US Patent 5,656,286: What Is Claimed in the Transdermal Adhesive System and Where It Sits in the Landscape

US 5,656,286 claims a specific transdermal drug delivery architecture built around a pressure-sensitive adhesive (PSA) blend plus a defined solubilized polyvinylpyrrolidone (PVP) component and optional enhancer. The claims are drafted to cover a wide drug genus while tying composition scope to particular PSA polymer families and, in dependent claims, to specific drug classes (notably steroids, β2-agonists, cardioactives, CNS agents, and others).

What is the core claim scope (independent claim 1)?

Independent claim 1 (composition-first)

Claim 1 is a transdermal drug delivery system that comprises:

A PSA composition consisting of a three-part polymer blend:
- (a)(i) One PSA polymer selected from a long list (block/branched rubbers and common PSA backbones), at 14% to 94% by weight of the PSA composition
- (a)(ii) Polyisobutylene at 10% to 90%
- (a)(iii) Polysiloxane at 5% to 95%
(b) Soluble polyvinylpyrrolidone (PVP) at 1% to 20% by weight of the PSA composition
(c) One drug or mixture of two or more drugs
(d) Optional enhancer at up to about [value missing in user text] by weight of the total PSA composition

Composition logic

The claim’s “center of gravity” is not the drug. It is the adhesive formulation system:

A multi-polymer PSA blend: PSA-family polymer + polyisobutylene + polysiloxane
A soluble PVP fraction (1 to 20 wt%)
Optional enhancer to modify drug partitioning/release

Practical scope implication

If a product matches the PSA blend ranges and contains soluble PVP within 1 to 20 wt% and uses transdermal delivery, it is within the claim framework regardless of whether the drug is an estrogen, antiseptic, CNS agent, or other listed genus.

Which dependent claims materially narrow or expand the patent’s coverage?

Polymer-level narrowing/variations

Claim 2: PSA is polysiloxane (narrows PSA selection to the polysiloxane species)
Claim 11: PSA is polysiloxane (same narrowing in a second dependent branch)
Claim 4 (alternative independent branch): Adds a second formulation constraint:
- Requires a polyacrylate at 5% to 85%
- Requires polyacrylate and the PSA (a) differ in solubility parameter by at least 2 (J/cm³)^(1/2)
- Keeps soluble PVP (1 to 20%) and drug (one or more) and optional enhancer (up to 20%)

Structural format coverage

Claim 5: System is in a defined geometric shape
Claim 6: Form is a sheet
Claim 7: Form is an individual dosage unit
Claim 8: Includes backing material substantially impermeable to the drug
Claim 9: Includes release liner over the adhesive surface opposite the backing
Claim 10: Covers a reservoir device where the adhesive portion is the blend

These claims widen the product-form footprint: not just “any patch,” but patches, defined shapes, sheet or unit forms, and reservoir architectures.

Process coverage

Claim 69: A process comprising blending the constituents as in claim 1
Claim 70: A process comprising blending the constituents as in claim 4 (including polyacrylate and solubility-parameter requirement)

Process claims expand leverage for formulation manufacture even if end-product design attempts to shift certain order-of-addition details, though infringement still requires meeting all claim elements.

What formulation element drives patent defensibility: PVP plus PSA blend plus solubility engineering?

PVP is a fixed composition anchor

In both claim 1 and claim 4 branches: soluble PVP at 1 to 20 wt%.
Claim 12 further limits molecular weight: 7,000 to 54,000 (for soluble PVP)
Claim 71 broadens molecular weight: 5,000 to 100,000 (in another dependent claim)

This creates two layered coverage bands around soluble PVP.

Solubility parameter engineering in claim 4

Claim 4 adds a formulation requirement that is unusually specific:

polyacrylate at 5% to 85%, and
solubility parameter difference between polyacrylate and the PSA (a) of at least 2 (J/cm³)^(1/2)

That element functions as a technical filter. It can separate “close” formulations that otherwise use similar polymer families and PVP.

How broad is the drug coverage (and where is it concentrated)?

Claim 1 drug scope is essentially genus-driven

Claim 1 states “one drug or mixture of two or more drugs” with no further limitation in the independent. Dependent claims then map major drug categories.

