United States Patent 6,195,582: Scope, Claims, Expiration and Electrotransport Patent Landscape

US 6,195,582 protects an electrotransport device that uses a high-resistance, electrochemically reactive electrode positioned at a common boundary with an electrolyte reservoir and a separate, lower-resistance current collector. The core concept is that the electrode initially conducts poorly, then becomes less resistive as electric current oxidizes or reduces the electrode material.

The patent covers both transdermal drug delivery and reverse-iontophoretic analyte sampling, including glucose sampling. Its strongest technical limitations are the discrete current collector, the initial resistance relationship, and the requirement that the electrode, collector and reservoir form a common boundary when current begins. The patent is a device patent rather than a drug patent. It does not create Orange Book exclusivity, FDA drug exclusivity, biosimilar exclusivity or a Paragraph IV pathway.

What does US Patent 6,195,582 protect?

The independent claim protects an electrotransport device having:

An anodic electrode assembly.
A cathodic electrode assembly.
A power source connected to both assemblies.
At least one solid-phase electrochemically reactive electrode.
An electrolyte reservoir containing a therapeutic agent or receiving a sampled analyte.
A separate current collector with lower electrical resistance than the electrode.
A common boundary among the electrode, collector and reservoir at the beginning of electrotransport.

The claim is functional and structural. It does not require a particular drug, analyte, voltage, current waveform, skin location or commercial product configuration.

The central inventive relationship is:

Initial electrode resistance > current-collector resistance, followed by a current-induced reduction in electrode resistance.

The claim therefore targets electrode assemblies that operate as electrochemically activated conductors rather than conventional low-resistance metal electrodes.

Claim 1 limitation map

Claim element	Scope
Electrotransport device	Covers iontophoretic delivery and sampling systems
Anodic and cathodic assemblies	Requires both electrode polarities
Power source	Must electrically connect to both assemblies
Solid-phase reactive electrode	Excludes a purely liquid or dissolved electrode material
Initial electrical resistance	Resistance exists before or at current initiation
Resistance decreases with current	Requires current-induced electrochemical activation
Electrolyte reservoir	Contains a delivered agent or receives a sampled agent
Ion-transmitting relation to body surface	Requires transdermal or body-surface operation
Discrete current collector	Collector must be separate from the reactive electrode
Lower collector resistance	Collector must conduct more efficiently than the initial electrode
Common boundary	Electrode, collector and reservoir meet at the relevant starting time

A product that lacks the common boundary may avoid literal infringement of claim 1 even if it uses a reactive electrode and current collector. A product with a common physical interface but no reduction in electrode resistance may also fall outside the literal claim.

How do dependent claims 2 through 9 define the cathodic electrode?

Claims 2 through 9 narrow the invention to a cathodic electrode assembly using a reducible material.

The covered material classes include:

Metal compounds.
Metal complexes.
Intercalation compounds.
Carbon intercalation hosts containing an alkali metal.
Electrochemically reducible polymers.
Silver, copper and zinc compounds or complexes.
Silver halides.
Tungsten-bronze-type compounds represented by Mx(WO3)y.
Metal ferrocyanide compounds represented by Mx[Fe(CN)6]y.
Silver chloride foil.

Claim 9 is commercially significant because it identifies silver chloride foil as a specific cathodic electrode. Claims 4 through 6 are also important because they cover silver-halide implementations that may be used in reverse iontophoresis and iontophoretic drug delivery.

The claims do not require that the entire cathodic electrode consist of the listed compound unless claim 31 is also satisfied. A polymer matrix containing the reactive material can fall within claim 17, while claim 31 narrows the electrode to one consisting essentially of the electrochemically reactive material.

What claims cover glucose sampling and reverse iontophoresis?

Claims 10 through 14 expressly cover analyte sampling.

Claim 12 identifies glucose as the sampled nonionic analyte. The claim structure is broad enough to encompass a device that extracts glucose through the skin into an anodic or cathodic reservoir, depending on the system configuration.

The relevant claim categories are:

Claim	Analyte or arrangement
10	Body analyte sampling generally
11	Nonionic analyte in an anodic or cathodic reservoir
12	Glucose
13	Cationic analyte in a cathodic reservoir
14	Anionic analyte in an anodic reservoir

The glucose claim does not require a glucose-specific sensor chemistry. A product could therefore implicate claim 12 based on the sampling architecture even if glucose detection occurs through a separate enzymatic, electrochemical or optical sensor.

