Details for Patent: 6,629,968

Summary for Patent: 6,629,968

Title:	Shelf storage stable iontophoresis reservoir-electrode and iontophoretic system incorporating the reservoir-electrode
Abstract:	A reservoir-electrode for an iontophoretic delivery device of the present invention includes an electrode; and a hydrophilic reservoir situated in electrically conductive relation to the electrode. The reservoir is formed from a bibulous hydrophilic cross-linked polymeric material having a substantially uniform concentration of an alkali metal chloride salt therein thereby substantially eliminating concentration gradients of the salt with respect to the electrode. The polymeric material has a first surface and a second surface that is adhesively adherent to the electrode. The first surface of the polymeric material is releasably adhesive to an applied area of a patient's skin. The polymeric material has a cohesive strength, wherein a bond strength of an adhesive bond between the second surface of the polymeric material to the electrode is greater than the cohesive strength of the polymeric material and an adhesive bond strength of the first surface of the polymeric material to the applied area of the patient is less than the cohesive strength of the polymeric material so that upon removal of the reservoir-electrode from the applied area of the patient, substantially no polymeric material remains on the applied area and the reservoir remains substantially intact and adhesively adherent to the electrode.
Inventor(s):	Uday K. Jain, Vilambi N R K Reddy, Bruce M. Eliash, Kevin John Carey, Vitaly Falevich, Preston Keusch
Assignee:	Vyteris Inc
Application Number:	US09/610,563
Patent Claim Types: see list of patent claims	Use; Process; Delivery; Device;

United States Patent 6,629,968: Claim Scope, Expiration, and Iontophoretic Drug-Delivery Patent Landscape

U.S. Patent No. 6,629,968 protects a preparation method for an iontophoretic electrode reservoir. Its central limitation is the addition of a medicament solution containing an alkali-metal halide salt to an absorbent reservoir that already has a substantially uniform concentration of that salt. The dependent claims narrow the technology to sodium chloride, lidocaine hydrochloride, epinephrine, polyvinylpyrrolidone-based reservoirs, and silver/silver chloride electrodes.

The patent does not broadly claim lidocaine, epinephrine, iontophoresis, or an iontophoretic device in isolation. It claims a specific reservoir-loading process and a reservoir-electrode made by that process. Because the patent issued in 2003, its ordinary 20-year patent term would have ended no later than the early 2020s, subject to the application’s actual earliest nonprovisional filing date, patent-term adjustment, terminal disclaimers, and any maintenance-fee event.[1][2]

What does U.S. Patent 6,629,968 protect?

The patent protects preparation of a reservoir-electrode assembly used in an iontophoretic delivery device. The claimed process has four central technical elements:

1. An absorbent electrode reservoir.
2. A substantially uniform concentration of an alkali-metal halide salt already present in that reservoir.
3. Addition of an aliquot of medicament solution to the reservoir.
4. A resulting reservoir-electrode assembly, in claim 13, made according to that process.

The patent therefore addresses reservoir conditioning and drug loading rather than the broad concept of electrically assisted transdermal delivery.

Core claim architecture

Claim	Type	Principal limitation
1	Independent method	Add medicament solution containing alkali-metal halide ions to an absorbent electrode reservoir having substantially uniform alkali-metal halide concentration
2	Dependent method	Alkali-metal halide is sodium chloride
3	Dependent method	Medicament solution contains lidocaine HCl
4	Dependent method	Lidocaine solution also contains epinephrine
5	Dependent method	Reservoir contains approximately 0.001% to 1% w/w sodium chloride
6	Dependent method	Reservoir contains approximately 0.06% w/w sodium chloride
7	Dependent method	Loading solution is applied as one or more droplets
8	Dependent method	Reservoir is a bibulous hydrophilic cross-linked material
9	Dependent method	Material includes poly(vinylpyrrolidone)
10	Dependent method	Electrode is a metal/metal-halide electrode
11	Dependent method	Electrode includes silver and silver chloride
12	Dependent method	Solution contains pharmacologically effective lidocaine HCl and epinephrine bitartrate
13	Independent product-by-process	Reservoir-electrode prepared by the process in the claim

How broad is independent claim 1?

