Scope and Claims of US Patent 4,915,950 and the U.S. Transdermal Device Patent Landscape

US 4,915,950 claims manufacturing methods for multilayer transdermal delivery and related laminate devices using (i) an adsorbent fabric “source” layer, (ii) a skin-contact pressure-sensitive adhesive that is drug-permeable, (iii) an anchor adhesive, and (iv) a backing layer that is substantially impermeable to the active. The core claim strategy is process-defined device construction: drug is “printed” in liquid form onto the adsorbent fabric (or incorporated into adhesives), with optional permeation enhancer, and with specific drug embodiments including nicotine (free base or salt), nitroglycerin, and fentanyl (base or salt). The second claim family addresses fragrance-releasing laminate devices with analogous architecture.

Because your excerpt reproduces only the claim set shown and not the patent’s specification, dependent claim numbering, figures, or prosecution history, the patent landscape below is structured strictly around the claim elements you supplied and the typical U.S. transdermal laminate/design-around patterns that map to those elements. No other scope is asserted.

What does US 4,915,950 claim: method steps for making a transdermal delivery device?

Answer (claim 1): A method with four laminations plus a printing step: laminate an adsorbent source layer to a drug-permeable contact adhesive; print a liquid drug onto the adsorbent fabric; laminate an anchor adhesive layer; laminate a substantially drug-impermeable backing layer.

Claim 1 element map (functional scope by process + materials)

(a) Lamination of adsorbent source layer to pressure-sensitive contact adhesive
- Adsorbent source layer: “adsorbent fabric” in claim 11; claim 1 uses “adsorbent source layer.”
- Contact adhesive: pressure-sensitive, pharmaceutically acceptable, permeable to the drug, defines basal surface for adhesion to skin.
(b) Printing a drug in liquid form onto the adsorbent fabric layer
- “Printing” is process-anchored. The claim does not require microdeposition, screen printing, or ink-jet, but it does require a printing deposition of drug in liquid form on the adsorbent fabric layer.
(c) Lamination of anchor adhesive layer
- Anchor adhesive layer is laminated to the source layer (claim 1) or laminated to the fabric layer (claim 11).
(d) Application of backing layer
- Backing defines the upper surface and is substantially impermeable to the drug.

Claim 2: Release liner step extends disposable construction

Adds release liner covering the lower surface of the contact adhesive, removable prior to use to expose the skin-adhesive surface.

Scope note: Claim 2 is likely to be a “standard” transdermal device accessory step, but it becomes claim-relevant because the rest of the claim is process-specific to the adsorbent/printing/backing architecture.

Does US 4,915,950 cover nicotine, nitroglycerin, and fentanyl transdermal patches?

Answer: Yes. The patent includes drug-specific dependent claims: nicotine (free base or salt), nitroglycerin, and fentanyl (base or pharmaceutically acceptable salt).

Drug-specific dependent claims (3 to 9)

Claim 3: drug is nicotine
Claim 4: nicotine is free base
Claim 5: nicotine is in salt form
Claim 6: drug is nitroglycerin
Claim 7: drug is fentanyl
Claim 8: fentanyl is fentanyl base
Claim 9: fentanyl is a pharmaceutically acceptable salt of fentanyl

What this means for infringement risk

For a generic manufacturer, process design-around is the primary lever:
- If the competitor makes a transdermal system with a different deposition approach than “printing” of a liquid drug onto an adsorbent fabric layer, they may avoid the literal method recitation.
- If the competitor uses a contact adhesive that is not “permeable to the drug” as claimed, or a backing that is not “substantially impermeable” to the drug, they shift into claim construction fights (but still a potential avoidance route).

How does US 4,915,950 treat permeation enhancers in the printing step?

Answer (claim 10): The method includes depositing the drug in liquid form on the source layer with a percutaneous absorption enhancer that increases skin permeability to the drug.

Scope implications

The enhancer is tied to the deposition step: it is part of what is deposited/printed with the drug liquid on the adsorbent source.
This is materially relevant to formulation manufacturing risk: if an application uses the enhancer in a different layer (for example, only in the contact adhesive, or only in the anchor adhesive), literal coverage depends on whether claim 10’s deposition-with-enhancer is met. That is a narrower requirement than claims that broadly require permeation enhancement.

What does claim 11 add: printing an enhancer vs incorporating drug into layers before lamination?

Answer (claim 11): A second manufacturing method where:

the adsorbent fabric is laminated to a permeable pressure-sensitive contact adhesive,
an enhancer is printed onto the adsorbent fabric,
an anchor adhesive is laminated,
backing is applied, and
before laminating, the drug is incorporated into the anchor adhesive layer, the contact adhesive layer, or both.

Claim 11 element map (distinct from claim 1)

Deposition sequence differs:
- Claim 1 prints the drug onto the adsorbent fabric.
- Claim 11 prints the enhancer onto the adsorbent fabric.
Drug placement changes:
- Claim 1 places drug on the adsorbent fabric by printing (as recited).
- Claim 11 allows incorporation of drug into the adhesives pre-lamination (anchor, contact, or both).

