US Patent 5,300,291 (Drug + Pressure-Sensitive Adhesive + Clay): Scope, Claim Structure, and US Patent Landscape
US 5,300,291 claims a targeted formulation and manufacturing workflow for drug-containing dermal systems that use a pressure sensitive adhesive (PSA) composition based on (i) a natural or synthetic rubber, (ii) a multipolymer made from ethylene/vinyl acetate (EVA) polymer + an acrylic polymer, and (iii) adhesiveness-increasing clay in a defined loading window. The patent is claim-centered on a combination that is specific on ratios, clay type, clay loading, and drug loading, with dependent claim fallbacks for particular embodiments (bentonite, steroids including 17β-estradiol, and EVA composition, polyisobutylene rubber, acrylic monomer content, and multiphase/shaped article structures).
What is the claimed invention in one line?
A method and a dermal composition in which a drug is incorporated into a PSA that contains a rubber + EVA/acrylic multipolymer in defined weight ratios, with 0.1% to 20% clay selected from a defined list, to increase adhesiveness.
Claim 1: What exactly is the core method scope?
Independent claim 1 elements (all must be present)
Claim 1 defines a method of increasing adhesiveness of a PSA composition that comprises:
-
Core PSA polymer system
- Natural or synthetic rubber (any within claim scope)
- Multipolymer comprising:
- ethylene/vinyl acetate polymer
- acrylic polymer
- Defined weight ratios
- EVA polymer : acrylic polymer = 1:20 to 20:1
- Multipolymer : rubber = 1:10 to 30:1
-
Drug + clay
- The method includes admixing:
- rubber
- acrylic polymer
- EVA polymer
- a drug
- at least one clay
- The resulting composition must contain:
- adhesiveness-increasing amount of clay
- Clay = 0.1% to 20% by weight of resulting composition
-
Clay species restriction
- Clay is natural or synthetic and selected from:
- hydrated aluminum silicate
- kaolinite
- montmorillonite
- atapulgite
- illite
- bentonite
- halloysite
Practical claim boundary from Claim 1
- Core invention is not “a drug patch” generically. It is a PSA adhesiveness-increasing method with a specific polymer architecture (rubber + EVA/acrylic multipolymer) and a clay loading and species list.
- Clay loading window is broad (0.1% to 20%), which expands infringement probability across formulation suppliers, but still requires the polymer ratio constraints and the defined clay list.
Dependent claim mapping: How the scope narrows or shifts
Drug loading limits
- Claim 2: drug < 10% by weight
- Claim 3: drug < 5% by weight
These restrict “drug heavy” formulations and align with typical transdermal loading regimes.
Clay-specific embodiments
- Claim 4: clay is bentonite
- Claim 5: clay 0.1% to 6%
- Claim 6: drug is a steroid and bentonite 0.1% to 3%
- Claims 16, 17: composition variants:
- Claim 16: clay 0.1% to 6%
- Claim 17: clay 0.1% to 3%
- Claims 19, 20: 17β-estradiol + bentonite 0.1% to 3%
Drug identity
- Claim 7: drug is 17-β-estradiol
- Claim 10: drug is an estrogen, with additional ratio and clay constraints
Ratio refinement
- Claim 8: multipolymer : rubber = 1:5 to 20:1
- Claim 9: multipolymer : rubber = 1:2 to 15:1
- Claim 10: multipolymer : rubber 3:1, clay 0.1% to 3%, drug is estrogen
Independent composition claim 11: adds dermal product form
Claim 11 converts the method’s PSA/clay architecture into a dermal composition with the same polymer ratio and clay constraints:
- EVA/acrylic multipolymer ratios:
- EVA : acrylic = 1:20 to 20:1
- multipolymer : rubber = 1:10 to 30:1
- clay loading = 0.1% to 20%
- clay list is the same
- includes drug, PSA rubber, and the multipolymer
Composition fallbacks in claims 12-36
Key additional constraints and manufacturing elements are added:
Clay identity
- Claim 12: clay is bentonite
Solvent system
- Claim 13: composition includes at least one liquid solvent
- Claim 15: solvent includes glycol
- Claim 21: glycol selected from propylene and butylene glycols
- Claim 14: approximate percent by weight:
- drug 0.5% to 50%
- clay 0.5% to 20%
- solvent 0.5% to 20%
Multipolymer and rubber specific specs
- Claim 32: EVA polymer has 4% to 50% by weight vinyl acetate
- Claim 33: rubber comprises polyisobutylene
- Claim 34: acrylic polymer contains at least 50% by weight of acrylate or alklyacrylates monomer units
Article structure
- Claim 25: shaped article with:
- two opposed faces
- backing on one face
- release liner on other
- Claims 26-27: adds backing layer and/or release liner
System architecture
- Claim 28: multiphase system
- Claim 29: first phase and second phase
- Claim 30: interpenetrating polymer phases
Adhesive additives
- Claim 31: further comprising a tackifying agent
Manufacturing method
- Claim 35: mixing components in presence of solvent, coating onto release liner, removing lower molecular weight solvents
- Claim 36: for claim 33 (polyisobutylene rubber), joining a backing layer to the mixture
What does this claim set cover from an infringement perspective?
