US Patent 6,862,473: Iontophoretic Lidocaine + Epinephrine Delivery Device With Crosslinked Water-Soluble Polymer Reservoirs
US Patent 6,862,473 claims a ready-to-use iontophoretic drug delivery device built around a single electrode assembly with separately configured working and return reservoirs, where both reservoirs independently contain at least one crosslinked water-soluble polymer. The working reservoir contains lidocaine plus epinephrine and is defined in some dependent claims with specific wt.% ranges and stabilizer systems (glycerin, sodium metabisulfite, EDTA).
What is the core claim scope (independent claim 1)?
Claim 1 elements (literal construction)
Claim 1 is directed to:
- Iontophoretic drug delivery device
- Single electrode assembly, comprising:
- Working electrode connected to a working reservoir
- Working reservoir comprising lidocaine and epinephrine
- Return electrode connected to a return reservoir
- Return reservoir comprising an electrolyte
- Polymer requirement (key limitation):
- Working reservoir and return reservoir independently comprise at least one crosslinked water soluble polymer
- Form-factor limitation:
- Electrode assembly is prepackaged as a ready to use device
Scope implications
Claim 1’s patentable distinction is not only the lidocaine/epinephrine formulation and the iontophoretic delivery, but the dual-reservoir polymer design:
- Both reservoirs must contain crosslinked and water-soluble polymer(s).
- The polymer presence is independent for each reservoir (working polymer does not substitute for return polymer, and vice versa).
That single drafting choice constrains design-around strategies more than generic “iontophoretic anesthetic” patents, because many competitor devices use:
- a polymer only in the drug matrix,
- or a polymer only as electrode interface,
- or uncrosslinked gels/hydrogels,
- or polymer only on the working side.
What do the dependent claims add to narrowing scope?
Polymer identity match
- Claim 2: working and return reservoirs comprise the same crosslinked water soluble polymer.
Impact: Narrows to matched polymer selection across reservoirs. A competitor using different polymers (working vs return) avoids claim 2 but can still fall within claim 1.
Quantitative drug formulation
- Claim 3: epinephrine about 0.1 wt.% (working reservoir total weight)
- Claim 4: lidocaine about 10 wt.% (working reservoir total weight)
- Claim 7: epinephrine about 0.1 wt.% and lidocaine about 10 wt.%
- Claim 6/8 provide “further comprising” excipient ranges (glycerin, sodium metabisulfite, EDTA)
Impact: These create tight formulation sub-scope pockets. If a competitor uses different drug loading (e.g., epinephrine 0.05 wt.% or 0.2 wt.%), it can avoid the numeric dependent claims, but still be exposed under claim 1 (which is not numeric).
Stabilizer system and carrier components
- Claim 5: further comprising glycerin, sodium metabisulfite, and EDTA
- Claims 6 and 8: provide specific wt.% targets:
- Glycerin: about 10 wt.%
- Sodium metabisulfite: about 0.05 wt.%
- EDTA (disodium in claim 8): about 0.01 wt.%
- Claim 12: stabilizer is at least one of sodium metabisulphite and EDTA
- Claim 14: additive selected from glycerin, propylene glycol, polyethylene glycol, and conductive salts
Impact: These are important for both litigation posture and formulation development. Claim 1 allows “working reservoir comprising lidocaine and epinephrine” with crosslinked polymer, but claim coverage becomes much more formulation-specific in the dependent claims.
Return electrode configuration
- Claim 9: further comprising one to three return electrodes
- Claim 10: return electrodes total surface area 1 to 5 cm²; working electrode surface area 2 to 10 cm²
Impact: Numeric electrode geometry and count narrow coverage. A competitor can still compete on claim 1 by staying within a different surface area envelope or different return electrode count, but the broader device concept remains relevant.
Crosslinked polymer function as adhesive
- Claim 15: crosslinked water soluble polymer acts as an adhesive
Impact: This introduces a functional characterization. A competitor can argue polymer is not adhesive in its device architecture, but if the device uses polymer to maintain contact or retain reservoirs, functional arguments can cut against them.
Polymer species list
- Claim 16: crosslinked water soluble polymer selected from:
- polyethylene oxide
- polyvinyl pyrrolidone
- polyvinyl alcohol
- polyacrylamide
Impact: Claim 1 uses broad “at least one crosslinked water soluble polymer,” while claim 16 narrows to listed polymers. A competitor using another crosslinked water-soluble polymer species can potentially avoid claim 16 but remain within claim 1.
Claim map (device architecture to coverage)
Below is a structured mapping of claimed limitations to likely design targets and the “avoidance” levers.
| Claim limitation |
What it requires |
Direct design-around lever(s) |
| “Ready to use” prepackaged electrode assembly |
Device sold/packaged as ready-to-use unit |
Packaging form factor only (may not eliminate core architecture) |
| Working electrode + working reservoir with lidocaine + epinephrine |
Dual drug actives in working reservoir |
Change actives (avoid lidocaine or epinephrine) |
| Return electrode + return reservoir with electrolyte |
Electrolyte-containing return reservoir |
Use different return medium; keep “electrolyte” risk |
| Working reservoir contains crosslinked water-soluble polymer |
Crosslinked polymer included in working reservoir |
Use uncrosslinked polymer, or non-water-soluble polymer (if feasible) |
| Return reservoir contains crosslinked water-soluble polymer |
Crosslinked polymer included in return reservoir |
Remove polymer from return reservoir; keep only working polymer |
| Return and working polymer independently comprise crosslinked polymer |
Each side must meet the polymer limitation |
If polymer only one side, avoid claim 1 |
| Same polymer on both sides (claim 2) |
Matching polymer identity |
Use different polymer(s) |
| epinephrine about 0.1 wt.% (claims 3,7) |
Numeric range at loading stage |
Adjust epinephrine loading |
| lidocaine about 10 wt.% (claims 4,7) |
Numeric range at loading stage |
Adjust lidocaine loading |
| glycerin + sodium metabisulfite + EDTA (claims 5-6,8) |
Specific excipient combination |
Remove/replace one component |
| specific excipient wt.% (claims 6,8) |
Numeric excipient ranges |
Shift excipient loading beyond claim values |
| 1-3 return electrodes (claim 9) |
Count limitation |
Use >3 or 0 return electrode architecture not covered (but claim 1 still requires return electrode) |
| electrode surface areas (claim 10) |
Numeric surface area windows |
Change electrode sizes and totals |
| polymer acts as adhesive (claim 15) |
Functional characterization |
Redesign polymer role away from adhesive function |
| polymer species list (claim 16) |
Named polymer selections |
Use different crosslinked water-soluble polymer species |
What does the patent landscape look like around this claim theme (iontophoresis + lidocaine/epinephrine)?