Concentrated steroid coverage

The patent gives extensive dependent detail for steroid selection and dosing:

Claim 18: steroid; Claim 19: estrogen selected from a long list
Claim 20: specifically 17β-estradiol, at 0.1% to 5%
Claims 21 to 26: progestational agents; Claim 23: norethindrone acetate at 1% to 5%
Claims 24 to 28: mixtures of progestational agent + estrogen; Claim 28: estrogen is 17β-estradiol
Claim 54: additional steroid list (including anabolic-androgenic steroid exemplars such as testosterone cypionate and enanthate)

This is the clearest “hot zone” of claim-specificity because it defines:

steroid class
sub-class enumerations
sometimes a dosing window

Other high-enumeration categories

β2-adrenergic agonists: Claim 29 to 31
- examples: metaproterenol, terbutaline, albuterol, etc.
- Claim 31: albuterol present at less than about 30 wt%
Cardioactives: Claim 32 to 34
- includes nitroglycerin, isosorbide derivatives, quinidine, verapamil class, ACE inhibitors, etc.
- Claim 34: nitroglycerin present at less than about 25 wt%
Cholinergic agonists: Claim 35 to 37
- includes choline, acetylcholine, methacholine, etc.
- Claim 37: pilocarpine at less than about 30 wt%
Tranquilizers: Claim 38 to 40
- includes alprazolam, halazepam, lorazepam, diazepam, etc.
- Claim 40: alprazolam (no explicit wt% in text)
Antipsychotics: Claim 41 to 43
- includes haloperidol, chlorpromazine, etc.
- Claim 43: haloperidol
Anesthetics: Claim 44 to 46
- includes lidocaine, tetracaine, bupivacaine, benzocaine, etc.
- Claim 46: lidocaine
Analgesics: Claim 47 to 48
- includes fentanyl, buprenorphine, codeine, baclofen, sumatriptan
Vasodilators: Claim 51 to 52
- papaverine
CNS action list: Claim 49 to 50
- nicotine, methylphenidate, tacrine
Other broad dependent categories cover multiple therapeutic areas:
- antiparkinsonian (Claim 55 to 56)
- non-steroidal anti-inflammatory drugs (Claim 57 to 58)
- anorectic (Claim 59 to 60)
- glucocorticoids (Claim 61)
- antinauseant (Claim 62)
- antibiotics (Claim 63 to 64)
- chlorhexidine and metronidazole (Claim 65)
- prostaglandins (Claim 66)
- misoprostol (Claim 67)
- antidiabetic example glypinamide (Claim 68)
- mineralcorticoid fludrocortisone (Claim 72 to 73)

Net effect

The drug portion is drafted to be broad at claim 1 and expansive via many dependent claims, which can support multiple infringement theories across different commercial drug candidates if they use the same adhesive system.

What optional add-ons extend coverage beyond the base PSA blend?

Enhancer

Claim 3 adds at least one enhancer.
Claim 14/15 provides a dependent enhancer range: 1% to 20 wt% (as written for claim 15).

Clay

Claim 16: includes a clay
Claim 17: bentonite

Clays can be used to affect water uptake, swelling, and mechanical properties. Claim 16 and 17 create another axis of differentiation for formulations that add inorganic particles.

Defined impermeable backing and release liner

Claims 8 and 9 add conventional patch layers, but they matter for devices where the drug is not retained without a barrier.

How does the patent landscape likely organize around this patent type (US filing context)?

US 5,656,286 is structured as a transdermal PSA formulation patent with:

a polymer blend platform,
a solubilized PVP platform element,
optional enhancer/clay platform elements,
and drug genus coverage via dependent enumerations.

In practice, landscape separation tends to fall into these competitive buckets:

1) “Same adhesive platform” competitors

Formulators who use:

PSA polymer family blends in ranges compatible with claim 1,
soluble PVP in 1 to 20 wt%,
transdermal patch or reservoir configurations.

These face direct platform-level claim risk, especially for estrogen and steroid products where dependent claims provide more anchors.

2) “Solubility-parameter engineered polyacrylate” competitors

Claim 4 introduces a distinct technical filter:

inclusion of polyacrylate in 5 to 85 wt%,
solubility parameter difference at least 2 between polyacrylate and the base PSA.

Products designed to avoid that condition may still fall under claim 1 if they omit polyacrylate entirely but still include the claim 1 PSA blend plus PVP.

