Scope, claims, and US patent landscape for US 6,181,963
US 6,181,963 claims a specific architecture for transdermal electrotransport devices: an anode that carries the therapeutic drug and an opposing cathode whose reservoir contains an aqueous medium in contact with a polymeric housing, where the aqueous medium includes a cetylpyridinium salt (CPS) at microbial-growth inhibitory levels and the polymer housing is compatible with CPS. Dependent claims sharpen the scope via (i) pH ranges, (ii) buffer, (iii) polymer species, (iv) CPS identity and concentration windows, (v) optional anion-exchange membrane placement, and (vi) a process requirement that CPS ions are not delivered to the patient from the cathode.
What is the claim “center of gravity” in US 6,181,963?
The independent claim (claim 1) ties infringement to three coupled limitations:
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Device form factor for electrotransport
- A transdermal electrotransport device has an anode, a cathode, and a power source electrically connected to both electrodes.
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Cathodic reservoir with CPS-containing aqueous medium in contact with polymer
- The cathode includes:
- a cathodic electrode, and
- a cathodic reservoir that has:
- a housing composed of a polymeric material, and
- an aqueous medium in contact with the housing.
- The aqueous medium contains:
- (i) a drug or an electrolyte salt (or mixture), and
- (ii) a cetylpyridinium salt at an amount sufficient to inhibit microbial growth in the aqueous medium.
- The polymer housing is compatible with the cetylpyridinium salt.
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Geography of where the drug goes vs. where CPS does not
- The device claim is framed as a system where the therapeutic drug can be electrotransported from the anode, while the CPS is required mainly as a reservoir antimicrobial. The sharper “no transdermal delivery of CPS ions from the cathode” limitation is in the process claim (claim 15) rather than claim 1.
How broad is the claim scope?
Device claim 1 scope
Claim 1 covers devices with:
- Any electrotransport layout consistent with the recited anode/cathode/power source arrangement.
- A cathodic reservoir containing CPS in an aqueous medium.
- The aqueous medium may include (a) a drug and/or (b) an electrolyte salt.
- The CPS can be any “cetylpyridinium salt,” subject to dependent narrowing.
Key breadth drivers:
- No specific CPS salt required in claim 1 (that is narrowed by claims 9–10).
- No specific CPS concentration required in claim 1 (that is narrowed by claims 11–13).
- No specific polymer restriction required in claim 1 (that is narrowed by claim 5).
- pH and buffer are optional add-ons in dependent claims (claims 2–4).
- A claim element is included that polymer is “compatible” with CPS, which is a functional-material compatibility limitation. The dependent polymer list narrows this.
Process claims 15 and 23 scope
Claim 15 (process) includes an additional functional transdermal constraint:
- Current is applied so the drug is transdermally delivered from the anodic reservoir.
- At the same time, cetylpyridinium ions are not transdermally delivered to the patient from the cathodic reservoir.
This requirement can materially narrow infringement relative to claim 1 because it imposes a “delivery selectivity” performance condition tied to electrotransport.
Claim 23 (device preparation) scopes manufacturing around:
- Preparing a CPS-containing aqueous medium.
- Placing it in a cathodic reservoir with a polymer housing compatible with CPS.
Claim-by-claim scope map (what each adds)
Claim 1 (independent): core CPS-in-polymer cathodic reservoir
Requires:
- Transdermal electrotransport device with anode/cathode/power source.
- Cathode cathodic reservoir:
- polymeric housing
- aqueous medium in contact with housing
- aqueous medium contains:
- drug and/or electrolyte salt, plus
- cetylpyridinium salt at antimicrobial-inhibitory amount
- polymer compatible with CPS.
Not required in claim 1:
- Specific CPS identity (depends on 9–10)
- Specific pH (depends on 2–3)
- Specific polymer family (depends on 5)
- Specific CPS concentration (depends on 11–13)
Claims 2–4: pH and buffer dependent limits
- Claim 2: aqueous medium pH 3 to 7.5
- Claim 3: aqueous medium pH 3.5 to 6.5
- Claim 4: aqueous medium includes a buffer
These dependents constrain the cathodic reservoir formulation when asserted.
Claim 5: polymer housing species
- Polymer is selected from:
- polyethylene terephthalate (PET)
- PET modified with cyclohexane dimethylol
- polypropylene
- mixtures thereof
This is a substantial narrowing from “compatible polymer” to named polymer options.
Claims 6–8: “substantially drug free” cathode reservoir; fentanyl on anode
- Claim 6: cathodic reservoir contains aqueous medium of an electrolyte salt and is substantially drug free
- Claim 7: anode includes an anodic reservoir that contains a drug
- Claim 8: anode reservoir contains fentanyl in a form deliverable when current flows
This set creates a common product configuration: drug at anode, antimicrobial CPS in cathode reservoir.
