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Patent landscape, scope, and claims: |
United States Patent 5,545,413: Scope, Claim-by-Claim Breakdown, and US Patent Landscape for Glipizide Oral Polymeric “Push/Displacement” Drug Delivery Systems
What does US Patent 5,545,413 claim for glipizide delivery—method claims vs dosage-form claims?
US 5,545,413 is directed to oral glipizide therapy using a compartmentalized dosage form with (i) a fluid-permeable wall, (ii) an internal laminar architecture, (iii) a “displacement lamina” swell/imbibe mechanism, and (iv) one or more controlled exit passageways for releasing glipizide after fluid uptake.
Core claim architecture across the set
- Oral dosage form: admits fluid from the patient’s GI environment.
- Wall: permeable to exterior fluid, with exit means/passageway(s) for delivery.
- Compartment + lamina system:
- Drug lamina containing glipizide 2 mg to 50 mg plus a first polymer (polyethylene oxide (PEO) with molecular weight range, or PEO plus other cellulosic/hydrated polymers).
- Displacement lamina containing a higher-MW polymer designed to imbibe fluid, expand, and displace the drug lamina.
- Mechanism: displacement causes transport of glipizide to exit passages, producing a therapeutically effective antidiabetic effect.
Distinct polymers appear by claim:
- PEO-based displacement (claims 1 and 3).
- Sodium carboxymethylcellulose (Na-CMC) based displacement (claim 2).
- Mixed-cellulose/hydration polymers (claims 5 and 7).
How broad are the “glipizide therapy” method claims in claim 1 and claim 2?
Claim 1 (method): PEO displacement lamina
Claim 1 scope
- Patient in need of glipizide therapy for hyperglycemia.
- Oral administration of a dosage form with:
- wall permeable to fluid
- compartment with:
- drug lamina: 2 to 50 mg glipizide + PEO (80,000 to 350,000 MW)
- displacement lamina: PEO (4,000,000 to 8,000,000 MW) that imbibes fluid, expands, and displaces the drug lamina
- at least one wall exit means for delivering glipizide
- Method steps mirror the dosage-form mechanism: imbibing fluid causes displacement and delivering a therapeutically effective amount.
Breadth drivers
- “Patient in need” language ties to intended use but not a narrow phenotype.
- The displacement polymer must be PEO in a specified MW band, which is limiting but still broad within that window.
- The wall polymer system is not enumerated in claim 1. Claim 4 later narrows to specific cellulose acylates/acetates.
Claim 2 (method): Na-CMC displacement lamina
Claim 2 scope
- Similar therapeutic and dosage-form structure.
- The key change: displacement lamina is Na-CMC (200,000 to 1,000,000 MW).
- Mechanistic language includes swelling pushing glipizide.
Breadth drivers
- Na-CMC MW window is narrower than PEO “any polymer” type, but Na-CMC is a widely-used excipient family.
- As with claim 1, the method still depends on a dosage form with a fluid-permeable wall and exit passageways.
Legal/technical implications
- Claim 1 and claim 2 establish two alternative displacement-material embodiments:
- PEO (multi-million MW) displacement
- Na-CMC (200k–1,000k MW) displacement
- Competitors using swellable, fluid-imbibing displacement layers must map either to PEO MW range or Na-CMC MW range plus the compartment/lamina architecture and exit passage delivery.
What is the scope of the dosage-form system claims (claim 3 and claim 4)?
Claim 3 (dosage form): PEO drug lamina + PEO displacement lamina + exit passageways
Claim 3 is the structural claim corresponding to claim 1. It requires:
- A wall permeable to exterior fluid, surrounding a compartment
- Drug lamina: glipizide 2–50 mg plus PEO 80,000–350,000 MW
- Displacement lamina: PEO 4,000,000–8,000,000 MW
- Exit passageway(s) in the wall connecting exterior to interior for delivering glipizide
Scope boundaries
- Tight constraint on both PEO MW ranges.
- Requires the specific internal lamina arrangement (drug lamina + displacement lamina) rather than a single-layer swell-controlled formulation.
Claim 4 (dosage form with specified wall polymers)
Claim 4 narrows claim 3 by specifying the wall contains at least one member selected from:
- cellulose acylates/acetates/diacetates/triacetates, i.e.:
- cellulose acylate, cellulose diacylate, cellulose triacylate
- cellulose acetate, cellulose diacetate, cellulose triacetate
Practical effect
- This claim limits wall excipient identity, likely relevant to manufacturing materials and permeability profile.
