Details for Patent: 4,994,278

Summary for Patent: 4,994,278

Title:	Breathable backing
Abstract:	A composition comprising a flexible backing for a transdermal drug preparation with a water vapor transmission rate about equal to or in excess of that of ethylene vinyl alcohol copolymer, namely equal to or in excess of, at one mil thickness, of about 2 to 4 grams and more preferably in excess of 6 grams per 24 hours per 100 square inches at 40° C. and 90% relative humidity and an oxygen transmission rate equal to or less than ethylene vinyl alcohol copolymer, namely at one mil thickness equal to or less than about 0.01 to 0.1 cubic centimeters per 100 square inches measured over 24 hours at 1 atmospheric pressure, 20° C. and 65% relative humidity.
Inventor(s):	Steven Sablotsky, Cheryl M. Gentile
Assignee:	Noven Pharmaceuticals Inc
Application Number:	US07/295,788
Patent Claim Types: see list of patent claims	Composition;

Scope and claims analysis for US Patent 4,994,278: transdermal systems with oxygen- and water-vapor–controlled plastic film backings

US 4,994,278 claims a transdermal drug-in-adhesive/carrier composition where the drug is in a transdermal carrier with a skin-contact surface and an opposite surface, and that opposite surface is covered by a plastic film “backing” layer (often multilayer) defined by quantitative water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) thresholds. The claim set is built to protect (i) the structural combination (transdermal carrier + defined backing on the non-skin surface) and (ii) specific barrier-performance windows (WVTR and OTR measured under defined test conditions), with dependent claims narrowing to higher WVTR and specific polymer backings (ethylene vinyl alcohol copolymer plus polyurethane layers).

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What does US 4,994,278 claim protect in a transdermal drug delivery system?

Core invention in one line: A transdermal composition where the drug-bearing carrier has a non-skin surface backed by a thin plastic film (0.2 to 3 mils) whose WVTR and OTR fall into specified ranges, with additional protection for multilayer backings and specific polymer pairings.

What is claimed, structurally?

Independent claim 1 requires:

1. A transdermal carrier with two surfaces

   • One surface “adapted for application to the skin”
   • The second surface “opposed thereto” (the non-skin side)

2. A pharmacologically active agent in the transdermal carrier

   • No specific drug identity is recited in the claim text you provided.
   • The agent is any pharmacologically active agent that can be incorporated into a transdermal system.

3. A backing on the second surface

   • “At least a first layer of a plastic film for said second surface of the carrier”
   • Backing thickness 0.2 to 3 mils
   • Backing performance is defined by:
     • WVTR (water vapor transmission rate) at 1 mil thickness in excess of 2 g / 100 in² / 24h at 40°C and 90% RH
     • OTR (oxygen transmission rate) at 1 mil thickness equal to or less than 0.1 cm³ / 100 in² / 24h at 20°C and 65% RH
   • The backing is characterized as having:
     • a first side facing the second surface of the transdermal carrier
     • a second side opposite thereto

How the claim defines “backing performance” (the claim’s boundary-drawing)

Claim 1 uses two key barrier metrics, each tied to a test scenario:

• WVTR target (must be high):
  • “Water vapor transmission rate at 1 mil thickness in excess of about 2 g per 100 square inches per 24 hours at 40°C and 90% RH”
• OTR target (must be low):
  • “Oxygen transmission rate at 1 mil thickness equal to or less than 0.1 cm³ per 100 square inches measured over 24 hours at 1 atmosphere pressure, at 20°C and 65% RH”

This structure creates a split property profile: the backing must block oxygen strongly while allowing water vapor to pass relatively readily under elevated humidity/temperature.

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What are the independent vs dependent claim narrowing steps in US 4,994,278?

Independent claim 1: main protection window (thin film + oxygen barrier + water-vapor transmission)

Claim 1 is the broadest set of constraints. It protects any transdermal composition meeting all of:

• transdermal carrier with two surfaces
• pharmacologically active agent in the carrier
• plastic film backing on non-skin side
• thickness 0.2 to 3 mils
• WVTR > ~2 g/100 in²/24h at 40°C/90% RH (at 1 mil thickness)
• OTR ≤ 0.1 cm³/100 in²/24h at 20°C/65% RH (at 1 mil thickness)

Dependent claims 2 to 6: progressively higher WVTR limits and multilayer WVTR architecture

• Claim 2: backing WVTR increased

  • WVTR > 2 to 4 g / 100 in² / 24h at 40°C/90% RH

• Claim 3: two-layer backing with higher WVTR for the inner layer

  • second layer (contacting the first side of the backing) has WVTR > ~6 g/100 in²/24h at 40°C/90% RH

• Claim 4: second layer WVTR minimum tightened

  • second layer WVTR ≥ ~6 g/100 in²/24h at 40°C/90% RH

• Claim 5: three-layer backing

  • adds a third layer adjacent the second layer
  • third layer WVTR > ~6 g/100 in²/24h at 40°C/90% RH

• Claim 6: both second and third layers have even higher WVTR

  • WVTR for both layers > 9 g/100 in²/24h at 40°C/90% RH

Practical narrowing effect: The dependent claims shift from a single backing-layer performance target (claim 1) to internal-layer WVTR compliance in multilayer structures (claims 3-6). That makes the internal layer design more critical for infringement and non-infringement positions.