This distinction matters for products resembling reverse-iontophoretic glucose monitors. The patent claims the electrode and reservoir arrangement, not the downstream analytical algorithm.

What formulations and electrode materials are protected?

The formulation claims are directed primarily to the electrolyte reservoir and the material environment around the electrode.

Polymer-matrix electrodes

Claim 17 covers an electrode comprising:

A polymer matrix; and
An electrochemically reactive material contained in that matrix.

Claim 18 narrows the construction by requiring the polymer matrix to be substantially free of electrically conductive material when electrotransport current begins. This limitation distinguishes a reactive polymer composite from a conventional conductive polymer electrode that already contains carbon black, graphite, metal particles or another conductive additive.

A device using a conductive polymer matrix from the outset may avoid claim 18, but it could still fall within claim 17 or claim 1 if the other limitations are present.

Resistance thresholds

Claims 15, 16 and 36 through 39 impose quantitative resistance limitations:

Claim	Limitation
15	Electrode sheet resistance greater than 100 ohms/square
16	Collector sheet resistance less than one-half the electrode resistance
36	Electrode sheet resistance greater than about 10,000 ohms/square
37	Collector sheet resistance less than 50,000 ohms/square
38	Collector sheet resistance less than 1,000 ohms/square
39	Collector sheet resistance less than 10 ohms/square

The claims create overlapping but commercially distinct protection. Claim 39 is directed to a highly conductive collector. Claim 36 captures a very high-resistance reactive electrode. A product satisfying both may present a stronger literal infringement case than a product meeting only the broader functional limitation in claim 1.

Reservoir composition

Claims 34 and 35 cover aqueous and gel electrolyte reservoirs. These claims are not limited to a particular buffer, salt, polymer, drug or analyte.

Claims 28 and 31 provide further material restrictions:

Claim 28 requires the solid reactive material to have solubility in the electrolyte below about 1 mg/ml.
Claim 31 requires the electrode to consist essentially of the reactive material.

These limitations address electrode dissolution and distinguish the claimed solid-phase architecture from an electrode based primarily on soluble redox species.

What claims cover anodic electrodes and therapeutic delivery?

Claims 19 through 25 cover anodic assemblies using oxidizable materials.

Claim 20 identifies:

The leuco form of polyaniline.
Transition-metal-halide-intercalated carbon or graphite.

Claim 21 specifically covers a polyaniline sheet.

Claims 22 through 24 cover therapeutic-agent delivery:

Claim	Delivery arrangement
22	Therapeutic agent delivered through skin
23	Cationic agent in an anodic donor reservoir
24	Anionic agent in a cathodic donor reservoir

The polarity limitations reflect iontophoretic transport principles. Positively charged agents are generally driven from an anode, while negatively charged agents are generally driven from a cathode. The patent does not identify a particular pharmaceutical compound.

A transdermal product using a conventional low-resistance electrode may avoid these claims even if it delivers the same drug. Conversely, a device using a polyaniline or other oxidizable electrode can raise infringement concerns even when the delivered agent differs from the examples in the patent.

How important are the common-boundary limitations?

The common-boundary requirement is the principal claim-construction issue.

At the beginning of current application, the claim requires the electrode, current collector and electrolyte reservoir to form a common boundary. The language can be read to require a contiguous interface or shared boundary condition, rather than merely sequential electrical connection through intervening layers.

Claims 26 through 30 add geometric and operating restrictions:

Claim	Added limitation
26	Boundary length-to-current ratio of at least 0.1 cm/mA
27	Boundary length of at least 0.1 cm
29	Linear, rectangular, circular or elliptical boundary
30	Multiple common boundaries

The ratio in claim 26 links current density and interface geometry. It may become important in litigation because it requires measurements tied to the operating current. Product documentation, electrode drawings, current logs and laboratory testing would likely determine whether a device satisfies this limitation.

The common-boundary requirement can also limit design-around exposure. A manufacturer may attempt to separate the collector from the reservoir with an insulating layer, use a noncontiguous interface, or place the collector behind a conductive intermediate layer. Whether such a design avoids the claim would depend on the claim construction and the specific physical arrangement.

When did US 6,195,582 lose patent exclusivity?

US 6,195,582 issued on February 27, 2001. Its ordinary US patent term was governed by the 20-year term measured from the applicable nonprovisional filing date under 35 U.S.C. § 154. On that basis, the patent expired before 2026 and is not an active blocking patent today, absent an unusual patent-term adjustment, extension or related enforceable continuation right recorded in the official prosecution history.[1][2]

The patent’s expiration does not eliminate historical infringement exposure for conduct during the enforceable term. It also does not invalidate later patents in the same family or separate patents covering commercial implementations.