3) “Drug-specific transdermal” competitors

Many later patents in transdermal space focus on:

drug choice,
dose,
permeation enhancer selection,
device layering.

US 5,656,286 creates vulnerability for those entrants if they use the same PSA blend and soluble PVP architecture, even when their innovation is “just” a drug selection.

4) “Structure-only” variants

Even if a competitor matches the structure layers (backing, liner, sheet/unit), infringement still requires meeting the adhesive composition claims. US 5,656,286’s emphasis on the PSA blend and PVP reduces the ability for competitors to “design around” by changing only patch geometry.

What does claim 4 add to the landscape (and why it matters)?

Claim 4 is a second major independent-like anchor within your provided claim set:

It expands PSA coverage by introducing polyacrylate.
It adds the solubility parameter constraint.
It still requires soluble PVP.

From a landscape perspective, claim 4 creates a second formulation family within the same patent:

Claim 1 family: PSA blend + PVP + drug + optional enhancer
Claim 4 family: PSA blend + polyacrylate + solubility-parameter constraint + PVP + drug + optional enhancer

This dual-track drafting is a common way to capture:

formulations that rely on PSA/PVP chemistry alone,
and formulations that also rely on polymer solubility parameter matching.

Where are the strongest commercially relevant claim hooks?

Based on the dependent claim enumerations, the most commercially visible drug categories include:

Hormone therapies (estrogens and progestogens), with explicit presence windows for 17β-estradiol and norethindrone acetate.
Cardiovascular and vasodilatory therapies, including nitroglycerin with explicit wt% cap.
β2-agonist respiratory therapies, including albuterol with explicit wt% cap.
Ophthalmic and cholinergic therapies, including pilocarpine with wt% cap.
Broad CNS agent lists (tranquilizers, antipsychotics, anesthetics, analgesics, and stimulants), which can broaden threat coverage across multiple therapeutic pipelines.

Key Takeaways

US 5,656,286 is a transdermal PSA platform patent anchored by a three-polymer PSA blend (PSA-family polymer + polyisobutylene + polysiloxane) plus soluble PVP (1 to 20 wt%).
The patent has a second formulation track via claim 4: polyacrylate (5 to 85 wt%) with a solubility parameter difference of at least 2 (J/cm³)^(1/2) relative to the PSA component.
Device coverage is broad: sheet, defined geometric shape, unit dosage, backing, liner, and reservoir adhesive portion.
Drug scope is wide at claim 1 and becomes highly specific in dependent claims, with dense coverage in steroids (estrogens/progestogens) and meaningful quantitative hooks for 17β-estradiol, norethindrone acetate, albuterol, nitroglycerin, and pilocarpine.
Landscape positioning: the most direct competitive risk comes from formulations that reuse the claim’s adhesive/PVP platform, not only from those copying a specific drug.

FAQs

1) Does claim 1 require a specific drug?

No. Claim 1 recites “one drug or a mixture of two or more drugs,” and dependent claims then enumerate drug classes and examples.

2) What is the fixed PVP requirement?

Across claim 1 and the claim 4 branch, soluble PVP must be present at about 1% to about 20% by weight of the total pressure-sensitive adhesive composition (dependent claims specify molecular weight bands).

3) What adhesive polymers are mandatory in the PSA blend?

The PSA blend is defined as including (i) a PSA polymer selected from a listed group at 14% to 94%, (ii) polyisobutylene at 10% to 90%, and (iii) polysiloxane at 5% to 95%.

4) How does claim 4 differ from claim 1?

Claim 4 adds polyacrylate (5% to 85%) and a constraint that the solubility parameter difference between polyacrylate and the base PSA (a) is at least 2 (J/cm³)^(1/2), while still requiring soluble PVP and drug plus optional enhancer.

5) Do the device-layer claims create standalone infringement risk?

They do not appear standalone in this claim set. Backing, release liner, and reservoir architecture are dependent to the composition-focused claim framework, so infringement still requires meeting the adhesive/PVP composition elements.

References

[1] US Patent No. 5,656,286. Transdermal drug delivery systems using pressure-sensitive adhesive blends with soluble polyvinylpyrrolidone and optional enhancers.

