US Patent 4,983,395: Claim Scope, Expiration, Patent Landscape, and Generic Entry Risk

US Patent 4,983,395 covers a reservoir-type transdermal or transmucosal patch with a specific peelable-seal architecture. Its central commercial contribution is the separation of the active-agent reservoir from an adhesive layer that may be chemically incompatible with formulation components. The patent issued on January 8, 1991, and, under the pre-1995 U.S. patent-term regime, expired on January 8, 2008, absent an unusual term adjustment or restoration. It therefore presents no current U.S. patent blocking risk, although its technical disclosures may remain relevant as prior art against later applications.

What does US Patent 4,983,395 protect?

The independent claim protects a multilayer drug-delivery device having both a reservoir and a controlled peelable-release structure. The claim is directed to the physical construction of the patch rather than to a particular therapeutic indication.

The required elements are:

Claim element	Required technical feature
Backing layer	Supports the patch and limits outward migration of formulation components
Active-agent-permeable membrane	Separates the reservoir from the skin or mucosa
Reservoir	Contains the active-agent formulation and has a smaller periphery than the backing and membrane
First peelable impermeable layer	Lies beneath the reservoir and part of the surrounding membrane/backing area
Adhesive layer	Covers the first peelable layer and the outwardly extending patch area
Second peelable impermeable layer	Covers the adhesive before use
Permanent heat seal	Seals the reservoir between the backing and membrane
Peelable heat seal	Located beneath the permanent seal and at an equal or greater radial distance
Coordinated liner removal	Removal of the second peelable layer breaks the peelable seal and removes the first peelable layer and underlying adhesive portion

The claim requires the interaction of these elements. A patch with a reservoir and adhesive is not enough. The accused product must also contain the specific nested seal and peel-off construction described in claim 1.

How should claim 1 be construed?

Claim 1 is a combination claim. Its scope depends on the presence of every material limitation.

Reservoir architecture

The reservoir must be located between the backing layer and the active-agent-permeable membrane. The reservoir must have a smaller periphery than those layers, leaving an outwardly extending border.

This limitation excludes a patch in which the drug-containing region extends to the outer edge of the backing and membrane. It also creates a structural distinction from many matrix systems in which the active ingredient is dispersed directly in the adhesive or polymeric body without a separate reservoir.

Permanent and peelable heat seals

The claim requires two different seals:

A permanent heat seal around the reservoir.
A peelable heat seal between the membrane and the first peelable impermeable layer.

The permanent seal protects the reservoir perimeter. The peelable seal protects the adhesive from formulation migration before use but is intended to break during removal of the protective liner.

The peelable seal must be located at a radius not less than that of the permanent seal. In practical terms, it is positioned at the same radial distance or farther from the reservoir center than the permanent seal. This relationship is a significant limitation because it defines the seal geometry rather than merely requiring any peelable seal.

Coordinated removal of layers

The first and second peelable layers must be bonded together. When the second layer is removed, it must pull away the first layer and the underlying portion of adhesive. The claim therefore covers a coordinated liner system that exposes the intended adhesive surface while removing adhesive material that may have been contaminated or chemically altered during storage.

A conventional single release liner may not satisfy this limitation unless its construction performs the same claimed layer-removal function and meets the remaining structural requirements.

What do dependent claims 2 through 6 add?

Claims 2 and 3 add constructional or compatibility limitations. Claims 4 through 6 identify specific active agents and formulations.

Claim	Added limitation	Scope
2	Adhesive is incompatible with one or more formulation components that permeate through the membrane	Functional compatibility limitation
3	Backing is a laminate with at least one formulation-impermeable layer and an inner heat-sealable layer	Specific backing construction
4	Acrylic adhesive; pindolol hydrochloride; ethyl alcohol and glycerol monooleate	Pindolol formulation embodiment
5	Acrylic adhesive; nicardipine hydrochloride; ethyl alcohol and glycerol monooleate	Nicardipine formulation embodiment
6	Silicone adhesive; calcitriol; ethanol, methyl laurate, and water	Calcitriol formulation embodiment

Claim 2: incompatible adhesive

Claim 2 is important because it identifies the technical problem addressed by the patent. Formulation components that pass through the membrane can migrate into an adhesive and cause swelling, loss of tack, extraction, crystallization, chemical degradation, or altered drug release.