- It does not require the polymeric identity of lamina layers beyond claim 3 linkage, so claim 4 functions as a further constrained “carboxylated/cellulose ester wall” embodiment.
How do claim 5 and claim 7 change the polymer composition and mechanism coverage?
Claim 5 (dosage form): first lamina includes glipizide + PEO + hydroxypropylmethylcellulose (HPMC 9,000–25,000 MW) plus displacement PEO
Claim 5 retains:
- fluid-permeable pharmaceutically acceptable wall
- compartment
- first lamina: glipizide 2–50 mg + PEO + HPMC 9,000–25,000 MW
- second displacement lamina: PEO 4,000,000–8,000,000 MW
- at least one wall passageway for delivering glipizide
Scope expansion relative to claim 3
- Claim 5 adds a second polymer class to the drug lamina: HPMC 9,000–25,000 MW alongside PEO.
- This can broaden “around” to formulations where the first lamina is not solely PEO.
Claim 6 (dependent): controlled porosity by leaching
Claim 6 narrows claim 5 by requiring the passageway is formed by leaching to provide controlled porosity.
Design-around note
- A competitor that uses different passageway manufacturing (e.g., laser drilling, pre-formed microchannels, or casting with controlled porosity) could aim to avoid the specific “leaching to provide controlled porosity” limitation if claim 6 is asserted.
Claim 7 (dosage form): different polymer system in first lamina and displacement lamina
Claim 7 requires:
- fluid-permeable wall
- compartment
- first lamina: glipizide 2–50 mg + hydroxypropylcellulose polymer + polyvinylpyrrolidone (PVP) polymer
- second displacement lamina: Na-CMC and hydroxypropylmethylcellulose
- exit passageway(s) in wall
Coverage meaning
- Claim 7 shifts from PEO-centered constructs to a hybrid:
- drug lamina: HPC + PVP with glipizide
- displacement lamina: Na-CMC + HPMC
- This is a material-sensitive claim that still preserves the required “displacement lamina” concept, but alters the set of permissible polymers.
Overall consequence
- The patent estate is not limited to one excipient family. It protects multiple polymer recipes that maintain:
- compartmentalized lamina drug layer
- swell/imbibe displacement layer
- exit passageway-driven release.
What are the claim-enforced invention “pillars” a generic or brand must map to avoid infringement?
Pillar A: lamina architecture and displacement function
Across claims, the system requires:
- a distinct drug lamina containing glipizide (2–50 mg) plus a polymer component
- a distinct displacement lamina that imbibes fluid and mechanically displaces drug lamina from the compartment
A design that changes from “mechanical displacement” to purely diffusive release or purely osmotic membrane-driven release without a displacement lamina risks losing literal coverage.
Pillar B: polymer molecular-weight ranges (where specified)
The patent uses specific molecular weight bands in multiple claims:
- PEO (drug lamina): 80,000–350,000
- PEO (displacement lamina): 4,000,000–8,000,000
- Na-CMC (displacement lamina in claim 2): 200,000–1,000,000
- HPMC (in claim 5 first lamina): 9,000–25,000
Any competitor can attempt to use polymers outside these bands. If the claim is asserted, the polymer grade and characterization evidence become pivotal.
Pillar C: fluid-permeable wall with exit passageways
Claims require:
- a wall permeable to exterior fluid
- at least one exit means/passageway
- a controlled connection between exterior fluid and interior delivery path
A competitor that avoids a “passageway in the wall” (for example, using a fully rupturable seal with no defined exit passage) may contest whether the construct meets the structural limitation.
How strong is US 5,545,413 likely to be against “generic” oral glipizide products?
Strength factors
- The claim language is structural and functional, anchored in:
- internal lamina arrangement
- displacement and exit delivery concept
- specific MW polymer bands in multiple claims
- The claims are not limited to a specific brand name or treatment regimen beyond “glipizide therapy.”
Vulnerability factors
- The claims are excipient- and MW-range-dependent in several places. Literal infringement can turn on polymer selection and characterization.
- Competing technologies using different release mechanisms (diffusion-controlled, osmotic pump without displacement lamina, matrix tablets) can reduce mapping to key limitations.
What patent families and landscape markers usually cluster around this technology?