Claim 1 is the principal infringement risk provision because it does not require sodium chloride, lidocaine, epinephrine, a particular electrode metal, a specified salt concentration, or droplet loading.

A process may fall within claim 1 if it uses:

• Any alkali-metal halide salt, subject to claim construction.
• Any absorbent electrode reservoir.
• A substantially uniform concentration of the salt in the reservoir.
• A medicament solution containing ions of that salt.
• Addition of an aliquot of that medicament solution to the reservoir.

Alkali-metal halide limitation

The phrase “alkali metal halide salt” potentially covers salts formed from an alkali metal and a halide ion, including sodium chloride, potassium chloride, sodium bromide, potassium bromide, and related combinations. Claim 2 expressly narrows the invention to sodium chloride, but claim 1 remains broader.

The claim requires ions of the salt in the medicament solution. A formulation containing sodium chloride in dissolved form would generally satisfy the ionic limitation more directly than a formulation containing only a nonionic excipient or a salt that is not an alkali-metal halide.

“Substantially uniform concentration”

This is a material limitation. The claim does not merely require that salt be present somewhere in the reservoir. It requires a concentration that is substantially uniform through the relevant reservoir structure.

Potential claim-construction questions include:

• Whether uniformity must exist throughout the entire reservoir or only across the drug-loading region.
• Whether uniformity is measured before or after the medicament solution is added.
• What quantitative deviation from the target concentration qualifies as “substantially uniform.”
• Whether a reservoir with salt gradients caused by drying, evaporation, or incomplete mixing falls outside the claim.

The patent claims do not state a numerical uniformity tolerance. That absence may create a fact-intensive infringement and validity issue, particularly where a commercial product uses a preconditioned reservoir but does not disclose its internal salt distribution.

“Adding an aliquot”

“Aliquot” generally denotes a measured portion of a larger solution. Claim 1 does not specify the aliquot volume, number of applications, loading rate, or timing. Claim 7 narrows the method to application as one or more droplets, but claim 1 is not limited to droplets.

The broader claim could cover pipetting, dispensing, metering, spraying, or another controlled addition method if the process adds a portion of the medicament solution to the reservoir.

What formulations are protected by U.S. Patent 6,629,968?

The strongest formulation-specific protection concerns iontophoretic local anesthetic solutions containing lidocaine and epinephrine.

Lidocaine hydrochloride

Claim 3 covers a medicament solution containing lidocaine HCl. Claim 12 narrows this to a pharmacologically effective amount of lidocaine hydrochloride and epinephrine bitartrate.

The claims do not state a lidocaine concentration, pH, buffer system, preservative, dosage volume, or delivery current. A formulation may therefore remain within claim 3 across a wide concentration range, provided that it contains lidocaine HCl and is used in the claimed reservoir-loading process.

Epinephrine

Claim 4 requires epinephrine in addition to lidocaine HCl. Claim 12 specifies epinephrine bitartrate and a pharmacologically effective amount of both active ingredients.

A formulation containing lidocaine HCl and a different epinephrine salt could present a claim 4 issue while potentially avoiding the narrower salt-specific language of claim 12. The result would depend on the construction of “epinephrine” in claim 4 and the product’s actual chemical form.

Sodium chloride

Claims 2, 5, and 6 create progressively narrower sodium chloride positions:

• Claim 2: sodium chloride, without a concentration limitation.
• Claim 5: approximately 0.001% to 1% w/w sodium chloride.
• Claim 6: approximately 0.06% w/w sodium chloride.

The range in claim 5 is broad. A product outside that range could still implicate claim 2 or claim 1. Claim 6 is narrower and may be more vulnerable to design-around through a materially different salt concentration, unless the accused concentration falls within a legally applicable equivalent range.

What materials and electrode structures are covered?

Bibulous hydrophilic cross-linked material

Claim 8 requires a bibulous, hydrophilic, cross-linked reservoir material. “Bibulous” generally refers to a material capable of absorbing and retaining liquid. The claim is directed to a porous or absorbent reservoir rather than a free-flowing liquid chamber.