Title:	Solubility parameter based drug delivery system and method for altering drug saturation concentration
Abstract:	A blend of at least two polymers, or at least one polymer and a soluble polyvinylpyrrolidone, in combination with a drug provides a pressure-sensitive adhesive composition for a transdermal drug delivery system in which the drug is delivered from the pressure-sensitive adhesive composition and through dermis when the pressure-sensitive adhesive composition is in contact with human skin. According to the invention, soluble polyvinylpyrrolidone can be used to prevent crystallization of the drug, without affecting the rate of drug delivery from the pressure-sensitive adhesive composition.
Inventor(s):	Jesus Miranda, Steven Sablotsky
Assignee:	Noven Pharmaceuticals Inc
Application Number:	US08/178,558
Patent Claim Types: see list of patent claims	Composition; Compound; Process; Delivery; Device;
Patent landscape, scope, and claims:	US Patent 5,656,286: What Is Claimed in the Transdermal Adhesive System and Where It Sits in the Landscape US 5,656,286 claims a specific transdermal drug delivery architecture built around a pressure-sensitive adhesive (PSA) blend plus a defined solubilized polyvinylpyrrolidone (PVP) component and optional enhancer. The claims are drafted to cover a wide drug genus while tying composition scope to particular PSA polymer families and, in dependent claims, to specific drug classes (notably steroids, β2-agonists, cardioactives, CNS agents, and others). What is the core claim scope (independent claim 1)? Independent claim 1 (composition-first) Claim 1 is a transdermal drug delivery system that comprises: A PSA composition consisting of a three-part polymer blend: (a)(i) One PSA polymer selected from a long list (block/branched rubbers and common PSA backbones), at 14% to 94% by weight of the PSA composition (a)(ii) Polyisobutylene at 10% to 90% (a)(iii) Polysiloxane at 5% to 95% (b) Soluble polyvinylpyrrolidone (PVP) at 1% to 20% by weight of the PSA composition (c) One drug or mixture of two or more drugs (d) Optional enhancer at up to about [value missing in user text] by weight of the total PSA composition Composition logic The claim’s “center of gravity” is not the drug. It is the adhesive formulation system: A multi-polymer PSA blend: PSA-family polymer + polyisobutylene + polysiloxane A soluble PVP fraction (1 to 20 wt%) Optional enhancer to modify drug partitioning/release Practical scope implication If a product matches the PSA blend ranges and contains soluble PVP within 1 to 20 wt% and uses transdermal delivery, it is within the claim framework regardless of whether the drug is an estrogen, antiseptic, CNS agent, or other listed genus. Which dependent claims materially narrow or expand the patent’s coverage? Polymer-level narrowing/variations Claim 2: PSA is polysiloxane (narrows PSA selection to the polysiloxane species) Claim 11: PSA is polysiloxane (same narrowing in a second dependent branch) Claim 4 (alternative independent branch): Adds a second formulation constraint: Requires a polyacrylate at 5% to 85% Requires polyacrylate and the PSA (a) differ in solubility parameter by at least 2 (J/cm³)^(1/2) Keeps soluble PVP (1 to 20%) and drug (one or more) and optional enhancer (up to 20%) Structural format coverage Claim 5: System is in a defined geometric shape Claim 6: Form is a sheet Claim 7: Form is an individual dosage unit Claim 8: Includes backing material substantially impermeable to the drug Claim 9: Includes release liner over the adhesive surface opposite the backing Claim 10: Covers a reservoir device where the adhesive portion is the blend These claims widen the product-form footprint: not just “any patch,” but patches, defined shapes, sheet or unit forms, and reservoir architectures. Process coverage Claim 69: A process comprising blending the constituents as in claim 1 Claim 70: A process comprising blending the constituents as in claim 4 (including polyacrylate and solubility-parameter requirement) Process claims expand leverage for formulation manufacture even if end-product design attempts to shift certain order-of-addition details, though infringement still requires meeting all claim elements. What formulation element drives patent defensibility: PVP plus PSA blend plus solubility engineering? PVP is a fixed composition anchor In both claim 1 and claim 4 branches: soluble PVP at 1 to 20 wt%. Claim 12 further limits molecular weight: 7,000 to 54,000 (for soluble PVP) Claim 71 broadens molecular weight: 5,000 to 100,000 (in another dependent claim) This creates two layered coverage