United States Patent 6,841,716: Claim Scope, Validity, Expiration, and Patch Patent Landscape

U.S. Patent No. 6,841,716 protects a transdermal or adhesive patch configuration in which the release liner has one or more specifically dimensioned wave-shaped slits. The patent does not claim a drug, active pharmaceutical ingredient, therapeutic indication, or drug-delivery method. Its protection is directed to the mechanical design of the patch and release liner.

The commercially important limitation is the combination of:

a support;
an adhesive layer;
a releasable release film;
a wave-shaped slit extending across the release film;
a wave pitch of 6 mm to 12.5 mm; and
a wave height of 4 mm to 8 mm.

The patent is narrow because an accused patch must satisfy each limitation of an asserted claim. Claims 2 through 8 add further structural and dimensional restrictions. Based on the 20-year patent-term framework, the patent’s enforceable term would ordinarily have ended in or around 2022, subject to the patent’s precise filing history, patent-term adjustment, terminal disclaimers, and any applicable extensions under 35 U.S.C. § 154.[1][2]

What does U.S. Patent 6,841,716 protect?

The patent protects a patch whose release liner is engineered to facilitate partial removal and application.

The claimed operating principle is as follows:

The release film remains attached to the adhesive layer.
A portion of the release film is peeled away along the wave-shaped slit.
The exposed adhesive is placed against the attachment site.
The support is bent slightly along the slit.
The remaining release-film edge protrudes outward from between the attachment site and adhesive layer.
The remaining release film can then be removed.

The invention therefore concerns application mechanics rather than pharmaceutical delivery. The claim language focuses on the relationship between the wave geometry, the support, the adhesive, and the remaining release liner.

What is the independent claim?

Claim 1 is the principal claim. It requires all of the following:

Claim 1 limitation	Scope
Patch	A patch article, not merely a release liner
Support	A backing or support layer
Adhesive layer	Laminated on one side of the support
Release film	Attached releasably to the adhesive layer
Slit	Extends from one edge of the release film to the opposite edge
Wave shape	The slit has a wave-shaped configuration
Functional result	Slight bending of the support causes the remaining release-film edge to protrude outward
Wave pitch	6 mm to 12.5 mm
Wave height	4 mm to 8 mm

The claim includes both structural and functional language. The structural limitations define the article. The functional language explains why the wave-shaped slit is present and what happens during use.

Under ordinary claim-construction principles, the functional language may limit the claim if it describes a required capability of the claimed structure rather than merely stating an intended use.[3] A product that has the specified geometry but cannot produce the claimed outward protrusion could present a claim-construction issue.

How do claims 2 through 8 narrow the patent?

Claims 2 through 8 are dependent claims that add increasingly specific configurations.

Claim	Added limitation	Commercial significance
2	Two substantially parallel wave-shaped slits	Covers a two-strip release configuration
3	Spacing between slits is 20 mm to 30 mm	Narrows the two-slit design by width
4	Wave height is 6 mm to 7 mm	Captures a narrower preferred geometry
5	Rounded patch corners with curvature radius of at least 5 mm	Addresses handling and skin-contact geometry
6	Adhesive thickness of 10 μm to 400 μm	Covers a broad adhesive-thickness range
7	Support thickness of 0.01 mm to 5 mm	Covers thin-film through relatively thick support structures
8	Combines two slits, 20-30 mm spacing, 6-7 mm wave height, rounded corners, adhesive thickness, and support thickness	Most detailed embodiment

Claim 8 is materially narrower than claim 1. It requires two slits even though claim 1 requires only one. It also fixes the wave height at 6 mm to 7 mm, rather than the broader 4 mm to 8 mm range.

What is the scope of claim 1 in an infringement analysis?

A literal infringement case under claim 1 would generally require proof that the accused patch has:

a support;
an adhesive layer laminated to that support;
a releasable release film;
a slit extending from one edge to the opposite edge;
a wave-shaped slit;
a pitch within 6 mm to 12.5 mm;
a height within 4 mm to 8 mm; and
the claimed bending and outward-protrusion functionality.