Without asserting additional documents, the landscape can still be described as to how comparable oral controlled-release glipizide systems tend to patent:
- Controlled-release, compartmental osmotic systems (exit ports, semipermeable membranes)
- Swelling/displacement excipient systems (PEO, Na-CMC, HPMC, HPC, PVP combinations)
- Manufacturing control (leached passageway porosity, membrane permeability control)
- Combination polymer systems for tuned release and mechanical behavior
For litigation and freedom-to-operate, the relevant search strategy typically focuses on:
- glipizide-specific micro/compartment displacement delivery
- oral controlled release dosage forms with polymeric swell layers
- exit passageway formation and membrane permeability using cellulose esters and similar materials
When does the exclusivity end for US 5,545,413 and what matters for generic timing?
No filing date, priority date, maintenance status, or terminal disclaimer terms are provided. Without those facts, the exclusivity end date cannot be accurately stated. The analysis therefore cannot determine whether the patent is currently enforceable or expired, nor whether a generic could have entered earlier under statutory timelines.
What are the likely litigation hooks if this patent is asserted?
Potential infringement theories
- Sale and manufacture of an oral glipizide dosage form containing:
- compartment and lamina system
- a fluid-permeable wall
- exit passageways
- a displacement layer that imbibes and expands (PEO or Na-CMC based as claimed)
Potential defenses
- Non-infringement via:
- absence of “displacement lamina” or mechanical displacement function
- use of displacement polymers outside MW ranges
- different internal architecture not meeting lamina/compartment structural requirements
- no exit passageways as claimed
- Invalidity arguments typically target:
- prior art swelling/displacement controlled-release systems
- prior art using the same polymers and MW ranges
- predictability of polymer swelling mechanics in controlled-release shells
What generic entry risks exist for “different” glipizide controlled-release delivery?
Risk depends on whether a competitor’s product can be characterized as:
- an oral dosage form with fluid-permeable wall + defined exit passageways, and
- a lamina-containing compartment where fluid-imbibing displacement occurs,
- with the displacement material and MW ranges falling within the claim.
High risk mapping scenario
- competitor adopts PEO multi-million MW as displacement and uses PEO 80k–350k with glipizide for drug lamina and includes exit ports.
Lower risk mapping scenario
- competitor uses different release mechanism (e.g., diffusion matrix without displacement lamina), or uses swelling polymers outside the stated MW bands, or uses an architecture without a distinct lamina displacement step.
Key Takeaways
- US 5,545,413 protects an oral glipizide dosage-form concept built on a compartmental lamina system where a fluid-imbibing displacement lamina expands and pushes/displaces glipizide to exit passageways.
- Claims 1–3 and 5 center on PEO-based displacement, with multiple molecular-weight bands that can materially affect infringement.
- Claims 2 and 7 provide alternative displacement approaches using Na-CMC (and in claim 7, Na-CMC plus HPMC) and alternative drug-lamina polymer sets (e.g., HPC and PVP).
- Dependent claims narrow manufacturing details (notably leaching to form controlled-porosity passageways).
- For freedom-to-operate, the decisive claim mapping points are (i) internal lamina architecture, (ii) displacement mechanism, (iii) polymer identity and MW ranges, and (iv) presence of defined exit passageways.
FAQs
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Do US 5,545,413 claims cover diffusive matrix tablets without a displacement lamina?
Coverage hinges on having a displacement lamina that imbibes fluid and expands to displace the glipizide lamina plus wall exit passageways; a purely diffusive matrix can fall outside these structural-functional limitations.
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If a glipizide product uses PEO but outside the listed molecular-weight bands, does it avoid infringement?
The relevant claims explicitly recite MW ranges for PEO in multiple lamina roles. A change outside those ranges is a primary non-infringement lever for the literal claim limitations.
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Is the wall polymer composition critical to infringement?
It is not required in the broader method claim (claim 1/2) and structural dosage-form claim (claim 3/5/7) versions, but it becomes critical in claim 4, which limits the wall to specified cellulose esters/acylates.
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Does controlled porosity passageway formation by leaching matter?
Yes for claim 6, which adds the leaching/controlled porosity limitation. It is not required by the independent dosage-form claims.
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Can a product with Na-CMC displacement still be outside claim 2 or claim 7?
Yes, by using a displacement polymer outside the claimed MW range (claim 2) or altering the displacement-lamina polymer combination/structure required by claim 7 while maintaining an overall different release mechanism.
References
- United States Patent 5,545,413.
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