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Patent landscape, scope, and claims: |
Scope, Claims, and US Patent Landscape for US Drug Patent 4,393,871
What does US 4,393,871 claim?
US 4,393,871 claims a vaginal, removable insertion device built as a water-catalyzed foamed urethane “sponge” that slowly releases an active agent in the vagina. The core actives are:
- A spermicide-foaming agent (claims 1, 4-8, 17-20)
- A separately loaded local-delivery drug (claims 2, 9-11, 12, 15, 21, 24)
- Optional pH-lowering acid (claims 3, 22)
The claims also cover formation methods for the foamed urethane sponge and delivery by insertion.
What is the claim scope by claim group?
1) Device claims tied to spermicide foaming + water-catalyzed foamed urethane
Claim 1 (independent device claim)
- A vaginal device for insertion and removal
- Comprises:
- Spermicide-foaming agent in dry weight about 10% to about 50%
- Water-catalyzed foamed urethane polymer from which the spermicide is slowly released during use
Claim 4
- Dry weight spermicide-foaming agent is at least 30%
Claim 5
- Spermicide-foaming agent is nonylphenoxy polyethoxyethanol
Claim 6
- Urethane polymer is water catalyzed from an isocyanate-capped hydrophilic polyoxyethylene polyol
Claim 7
- Device shape: flattened ball; one side has cervical os recess shaped to fit over the os
Claim 8
- Same as claim 4 (duplicative dependent limit)
Scope implications
- The independent anchor is not the foam chemistry alone. It is a structured combination:
1) Specific foam/release architecture: water-catalyzed foamed urethane
2) Specific loading type and ratio: spermicide-foaming agent at 10% to 50% dry weight
3) Kinetics promise embedded in claim: “slowly released during use”
2) Device claims that load additional local-delivery drugs
Claim 2 (dependent from claim 1)
- Adds: a drug for local delivery slowly released during use
Claim 9 (independent device claim for local drug administration with foam architecture)
- Device for local administration of a drug comprising:
- Drug (local delivery to vaginal area)
- Foaming agent in dry weight about 10% to about 50%
- Water-catalyzed foamed urethane polymer from which the drug is slowly released
Claim 10
- Drug selected from:
- anti-infectives
- anti-inflammatories
- estrogenic steroids
- progestational agents
- prostaglandins
Claim 11
- Shape: flattened ball; one side has cervix os recess
Scope implications
- Claim 9 broadens beyond a spermicide-specific agent by recasting the “foaming agent” as a component contributing to the sponge formulation while the drug release is tied to the urethane sponge.
- Claim 10 is limited to drug classes, not a complete list of molecules.
3) Device claims with explicit pH adjustment
Claim 3
- Adds: non-toxic acid lowering pH of the device to between 4.0 and 5.0
Scope implications
- Claim 3 does not require the acid to be tied to the drug or spermicide; it requires pH range of the device.
What method claims exist, and what do they cover?
4) Forming the drug-delivery sponge (general local-delivery device method)
Claim 12 (method)
- A method for forming the vaginal device
- Steps:
- Mix 10% to 50% by dry weight foaming agent with:
- water-catalyzed, foam-forming urethane prepolymer
- a dry agent for local delivery to the vaginal area
- Permit mixture to foam and form stable flexible sponge-like structure
- Sponge slowly releases the drug in vagina over time
Claim 13
- Shape: flattened ball; cervical os recess
Claim 14
- Foaming agent is a spermicide
Claim 15
- Drug class list same as claim 10:
- anti-infectives
- anti-inflammatories
- estrogenic steroids
- progestational agents
- prostaglandins
Claim 16
- Urethane prepolymer is isocyanate-capped hydrophilic polyoxyethylene polyol
Scope implications
- Claim 12 is a process claim that captures the manufacturing sequence that produces the claimed structure and release behavior.
5) Forming the spermicide sponge (spermicide as active and foaming agent)
Claim 17 (method for spermicide device)
- Mix:
- 10% to 50% by dry weight spermicide-foaming agent with
- water-catalyzed foam-forming urethane prepolymer
- Permit to foam to form stable flexible sponge-like structure
- Spermicide-foaming agent is slowly released in vagina
Claim 18
- Prepolymer is isocyanate-capped hydrophilic polyoxyethylene polyol
Claim 19
- Spermicide-foaming agent is nonylphenoxypoly ethoxyethanol
Claim 20
- Spermicide-foaming agent dry weight at least 30%
Claim 21
- Drug for local delivery is mixed with spermicide-foaming agent and prepolymer
Claim 22
- Non-toxic acid lowers device pH to about 4.0 to 5.5
Claim 23
- Shape: flattened ball; cervical os recess
Scope implications
- These method claims are tightly aligned with the device claims and appear designed to block:
- alternative formulations that avoid “device” wording
- alternative manufacturing routes that still produce the same sponge architecture
- omission of pH adjustment, given dependent claim 22
6) Delivery method by insertion
Claim 24
- Method of delivering an effective amount of a drug to vaginal area by inserting into human female vagina the device of claim 2
Scope implications
- Claim 24 is a use by insertion claim anchored to claim 2’s device composition (spermicide + drug + urethane sponge).
Key architectural elements that define infringement risk
From the claim set, the infringement boundary is built around 4 technical pillars:
A) Water-catalyzed foamed urethane sponge
- Appears in every core device and method claim.
- Defined as:
- “water-catalyzed foamed urethane polymer”
- and in method claims: “water-catalyzed foam-forming urethane prepolymer”
- with a specific chemistry option: isocyanate-capped hydrophilic polyoxyethylene polyol
B) Dry weight fraction of foaming/spermicide agent
- Repeated range: about 10% to about 50%
- Tightening dependent: at least 30%
C) Slow release “during use” / “over a period of time”
- Embedded in product and method claims; it functions as a claim limitation, not mere description.