A design with a straight slit would not literally satisfy the wave-shaped slit limitation. A sinusoidal, zigzag, scalloped, or other repeating slit could raise a claim-construction issue depending on the patent specification and prosecution history.

A design may avoid literal infringement by changing one material limitation, including:

using a straight or irregular slit;
placing the slit only partway across the release film;
using a pitch below 6 mm or above 12.5 mm;
using a wave height below 4 mm or above 8 mm;
using a release liner that does not protrude outward when the support is bent; or
replacing the slit with a perforation, score line, tab, or separate removable section.

The doctrine of equivalents could still be asserted against some variations, but prosecution-history estoppel and the all-elements rule would constrain that analysis.[4][5]

How should “wave pitch” and “wave height” be measured?

The claim does not, on its face, define every measurement convention. The specification, drawings, prosecution history, and industry measurement practice would be relevant.

Potential disputes include:

whether pitch means crest-to-crest distance;
whether wave height means crest-to-trough distance or amplitude;
whether measurements are taken in the relaxed or stretched condition;
whether the dimensions apply at the release-film edge or along the slit centerline; and
how irregular or nonuniform waves are measured.

These dimensions are central to claim scope. A product specification that gives only a nominal value may not resolve whether the entire slit satisfies the claimed range.

What patent protection exists for two-slit release liners?

Claims 2, 3, and 8 target a two-slit release liner. The two slits must be substantially parallel under claim 2. Claim 3 requires 20 mm to 30 mm spacing. Claim 8 combines that spacing with the 6 mm to 7 mm wave-height range and the other dimensional limitations.

A two-slit patch can fall outside claims 2, 3, and 8 if:

the slits are not substantially parallel;
the spacing is less than 20 mm or greater than 30 mm;
the wave height falls outside 6 mm to 7 mm for claim 8; or
the patch lacks the specified rounded corners, adhesive thickness, or support thickness.

Those changes would not necessarily avoid claim 1. Claim 1 does not require two slits, rounded corners, or the specified thickness ranges.

What formulations are protected by U.S. Patent 6,841,716?

No pharmaceutical formulation is expressly claimed in the supplied claims.

The patent does not require:

a particular active ingredient;
a drug concentration;
a permeation enhancer;
a polymer matrix;
a reservoir system;
a drug-in-adhesive composition;
a dosage amount;
a therapeutic indication; or
a route of administration.

The adhesive thickness limitation in claims 6 and 8 is a physical-product limitation. It does not convert the patent into a formulation patent.

A patch containing fentanyl, nicotine, lidocaine, hormone, nonsteroidal anti-inflammatory drug, capsaicin, or another active ingredient could potentially fall within the claims if the patch has the claimed structural features. Conversely, a drug patch with a different release-liner design would not infringe solely because it is a transdermal patch.

What is the FDA and Orange Book status of this patent?

U.S. Patent 6,841,716 is not, based on the supplied claims, a drug patent of the type normally listed in the FDA Orange Book.

The Orange Book identifies patents submitted for approved drug products, including patents claiming the drug substance, drug product, or approved method of use.[6] A stand-alone patch-construction patent generally does not create an Orange Book-listed barrier unless it is submitted in connection with an approved drug product and satisfies FDA listing requirements.

The patent therefore does not itself create:

FDA pediatric exclusivity;
new chemical entity exclusivity;
three-year clinical-investigation exclusivity;
five-year drug-substance exclusivity;
a Paragraph IV certification issue; or
a Hatch-Waxman regulatory stay.

A generic drug company could face separate patent issues if an approved product used the claimed patch configuration and the patent were listed. The supplied patent claims alone do not establish that listing.

When does U.S. Patent 6,841,716 lose exclusivity?

The patent’s ordinary term is governed by the filing-date rules in 35 U.S.C. § 154. For a modern utility patent, the term generally runs 20 years from the earliest effective nonprovisional U.S. filing date, subject to patent-term adjustment and other statutory modifications.[1]

Public patent records identify U.S. Patent 6,841,716 as an issued utility patent from the early 2000s. Its ordinary enforceable term would therefore have ended approximately two decades after the effective U.S. filing date, generally placing expiration in or around 2022. The exact enforceability date depends on the patent’s official term calculation, including any patent-term adjustment.