Claim 9 identifies poly(vinylpyrrolidone), commonly abbreviated PVP, as the material. The claim text uses “poly(vinylpyrolidone),” which appears to be a spelling variation of poly(vinylpyrrolidone).

A reservoir made from a non-cross-linked hydrogel, a non-bibulous membrane, a dry powder, or a liquid-filled chamber may avoid claims 8 and 9, but it could still implicate claim 1 if it qualifies as an absorbent material.

Silver/silver chloride electrodes

Claims 10 and 11 cover metal/metal-halide electrodes and specifically silver/silver chloride electrodes. These structures are common in iontophoretic systems because Ag/AgCl electrodes support reversible electrochemical reactions and chloride-ion transport.

The electrode-material claims are dependent. A device using a different electrode construction may avoid claims 10 and 11 while remaining exposed to claim 1 if all other process limitations are met.

How should claim 13 be interpreted?

Claim 13 is an independent reservoir-electrode product-by-process claim. It covers a reservoir-electrode “prepared according to” a process that includes the same salt-conditioned reservoir and medicament-loading step.

Product-by-process claims generally raise two questions:

1. Whether the product must possess identifiable structural or compositional characteristics resulting from the claimed process.
2. Whether the process limitations restrict infringement even if the accused product is structurally identical but made by a different process.

For infringement analysis, the most important evidence would include:

• The salt concentration and distribution in the reservoir.
• The identity of the reservoir material.
• The presence of residual medicament.
• Manufacturing records showing how the solution was loaded.
• Whether the loading process creates a measurable product characteristic.

Claim 13 is not a broad claim to every iontophoretic electrode containing lidocaine. It is tied to the claimed preparation process and its resulting reservoir-electrode.

When does U.S. Patent 6,629,968 lose exclusivity?

The patent issued in 2003. Under the modern U.S. patent-term framework, utility patents generally expire 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment and related statutory modifications.[2]

The patent’s ordinary term should be treated as expired by the early 2020s unless an official USPTO record establishes an unusual term adjustment or other extension. A drug-device patent of this type generally does not receive Hatch-Waxman patent-term extension merely because it supports delivery of an FDA-approved drug. Patent-term extension under 35 U.S.C. § 156 is product-specific and regulatory, not an automatic benefit for every patent covering a delivery device.[3]

Practical exclusivity status

Issue	Assessment
Patent type	U.S. utility patent
Issue year	2003
Subject matter	Iontophoretic reservoir preparation and reservoir-electrode
Ordinary term	20 years from earliest effective nonprovisional filing date
Expected current status	No ordinary enforceable term should be assumed in 2025
Orange Book listing	Not expected for this device-focused patent
Regulatory exclusivity	Not created by the patent
Paragraph IV relevance	Limited unless a drug sponsor listed the patent against an NDA product, which is not apparent from the claim subject matter alone

An expiration analysis should distinguish patent expiration from maintenance-fee expiration. If maintenance fees were not timely paid, the patent may have ceased to be enforceable before the end of its statutory term. Conversely, payment of maintenance fees would not extend the patent beyond its statutory term.[2][4]

What is the Orange Book status of this patent?

U.S. Patent 6,629,968 is directed to a medical-device preparation process and reservoir-electrode assembly. It is not, on its face, a patent claiming the active ingredient, drug formulation, or method of treating a disease with a drug.

The FDA Orange Book primarily lists patents submitted by NDA holders that claim approved drug substances, drug products, or approved methods of use.[5] A device patent may appear in an Orange Book context only when it qualifies under the applicable listing rules and is submitted in connection with an approved drug product. The claim language provided does not establish such a listing.

The patent should therefore be analyzed primarily as a device and manufacturing patent, not as an Orange Book drug patent.

Does the patent create Paragraph IV risk?

Paragraph IV certification risk depends on whether the patent is listed in the Orange Book for a particular reference-listed drug. The claims supplied do not establish that U.S. Patent 6,629,968 is listed against a lidocaine, epinephrine, or other drug product.

If the patent is not Orange Book-listed, a generic applicant would not ordinarily make a Paragraph IV certification specifically against it. The patent could still be asserted in conventional patent litigation against a manufacturer, device supplier, or drug-device combination developer if an enforceable term remained.

