US Patent 5,840,327: Claim Scope, Expiration, Orange Book Status, and Transdermal Testosterone Patent Landscape

US Patent 5,840,327 covers a flexible reservoir transdermal patch using a non-adhesive ethylene-vinyl acetate carrier, a backing layer, and a discontinuous adhesive pattern occupying about 8% to 16% of the skin-facing surface. Its strongest commercial focus is a testosterone patch for scrotal administration, although claim 1 also covers estradiol and progesterone devices for sensitive body areas.

The patent issued November 24, 1998, and its statutory patent term ended in approximately 2016 based on the applicable US filing date. It is no longer an enforceable US patent. The patent therefore has historical importance for Testoderm-type testosterone delivery systems but does not create a current blocking right against generic or follow-on transdermal products.

What does US Patent 5,840,327 protect?

The patent protects a specific patch architecture rather than testosterone as a molecule or transdermal delivery generally.

The core claimed combination has four technical elements:

A drug-containing reservoir.
A non-adhesive polymeric carrier permeable to the drug.
A discontinuous adhesive pattern on the skin-facing surface.
A backing layer on the opposite surface.

The adhesive is limited to approximately 8% to 16% of the reservoir surface area. The adhesive surface must lie in a different plane from the reservoir's drug-transfer surface. This limitation describes a raised or offset adhesive arrangement in which the adhesive contacts skin while the reservoir surface is positioned differently.

Independent claim 1 covers:

Testosterone, estradiol, or progesterone;
Administration through intact skin;
Sensitive body areas;
A flexible and compliant device;
A non-adhesive polymeric reservoir;
A discontinuous adhesive pattern covering about 8% to 16% of the reservoir surface.

Independent claim 7 is narrower. It requires:

Testosterone;
Administration through intact scrotal skin;
The same reservoir, adhesive, and backing configuration;
The same 8% to 16% adhesive coverage range;
The adhesive surface and reservoir contact surface lying in different planes.

Claims 2 through 6 narrow claim 1. Claims 8 through 12 narrow claim 7.

Claim group	Principal subject matter	Key narrowing limitations
1	Testosterone, estradiol, or progesterone patch	Sensitive body area; 8% to 16% discontinuous adhesive; offset planes
2	Claim 1 patch	EVA carrier with 40% vinyl acetate
3	Claim 2 patch	Polyisobutylene adhesive
4	Claim 1 patch	About 12% adhesive coverage
5	Claim 4 patch	1 to 8 parallel longitudinal adhesive stripes
6	Claim 5 patch	Five stripes separated by about 1.27 cm
7	Testosterone scrotal patch	Same structural limitations as claim 1, expressly limited to scrotal skin
8	Claim 7 patch	EVA carrier with 40% vinyl acetate
9	Claim 8 patch	Polyisobutylene adhesive
10	Claim 7 patch	About 12% adhesive coverage
11	Claim 10 patch	1 to 8 parallel longitudinal stripes
12	Claim 11 patch	Five stripes separated by about 1.27 cm

What are the broadest enforceable claim concepts?

Claim 1 is the broadest claim in the patent, but it is narrower than a generic claim to a testosterone patch.

A competing product would need to satisfy the claimed limitations in combination. The most important limitations are:

Drug selection

Claim 1 is limited to testosterone, estradiol, or progesterone. A patch delivering another drug does not fall within claim 1 because of the express Markush group.

Claim 7 is limited to testosterone. It does not cover estradiol or progesterone products.

Reservoir construction

The drug must be dispersed throughout a non-adhesive polymeric carrier permeable to the drug. A matrix in which the adhesive itself contains the drug may avoid this limitation. So may a liquid reservoir, gel reservoir, or drug-in-adhesive system, depending on the precise product construction.

The claims do not cover every polymeric reservoir. Claims 2 and 8 specifically require ethylene-vinyl acetate with 40% vinyl acetate, but the independent claims do not impose that EVA composition.

Adhesive coverage

The adhesive must be discontinuous and occupy about 8% to 16% of the reservoir's skin-facing surface. A continuous adhesive layer, a drug-in-adhesive construction, or an adhesive pattern outside the claimed range would provide a potential design-around route.

The word "about" creates a boundary dispute risk. Courts generally assess the term in view of the specification, prosecution history, measurement method, and technical context. Coverage should be measured consistently against the reservoir skin-facing area, not the total patch area, unless the patent specification establishes another method.

Plane relationship

The adhesive skin-contacting surface must lie in a different plane from the reservoir's skin-facing drug-transfer surface. This is a structural limitation, not merely a result-oriented statement.

A product with a flush adhesive and reservoir surface could avoid the limitation. A product with a recessed reservoir, raised adhesive strips, or another offset arrangement could satisfy it.

How do claims 1 and 7 differ?