After expiration, the claims no longer support a new infringement action for post-expiration commercial activity. Patent expiration does not erase historical liability for acts occurring while the patent was enforceable, subject to applicable limitation periods and litigation defenses.[2]

How strong is the patent estate for this patch technology?

The patent estate appears narrow but technically coherent.

Strengths

The independent claim combines multiple objective structural limitations.
The wave pitch and wave-height ranges provide measurable boundaries.
The claim covers a functional application advantage tied to the release-liner geometry.
Claims 2 through 8 create fallback positions for preferred two-slit designs.
The claim is not limited to a specific drug, allowing use across multiple patch products.

Weaknesses

The invention is directed to a mechanical release-liner arrangement that may be vulnerable to earlier patch and packaging art.
The dimensional ranges may be susceptible to anticipation by products using similar wave geometries.
The claim does not cover all partial-peel or tab-based release liners.
A competitor may be able to design around the numerical ranges.
The lack of active-ingredient or therapeutic limitations reduces the patent’s relevance to drug-specific exclusivity.
The functional protrusion language could create claim-construction disputes.

The highest-risk validity issues would be anticipation and obviousness based on earlier transdermal patches, adhesive bandages, surgical dressings, medical tapes, and release-liner designs with scored, perforated, zigzag, or curved separation lines.[7]

Which companies could be relevant to the competitive patent landscape?

The relevant commercial landscape includes companies that manufacture transdermal systems, adhesive medical products, and patch converting equipment. Potentially relevant industry participants include:

Hisamitsu Pharmaceutical;
3M;
Nitto Denko;
Teikoku Seiyaku;
Lohmann Therapie-Systeme;
Noven Pharmaceuticals;
Mylan and other generic patch manufacturers;
Corium;
LTS Lohmann Therapie-Systeme; and
contract patch converters and medical adhesive suppliers.

The patent does not necessarily cover the core commercial technology of any particular company. A company may sell a patch using a different liner design, license a release-liner technology, or obtain the liner from a converter whose own intellectual-property position differs from the drug-product sponsor’s position.

What licensing and freedom-to-operate issues arise?

A license to the drug formulation does not automatically authorize use of a patented patch-construction technology. Conversely, a license to a release-liner design does not necessarily cover:

the active ingredient;
the adhesive chemistry;
manufacturing processes;
packaging;
regulatory data;
trademarks; or
method-of-use rights.

A freedom-to-operate review should separate at least four layers:

drug substance patents;
drug-in-adhesive or matrix formulation patents;
patch architecture and release-liner patents; and
manufacturing, coating, laminating, and converting patents.

For U.S. Patent 6,841,716 specifically, the principal historical FTO question was whether the commercial patch used the claimed wave geometry and dimensional ranges. Because the patent term has likely ended, the current U.S. risk is primarily historical rather than an obstacle to a new launch.

What litigation or Paragraph IV risk affects this patent?

The supplied information does not establish a reported infringement action, settlement agreement, inter partes review, post-grant proceeding, or Paragraph IV certification involving U.S. Patent 6,841,716.

The patent’s subject matter makes a conventional Paragraph IV dispute less likely unless the patent was listed for a specific approved drug product. A generic sponsor would typically assess the patent through:

Orange Book listing review;
product-by-product claim mapping;
a Paragraph IV certification if the patent were listed;
noninfringement based on liner geometry;
invalidity based on prior art; and
a launch-at-risk analysis if the patent remained enforceable.

A patent covering only a patch component could still be asserted against a finished drug product if the product practices every limitation, but the patent would need to be enforceable and procedurally available for the relevant statutory pathway.

How does this patent compare with typical transdermal patch patents?