Exclusivity timeline

Event	Date or status
US 6,195,582 filed	Before issuance; term measured under 35 U.S.C. § 154
Patent issued	February 27, 2001
Ordinary patent term	20 years from applicable nonprovisional filing
Current status	Expired before 2026 under ordinary term rules
FDA drug exclusivity	Not applicable
FDA device exclusivity	No Orange Book exclusivity
Paragraph IV litigation	Not applicable to this device patent
Biosimilar litigation	Not applicable

The patent is not a patent on an active pharmaceutical ingredient. Its expiration therefore does not establish generic entry for any drug.

What is the Orange Book status of US 6,195,582?

US 6,195,582 should not be treated as an Orange Book-listed patent. The FDA Orange Book covers patents and exclusivity associated with approved drug products, including product, formulation and method-of-use patents submitted by drug sponsors.[3]

US 6,195,582 claims an electrotransport apparatus. It does not claim:

A drug substance.
A drug formulation independent of the device.
A tablet, capsule, injectable or biologic.
A drug-specific method of treatment.
A drug product identified by an NDA.

The patent therefore does not create a Paragraph IV certification route by itself. A generic drug applicant would address the patent only if the generic product incorporated a covered electrotransport delivery system and the patent remained enforceable.

Which companies and technologies compete with the claimed estate?

The relevant competitive landscape is the broader field of iontophoresis, reverse iontophoresis, transdermal delivery and wearable biosensing.

Iontophoretic drug delivery

Competing technology categories include:

Conventional metal electrodes.
Carbon and graphite electrodes.
Conductive polymer electrodes.
Hydrogel-based reservoirs.
Microfluidic transdermal systems.
Pulsed-current iontophoresis.
Electroporation-assisted delivery.
Passive transdermal patches.

The patent is most relevant where a product uses a reactive electrode that changes resistance during operation. It is less relevant to systems using stable low-resistance electrodes with no current-induced electrochemical activation.

Reverse-iontophoretic glucose monitoring

Commercial and historical glucose-monitoring programs have used reverse iontophoresis, electrochemical sensing and skin-contact reservoirs. Cygnus Inc.'s GlucoWatch system is a prominent example of reverse-iontophoretic glucose monitoring, although the relevant patent portfolio included multiple patents covering extraction, sensing, calibration, skin interfaces and device control.[4]

A freedom-to-operate review for a reverse-iontophoretic glucose product must separate:

Electrode architecture.
Analyte extraction.
Enzymatic or electrochemical detection.
Calibration and signal processing.
Sensor replacement and skin-contact assemblies.
Wireless or wearable data transmission.

US 6,195,582 principally addresses the first two categories.

How strong is the patent estate?

The patent had meaningful historical scope but limited present-day blocking power because the issued patent has expired.

Historical strengths

Claim 1 covers both delivery and sampling.
The claim does not require a particular therapeutic agent.
The common-boundary architecture is technically specific.
Claims cover both cathodic reduction and anodic oxidation.
Glucose sampling is expressly claimed.
Quantitative resistance claims provide multiple infringement theories.
Claims cover aqueous and gel reservoirs.
The patent addresses both material selection and electrode geometry.

Weaknesses and litigation pressure points

The common-boundary limitation may be difficult to prove on layered commercial products.
The initial-resistance and current-induced-resistance limitations require technical testing.
Sheet-resistance measurements can vary with test method, humidity, pressure and electrode geometry.
Several dependent claims require specific material chemistries that may not be used in modern systems.
Expiration removes prospective injunction leverage.
The patent does not protect the drug molecule or the core glucose-sensing chemistry.

The estate is therefore best characterized as a historical platform patent with narrow physical-architecture limitations, not as a current pharmaceutical exclusivity asset.

What patent litigation and settlement issues affect the patent?

A Paragraph IV challenge, biosimilar dispute or Hatch-Waxman settlement is not the expected litigation framework for US 6,195,582. The patent covers a device and is outside the ordinary Orange Book certification system.

Potential historical litigation would more likely involve:

Patent infringement claims against an iontophoretic-device manufacturer.
Declaratory judgment actions concerning electrode architecture.
License negotiations involving electrotransport platforms.
Patent-owner disputes over reverse-iontophoretic glucose monitors.
Contractual allocation of patent rights in device, sensor or transdermal-product collaborations.