Dependent claims 7 and 8: specific polymer composition and layer-by-layer WVTR in combination with oxygen barrier

• Claim 7: specific backing materials

  • backing is ethylene vinyl alcohol copolymer meeting:
    • WVTR > ~6 g/100 in²/24h at 40°C/90% RH
    • OTR < ~0.1 cm³/100 in²/24h at 20°C/65% RH
  • plus a second layer of polyurethane meeting:
    • WVTR > 6 g/100 in²/24h at 40°C/90% RH

• Claim 8: adds a third polyurethane layer with higher WVTR

  • three-layer structure (as stated)
  • third polyurethane WVTR > 9 g/100 in²/24h at 40°C/90% RH

Claim 7/8 materially matters in litigation: they create a pathway to infringement that turns on polymer identity (EVOH + polyurethane) and WVTR/OTR performance.

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What is the technical role of EVOH vs polyurethane inside the claimed backing?

The claim language implies a layered functional design:

• EVOH copolymer layer is tied to the low oxygen transmission requirement (OTR ≤ ~0.1 at specified conditions) while also having WVTR above the stated minimum.
• Polyurethane layers are tied to higher WVTR (e.g., >6 and >9 depending on dependent claims), supporting the “water vapor transmission in excess” performance.

This is consistent with a design where oxygen protection is delivered by an oxygen-barrier polymer, while water vapor transport is tuned through more permeable layers.

For claim interpretation and infringement analysis, the key is that the dependent claims define both:

• which layer is made of which polymer (claim 7), and
• the WVTR compliance threshold per layer (claims 3-6 and 7-8).

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How do the measurement conditions and “at 1 mil thickness” language affect claim scope?

Claim 1’s performance thresholds are explicitly “at 1 mil thickness.” That matters because the backing thickness in claim 1 is also given as 0.2 to 3 mils.

Two claim-scope consequences follow from this structure:

1. WVTR/OTR compliance is anchored to a standardized 1 mil test basis

   • Even if the actual backing is not exactly 1 mil thick, the claim uses “at 1 mil thickness” language to define the acceptable material performance category.

2. The thickness range and the 1 mil performance basis can be read as complementary constraints

   • Thickness range governs whether the backing is within the physical structural invention
   • Test basis governs whether the backing material qualifies as meeting the oxygen and water vapor behavior required for the invention

In infringement analysis, this creates a testing-and-translation issue: accused products must be mapped to claim tests under the claim’s “at 1 mil thickness” method or an equivalent approach that yields the same standardized WVTR/OTR values.

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What is the likely prior-art and design-around landscape for this patent claim structure?

US 4,994,278 is not claiming “a patch with any backing.” It is claiming quantified film performance plus structured placement (backing on the non-skin side of a two-surface transdermal carrier) and sometimes specific polymer identity.

Design-around levers

A manufacturer seeking to avoid the claim set would typically focus on at least one of these:

1. OTR exceedance above the ≤ 0.1 cm³/100 in²/24h threshold at 20°C/65% RH (1 mil basis)
2. WVTR falling at or below the “in excess” thresholds at 40°C/90% RH (1 mil basis)
3. Backings outside the 0.2 to 3 mil thickness range
4. Different architecture
   • e.g., using a backing that is not a plastic film as described
   • or not placing the plastic film on the second surface of the transdermal carrier in the claimed manner
5. Layer-specific changes
   • If accused relies on multilayer films, infringement of dependent claims 3-6 can hinge on whether the “second layer” and “third layer” both achieve >6 or >9 WVTR thresholds
6. Polymer identity for claims 7-8
   • A backing that is not an EVOH copolymer on the oxygen-barrier side and not polyurethane on the WVTR side may avoid claims 7-8 even if performance metrics are similar

Prior-art pressure points

Because the claims use testable numeric thresholds, the most relevant prior art typically includes:

• transdermal films and backing laminates with controlled WVTR/OTR
• oxygen barrier films used for moisture- and oxidation-sensitive actives
• EVOH-based oxygen barrier films combined with more permeable laminates

Claims 7-8 are more vulnerable to prior-art anticipation where EVOH and polyurethane lamination was already disclosed for similar backing roles with comparable WVTR/OTR windows.