Patent category	Typical subject matter	6,841,716 position
Drug-substance patent	Active molecule or salt	Not covered
Formulation patent	Drug-in-adhesive, matrix, enhancer	Not expressly covered
Method-of-use patent	Treating a disease or patient group	Not covered
Delivery-system patent	Reservoir, matrix, membrane, dose control	Not expressly covered
Patch-structure patent	Backing, adhesive, liner, geometry	Primary category
Manufacturing patent	Coating, drying, laminating, die cutting	Not expressly covered
Packaging patent	Pouch, seal, storage, applicator	Not expressly covered

The patent has less breadth than a drug-substance patent but can be relevant to multiple products using the same patch-construction solution. Its commercial value would have depended on adoption of the claimed release-liner geometry and the remaining patent term.

Key Takeaways

U.S. Patent 6,841,716 claims a patch and wave-shaped release liner, not a drug or therapeutic method.
Claim 1 requires a wave-shaped slit with a 6 mm to 12.5 mm pitch and a 4 mm to 8 mm height.
Claims 2, 3, and 8 cover narrower two-slit configurations with 20 mm to 30 mm spacing.
Claims 5 through 8 add dimensional restrictions for corners, adhesive thickness, and support thickness.
A straight slit, different dimensional range, partial slit, tab system, or nonprotruding liner may provide design-around positions.
The patent is not inherently an Orange Book drug patent and does not create FDA drug exclusivity by itself.
Its ordinary U.S. patent term likely ended in or around 2022, subject to the official patent-term calculation.
The principal historical validity risks were prior art involving wave-shaped, scored, perforated, or partially removable release liners.
No litigation, settlement, Paragraph IV challenge, or licensing transaction is established by the supplied record.
Current commercial risk is primarily associated with historical use during the enforceable term, not a new U.S. launch after expiration.

Frequently Asked Questions

Does U.S. Patent 6,841,716 cover fentanyl or nicotine patches?

No. The claims do not require fentanyl, nicotine, or any other active ingredient. A product could fall within the claims only if its physical patch structure satisfies the claimed release-liner geometry and other limitations.

Can a competitor avoid the patent by using a straight release-liner slit?

A straight slit would not literally satisfy the wave-shaped slit limitation in claim 1. The remaining risk would depend on claim construction and any assertion under the doctrine of equivalents.

Does claim 8 require two wave-shaped slits?

Yes. Claim 8 incorporates the two-slit configuration and requires 20 mm to 30 mm spacing, a 6 mm to 7 mm wave height, rounded corners, a 10 μm to 400 μm adhesive layer, and a 0.01 mm to 5 mm support.

Is the patent relevant to biosimilar competition?

No direct biosimilar issue arises. Biosimilars concern biologic products, while this patent claims a physical patch structure. It could become relevant only as a separate device or combination-product patent if a biologic were delivered through the claimed patch.

Does patent expiration eliminate all regulatory barriers to a competing patch?

No. Expiration removes the patent exclusion right, but a competing product may still require FDA approval, bioequivalence or clinical support, manufacturing compliance, labeling approval, and compliance with other unexpired patents.

References

United States Code. (2023). 35 U.S.C. § 154: Contents and term of patent; provisional rights. U.S. Government Publishing Office.
United States Code. (2023). 35 U.S.C. § 271: Infringement of patent. U.S. Government Publishing Office.
United States Patent and Trademark Office. (2023). Manual of Patent Examining Procedure § 2111: Claim interpretation; broadest reasonable interpretation.
United States Supreme Court. (1997). Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17.
United States Supreme Court. (2002). Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722.
U.S. Food and Drug Administration. (2023). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book.
United States Patent and Trademark Office. (2005). U.S. Patent No. 6,841,716: Patch.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Japan	11/133037	May 13, 1999

PCT Information
PCT Filed	April 27, 2000	PCT Application Number:	PCT/JP00/02791
PCT Publication Date:	November 23, 2000	PCT Publication Number:	WO00/69422

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	253355	⤷ Start Trial
Brazil	0010467	⤷ Start Trial
China	1177585	⤷ Start Trial
China	1350451	⤷ Start Trial
Germany	60006380	⤷ Start Trial
European Patent Office	1181930	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,841,716

Summary for Patent: 6,841,716