US Patent 4,842,864: Self-Adhesive Percutaneous Matrix Drug Patch (Scope, Claims, and Landscape)
US Patent 4,842,864 claims a self-adhesive matrix formulated for percutaneous administration of an active ingredient, with tightly defined polymer-adhesive/hydration components, a cellulose derivative, a polyhydric alcohol, and a specified ratio constraint. The claims also include formulation sub-ranges, specific exemplified compositions, and a manufacturing process tied to high-temperature mixing, solvent incorporation, coating, and solvent evaporation.
What Is Claimed: Core Composition Architecture
The independent claim (Claim 1) defines a matrix consisting of five ingredient classes:
- (a) Ethylene/vinyl acetate copolymer (EVA)
- (b) Higher aliphatic monoalcohol
- (c) Cellulose derivative
- (d) Polyhydric alcohol
- (e) Percutaneously administrable active ingredient
- 0.01 to 10 parts by weight
- Constraint: weight ratio (a + c) / (b + d) is between 0.7 and 1.3
This ratio constraint is the key structural limiter that prevents the claim from sweeping in EVA-and-wax-like hot-melt compositions without cellulose/polyol balance.
Claim 1: Formal Scope (Composition)
| Element |
Component class |
Weight range (parts by weight) |
| (a) |
Ethylene/vinyl acetate copolymer material |
40 to 60 |
| (b) |
Higher aliphatic monoalcohol compound |
40 to 60 |
| (c) |
Cellulose derivative material |
1 to 20 |
| (d) |
Polyhydric alcohol compound |
0.1 to 8 |
| (e) |
Percutaneously administrable active ingredient |
0.01 to 10 |
| Limitation |
Ratio (a + c) / (b + d) |
0.7 to 1.3 |
Claim construction implication: For infringement analysis, the most actionable “claim-killer” variables are (i) whether the formula includes cellulose derivative in the claimed band and (ii) whether the (a+c)/(b+d) ratio falls inside the 0.7 to 1.3 window.
How Claim Scope Expands: Active Ingredient Language
Is the claim limited to particular drugs?
Claim 1 is broad on actives: it covers “an active ingredient which can be administered percutaneously” (0.01 to 10 parts).
Claim 2 narrows actives by specifying that the active ingredient (e) is a steroid selected from:
- estradiol
- progesterone
- testosterone
- derivatives of those steroids
- and corticosteroids
Claim 2: Formal Scope (Steroid/Corticosteroid-Directed)
| Element |
Component class |
Weight range (parts by weight) |
| (a) |
EVA |
40 to 60 |
| (b) |
Higher aliphatic monoalcohol |
40 to 60 |
| (c) |
Cellulose derivative |
1 to 20 |
| (d) |
Polyhydric alcohol |
0.1 to 8 |
| (e) |
Steroid: estradiol/progesterone/testosterone + derivatives; corticosteroids |
0.01 to 10 |
| Limitation |
Ratio (a + c) / (b + d) |
0.7 to 1.3 |
Practical consequence: If a competitor uses the same matrix system but an active outside steroid/corticosteroid families, Claim 2 may not apply while Claim 1 could still apply.
Narrowing Claims: Polymer and Substituent Parameters
What EVA composition bounds are required in dependent claims?
Claims 3 and 4 introduce vinyl acetate unit content requirements.
- Claim 3: vinyl acetate content 35 to 55% by weight (relative to EVA)
- Claim 4: vinyl acetate content around 45% by weight
This reduces the reachable supplier EVA pool. EVA grades with vinyl acetate outside these bands move out of the dependent claim scope.
EVA vinyl acetate unit narrowing
| Claim |
EVA vinyl acetate content |
| 3 |
35% to 55% |
| 4 |
about 45% |
Which monoalcohols are covered?
Claim 5 limits higher aliphatic monoalcohols to:
- saturated or unsaturated monoalcohols having 12 to 20 carbon atoms
This matters for wax selection. Common candidates in this band (C12-C20 aliphatic alcohols) remain inside.
Which cellulose derivatives are covered?
Claim 6 restricts cellulose derivative selection to:
- alkyl celluloses
- hydroxyalkyl celluloses
Claim 7 enumerates specifically:
- methyl cellulose
- ethyl cellulose
- propyl cellulose
- methylpropyl cellulose
- hydroxymethyl cellulose
- hydroxyethyl cellulose
- hydroxypropyl cellulose
Which polyhydric alcohols are covered?
Claim 8 defines polyhydric alcohol as a glycol compound selected from alkylene glycols.
Claim 9 further lists examples:
- ethylene glycol
- propylene glycol
- butylene glycol
- triethylene glycol
- diethylene glycol
- polyethylene glycol
- polypropylene glycol
This makes it easier to invalidate dependent scope if a competitor uses different polyols (e.g., glycerol, sorbitol, sugar alcohols) not falling into the listed alkylene glycol framing.