How US 6,862,473 is positioned
US 6,862,473 sits at the intersection of:
- Iontophoretic delivery devices (electrode-based transdermal delivery)
- Local anesthetic formulations containing lidocaine
- Vasoconstrictor co-administration via epinephrine
- Engineered reservoir matrices using crosslinked water-soluble polymer layers on both working and return sides
The standout landscape feature is the dual-reservoir crosslinked polymer requirement paired with a prepackaged ready-to-use device framing.
Landscape tension points
In practice, competitors typically diverge in one of three ways:
- Polymer placement: polymer only in working reservoir (not return) or only at the electrode interface.
- Crosslinking: use uncrosslinked hydrogels or polymer solutions.
- Drug loading: use different wt.% ratios or omit epinephrine or lidocaine.
US 6,862,473’s claim structure makes all three divergence paths relevant:
- If the return reservoir does not “independently comprise” the crosslinked water-soluble polymer, claim 1 is harder to reach.
- If the polymer is not crosslinked or not water-soluble, the claim’s polymer limitation becomes a direct eligibility filter.
Enforcement-relevant claim construction factors
“Crosslinked water soluble polymer” (central battleground)
Claim 1 requires:
- crosslinked polymer
- water soluble
- present in both working and return reservoirs independently
This creates likely technical disputes on:
- whether a polymer is chemically or physically crosslinked to the claimed degree,
- whether the polymer remains water soluble at use conditions (hydration state),
- whether polymer is actually present in each reservoir (not merely nearby).
“Acts as an adhesive” (functional narrowing)
Claim 15 adds a functional gloss. If enforcement focuses on claim 1, claim 15 is not needed. If asserted as a dependent narrowing, the “adhesive” function must align with device reality.
Prepackaged “ready to use” (commercial product identity)
Claim 1’s “prepackaged as a ready to use device” can matter for commercial models:
- kit format
- prefilled disposable reservoirs
- assembled electrode cartridge
A competitor building an iontophoretic assembly in a different packaging workflow can still meet the physical limitations, but “ready to use device” can be argued as a manufacturing/marketing feature.
Where the numeric sub-claims create “safe corridors”
Numeric ranges in dependent claims form practical design corridors:
- epinephrine around 0.1 wt.%
- lidocaine around 10 wt.%
- glycerin around 10 wt.%
- sodium metabisulfite around 0.05 wt.%
- EDTA around 0.01 wt.%
If a competitor stays outside these numeric anchor points, they can often reduce exposure to those specific dependent claims while retaining potential risk under claim 1.
Operational implication for R&D portfolios
From a portfolio perspective, US 6,862,473 is likely strongest as:
- a coverage anchor for iontophoretic drug cartridges with:
- lidocaine + epinephrine in the working reservoir,
- electrolyte-containing return reservoir,
- polymer matrices on both sides that are crosslinked and water soluble,
- and a preassembled device format.
It is weaker as:
- a “generic” iontophoresis claim covering any anesthetic with any reservoir gel,
because claim 1’s polymer limitation is bilateral (working and return).
Key Takeaways
- US 6,862,473 claim 1 is built around a single electrode assembly with lidocaine + epinephrine in the working reservoir and an electrolyte return reservoir, where both reservoirs independently contain at least one crosslinked water-soluble polymer.
- Dependent claims narrow coverage by adding: matched polymer identity (claim 2), precise wt.% drug and excipient loading (claims 3-8), return electrode count and surface area (claims 9-10), and polymer function as an adhesive (claim 15).
- The most practical design-around lever against claim 1 is to ensure the return reservoir does not contain the required crosslinked water-soluble polymer (or to remove/alter polymer properties so the “crosslinked” and “water soluble” limitations are not met).
- Numeric sub-claims create formulation-safe corridors, but they do not eliminate exposure under the broad, non-numeric structure of claim 1.
FAQs
1) What is the single most important limitation in claim 1?
The requirement that both the working reservoir and the return reservoir independently comprise at least one crosslinked water soluble polymer.
2) Can a device avoid the patent by changing lidocaine or epinephrine loading?
Changing loading may avoid dependent numeric claims, but claim 1 still requires the working reservoir to comprise lidocaine and epinephrine regardless of numeric level.
3) Does claim 2 require the same polymer in both reservoirs?
Yes. Claim 2 narrows to devices where the working and return reservoirs comprise the same crosslinked water-soluble polymer.
4) Are electrode size and number part of claim 1?
No. Return electrode count (1 to 3) and surface area ranges are in dependent claims (claims 9 and 10).
5) Which dependent claim locks down the polymer species list?
Claim 16, which lists polyethylene oxide, polyvinyl pyrrolidone, polyvinyl alcohol, and polyacrylamide as the selected polymers.
References
[1] United States Patent 6,862,473. (Claim text as provided by user).