bands around soluble PVP. Solubility parameter engineering in claim 4 Claim 4 adds a formulation requirement that is unusually specific: polyacrylate at 5% to 85%, and solubility parameter difference between polyacrylate and the PSA (a) of at least 2 (J/cm³)^(1/2) That element functions as a technical filter. It can separate “close” formulations that otherwise use similar polymer families and PVP. How broad is the drug coverage (and where is it concentrated)? Claim 1 drug scope is essentially genus-driven Claim 1 states “one drug or mixture of two or more drugs” with no further limitation in the independent. Dependent claims then map major drug categories. Concentrated steroid coverage The patent gives extensive dependent detail for steroid selection and dosing: Claim 18: steroid; Claim 19: estrogen selected from a long list Claim 20: specifically 17β-estradiol, at 0.1% to 5% Claims 21 to 26: progestational agents; Claim 23: norethindrone acetate at 1% to 5% Claims 24 to 28: mixtures of progestational agent + estrogen; Claim 28: estrogen is 17β-estradiol Claim 54: additional steroid list (including anabolic-androgenic steroid exemplars such as testosterone cypionate and enanthate) This is the clearest “hot zone” of claim-specificity because it defines: steroid class sub-class enumerations sometimes a dosing window Other high-enumeration categories β2-adrenergic agonists: Claim 29 to 31 examples: metaproterenol, terbutaline, albuterol, etc. Claim 31: albuterol present at less than about 30 wt% Cardioactives: Claim 32 to 34 includes nitroglycerin, isosorbide derivatives, quinidine, verapamil class, ACE inhibitors, etc. Claim 34: nitroglycerin present at less than about 25 wt% Cholinergic agonists: Claim 35 to 37 includes choline, acetylcholine, methacholine, etc. Claim 37: pilocarpine at less than about 30 wt% Tranquilizers: Claim 38 to 40 includes alprazolam, halazepam, lorazepam, diazepam, etc. Claim 40: alprazolam (no explicit wt% in text) Antipsychotics: Claim 41 to 43 includes haloperidol, chlorpromazine, etc. Claim 43: haloperidol Anesthetics: Claim 44 to 46 includes lidocaine, tetracaine, bupivacaine, benzocaine, etc. Claim 46: lidocaine Analgesics: Claim 47 to 48 includes fentanyl, buprenorphine, codeine, baclofen, sumatriptan Vasodilators: Claim 51 to 52 papaverine CNS action list: Claim 49 to 50 nicotine, methylphenidate, tacrine Other broad dependent categories cover multiple therapeutic areas: antiparkinsonian (Claim 55 to 56) non-steroidal anti-inflammatory drugs (Claim 57 to 58) anorectic (Claim 59 to 60) glucocorticoids (Claim 61) antinauseant (Claim 62) antibiotics (Claim 63 to 64) chlorhexidine and metronidazole (Claim 65) prostaglandins (Claim 66) misoprostol (Claim 67) antidiabetic example glypinamide (Claim 68) mineralcorticoid fludrocortisone (Claim 72 to 73) Net effect The drug portion is drafted to be broad at claim 1 and expansive via many dependent claims, which can support multiple infringement theories across different commercial drug candidates if they use the same adhesive system. What optional add-ons extend coverage beyond the base PSA blend? Enhancer Claim 3 adds at least one enhancer. Claim 14/15 provides a dependent enhancer range: 1% to 20 wt% (as written for claim 15). Clay Claim 16: includes a clay Claim 17: bentonite Clays can be used to affect water uptake, swelling, and mechanical properties. Claim 16 and 17 create another axis of differentiation for formulations that add inorganic particles. Defined impermeable backing and release liner Claims 8 and 9 add conventional patch layers, but they matter for devices where the drug is not retained without a barrier. How does the patent landscape likely organize around this patent type (US filing context)? US 5,656,286 is structured as a transdermal PSA formulation patent with: a polymer blend platform, a solubilized PVP platform element, optional enhancer/clay platform elements, and drug genus coverage via dependent enumerations. In practice, landscape separation tends to fall into these competitive buckets: 1) “Same adhesive platform” competitors Formulators who use: PSA polymer family blends in ranges compatible with claim 1, soluble PVP in 1 to 20 wt%, transdermal patch or reservoir configurations. These face direct platform-level claim risk, especially for estrogen and steroid products where dependent claims provide more anchors. 