Claim 7 is a species claim nested within the broader subject matter of claim 1.

Issue	Claim 1	Claim 7
Drug	Testosterone, estradiol, or progesterone	Testosterone only
Anatomical site	Sensitive body areas	Scrotal skin
Delivery route	Through intact skin	Through intact scrotal skin
Reservoir	Non-adhesive permeable polymeric carrier	Same
Adhesive	Discontinuous, 8% to 16%	Same
Plane limitation	Required	Required
Commercial relevance	Broader sensitive-area patch platform	Testosterone scrotal patch

A testosterone patch applied to scrotal skin could potentially satisfy both claims 1 and 7. A testosterone patch for the upper arm would not satisfy claim 7 because the claim requires scrotal administration, although it could satisfy claim 1 if all other limitations are met.

What formulations are protected by US Patent 5,840,327?

The patent protects reservoir-based formulations using a permeable, non-adhesive polymeric carrier. The dependent claims identify a preferred carrier and adhesive combination.

EVA reservoir

Claims 2 and 8 require an ethylene-vinyl acetate copolymer with 40% vinyl acetate. This composition is materially narrower than the independent claims.

A product using EVA with a materially different vinyl acetate percentage may avoid literal infringement of claims 2 and 8, although it could remain within claim 1 or claim 7 if the independent claim limitations are satisfied.

Polyisobutylene adhesive

Claims 3 and 9 require polyisobutylene adhesive. These claims do not cover every pressure-sensitive adhesive.

A silicone, acrylate, rubber-based, or other adhesive could avoid those dependent claims. It could still raise an issue under the independent claims if the adhesive pattern, coverage percentage, plane relationship, and remaining limitations are present.

Stripe configuration

Claims 5 and 11 cover a pattern having 1 to 8 parallel longitudinal adhesive stripes separated by a predetermined distance. Claims 6 and 12 narrow that structure to five stripes separated by approximately 1.27 cm.

The stripe claims are substantially narrower than claims 1 and 7. A product using circular islands, a perimeter frame, a grid, a different number of stripes, or a materially different spacing would present a stronger noninfringement position against those claims.

When did US Patent 5,840,327 lose exclusivity?

The patent lost enforceable exclusivity in approximately 2016. The relevant term is generally 20 years from the earliest effective US nonprovisional filing date, subject to patent-term adjustment or other statutory modifications. The November 24, 1998 issue date did not independently determine expiration.

Event	Date or status
US patent issued	November 24, 1998
Patent term basis	20 years from applicable US nonprovisional filing date
Approximate statutory expiration	2016
Current enforceability	Expired
Current patent-based generic block	None from US 5,840,327

Because the patent is expired, claims 1 through 12 cannot support a new US infringement action for post-expiration activity. The patent may still matter in freedom-to-operate reviews as evidence of disclosed technology, claim construction history, or prior-art content, but not as a live exclusionary right.

What is the Orange Book status of US Patent 5,840,327?

US Patent 5,840,327 should not be treated as a current Orange Book barrier.

The FDA Orange Book lists patents submitted by approved-drug applicants for approved products. A patent can be relevant to a product's historical approval record without remaining enforceable after expiration. Orange Book listing and patent validity are separate questions.

For transdermal testosterone products, regulatory analysis must distinguish among:

Drug substance patents;
Reservoir and patch construction patents;
Method-of-use patents;
FDA-listed product patents;
Regulatory exclusivity;
Patent term expiration.

Testoderm and Androderm were approved testosterone transdermal systems, but the presence of a testosterone patch in the Orange Book does not establish that US 5,840,327 is currently listed, active, or enforceable. The FDA Orange Book must be reviewed by product and application number for the applicable historical and current listing status. The expired patent itself does not create a present-day filing bar under an abbreviated new drug application.

What FDA regulatory pathway applies to a testosterone patch?

A follow-on testosterone patch generally requires an FDA approval pathway appropriate to the reference product and product design.

Generic or abbreviated pathway

A conventional ANDA may be difficult if the proposed patch differs materially from the reference product in:

Reservoir technology;
Adhesive composition;
Application site;
Drug release profile;
Adhesion performance;
Systemic exposure;
Local tolerability.

Where the reference product is not suitable for a conventional ANDA or where the proposed device differs substantially, an applicant may need a 505(b)(2) application. The regulatory pathway depends on the reference listed drug, the degree of formulation and device similarity, and the evidence needed to establish safety and effectiveness.

Testosterone-specific requirements

FDA product review may address:

Testosterone exposure;
Dose proportionality;
Adhesion during use;
Skin irritation and sensitization;
Transfer risk;
Application-site tolerability;
Product performance across temperature and activity conditions;
Scrotal or non-scrotal administration, as applicable.

US 5,840,327 does not provide regulatory exclusivity after expiration. FDA approval and patent freedom to operate remain separate analyses.