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Which infringement scenarios map most directly onto US 4,994,278?

Best case for plaintiffs (strongest claim match)

1. A transdermal patch with:
   • a two-surface carrier
   • an active within the carrier
   • a multilayer plastic film backing laminated to the non-skin side
2. Backing thickness within 0.2 to 3 mil
3. Backing materials engineered so that:
   • oxygen transmission is ≤ 0.1 cm³/100 in²/24h at 20°C/65% RH (1 mil basis)
   • water vapor transmission is > 2 g/100 in²/24h at 40°C/90% RH (1 mil basis)
4. If asserting dependent claims:
   • show the second layer (and third layer, if applicable) meets the specific higher WVTR thresholds (>6 and >9) at claim conditions
5. If asserting claims 7-8:
   • show EVOH copolymer is used as the oxygen-relevant layer and polyurethane layers meet the WVTR targets

Most plausible non-infringement path

• A backing that uses a different oxygen barrier strategy (e.g., different oxygen barrier polymer or structure) that yields OTR > 0.1 under the claim measurement conditions or yields WVTR ≤ 2 under the claim’s WVTR conditions.
• Or a backing that meets performance but uses a material stack not covered by polymer identity limits in claims 7-8.

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How does the claim set handle multilayer backings and layer attribution?

Dependent claims 3-6 and 7-8 all assume that:

• the backing has discrete layers with individually measurable WVTR
• “second layer” and “third layer” can be identified relative to the carrier-facing side

That makes layer attribution critical. In practice, infringement disputes can hinge on:

• how the accused laminate is constructed (order of layers)
• which layer corresponds to “second layer in contact with said first second side”
• the WVTR of each layer and whether test measurements can be mapped onto a single-layer property vs an effective laminate property

Because the claims phrase layer performance as “having a water vapor transmission rate” for the layer, the evidence typically needs to show layer-level WVTR rather than only whole-laminate performance.

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What is the commercial/portfolio relevance of this kind of transdermal backing patent?

This patent targets a design variable common across transdermal portfolios: the backing film system, especially when the active is sensitive to:

• oxidation (hence low OTR)
• moisture balance and permeation behavior (hence relatively higher WVTR)

From a licensing posture, this creates a meaningful “patch platform” argument: once a company’s patch uses an EVOH/polyurethane (or equivalent oxygen barrier/high WVTR laminate) on the non-skin side, the patent can be asserted across multiple products where the backing architecture is reused.

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Key takeaways

• US 4,994,278 claims a transdermal composition with a carrier containing the active drug and a plastic film backing on the non-skin side, with thickness 0.2 to 3 mil.
• The backing is defined primarily by WVTR > ~2 g/100 in²/24h at 40°C/90% RH (at 1 mil thickness) and OTR ≤ 0.1 cm³/100 in²/24h at 20°C/65% RH (at 1 mil thickness).
• Dependent claims narrow the scope to multilayer structures with layer-specific WVTR thresholds (>6 and >9 g/100 in²/24h) and finally to specific materials: EVOH copolymer + polyurethane (with a third polyurethane layer for claim 8).
• The most direct infringement scenario is a patch using a non-skin backing laminate that meets both numeric thresholds and, for dependent claims, layer-specific WVTR performance and EVOH/polyurethane identity.

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FAQs

1. Does US 4,994,278 cover any transdermal active, or only specific drugs?
The claim language covers a “pharmacologically active agent” without limiting identity, so the scope is not confined to a named drug.

2. What parameter is more critical for claim 1: oxygen barrier or water vapor permeability?
Both are critical. Claim 1 requires low OTR (≤0.1) and high WVTR (>2) under the specified test conditions.

3. How do claims 3-6 change the infringement test compared with claim 1?
Claims 3-6 require that the second (and third) layers individually meet higher WVTR thresholds (>6 and >9), not just the overall backing.

4. When do polymer identity limitations (EVOH + polyurethane) matter?
They matter for dependent claims 7 and 8, which require an ethylene vinyl alcohol copolymer layer plus polyurethane layers and corresponding WVTR/OTR performance.

5. What is the role of the “1 mil thickness” language?
It anchors the WVTR and OTR thresholds to a standardized basis, which can be pivotal in testing disputes where the accused backing thickness differs from 1 mil within the 0.2 to 3 mil structural range.

Drugs Protected by US Patent 4,994,278

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

International Family Members for US Patent 4,994,278

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	002355
Austria	122240
Austria	144704
Austria	148633
Austria	223185
Austria	235898
Austria	99175