2) “Solubility-parameter engineered polyacrylate” competitors Claim 4 introduces a distinct technical filter: inclusion of polyacrylate in 5 to 85 wt%, solubility parameter difference at least 2 between polyacrylate and the base PSA. Products designed to avoid that condition may still fall under claim 1 if they omit polyacrylate entirely but still include the claim 1 PSA blend plus PVP. 3) “Drug-specific transdermal” competitors Many later patents in transdermal space focus on: drug choice, dose, permeation enhancer selection, device layering. US 5,656,286 creates vulnerability for those entrants if they use the same PSA blend and soluble PVP architecture, even when their innovation is “just” a drug selection. 4) “Structure-only” variants Even if a competitor matches the structure layers (backing, liner, sheet/unit), infringement still requires meeting the adhesive composition claims. US 5,656,286’s emphasis on the PSA blend and PVP reduces the ability for competitors to “design around” by changing only patch geometry. What does claim 4 add to the landscape (and why it matters)? Claim 4 is a second major independent-like anchor within your provided claim set: It expands PSA coverage by introducing polyacrylate. It adds the solubility parameter constraint. It still requires soluble PVP. From a landscape perspective, claim 4 creates a second formulation family within the same patent: Claim 1 family: PSA blend + PVP + drug + optional enhancer Claim 4 family: PSA blend + polyacrylate + solubility-parameter constraint + PVP + drug + optional enhancer This dual-track drafting is a common way to capture: formulations that rely on PSA/PVP chemistry alone, and formulations that also rely on polymer solubility parameter matching. Where are the strongest commercially relevant claim hooks? Based on the dependent claim enumerations, the most commercially visible drug categories include: Hormone therapies (estrogens and progestogens), with explicit presence windows for 17β-estradiol and norethindrone acetate. Cardiovascular and vasodilatory therapies, including nitroglycerin with explicit wt% cap. β2-agonist respiratory therapies, including albuterol with explicit wt% cap. Ophthalmic and cholinergic therapies, including pilocarpine with wt% cap. Broad CNS agent lists (tranquilizers, antipsychotics, anesthetics, analgesics, and stimulants), which can broaden threat coverage across multiple therapeutic pipelines. Key Takeaways US 5,656,286 is a transdermal PSA platform patent anchored by a three-polymer PSA blend (PSA-family polymer + polyisobutylene + polysiloxane) plus soluble PVP (1 to 20 wt%). The patent has a second formulation track via claim 4: polyacrylate (5 to 85 wt%) with a solubility parameter difference of at least 2 (J/cm³)^(1/2) relative to the PSA component. Device coverage is broad: sheet, defined geometric shape, unit dosage, backing, liner, and reservoir adhesive portion. Drug scope is wide at claim 1 and becomes highly specific in dependent claims, with dense coverage in steroids (estrogens/progestogens) and meaningful quantitative hooks for 17β-estradiol, norethindrone acetate, albuterol, nitroglycerin, and pilocarpine. Landscape positioning: the most direct competitive risk comes from formulations that reuse the claim’s adhesive/PVP platform, not only from those copying a specific drug. FAQs 1) Does claim 1 require a specific drug? No. Claim 1 recites “one drug or a mixture of two or more drugs,” and dependent claims then enumerate drug classes and examples. 2) What is the fixed PVP requirement? Across claim 1 and the claim 4 branch, soluble PVP must be present at about 1% to about 20% by weight of the total pressure-sensitive adhesive composition (dependent claims specify molecular weight bands). 3) What adhesive polymers are mandatory in the PSA blend? The PSA blend is defined as including (i) a PSA polymer selected from a listed group at 14% to 94%, (ii) polyisobutylene at 10% to 90%, and (iii) polysiloxane at 5% to 95%. 4) How does claim 4 differ from claim 1? Claim 4 adds polyacrylate (5% to 85%) and a constraint that the solubility parameter difference between polyacrylate and the base PSA (a) is at least 2 (J/cm³)^(1/2), while still requiring soluble PVP and drug plus optional enhancer. 5) Do the device-layer claims create standalone infringement risk? They do not appear standalone in this claim set. Backing, release liner, and reservoir architecture are dependent to the composition-focused claim framework, so infringement still requires meeting the adhesive/PVP composition elements. References [1] US Patent No. 5,656,286. Transdermal drug delivery systems using pressure-sensitive adhesive blends with soluble polyvinylpyrrolidone and optional enhancers. More… ↓ ⤷ Start Trial

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Summary for Patent: 5,656,286