Because the patent’s ordinary term appears to have ended, Paragraph IV risk is not the principal commercial concern in 2025.

Which companies are likely to face claim overlap?

The most exposed businesses would be companies commercializing:

• Iontophoretic local-anesthesia systems.
• Preloaded or factory-conditioned electrode reservoirs.
• Lidocaine HCl and epinephrine iontophoretic delivery systems.
• Ag/AgCl electrode assemblies.
• Cross-linked PVP absorbent reservoirs.
• Manufacturing processes that add measured droplets of drug solution to salt-conditioned reservoirs.

The risk is lower for:

• Passive transdermal patches.
• Injectable lidocaine products.
• Topical creams and gels.
• Iontophoretic devices using unconditioned reservoirs.
• Systems using a liquid chamber rather than an absorbent reservoir.
• Devices using different reservoir materials and no alkali-metal halide salt.
• Products manufactured after expiration of the patent term.

How strong is the patent estate?

The patent appears to represent a focused, single-patent position rather than a broad pharmaceutical patent estate.

Strengths

• Claim 1 covers the salt-conditioning concept without limiting the salt to sodium chloride.
• The claim does not require lidocaine or epinephrine.
• The process can cover multiple loading techniques because claim 1 does not require droplets.
• Dependent claims provide commercially relevant embodiments involving sodium chloride, lidocaine, epinephrine, PVP, and Ag/AgCl.
• Claim 13 attempts to capture the resulting reservoir-electrode as well as the preparation method.

Vulnerabilities

• “Substantially uniform concentration” lacks a numerical definition.
• The claims may face prior-art issues involving preconditioned absorbent reservoirs, saline-containing electrode systems, and iontophoretic anesthetic delivery.
• Claim 1 requires both salt in the reservoir and salt ions in the medicament solution, creating a technical proof burden.
• Claims 5 and 6 depend on concentration measurements that may vary by dry weight, wet weight, sampling location, and manufacturing stage.
• Claim 13 may face product-by-process construction issues.
• The patent is old enough that expiration, not claim breadth, is likely the controlling commercial issue.

What prior-art and validity issues matter most?

The principal prior-art categories are:

1. Iontophoretic delivery devices using absorbent electrode reservoirs.
2. Saline or chloride conditioning of electrode reservoirs.
3. Ag/AgCl electrode systems.
4. PVP or cross-linked hydrophilic absorbent materials.
5. Iontophoretic delivery of lidocaine and epinephrine.
6. Droplet or aliquot loading of medicament solutions.
7. Reservoir systems designed to improve current distribution or drug uniformity.

A validity challenge would likely focus on whether a skilled person would have combined known saline conditioning, absorbent electrode materials, and local-anesthetic loading. The dependent claims may be stronger against a generic anticipation attack because they combine several specific limitations, but combinations of references could raise obviousness issues under 35 U.S.C. § 103.[6]

The most important technical evidence would be laboratory data showing salt concentration uniformity, reservoir composition, drug loading, and electrode chemistry.

What generic launch risks exist?

For a conventional generic lidocaine product, this patent presents little direct risk because the claims do not cover injectable, topical, or oral lidocaine products.

For an iontophoretic lidocaine product, the risk historically would have depended on:

• Whether the product used an absorbent reservoir.
• Whether the reservoir contained a uniform alkali-metal halide concentration.
• Whether the medicament solution contained the same salt ions.
• Whether the product used lidocaine HCl and epinephrine.
• Whether the product used PVP or Ag/AgCl.
• Whether the patent remained enforceable at launch.

For a new iontophoretic product launched after the apparent end of the patent term, this patent should not block market entry based solely on the claims provided. Current freedom-to-operate analysis would instead focus on later continuation patents, foreign counterparts, improvements, device patents, and patents covering the commercial product’s electronics, electrode architecture, formulation, and manufacturing process.

What patent landscape surrounds iontophoretic drug delivery?