The supplied claim set does not establish a litigation history, settlement agreement or license transaction. No such event should be attributed to the patent without a docket, assignment record, license announcement or court opinion.

What generic entry risks exist for products using this patent?

There is no conventional generic-entry risk based solely on US 6,195,582 because the patent is expired and does not claim a drug product.

The commercial risks are different:

Product type	Risk from US 6,195,582
Oral generic drug	None
Injectable generic drug	None
Standard transdermal patch	Generally low unless it uses the claimed electrode architecture
Iontophoretic drug-delivery device	Historical risk; current risk depends on related active patents
Reverse-iontophoretic glucose monitor	Historical risk, with broader family and sensor patents requiring separate review
Biosimilar	None from this patent
Wearable analyte sampler	Architecture-specific risk only

The principal current risk is not this expired patent. It is the possibility that a continuation, divisional, foreign counterpart or later patent claims the same commercial implementation with a later expiration date. Patent-family review must therefore distinguish the issued claims of US 6,195,582 from related applications.

How does US 6,195,582 compare with conventional electrode patents?

Issue	US 6,195,582	Conventional electrode patent
Electrode state	Initially high resistance and electrochemically activated	Usually conductive from the outset
Collector	Separate lower-resistance collector required	May be integrated or not separately claimed
Reservoir interface	Common boundary required	Often claims reservoir chemistry or geometry
Use cases	Delivery and reverse sampling	Often delivery, sensing or power transfer
Material scope	Reactive solids, polymers, metal compounds	Metals, carbon, conductive polymers or gels
Key proof issue	Resistance change and interface geometry	Composition, dimensions and electrical connection
FDA status	Device architecture	Depends on the associated product
Current exclusivity	Expired patent	Depends on each later patent

Key Takeaways

US 6,195,582 covers an electrotransport electrode assembly with a high-resistance reactive electrode, a separate lower-resistance current collector and a common electrode-collector-reservoir boundary.
The claims cover both transdermal delivery and body-analyte sampling.
Glucose sampling is expressly covered by claim 12.
Silver chloride foil, silver halides, polyaniline, metal complexes and reactive polymer matrices are among the claimed materials.
Claims 15, 16 and 36 through 39 add sheet-resistance thresholds that may require laboratory verification.
The patent issued on February 27, 2001 and expired before 2026 under the ordinary US patent-term framework.
It is not an Orange Book patent and does not create Hatch-Waxman Paragraph IV or biosimilar exclusivity exposure.
Current freedom-to-operate analysis should focus on related family members, continuation patents and later patents covering commercial iontophoresis, reverse-iontophoresis, glucose sensing and wearable device implementations.
The patent remains relevant as prior art and as a historical platform patent, but it is not a current standalone barrier to generic drug entry.

FAQs About US Patent 6,195,582

Does US 6,195,582 cover a specific drug?

No. It covers an electrotransport device and generic delivery or sampling configurations. It does not claim a particular active pharmaceutical ingredient.

Does claim 12 cover every glucose monitor?

No. Claim 12 is directed to glucose sampling through the claimed electrotransport architecture. A glucose monitor using an unrelated blood, interstitial-fluid or optical-sensing architecture would not satisfy the claim merely because it measures glucose.

Can a product avoid the patent by using a metal electrode?

Potentially. A conventional metal electrode may avoid the requirement for a solid-phase electrochemically reactive electrode whose resistance decreases upon current exposure. The full claim, including the common-boundary and collector limitations, must still be analyzed.

Are foreign patents equivalent to US 6,195,582?

Not automatically. Foreign counterparts are examined under different laws, may have different amended claims and may expire on different dates. Each national family member requires separate legal-status and claim review.

Does expiration of US 6,195,582 clear all iontophoresis patent risk?

No. Expiration clears only this patent. Later patents may cover electrode compositions, hydrogel reservoirs, sensing chemistry, calibration, skin interfaces, device controls or specific drug-delivery systems.

References

United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term calculation under 35 U.S.C. § 154. USPTO.
United States Patent and Trademark Office. (2001). U.S. Patent No. 6,195,582, Electrotransport device with improved electrode assembly. USPTO.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
Cygnus, Inc. (2002). GlucoWatch Biographer system and reverse-iontophoretic glucose monitoring materials. FDA device records.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	274973	⤷ Start Trial
Austria	279232	⤷ Start Trial
Australia	2346499	⤷ Start Trial
Australia	2346599	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,195,582

Summary for Patent: 6,195,582