Is there biosimilar risk for the product protected by US 5,840,327?

No conventional biosimilar risk applies. Testosterone, estradiol, and progesterone are small-molecule active ingredients, not biological products regulated through the biosimilar pathway under section 351(k) of the Public Health Service Act.

The relevant competitive threats are:

ANDA generic patches;
505(b)(2) transdermal products;
Compounded testosterone products;
Topical gels and solutions;
Injectable testosterone;
Oral testosterone formulations;
Implanted testosterone products.

The expired patent removes one historical barrier, but device complexity, clinical performance, manufacturing scale, and FDA requirements can still affect entry.

Which companies challenged or competed with the relevant products?

The historical commercial field included companies associated with Testoderm, Androderm, and successor or generic testosterone products. The principal commercial competition has not been limited to identical scrotal patches.

Product or category	Delivery system	Competitive relevance
Testoderm	Scrotal testosterone patch	Closest historical product concept
Androderm	Non-scrotal testosterone patch	Competing transdermal system
Testosterone gels	Topical gel	Major alternative to patches
Testosterone solutions	Topical liquid	Alternative topical delivery
Injectable testosterone	Intramuscular or subcutaneous	Competes on price, dosing interval, and adherence
Oral testosterone undecanoate	Oral systemic delivery	Competes with transdermal therapy
Testosterone pellets	Implantable delivery	Long-acting alternative

A specific Paragraph IV challenge to US 5,840,327 is not commercially material today because the patent has expired. Paragraph IV litigation historically may have involved patents listed for particular testosterone products, but those patents must be separated from US 5,840,327.

What Paragraph IV risks existed before expiration?

Before expiration, a generic applicant could have challenged the patent under a Paragraph IV certification if it was listed for the reference product and asserted that the patent was invalid, unenforceable, or not infringed.

The principal potential Paragraph IV arguments against the claims would have included:

Anticipation: A prior patch disclosed a drug reservoir, discontinuous adhesive pattern, backing, and offset adhesive plane.
Obviousness: The claimed adhesive percentage, stripe pattern, EVA carrier, and polyisobutylene adhesive were predictable modifications of known transdermal systems.
Indefiniteness: Terms such as "about," "sensitive body areas," "flexible and compliant," and "different plane" could have been challenged if the specification did not provide adequate boundaries.
Noninfringement: A generic could use a drug-in-adhesive system, a continuous adhesive, a different reservoir polymer, or a different patch geometry.
Written-description or enablement issues: A challenge could target the breadth of the claims covering three hormones and multiple sensitive body areas.

These issues no longer create a launch barrier because the patent term has ended.

How strong was the patent estate around Testoderm-type patches?

US 5,840,327 had moderate historical value as a device patent but limited breadth against alternative transdermal architectures.

Strengths

Claim 7 directly targeted testosterone delivery through scrotal skin.
The claims combined anatomical site, reservoir construction, adhesive geometry, and surface-plane positioning.
Claims 6 and 12 provided a commercially specific five-stripe configuration.
The patent addressed adhesion at sensitive sites, an important product-performance problem.

Weaknesses

The claims did not cover testosterone generally.
The patent did not cover all transdermal testosterone systems.
Drug-in-adhesive systems could avoid the reservoir limitation.
Continuous adhesive systems could avoid the discontinuous-pattern limitation.
Alternative polymers and adhesives could avoid the dependent claims.
The 8% to 16% range and "about" language could invite factual disputes.
The patent was vulnerable to design-around through patch geometry and layer relationships.
The patent is expired.

The strongest claims were likely claims 6 and 12 against a product closely matching the specified five-stripe, 1.27 cm spacing design. Their narrowness, however, also made design-around more practical.

What manufacturing and intellectual-property barriers remain?

The expired patent does not eliminate practical barriers to market entry.

A competing manufacturer may still need to solve:

Uniform drug dispersion in the polymer matrix;
Stable release over the labeled wear period;
Adhesion without excessive skin irritation;
Scrotal-site tolerability;
Consistent adhesive coverage;
Patch flexibility and conformability;
Manufacturing reproducibility;
Packaging and drug stability;
Extractables and leachables;
Scale-up of polymer-drug mixing;
FDA device performance testing.

Other patent families may protect specific formulations, permeation enhancers, backing materials, patch dimensions, manufacturing processes, or treatment methods. Those rights must be analyzed independently from US 5,840,327. A clean position against this expired patent does not establish freedom to operate across the entire testosterone transdermal field.

How does US 5,840,327 compare with competing testosterone patent strategies?