High-probability infringement zones (from the claim text alone)
- Drug-in-PSA dermal systems where the PSA contains:
- rubber + EVA/acrylic multipolymer with specified EVA:acrylic and multipolymer:rubber ratios, and
- clay from the specified list at 0.1% to 20% loading.
- Formulations specifically using:
- bentonite
- steroid drugs including 17β-estradiol
- Designs that also match:
- glycol solvent systems (propylene or butylene glycols)
- EVA vinyl acetate content (4% to 50%)
- polyisobutylene rubber
- acrylic monomer unit content (>=50%)
Key “escape” variables that are still claim-controlled
- Using a clay type outside the listed group (if true) can avoid direct claim 1/11 clay limitation.
- Failing the required EVA:acrylic ratio or multipolymer:rubber ratio can avoid claim 1/11 even if clay is present.
- Clay content outside 0.1%-20% breaks the broad claim window, though dependent claims create narrower sub-ranges.
How broad is the polymer ratio coverage?
EVA polymer to acrylic polymer (Claim 1 and 11)
- 1:20 to 20:1
This is extremely wide. It allows EVA-dominant or acrylic-dominant multipolymer composition and suggests the invention is anchored more on the presence of the multipolymer in combination with rubber and clay, rather than a single fixed multipolymer internal stoichiometry.
Multipolymer to rubber (Claim 1 and 11)
- 1:10 to 30:1
This is also wide, spanning rubber-rich to multipolymer-rich systems. Dependent claims narrow to:
- 1:5 to 20:1 (Claim 8)
- 1:2 to 15:1 (Claim 9)
- about 3:1 (Claim 10; also tied to estrogen + clay 0.1%-3%)
What is the drug scope?
Independent claims
- Claim 1: drug is not limited by identity.
- Claim 11: drug is not limited by identity.
Dependent claim coverage
- Specific drug embodiments:
- steroids (Claim 6, Claim 18)
- 17β-estradiol (Claim 7)
- estrogens (Claim 10 and Claim 24)
Drug loading windows
- In method claim hierarchy:
- <10% (Claim 2)
- <5% (Claim 3)
- In composition claim hierarchy:
- Claim 14 states drug 0.5% to 50% by weight (approximate percent by weight)
This creates an interpretive split: claim 2/3 tighten the drug loading for the method, while claim 14 permits wide drug loading in the composition form.
Does the patent include manufacturing/process protection?
Yes. Claim 35 and Claim 36 provide process steps for making the claimed composition into a coated system, tying to:
- mixing in solvent
- coating onto release liner
- removing low molecular weight solvents
- joining backing for specific rubber (polyisobutylene)
These claims can matter where formulation is outsourced and the manufacturing workflow is distinctive.
Key structural and product-form limitations
Claims 25-30 capture typical transdermal product architecture:
- backing + release liner
- shaped article
- multiphase system with interpenetrating polymer phases (Claim 30)
This makes the patent relevant not only to bulk adhesive formulation but to the final device structure.
US patent landscape: what to expect around US 5,300,291 (claim-driven map)
The provided text contains the claims but does not supply:
- filing date, priority, assignee, or patent bibliographic data
- prosecution history
- cited references
- related continuations or family members
- expiration/terminal disclaimer status
- enforcement history
Under those constraints, a complete patent landscape that enumerates neighboring US patents, overlaps, and likely citation clusters cannot be produced with accuracy.
Given that limitation, only the landscape dimensions that are directly inferable from the claim language can be identified as the relevant technology clusters for prior art and freedom-to-operate review:
Technology clusters implicitly implicated by the claim language
- Clay-modified pressure sensitive adhesives
- Adhesiveness enhancement with clays such as bentonite, montmorillonite, kaolinite, illite
- Drug-in-PSA dermal patches
- Incorporation of actives (steroids, estrogens like 17β-estradiol) into PSA adhesive systems
- Rubber + tacky polymer blends
- Rubber as base (including polyisobutylene as a dependent-spec embodiment)
- EVA/acrylic multipolymer architecture
- EVA vinyl acetate content window (dependent claim)
- Solvent and processing
- glycol solvents and solvent removal after coating
- Device construction
- backing + release liner, multiphase systems
These clusters define where most overlaps will occur in a landscape search: clay-containing PSA patents, transdermal steroid PSA patents, and EVA/acrylic adhesive systems.
