US Patent 5,269,321 (United States) — Scope, Claim Architecture, and Patent Landscape
What does US 5,269,321 claim, in operational terms?
US 5,269,321 is directed to a retrievable intravaginal or intrarectal pessary built around a non-biodegradable, non-erodible, water-swellable hydrogel matrix that releases a pharmacologically active ingredient in a controlled manner. The core technical problem it addresses is retaining a swollen hydrogel drug body without dispersal while still allowing retrieval after use.
The claim set you provided is dominated by claim 1, which defines a composite device architecture (drug body + knitted net retention + retrieval tape). Claims 2 and 3 add functional constraints (systemic absorption capability; lozenge shape).
Scope: What are the claim elements in claim 1 (and what must be true)?
Claim 1 requires all limitations below to be present, as written.
1) Drug body: water-swellable hydrogel, non-erodible/non-biodegradable
The pessary includes:
- An elongate solid body made of a water-swellable hydrogel
- The solid body comprises a pharmacologically active ingredient
- The active is adapted to be released in a controlled manner
- The solid body is non-biodegradable and non-erodible
- The solid body is not dispersed inside the patient during use
Practical scope impact
- The hydrogel must swell on hydration but must not fragment, erode, or biodegrade in vivo.
- Release is controlled from a swollen, intact matrix, not from a dissolving or eroding carrier.
2) Retention: integrally knitted biologically acceptable net
Claim 1 requires:
- A net retaining means formed of a biologically acceptable material
- The net retaining means is integrally formed by knitting
- It includes:
- A longitudinally extending knitted pouch portion
- The pouch portion is stretchable to accommodate swelling of the hydrogel body
- It has:
- first end and second end opposite it
- the second end is closed
- An elongate extension integrally formed with the pouch portion
- Extends from the first end of the pouch portion
- Forms an elongate retrieval means “in the form of a tape”
- The pouch portion includes structural interface:
- A slot in a wall of the pouch portion
- The slot is:
- longitudinal along the pouch
- adjacent to the second closed end
- permits insertion of the solid hydrogel body into the pouch
- During swelling, the slot location is such that the hydrogel stays retained as it swells from initial to swollen state
Practical scope impact
- Retention is not a generic “cover.” It is specifically:
- knit,
- pouch geometry, and
- a slot positioned adjacent to the closed end.
- Retrieval is not a generic tether. It is an integrally knitted tape extension extending from the first end.
3) Device-level form factor is elongate and retrievable
Claim 1 describes:
- A retrievable pessary
- For intravaginal or intrarectal use
- An elongate retrieval means (tape) to withdraw after use
Practical scope impact
- If a carrier swells but is not retrievable by a tape extension, it is outside claim 1 as written.
What is added by claim 2?
Claim 2 depends on claim 1 and specifies:
- The pharmacologically active ingredient is capable of being systemically absorbed into the patient.
Scope impact
- Claim 2 targets actives with expected systemic exposure, not purely local-only action.
- It still requires the hydrogel/net/tape architecture of claim 1.
What is added by claim 3?
Claim 3 depends on claim 1 and specifies:
- The elongate solid body is lozenge shaped.
Scope impact
- Claim 3 narrows shape geometry of the drug hydrogel body.
How strong is the claim funnel? (Element-by-element narrowing)
The patent’s practical enforceability and design-around sensitivity comes from the stacking of structural constraints:
Core “must-have” (claim 1)
- Non-erodible, non-biodegradable hydrogel that swells
- Knitted pouch retention with a stretchable knitted pouch
- Closed second end
- Slot adjacent to the closed end, longitudinally extending
- Integrally knitted retrieval tape extension from the first end
Meaningfully narrowing sub-claims
- Claim 2: systemic absorption capability of the active
- Claim 3: lozenge-shaped hydrogel body
This is a device claim with strong physical limitations. Invalidation or design-around tends to focus on:
- Whether the carrier is actually non-erodible/non-biodegradable in vivo
- Whether the retention is “integrally formed by knitting”
- Whether the retrieval means is a tape integrally formed as claimed
- Whether the pouch has the claimed slot position and configuration
Patent landscape: what prior art and design space does this claim likely collide with?
Below is a structured landscape view based on the claim’s distinctive combination: retrievable swollen non-erodible hydrogel + knitted retention pouch + slot insertion + tape retrieval tether.