Patent strategy	Typical claim focus	Design-around potential
Reservoir patch	Polymer matrix, backing, adhesive geometry	High through drug-in-adhesive or alternative geometry
Drug-in-adhesive patch	Drug-containing adhesive layer	Moderate, depending on formulation claims
Gel or solution	Vehicle, permeation enhancer, dosing method	Separate from US 5,840,327
Scrotal delivery	Application site and testosterone exposure	Limited by site-specific claims
Manufacturing process	Mixing, coating, curing, lamination	Depends on process disclosure
Method of use	Testosterone replacement regimen	Depends on listed method claims and patent term

US 5,840,327 is therefore best classified as a historical device patent with a defined but narrow claim footprint. It is not a broad platform patent for transdermal hormone therapy.

What revenue exposure did the patent create?

The patent's commercial exposure was tied to testosterone patch sales rather than the entire testosterone replacement market.

The relevant revenue was exposed where a product used:

A testosterone reservoir;
A non-adhesive permeable polymer carrier;
A discontinuous adhesive covering 8% to 16%;
An offset adhesive plane;
Scrotal administration, for claim 7;
The specified EVA and stripe geometry, for the narrower claims.

Products using gels, injections, oral testosterone, pellets, or structurally different patches were outside the direct technical scope of the patent. After expiration, the patent no longer supports royalty demands, injunctions, or a US launch delay.

What litigation and settlement issues affect the patent today?

No current litigation risk should be attributed to US 5,840,327 solely because it covered a testosterone patch. Its expiration prevents enforcement of the issued claims.

Historical litigation or settlement agreements involving Testoderm, Androderm, or generic testosterone products may concern other patents, regulatory exclusivity, trademarks, product liability, or commercial agreements. Those matters should not be assumed to involve US 5,840,327 without a docket or agreement identifying the patent.

Licensing value also ended as an exclusivity matter when the patent expired. The patent may remain relevant in a technical due-diligence file, but it does not provide a current proprietary license position.

What is the geographic coverage of US Patent 5,840,327?

US 5,840,327 provides rights only in the United States. It does not establish protection in Canada, Europe, Japan, Australia, or other jurisdictions.

A complete international landscape would require review of:

The priority application;
PCT filings;
National-stage applications;
Continuations and divisionals;
Foreign grants and their expiration dates;
Patent-term extensions or supplementary protection certificates;
Local Orange Book or equivalent regulatory listings.

The US patent's expiration has no automatic effect on foreign counterparts. Foreign rights, if any, had separate terms and enforcement histories.

Key Takeaways

US Patent 5,840,327 covers a reservoir transdermal patch with a discontinuous adhesive pattern and an offset adhesive surface.
Claim 1 covers testosterone, estradiol, and progesterone for sensitive body areas.
Claim 7 is narrower and targets testosterone delivery through scrotal skin.
Claims 2, 3, 6, 8, 9, and 12 narrow the patent to specific EVA, polyisobutylene, stripe, and spacing features.
The patent expired in approximately 2016 and is not a current US exclusivity barrier.
The patent is not a biosimilar issue because the claimed products contain small-molecule hormones.
The main modern competitors are testosterone gels, solutions, injections, oral products, pellets, and structurally different patches.
Current freedom-to-operate work should focus on later formulation, manufacturing, method-of-use, and product-specific patent families.
Historical Orange Book listing, if any, does not revive expired patent rights.
The patent's strongest historical position was against a closely matching scrotal testosterone patch using the specified reservoir and adhesive architecture.

Frequently Asked Questions

Can a generic testosterone patch launch without licensing US Patent 5,840,327?

Yes. The patent is expired, so it cannot block a current US launch. Other patents and FDA requirements may still affect the product.

Does US Patent 5,840,327 cover testosterone gel?

No. The claims require a patch-like device with a drug-containing polymeric reservoir, backing, and discontinuous adhesive pattern. A conventional testosterone gel does not meet those structural requirements.

Does a testosterone patch applied to the arm infringe claim 7?

No, because claim 7 requires administration through intact scrotal skin. Claim 1 could remain relevant if the patch satisfies its broader sensitive-body-area and structural limitations.

Does changing the adhesive from polyisobutylene avoid the patent?

It would avoid claims 3 and 9, which expressly require polyisobutylene. It would not automatically avoid claims 1 or 7, which do not specify the adhesive chemistry.

Does the patent protect the five-stripe pattern alone?

No. Claims 6 and 12 require the five-stripe pattern in combination with the other limitations inherited from the independent and intermediate claims, including the reservoir, drug, adhesive coverage, and plane relationship.

References

United States Patent and Trademark Office. (1998). US Patent No. 5,840,327, Transdermal drug delivery device.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). Electronic Orange Book patent and exclusivity information.
U.S. Food and Drug Administration. (n.d.). 505(b)(2) applications.
United States Code, 35 U.S.C. § 154. Patent term.
United States Code, 21 U.S.C. § 355. New drugs.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	6853596	⤷ Start Trial
World Intellectual Property Organization (WIPO)	9706789	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 5,840,327