Green Cross Corp Japan owns this patent, granted in 1991.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 5002952 cited by?
This patent has been cited by 16 later patents that build on its ideas.
What problem does this patent solve?
Many potent drugs fail in clinical trials simply because the body cannot absorb them efficiently. This patent addresses the 'bioavailability' problem, which is a major hurdle in pharmaceutical development. By providing a standardized way to formulate these compounds, it allows researchers to turn promising chemical candidates into viable, usable medicines.
What does this patent NOT cover?
Does not cover benzoyl urea compounds outside the specific chemical structure defined in claim 1.
Patent monitoring