The claim does not appear to require that the adhesive fail completely. It requires incompatibility with one or more components that permeate through the membrane to the skin or mucosa. The phrase is functional and may present claim-construction questions concerning the test used to establish incompatibility.

Claim 3: laminated backing

Claim 3 requires a backing laminate containing:

an outer layer impermeable to the formulation; and
an inner heat-sealable layer.

This limitation narrows the patent to a composite backing capable of both resisting formulation migration and forming the permanent heat seal. A monolithic backing that performs both functions may fall outside the literal language unless it can be characterized as a laminate or equivalent structure.

Claims 4 and 5: pindolol and nicardipine

Claims 4 and 5 do not cover every transdermal pindolol or nicardipine system. They require the claim 1 device, an acrylic adhesive, the specified hydrochloride salt, and a formulation containing ethyl alcohol and glycerol monooleate.

The claims therefore have narrow product-by-process implications. A patch using another adhesive, another permeation enhancer, another solvent system, or a matrix rather than the claimed reservoir architecture would not literally satisfy these dependent claims.

Claim 6: calcitriol

Claim 6 is directed to a silicone-adhesive patch containing calcitriol with ethanol, methyl laurate, and water. It is narrower than claims 4 and 5 because it specifies the active ingredient, adhesive class, and three formulation components.

A calcitriol product using a different adhesive or omitting one of the specified formulation components would not literally meet claim 6, although claim 1 could still be relevant if the physical device satisfies its broader structural limitations.

How broad is the patent compared with matrix and other reservoir patches?

The patent is broader than the dependent formulation claims but narrower than a generic concept of transdermal delivery.

Patch type	Likely relationship to claim 1
Claimed reservoir patch with dual seals and coordinated liners	Within the core claim architecture
Reservoir patch with one protective liner and no removable inner layer	Potentially outside claim 1
Drug-in-adhesive matrix patch	Generally outside the reservoir limitation
Polymer matrix patch with no separate membrane	Generally outside claim 1
Patch with a permanent perimeter seal but no peelable heat seal	Outside the express seal combination
Patch with a peelable seal located inside the permanent seal	Potentially outside the radial-placement limitation
Topical gel or cream without a laminated patch	Outside the claimed device
Microneedle, iontophoretic, or electronic delivery system	Generally outside the claimed passive reservoir structure

The patent does not claim a particular drug-release rate, patch size, dosage, treatment duration, patient population, or disease. Those omissions make claim 1 potentially relevant to multiple active agents, but only where the claimed physical arrangement is present.

When did US Patent 4,983,395 lose exclusivity?

US Patent 4,983,395 issued on January 8, 1991. Because it was a pre-June 8, 1995 patent, the governing term was generally 17 years from issuance under the transition rules in 35 U.S.C. § 154(c)(1). On that basis, the patent expired on January 8, 2008.[1][2]

Event	Date
Patent issued	January 8, 1991
Standard U.S. term	17 years from issue
Expected expiration	January 8, 2008
Current enforceability	Expired

An expired patent cannot support a new U.S. infringement action for post-expiration conduct. Its claims can remain relevant as prior art, however, particularly in evaluating later patent applications directed to seal geometry, drug-in-adhesive compatibility, reservoir patches, and protective-liner systems.

What is the Orange Book status of US Patent 4,983,395?

The patent is a device patent and does not, on the supplied claim set, claim an FDA-approved drug product, drug substance, method of use, or packaging configuration tied to a specific approved product. It is therefore not the type of patent ordinarily relied upon as an Orange Book-listed drug patent.