Claim-by-claim “scope scoreboard” (quick reference)
| Claim |
What it adds |
Main restriction axis |
| 1 |
Method: rubber + EVA/acrylic multipolymer + drug + clay (0.1%-20%); clay list |
Adhesive architecture + clay + ratios |
| 2 |
Drug <10% |
Drug loading |
| 3 |
Drug <5% |
Drug loading |
| 4 |
Bentonite |
Clay identity |
| 5 |
Clay 0.1%-6% |
Clay loading |
| 6 |
Steroid + bentonite 0.1%-3% |
Drug identity + clay loading |
| 7 |
17β-estradiol |
Drug identity |
| 8 |
Multipolymer:rubber 1:5 to 20:1 |
Ratio |
| 9 |
Multipolymer:rubber 1:2 to 15:1 |
Ratio |
| 10 |
Estrogen + multipolymer:rubber ~3:1 + clay 0.1%-3% |
Drug identity + ratio + clay loading |
| 11 |
Independent dermal composition |
Converts method into composition with same core constraints |
| 12 |
Bentonite |
Clay identity |
| 13 |
Includes solvent |
Formulation |
| 14 |
Approx wt%: drug 0.5%-50%, clay 0.5%-20%, solvent 0.5%-20% |
Quantitative composition window |
| 15 |
Solvent includes glycol |
Solvent type |
| 16 |
Clay 0.1%-6% |
Clay loading |
| 17 |
Clay 0.1%-3% |
Clay loading |
| 18 |
Steroid |
Drug identity |
| 19 |
17β-estradiol + bentonite |
Drug identity + clay identity |
| 20 |
Bentonite 0.1%-3% |
Clay loading |
| 21 |
Glycol: propylene/butylene glycols |
Solvent subtype |
| 22 |
Multipolymer:rubber 1:5 to 20:1 |
Ratio |
| 23 |
Multipolymer:rubber 1:2 to 15:1 |
Ratio |
| 24 |
Estrogen + multipolymer:rubber ~3:1 + clay 0.1%-3% |
Drug + ratio + clay loading |
| 25 |
Shaped article + backing + release liner |
Device structure |
| 26 |
Adds backing layer |
Device structure |
| 27 |
Adds release liner |
Device structure |
| 28 |
Multiphase system |
System architecture |
| 29 |
Two phases |
System architecture |
| 30 |
Interpenetrating phases |
System architecture |
| 31 |
Tackifying agent |
Additive |
| 32 |
EVA vinyl acetate 4%-50% |
EVA spec |
| 33 |
Rubber comprises polyisobutylene |
Rubber spec |
| 34 |
Acrylic monomer units >=50% |
Acrylic spec |
| 35 |
Method of producing: mix with solvent, coat on release liner, remove low MW solvent |
Processing |
| 36 |
For polyisobutylene embodiment: join backing |
Processing + device assembly |
Key Takeaways
- US 5,300,291 is claim-centered on clay-loaded PSA compositions that include rubber + EVA/acrylic multipolymer with broad internal ratios and a specific clay species list at 0.1%-20% loading.
- The drug is broadly covered in independent claims, with dependent claims focusing on steroids, 17β-estradiol, and estrogens, plus drug loading constraints in method claims.
- The patent includes both formulation scope (composition claims) and manufacturing scope (mixing/coating/solvent removal) plus transdermal device structure (backing, release liner, shaped article, multiphase/interpenetrating phases).
- A complete US patent landscape (overlap mapping, prior art, prosecution-cited references, family members, and expiration/enforceability) cannot be produced from the claim text alone; landscape work must be anchored to the patent’s bibliographic and citation record.
FAQs
1) What clay types are explicitly allowed?
Hydrated aluminum silicate, kaolinite, montmorillonite, atapulgite, illite, bentonite, and halloysite.
2) What is the clay loading range in the broad independent claims?
0.1% to 20% by weight of the resulting composition.
3) Are EVA/acrylic ratios fixed?
No. EVA polymer to acrylic polymer is 1:20 to 20:1 in both Claim 1 and Claim 11.
4) Does the patent cover specific drugs like 17β-estradiol?
Yes. Claim 7 covers 17β-estradiol in the method; Claim 19 covers 17β-estradiol with bentonite in the composition.
5) Does the patent include a manufacturing method?
Yes. Claim 35 covers mixing with solvent, coating onto release liner, and removing lower molecular weight solvents; Claim 36 adds joining a backing layer for the polyisobutylene embodiment.
References
[1] US Patent 5,300,291 (provided claim text).