Exemplified Composition Claim: A Concrete Estradiol Formulation
Is there a claim that locks in a specific formulation?
Yes. Claim 10 provides a composition with explicit substituents and an estradiol active.
It specifies:
- (a) 40 to 60 parts EVA
- (b) 2-octyldodecan-1-ol
- (c) 1 to 20 parts ethyl cellulose
- (d) 0.1 to 8 parts dipropylene glycol
- (e) 0.01 to 10 parts estradiol
- ratio constraint (a+c)/(b+d) between 0.7 and 1.3
Claim 11 gives a narrower “about 45% EVA / 45% VA” style band and tighter subranges including viscosity and the active level for β-estradiol.
Claim 10: Estradiol + Specific Excipients
| Element |
Component |
Weight range |
| (a) |
EVA (ethylene/vinyl acetate copolymer) |
40 to 60 |
| (b) |
2-octyldodecan-1-ol |
40 to 60 |
| (c) |
Ethyl cellulose |
1 to 20 |
| (d) |
Dipropylene glycol |
0.1 to 8 |
| (e) |
Estradiol |
0.01 to 10 |
| Limitation |
(a + c)/(b + d) |
0.7 to 1.3 |
Claim 11: Narrower β-Estradiol Variant with Process-Adjacent Spec
| Element |
Component |
Weight range or spec |
| (a) |
EVA |
about 45 parts; about 45% vinyl acetate |
| (b) |
2-octyldodecan-1-ol |
40 to 45 parts |
| (c) |
Ethyl cellulose |
5 to 10 parts; viscosity 2×10^-2 to 2×10^-1 Pa·s |
| (d) |
Dipropylene glycol |
1 to 5 parts |
| (e) |
β-estradiol |
3 to 5 parts |
| Limitation |
(a + c)/(b + d) |
0.7 to 1.3 |
Scope note: Claim 11’s viscosity window on ethyl cellulose and its “about” EVA/VA concentration substantially reduce design-around space but still leaves room within the broader Claim 1 if actives differ or cellulose type changes.
What Is Claimed: Manufacturing Method (Process Claim 12)
Is there a process claim tied to production conditions?
Yes. Claim 12 is a multi-stage process with explicit temperature thresholds and operational parameters.
Claim 12: Step-by-step method elements
- Mix (a) and part of (b) with stirring at ≥ 110°C.
- Incorporate (c) into the stage-1 mixture at ≥ 110°C, then homogenize.
- Add the remainder of (b) at ≥ 110°C, stir.
- Homogenize at ≥ 110°C, then stand at least 8 hours.
- Heat at 50°C to 70°C (preferably 60°C) for at least 0.25 h, then incorporate (d) and the active in a solvent at that temperature.
- Homogenize for ≥ 0.5 h without heating.
- Deposit onto a temporary support (especially silicone-treated paper) at 50°C to 70°C, coating rate 100 to 300 g/m².
- Heat the coated assembly at 70°C to 90°C to evaporate the active solvent until residual proportion is < 5% by weight.
- Transfer the dry matrix onto an appropriate support.
Process-structure implication: A competitor could avoid Claim 12 by:
- changing the order of addition,
- altering the solvent evaporation endpoint,
- using different deposition mechanics,
- or avoiding the high-temperature ≥110°C mixing/homogenization and the ≥8-hour standing stage.
However, Claim 12 is dependent on “a matrix as claimed in claim 1,” so process design-around still matters only if they land outside the composition claims.
Claim Dependency Map (Practical Enforcement View)
| Claim |
Coverage type |
Main narrowing levers |
| 1 |
Independent composition |
Ratio (a+c)/(b+d) and core component ranges; active any percutaneous |
| 2 |
Dependent composition |
Active limited to estradiol/progesterone/testosterone/derivatives and corticosteroids |
| 3 |
Dependent |
EVA vinyl acetate 35-55% |
| 4 |
Dependent |
EVA vinyl acetate ~45% |
| 5 |
Dependent |
monoalcohol C12-C20 (saturated/unsaturated) |
| 6 |
Dependent |
cellulose derivative limited to alkyl and hydroxyalkyl celluloses |
| 7 |
Dependent |
specific cellulose derivative list (methyl/ethyl/propyl/etc.) |
| 8 |
Dependent |
polyhydric alcohol is alkylene glycol class |
| 9 |
Dependent |
enumerated glycols including PEG/PPG |
| 10 |
Dependent composition |
specific ingredients: 2-octyldodecan-1-ol + ethyl cellulose + dipropylene glycol + estradiol |
| 11 |
Dependent narrow variant |
“about 45” EVA/VA; specific parts; ethyl cellulose viscosity range; β-estradiol 3-5 parts |
| 12 |
Dependent method |
specific mixing temperatures and time, coating rate, solvent endpoint, and support type |
Patent Landscape: Where This Patent Sits in Technology Space
What is the likely invention focus?