Claims 4 through 6 identify pindolol hydrochloride, nicardipine hydrochloride, and calcitriol formulations, but identifying an active ingredient in a device claim does not by itself establish Orange Book eligibility. The FDA Orange Book generally addresses patents associated with approved drug products and their labeled uses, including certain product, formulation, and method-of-use patents.[3]

The practical result is:

no current Orange Book barrier arises from the expired patent;
an ANDA applicant would not ordinarily need to address this patent through a Paragraph IV certification;
the patent would not create a current Hatch-Waxman stay or automatic 30-month litigation period.

Were Paragraph IV challenges or generic litigation relevant?

A Paragraph IV certification is used when an ANDA applicant asserts that a listed patent is invalid, unenforceable, or will not be infringed. Because US Patent 4,983,395 expired in 2008 and is not, based on its claim character, a conventional Orange Book-listed drug patent, it is not a current Paragraph IV obstacle.

The patent could have been relevant historically to a transdermal product sponsor, but the supplied information does not establish:

an Orange Book listing;
a Paragraph IV notice letter;
an ANDA litigation case;
a judicial claim-construction ruling;
a settlement agreement; or
a covenant not to sue.

No current U.S. patent litigation risk follows from the expired patent itself.

What patent landscape surrounds the invention?

The relevant landscape consists of several distinct patent categories rather than a single blocking right.

Transdermal delivery platforms

The broader field includes patents covering:

reservoir patches;
drug-in-adhesive systems;
polymer matrices;
permeation enhancers;
rate-controlling membranes;
multilayer laminates;
release liners;
heat-sealing processes; and
adhesive compatibility.

US Patent 4,983,395 occupies the intersection of reservoir delivery, dual-seal packaging, and selective adhesive removal. It does not necessarily dominate every reservoir patch or every transdermal formulation.

Formulation patents

The listed formulations may have been subject to separate patent rights directed to:

pindolol delivery;
nicardipine transdermal administration;
calcitriol delivery;
glycerol monooleate as a permeation enhancer;
methyl laurate-containing formulations;
solvent and enhancer combinations; and
defined flux or dosage ranges.

Those rights would need to be analyzed independently. Expiration of US Patent 4,983,395 does not establish freedom to operate for a drug formulation covered by a different patent.

Adhesive and membrane patents

A commercial patch can implicate separate patents covering:

acrylic pressure-sensitive adhesives;
silicone pressure-sensitive adhesives;
membrane polymers;
adhesive crosslinking;
drug partitioning;
liner coatings; and
heat-sealable polymer films.

The present patent's claim 2 addresses incompatibility at a high level. It does not claim every adhesive or membrane that solves the same problem.

Manufacturing and process rights

The disclosed structure may require process controls for:

aligning two concentric or nested seals;
forming a permanent seal without damaging the membrane;
forming a peelable seal with controlled peel strength;
avoiding drug migration into the adhesive;
bonding the two peelable layers; and
maintaining seal integrity during storage.

Process patents or trade secrets could remain commercially important even though the product patent has expired. Those rights would not extend the term of US Patent 4,983,395.

How strong was the patent estate?

The patent's historical strength was concentrated in claim 1's combination of structural limitations. Its strongest features were:

the smaller reservoir periphery;
the permanent heat seal;
the outer peelable heat seal;
the radial relationship between the two seals; and
coordinated removal of the two peelable layers and underlying adhesive.

Its limitations were equally material. The claim does not cover a general transdermal patch, a general reservoir patch, or an adhesive-compatible formulation. A design-around could target any of the following:

use a matrix rather than a reservoir;
eliminate the first peelable layer;
use a single release liner;
place the peelable seal inside the permanent seal;
use a non-heat-sealed construction;
use a different adhesive-removal mechanism; or
configure the reservoir to extend to the patch perimeter.

Because the patent expired, these design-around questions now have historical or prior-art significance rather than current infringement significance.