D) Vaginal placement and removable delivery
- All device claims specify insertion and subsequent removal from human vaginal cavity.
Practical claim mapping (what must be present)
Device coverage matrix
| Feature |
Covered in |
Claim language effect |
| Vaginal insertable/removable device |
1-3, 7-8, 9-11 |
Mandatory structural/functional context |
| Water-catalyzed foamed urethane sponge |
1-3, 7-11, 9, 12-13 |
Central limitation |
| Foaming agent loading: 10% to 50% dry weight |
1, 9 |
Range limitation |
| Spermicide-foaming agent concept |
1, 4-8, 14, 17-20 |
Narrows “foaming agent” in these routes |
| Specific spermicide identity (nonylphenoxy polyethoxyethanol) |
5, 19 |
Narrow literal coverage |
| Local-delivery drug loaded and slowly released |
2, 9-11, 12, 15, 21, 24 |
Drug class and release requirement |
| pH-lowering non-toxic acid |
3, 22 |
Adds device pH range limitation |
| Shape: flattened ball with cervical os recess |
7, 11-13, 23 |
Adds anatomy fit limitation (dependent) |
What is the likely patent landscape around US 4,393,871?
1) Landscape by claim theme
US 4,393,871 sits at the intersection of:
- vaginal drug delivery systems
- spermicide delivery
- foam/sponge polymer matrices
- urethanes formed by in-situ foaming using water catalysis
- pH modification for vaginal compatibility
This claim structure typically overlaps (in practice) with patents covering:
- vaginal sponges using polymers or gels
- spermicide-containing intravaginal inserts
- controlled-release carriers (urethanes, polyurethanes, hydrogels)
- intravaginal pH adjustment formulations
- combination products that include both a spermicide and additional therapeutics
2) How competitors could design around (claim-specific)
Design-around strategies, based purely on claim limitations:
- Change the matrix chemistry
Avoid a “water-catalyzed foamed urethane polymer” (or the specific urethane prepolymer mechanism).
- Change the loading role
Avoid having the “foaming agent” be the same agent contributing to spermicide function at 10% to 50% dry weight, or avoid using a spermicide-foaming agent at 10% to 50%.
- Avoid slow-release sponge mechanism
Claims require “slowly released … during use” or “over a period of time.” Faster release or a non-sponge mechanism reduces literal coverage.
- Avoid the claimed pH range
For claim 3/22, use of a different pH-targeting strategy outside 4.0-5.0 (device) or 4.0-5.5 (method) reduces dependent claim risk.
- Avoid “flattened ball” cervical os recess anatomy
This is only in dependent claims (7, 11-13, 23), but it narrows the scope for those variants.
What does the claim set suggest about prosecution intent?
The claim structure shows deliberate layering:
- Two device independent claims:
- claim 1 (spermicide-foaming agent + urethane sponge)
- claim 9 (drug local delivery + foaming agent + urethane sponge)
- Multiple method pathways:
- general local drug + foaming agent (claim 12)
- spermicide-foaming agent specific (claim 17)
- optional drug addition (claim 21)
- Dependent refinements on identity and boundaries:
- spermicide identity (claim 5/19)
- urethane prepolymer identity (claim 6/16/18)
- spermicide loading threshold (claim 4/8/20)
- shape and os recess (claim 7/11-13/23)
- pH band (claim 3/22)
Litigation or enforcement posture (what claims support)
If enforced, US 4,393,871 is strongest against products that:
- are marketed as intravaginal foams/sponge inserts
- rely on in-situ foaming urethane chemistry catalyzed by water
- carry spermicide and/or other vaginal drugs with controlled slow release
- match the 10% to 50% dry weight foaming agent / spermicide loading ranges
The presence of both device and method claims is designed to capture:
- finished goods (device infringement)
- manufacturing processes (method infringement)
- use by insertion (claim 24)
Key Takeaways
- US 4,393,871 claims a water-catalyzed foamed urethane vaginal sponge that slowly releases either (i) a spermicide-foaming agent or (ii) a local-delivery drug (with spermicide as one option).
- The strongest claim anchors are:
(1) water-catalyzed foamed urethane matrix, (2) foaming/spermicide agent dry weight 10% to 50%, and (3) slow release during vaginal use.
- The claim set includes narrower dependent limitations on: nonylphenoxy polyethoxyethanol, isocyanate-capped hydrophilic polyoxyethylene polyol, ≥30% spermicide loading, flattened ball with cervical os recess, and device pH 4.0 to 5.0.
- The manufacturing claims (12 and 17) allow enforcement against processes that mix the dry components and allow water-catalyzed foaming to form the sponge.
FAQs
1) What is the independent device claim with the broadest structural concept?
Claim 1 anchors the sponge concept with spermicide-foaming agent and 10% to 50% dry weight, released from a water-catalyzed foamed urethane during use.
2) Can the device claim cover drugs other than spermicide?
Yes. Claim 2 and claim 9 cover local-delivery drugs slowly released from the urethane sponge during use, with drug class examples in claim 10.
3) How important is the “10% to 50% by dry weight” range?
It is a core limitation in claim 1 and claim 9 and in the corresponding method claims (12 and 17). Moving outside the range is a direct route to reducing literal scope.
4) Does the patent require a specific urethane prepolymer?
Not in claim 1/9 as written, but dependent claims (6, 16, 18) require isocyanate-capped hydrophilic polyoxyethylene polyol, narrowing those specific variants.
5) Is the flattened-ball/cervical os recess shape required?
No. It is only in dependent claims (7, 11-13, 23). The core coverage exists without that anatomy-specific feature.
References
[1] U.S. Patent No. 4,393,871.
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