This patent sits at the intersection of:
- adhesive matrix transdermal/percutaneous delivery, using EVA + high aliphatic alcohol plus cellulose derivative and polyhydric glycol
- formulation control via a quantified ratio constraint
- process conditions that support matrix formation and solvent removal
Landscape segmentation (actionable for freedom-to-operate)
Because the claims are composition-led with narrow dependent fallbacks and a single multi-step process claim, the landscape risk concentrates on:
- EVA + C12-C20 monoalcohol + cellulose derivative + alkylene glycol systems with the same ratio window.
- Steroid/corticosteroid transdermal or percutaneous patches using this matrix.
- Manufacturing routes with the specific ≥110°C mixing, ≥8-hour stand, and solvent residual <5% criterion.
Design-around vectors implied by the claim set
Using only the claim text, the most direct “escape hatches” are:
- move the ratio (a+c)/(b+d) outside 0.7 to 1.3
- replace cellulose derivative with a non-covered polymer class
- use polyols outside the alkylene glycol framing
- change the EVA vinyl acetate content outside 35-55% (for dependent scope)
- switch monoalcohol to outside C12-C20
- replace estradiol/progesterone/testosterone/corticosteroids if only dependent Claim 2 is relevant
- change process parameters to avoid Claim 12’s defined sequence/thresholds
Freedom-to-Operate Risk Heat Map (Based on Claim Language Only)
| Implementation feature |
Closest to claims |
Risk impact |
| EVA present at 40-60 parts |
Matches (a) |
High if combined with other elements |
| Higher aliphatic monoalcohol at 40-60 parts |
Matches (b) |
High if C12-C20 and ratio aligns |
| Cellulose derivative at 1-20 parts |
Matches (c) |
High; removal or substitution reduces risk |
| Polyhydric alcohol/alkylene glycol 0.1-8 parts |
Matches (d) |
Medium to high depending on polyol choice |
| Ratio (a+c)/(b+d) in 0.7-1.3 |
Key constraint |
High; ratio failure can clear even if materials match |
| Active is steroid/corticosteroid |
Matches (e) for Claim 2 |
Medium (Claim 1 may still apply) |
| EVA VA content 35-55% or ~45% |
Matches dependent claims |
Medium for dependent scope only |
| Ethyl cellulose viscosity in specified band |
Matches Claim 11 |
Low unless formulating that exact variant |
| Process uses ≥110°C steps and specific coating/evaporation endpoints |
Matches Claim 12 |
Medium only if compositions also match Claim 1 |
Key Takeaways
- Claim 1 is the main enforcement anchor: a EVA + C12-C20-type monoalcohol matrix with a cellulose derivative and alkylene glycol plus a strict (a+c)/(b+d) ratio of 0.7 to 1.3.
- Claim 2 narrows active to estradiol/progesterone/testosterone/derivatives and corticosteroids, but Claim 1 remains broad on active type.
- Dependent claims narrow EVA vinyl acetate content (35-55% or ~45%), specific cellulose derivatives, and polyol class (alkylene glycols).
- Claims 10 and 11 hard-code specific excipient choices and an estradiol/β-estradiol concentration profile, including ethyl cellulose viscosity in Claim 11.
- Claim 12 is process-specific: high-temperature mixing and homogenization at ≥110°C, ≥8-hour stand, controlled coating at 50-70°C with 100-300 g/m², and solvent evaporation to <5% residual after heating 70-90°C.
FAQs
What is the single most important numeric limitation across the independent claim?
The weight ratio (a+c)/(b+d) must be between 0.7 and 1.3 (Claim 1).
Does the patent require a particular EVA grade?
Not in Claim 1, but dependent claims require EVA vinyl acetate content 35-55% (Claim 3) and about 45% (Claim 4).
Are the monoalcohols restricted to a carbon-count range?
Yes. Dependent Claim 5 restricts higher aliphatic monoalcohols to saturated/unsaturated monoalcohols with 12 to 20 carbon atoms.
Is the matrix limited to steroid and corticosteroid drugs?
Claim 1 is not. It covers any percutaneously administrable active ingredient. Claim 2 limits actives to estradiol/progesterone/testosterone/derivatives and corticosteroids.
Is there a specific manufacturing procedure claimed?
Yes. Claim 12 specifies a staged mixing and deposition process with defined temperature thresholds, coating rate, and solvent residual target (<5% by weight).
References
[1] US Patent No. 4,842,864. “Self-adhesive matrix for percutaneous administration of an active ingredient” (claims 1-12 as provided).