A. Intravaginal/intrarectal hydrogel drug delivery (general category)
The concept of intravaginal or intrarectal drug delivery using swellable hydrogels is well-established historically in pharma delivery R&D. The claim does not cover:
- purely dissolving systems
- erodible matrices
- non-retrievable or dissolvable devices without intact retention
The novelty, as claimed, is the pairing of:
- non-erodible/non-biodegradable swelling with
- knitted, stretchable retention that holds the intact swollen body and still supports a retrieval tape.
B. Retrievable vaginal/rectal devices with tethers
Retrieval elements (strings, tapes, or other withdrawal means) appear across suppository and pessary technologies. The claim narrows the tether by requiring:
- it is an elongate extension integrally formed with the knitted pouch,
- it is “in the form of a tape,” and
- it extends from the pouch first end, not separately attached in a way that would not be “integrally formed.”
C. Pouch nets and knitted retainers
Many retention approaches exist (woven meshes, nonwoven wraps, polymeric sheaths). The claim narrows retention to:
- integrally formed by knitting
- specific pouch geometry (stretchable, longitudinally extending, with a closed end)
- an insertion slot located longitudinally and adjacent to the closed end
Design-around efforts in this area typically target:
- avoiding knit construction
- avoiding the specific slot placement/geometry
- avoiding a closed second end configuration
D. Swelling accommodation mechanics
The claim requires:
- stretchability of the knitted pouch to accommodate swelling
- retention of the hydrogel as it moves from initial to swollen state without dispersion
This excludes systems where the carrier swells and then leaks/disperses, or where the net does not accommodate expansion.
Claim scope vs. typical design-around strategies (what could avoid infringement)
Because the claim is structural, design-around tends to be mechanical:
1) Change the swelling carrier type
- Use a hydrogel that is erodible/biodegradable or breaks up under use.
- Use a dissolvable carrier where the solid body is not “non-erodible and non-biodegradable.”
2) Change retention construction method
- Use a non-knit wrap or sheath (woven or nonwoven) rather than “integrally formed by knitting.”
- Use a detachable cover not integrally knitted to the pouch.
3) Change retrieval architecture
- Use a retrieval element that is not integrally formed as a tape extension from the first end.
- Replace tape with another retrieval form that breaks the “in the form of a tape” limitation.
4) Change pouch slot configuration
- Eliminate the longitudinal slot or reposition it so it is not adjacent to the closed second end.
- Use a different insertion interface that does not match the claimed “slot in a wall” longitudinally extending configuration.
5) Change hydrogel geometry
- If targeting claim 3 specifically, avoid lozenge shape.
Commercial and R&D implications for drug-device combination programs
This patent’s device limitations likely matter most when:
- your hydrogel is intended to remain intact and non-erodible in vivo,
- you need active release over a period during intravaginal/rectal residence,
- you want a retrievable format without introducing dispersion risk, and
- you plan to use a knitted pouch/net carrier with an integral tape retrieval element.
The strongest read-through risk is for competitors building “retrievable swellable non-erodible hydrogel” products that use a knitted net and a tape retrieval.
Key takeaways
- US 5,269,321 claim 1 is a composite device claim requiring an elongate non-erodible/non-biodegradable swellable hydrogel drug body plus a knitted stretchable pouch that retains swelling without dispersion, with a longitudinal slot adjacent to the closed end and an integrally knitted tape retrieval extension.
- Claim 2 narrows to actives capable of systemic absorption.
- Claim 3 narrows hydrogel body shape to lozenge-shaped.
- The enforceable scope is driven less by the drug class and more by carrier retention and retrieval structure; design-arounds most often target knit construction, slot geometry/position, non-erodibility, or retrieval tether integration.
FAQs
1) Does claim 1 cover dissolvable hydrogels?
No. Claim 1 requires the hydrogel solid body to be non-biodegradable and non-erodible, and not dispersed inside the patient during use.
2) Is retrieval required?
Yes. Claim 1 requires an elongate retrieval means in the form of a tape to withdraw the pessary after use.
3) Must the knitted pouch have a longitudinal slot?
Yes for claim 1. It must have a slot in a wall that is longitudinal and located adjacent to the second closed end.
4) Does claim 2 cover locally acting only drugs?
No. Claim 2 requires the active ingredient to be capable of systemic absorption.
5) What is the additional limitation in claim 3?
The hydrogel solid body must be lozenge shaped.
References
- United States Patent 5,269,321.