What generic or competitive entry risks exist?

There is no current generic-entry risk from this patent. A developer commercializing a transdermal product today would instead assess:

active-ingredient patents;
formulation patents;
method-of-use patents;
device patents filed after 2008;
manufacturing patents;
regulatory exclusivity;
foreign patent rights; and
product-specific Orange Book listings.

For products involving pindolol, nicardipine, or calcitriol, the principal commercial questions are likely to concern clinical development, formulation performance, FDA approval requirements, and other patent families rather than US Patent 4,983,395.

Does the patent have biosimilar relevance?

No material biosimilar issue arises. Pindolol, nicardipine, and calcitriol are small-molecule active ingredients, and the patent claims a delivery device rather than a biologic molecule. Biosimilar exclusivity and the Biologics Price Competition and Innovation Act pathway do not apply to this patent's core subject matter.[4]

What geographic coverage did the patent provide?

US Patent 4,983,395 provided rights only in the United States. Any foreign counterparts would have required separate national filings and separate term and maintenance-fee analysis.

The U.S. expiration did not automatically determine the status of corresponding patents in Europe, Canada, Japan, or other jurisdictions. Geographic freedom to operate therefore depends on the relevant foreign patent family, national grant, lapse history, and local term rules.

Key Takeaways

US Patent 4,983,395 covers a specific reservoir transdermal or transmucosal patch architecture.
Claim 1 requires a permanent reservoir seal, a separate peelable heat seal, nested layer geometry, and coordinated removal of two peelable layers.
The patent is not a broad claim to all transdermal patches.
Claims 4 through 6 narrow the scope to formulations involving pindolol hydrochloride, nicardipine hydrochloride, or calcitriol.
The patent issued January 8, 1991, and expired January 8, 2008, under the applicable pre-1995 patent-term rules.
It creates no current U.S. infringement, Paragraph IV, Orange Book, or biosimilar barrier.
Later patents covering formulations, adhesives, membranes, manufacturing methods, or foreign counterparts must be assessed separately.
The patent's principal historical value was its dual-seal and adhesive-protection architecture.

FAQs

Could a drug-in-adhesive patch infringe US Patent 4,983,395?

Usually not if it lacks the claimed reservoir between a backing layer and an active-agent-permeable membrane. Claim 1 is directed to a reservoir system, not merely to any patch containing an adhesive and active ingredient.

Does claim 4 cover every transdermal pindolol product?

No. Claim 4 requires the claim 1 device, an acrylic adhesive, pindolol hydrochloride, ethyl alcohol, and glycerol monooleate. A different device or formulation may fall outside the claim.

Is the patent relevant to current FDA approval of a transdermal product?

The patent itself is expired and does not create a current FDA exclusivity period. A sponsor must still address current regulatory requirements and any unexpired patents covering the active ingredient, formulation, manufacturing process, or device.

Can the expired patent be used to challenge a later patent?

Yes. Its publication and disclosure may qualify as prior art against later patent claims, subject to the later application's filing date, the applicable prior-art rules, and the specific content of the later claims.

Does expiration in the United States terminate foreign patent rights?

No. U.S. expiration applies only to the U.S. patent. Foreign counterparts require separate country-by-country status analysis.

References

United States Patent No. 4,983,395. (1991, January 8). Device for administering an active agent to the skin or mucosa. United States Patent and Trademark Office.
35 U.S.C. § 154(c)(1). Patent term transition provisions for patents issued before June 8, 1995.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations.
Biologics Price Competition and Innovation Act of 2009, Pub. L. No. 111-148, §§ 7001-7003, 124 Stat. 119.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	154751	⤷ Start Trial
Austria	81023	⤷ Start Trial
Australia	2467788	⤷ Start Trial
Australia	5341690	⤷ Start Trial
Australia	603531	⤷ Start Trial
Australia	631417	⤷ Start Trial
Canada	1302824	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,983,395

Summary for Patent: 4,983,395