Landscape impact: Claim 11 is a common “escape hatch” for process variations where drug is not deposited onto the adsorbent fabric as the printed component, but enhancer is. That means manufacturers that try to avoid claim 1 by embedding drug elsewhere may still face claim 11 exposure if they print enhancer onto the adsorbent fabric and meet the layer-impermeability/permeability constraints.

What does US 4,915,950 claim about fragrance-releasing devices?

Answer (claim 12): A method for a fragrance device using:

adsorbent fabric initially retaining fragrance in liquid form,
laminating to a contact adhesive defining a basal surface,
printing fragrance in liquid form onto the adsorbent fabric so it is incorporated and initially retained,
laminating an anchor adhesive layer substantially permeable to fragrance,
applying a backing layer substantially permeable to fragrance.

Why claim 12 matters for device manufacturers

It extends the same architecture logic to non-drug volatile actives.
A manufacturer with a platform for transdermal-like laminate devices may be exposed to both drug delivery and fragrance device claims if the manufacturing architecture matches.

Key difference vs transdermal claims

In transdermal method claim 1:
- backing is substantially impermeable to the drug.
In fragrance claim 12:
- backing is substantially permeable to fragrance.
This indicates the patent’s method framework is adaptable: same layer roles but different permeability targets aligned to whether the active must be retained or released.

How strong is the patent estate for this manufacturing concept: what adjacent claim themes exist?

Below are the dominant adjacent themes that typically appear around adsorbent-fabric transdermal and “printed liquid loading” concepts, and how they intersect with your claim elements. This is a landscape map, not a claim-by-claim enumeration, because you provided only the claim text for US 4,915,950.

1) Adsorbent fabric “source layer” transdermal loading

Your claims hinge on a distinct “adsorbent fabric/source layer” laminated to a permeable pressure-sensitive adhesive.
Adjacent patents often claim:
- specific adsorbent structures (foam, nonwoven, woven, treated fibers),
- drug loading methods into the adsorbent,
- binding/retention chemistries controlling release kinetics.

Design-around vector: replace the adsorbent fabric with a different reservoir form (matrix gel, microreservoir, solid dispersion in adhesive) or remove “laminated adsorbent fabric” as a structural prerequisite.

2) “Printed” deposition of liquid actives

Claim language uses “printing.”
Adjacent patents may cover:
- coating, spraying, gravure coating, slot die coating,
- microarray deposition,
- transfer printing.

Design-around vector: avoid “printing onto” the adsorbent fabric; use batch coating or in-situ impregnation during web formation. Literal infringement hinges on whether the competing process is “printing” under claim construction.

3) Layer permeability partition: drug-permeable contact adhesive, impermeable backing

Claim 1 specifies:
- contact adhesive is permeable to the drug,
- backing is substantially impermeable to the drug.
Adjacent patents can be broader or narrower:
- define permeability as a measured property range,
- tie permeability to specific polymer families,
- specify multilayer barrier films.

Design-around vector: change the role of the backing, such as making it “controlled-permeability” rather than “substantially impermeable,” or using a rate-limiting membrane approach not met by the “substantially impermeable” constraint.

4) Permeation enhancer placement

Claim 10 ties enhancer to deposition with the drug.
Claim 11 ties enhancer printing while drug is in adhesives.
Adjacent patents often claim enhancer in:
- the contact adhesive,
- a separate enhancer layer,
- the drug reservoir.

Design-around vector: relocate enhancer out of the printed deposition step; keep drug deposition/enhancer deposition in different layers not meeting the recited deposition sequence.

5) Liner and standard patch construction

Claim 2 adds a release liner covering the skin-contact side.
Adjacent patents generally treat liners as conventional, but in a process method claim they can still be asserted as required steps.

What patent disputes typically arise from this type of method claim: “process method” vs “product-by-process” issues?

Your claims are methods for making a device. U.S. patent infringement of method claims depends on the accused party performing the claimed manufacturing steps. That creates a litigation pattern:

Common infringement theories

Direct infringement:
- patch maker performs laminating, printing steps, and applies backing.
Inducement/contributory:
- formulation house and converter coordinate steps.

Common validity attack themes for this claim type

Obviousness based on prior transdermal laminates with:
- adhesive-permeable contact layers,
- reservoir or adsorbent layers,
- impermeable backs,
- printing or coating deposition techniques,
- known enhancers in transdermal systems.

Common claim construction fights

Meaning of “printing”
Whether the contact adhesive is “permeable” and the backing is “substantially impermeable”
Whether a layer is an “adsorbent fabric” vs a coating on non-adsorbent substrates
Whether the deposition is “onto” the source layer in the recited laminate stack context

Exclusivity timelines: when would US 4,915,950 matter for entry?

For exclusivity and launch timing, the decisive facts are the patent’s filing date, priority, maintenance status, and any terminal disclaimers. Those are not present in your excerpt, so exact expiration or adjusted term cannot be computed here.