The relevant landscape extends beyond U.S. Patent 6,629,968 and normally includes five overlapping patent groups:

Patent group	Typical protected subject matter	Relevance to this patent
Device architecture	Electrodes, controller, current regulation, adhesive assembly	Adjacent but not directly claimed
Reservoir and formulation	Absorbent matrices, gels, buffers, salts, drug stability	Closest technical overlap
Method of use	Applying current to deliver anesthetics or other drugs	Separate claim category
Manufacturing	Filling, drying, sealing, conditioning, quality control	Claim 1 and claim 13 overlap
Regulatory/product patents	Drug-device combinations and approved uses	Potential Orange Book relevance, if listed

The principal competitive technologies include passive topical anesthetic products, injectable local anesthesia, needle-free systems, and iontophoretic devices using alternative reservoir chemistry. The patent does not create a monopoly over the iontophoretic delivery market.

What litigation and settlement issues should be checked?

The claims alone do not establish whether U.S. Patent 6,629,968 was litigated, licensed, challenged, abandoned for maintenance-fee purposes, or included in a settlement. A litigation search should distinguish:

• District-court infringement cases.
• Patent Trial and Appeal Board proceedings.
• Declaratory-judgment actions.
• ANDA litigation.
• Licensing agreements involving the patent family.
• Assignments and security interests recorded with the USPTO.
• Continuations, divisionals, and foreign family members.

Because the patent is device-focused and apparently expired, current litigation exposure is more likely to arise from later family members or related patents than from the original patent itself.

Key Takeaways

• U.S. Patent 6,629,968 claims preparation of a salt-conditioned absorbent electrode reservoir for iontophoretic drug delivery.
• Claim 1 is the broadest claim and is not limited to sodium chloride, lidocaine, epinephrine, PVP, droplets, or Ag/AgCl.
• Claims 2 through 12 narrow the invention to commercially recognizable embodiments, especially sodium chloride, lidocaine HCl, epinephrine, PVP, and silver/silver chloride.
• Claim 13 is a product-by-process claim directed to the resulting reservoir-electrode.
• The patent does not broadly protect lidocaine, epinephrine, iontophoresis, or topical anesthesia.
• The patent’s ordinary term should have ended by the early 2020s, making current infringement risk low unless an unusual term adjustment or related unexpired patent applies.
• The patent should not be assumed to have Orange Book or Paragraph IV significance without evidence of an FDA listing against a specific NDA product.
• The strongest historical design-around paths involve eliminating the uniform alkali-metal halide conditioning step, changing the reservoir architecture, using different electrode chemistry, or avoiding the claimed manufacturing sequence.

FAQs About U.S. Patent 6,629,968

Does U.S. Patent 6,629,968 cover ordinary lidocaine injections?

No. Its claims require an iontophoretic electrode reservoir and a specific reservoir-loading process. Injectable lidocaine products do not ordinarily satisfy those limitations.

Can a product avoid claim 1 by using potassium chloride instead of sodium chloride?

Not necessarily. Claim 1 is not limited to sodium chloride. Potassium chloride may remain within the broader alkali-metal halide limitation if the other claim elements are present.

Does using a gel instead of PVP avoid infringement?

It may avoid claims 8 and 9 if the gel is not a bibulous hydrophilic cross-linked material or does not contain PVP. It would not automatically avoid claim 1, which broadly recites an absorbent material.

Is a patent license still needed after patent expiration?

A license is generally not needed for acts occurring after expiration of the patent, but later patents in the same family or related patent portfolios may remain enforceable. The original patent’s expiration should be confirmed against the USPTO term and maintenance records.

Does claim 13 cover a reservoir-electrode made by a different process?

The answer depends on the legal construction of the product-by-process claim and whether the resulting product has structural characteristics associated with the claimed process. A different manufacturing route does not automatically eliminate risk.

References

1. United States Patent No. 6,629,968, claims 1-13 (2003).
2. United States Patent and Trademark Office. (2024). Patent term calculator and patent term provisions.
3. 35 U.S.C. § 156.
4. 35 U.S.C. § 41(b).
5. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book.
6. 35 U.S.C. §§ 102, 103.

Drugs Protected by US Patent 6,629,968

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

International Family Members for US Patent 6,629,968

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	369891
Australia	7310401
Canada	2413624
Germany	60129965
European Patent Office	1294439