What can be stated from the claim set is how it would affect exclusivity posture once the patent is in force:

Any competitor manufacturing nicotine/nitroglycerin/fentanyl transdermal devices using the adsorbent-fabric + printed liquid loading + permeable contact adhesive + impermeable backing architecture risks method-claims exposure.
Competitors may shift to:
- different deposition mechanics than “printing,”
- different drug placement (drug in adhesives rather than on adsorbent fabric),
- different permeability regime for backing/contact adhesive,
- different intermediate layers that change the laminate’s required “substantially” thresholds.

Key design-around matrix tied to the specific claim limitations

Claim limitation cluster	Literal requirement (per excerpt)	High-probability design-around
Adsorbent source layer laminated to drug-permeable contact adhesive	“adsorbent fabric/source layer” + pressure-sensitive adhesive permeable to drug, defining basal skin surface	Replace adsorbent fabric with a different drug reservoir architecture; use a contact layer that is not “permeable” as construed
Drug printed in liquid form onto adsorbent layer (claim 1)	“printing a drug in liquid form onto” the source layer	Use non-printing impregnation/coating, or print only enhancer (map to claim 11 structure)
Anchor adhesive lamination	Laminating anchor adhesive to source/fabric layer	Change stack so anchor adhesive is absent or replaced by different intermediate layers not matching claim structure
Backing substantially impermeable to drug (claim 1)	“substantially impermeable to the drug”	Use controlled-permeability backing, different barrier film system, or redesign so backing is not substantially impermeable
Release liner (claim 2)	Apply release liner covering lower adhesive surface	Manufacture/assemble without liner (or change liner integration method)
Enhancer with printed drug deposition (claim 10)	Deposit drug liquid with a percutaneous absorption enhancer	Place enhancer only in other layers or apply enhancer post-deposition in a way that does not match the “deposited with” limitation
Claim 11: print enhancer; drug pre-incorporated into anchor/contact adhesives	Pre-lamination incorporation of drug into adhesives; enhancer printed onto adsorbent	Reverse deposition steps only if you still meet claim 11’s remaining constraints; otherwise change deposition approach

How this claim scope maps to commercial transdermal platforms

Even without knowing the patent’s drug products, the claim structure corresponds to a common transdermal platform pattern:

Reservoir layer: adsorbent fabric that holds liquid actives initially.
Skin interface: pressure-sensitive contact adhesive that must allow drug permeation.
Barrier layer: backing to limit lateral and/or upward migration and control release.
Optional enhancer: liquid-phase enhancer integrated via deposition approach.

From a licensing and competitive standpoint, the highest economic overlap is with platforms that:

use web-fed adsorbent/nonwoven reservoir layers,
load actives by liquid deposition,
maintain consistent barrier/backing systems.

Key Takeaways

US 4,915,950 is process-focused: it claims manufacturing steps for multilayer transdermal (and fragrance) laminate devices using an adsorbent fabric reservoir, a drug-permeable pressure-sensitive skin adhesive, an anchor adhesive, and a backing that is substantially impermeable to the drug.
The drug coverage is claim-dependent: nicotine (free base and salt), nitroglycerin, and fentanyl (base and salts) appear in dependent claims.
Two manufacturing routes are claimed:
- claim 1: print the drug in liquid form onto the adsorbent fabric,
- claim 11: print the enhancer onto the adsorbent fabric while incorporating the drug into the adhesives pre-lamination.
Design-around hinges on “printing,” permeability thresholds, and layer placement:
- change deposition mechanics,
- relocate drug/enhancer to different steps/layers,
- use a backing system not “substantially impermeable.”
Litigation posture typically centers on method performance: infringement requires the accused party to practice the recited manufacturing steps; validity often targets obviousness over prior transdermal laminate concepts plus known deposition methods.

FAQs

1) Can a company avoid US 4,915,950 by incorporating the drug into the contact adhesive rather than printing it onto the adsorbent fabric?
Claim 11 already contemplates drug incorporation into the anchor adhesive, contact adhesive, or both, while printing enhancer on the adsorbent fabric. Avoidance depends on whether the competitor also matches the remaining structural and step-specific constraints.

2) If the competitor uses coating instead of “printing,” is it still covered?
US 4,915,950 requires “printing” onto the adsorbent fabric in the relevant claim paths. Whether “printing” reads on coating depends on claim construction and how the competitor’s deposition technology is characterized.

3) Does the patent cover nicotine free base and nicotine salt differently?
Yes. Claim 4 narrows to nicotine free base, while claim 5 narrows to nicotine salts.

4) What role does the backing layer play in infringement risk?
Claim 1 requires a backing layer that is substantially impermeable to the drug. Changing the backing’s permeability regime is a central design-around lever.

5) Is fragrance device manufacturing covered even if no drug is used?
Yes. Claim 12 claims a fragrance-releasing laminate method using analogous adsorbent fabric and laminate steps with permeability rules set for fragrance.

References (APA)

United States Patent 4,915,950.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	127331	⤷ Start Trial
Australia	4031289	⤷ Start Trial
Australia	639892	⤷ Start Trial
Canada	1336324	⤷ Start Trial
Germany	68924157	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,915,950

Summary for Patent: 4,915,950