Claims 9–10: CPS as halide salt; CPC chloride
- Claim 9: cetylpyridinium salt is a halide salt
- Claim 10: cetylpyridinium halide is cetylpyridinium chloride
These narrow identity to a specific salt form.
Claims 11–13: CPS concentration windows
- Claim 11: at least 0.005% by weight CPS
- Claim 12: 0.005% to 2% CPS
- Claim 13: 0.01% to 1% CPS
These provide concentration “fences” useful for claim charts.
Claim 14: optional anion exchange membrane
- Claim 14: includes an anion exchange membrane between cathodic electrode and cathodic reservoir
This adds a barrier/selectivity element, consistent with the “no CPS delivery” concept.
Claim 15 (independent process): drug delivered from anode; CPS not delivered from cathode
Process for transdermally delivering a drug by electrotransport from a device with anode/cathode/power source, where:
- Cathode cathodic reservoir comprises:
- polymer housing
- aqueous medium: electrolyte salt + CPS at antimicrobial amount
- polymer compatible with CPS
- Current is applied so:
- drug is delivered from the anodic reservoir
- cetylpyridinium ions are not transdermally delivered from the cathodic reservoir
This process claim adds a critical selectivity requirement beyond claim 1.
Claims 16–22: fentanyl variants and “no drug from cathode”
- Claim 16: drug is fentanyl
- Claim 17: aqueous medium is a hydrogel comprising at least 0.005% CPS
- Claim 18: hydrogel CPS 0.005% to 2%
- Claim 19: hydrogel CPS 0.01% to 1%
- Claim 20: CPS is cetylpyridinium chloride
- Claim 21: substantially no drug is delivered from cathodic reservoir when current flows
- Claim 22: drug comprises fentanyl
Claims 17–19 and 21 tighten formulation and delivery behavior.
Claims 23–26 (independent process): manufacturing aqueous medium + loading into cathode reservoir
Claim 23 requires:
- Prepare aqueous medium: drug and/or electrolyte salt + CPS at antimicrobial inhibitory amount
- Place into cathodic reservoir of device:
- anode/cathode/power source
- cathode includes cathodic electrode + cathodic reservoir with polymer housing
- aqueous medium in contact with polymer housing
- polymer selected as compatible with CPS
Claim 24: polymer from the same named group as claim 5
Claim 25: aqueous medium is substantially drug free
Claim 26: CPS is a halide salt
Structural patent landscape: how this claim family likely clusters
US 6,181,963 sits in a niche intersection of:
- electrotransport/transdermal iontophoresis-like delivery, and
- antimicrobial catholyte design using cetylpyridinium salts,
- with polymer compatibility to maintain CPS activity and avoid adverse interactions,
- plus optional membrane barriers to prevent unwanted ionic transport.
Practical “design-around” pressure points visible in the claims
Even without access to the full prosecution history, the claim set reveals the levers most likely policed by examiners and most likely used by competitors:
- CPS in cathode reservoir aqueous medium
- Claims hinge on “cetylpyridinium salt” specifically.
- Polymeric housing compatible with CPS
- Substitution to incompatible polymers or different housing materials can matter.
- Selectivity requirement (process claim 15)
- The “CPS ions are not transdermally delivered” limitation can constrain electrotransport conditions or membrane placement.
- Concentration/pH fences
- 0.005% to 2% (and narrower 0.01% to 1% in dependents), plus pH bands if asserted through dependents.
- Halide identity and chloride (dependent claims)
- Competitors can attempt CPC salt variant strategies, though claim 1 still covers “cetylpyridinium salt.”
Enforcement-relevant claim construction risks and how the scope plays out
“Compatible with cetylpyridinium salt”
Claim 1 and claim 15 require polymer compatibility but do not quantify it. In practice, this creates a factual linkage to:
- whether CPS leaches from the polymer interface,
- whether polymer physically degrades or changes CPS effective antimicrobial concentration,
- or whether CPS adsorption/partitioning invalidates antimicrobial performance.
From a landscape view, this limitation raises the importance of material selection and formulation stability.
“Amount sufficient to inhibit microbial growth”
This functional phrase means antimicrobial efficacy is a performance-based requirement. For landscape mapping, this often aligns with:
- documented antimicrobial effectiveness tests for the cathode reservoir medium.
This can be a high-friction area for product teams that want to re-formulate CPS analogs or reduce levels.
“Cetylpyridinium ions are not transdermally delivered”
This is a direct delivery-performance limitation in claim 15. It implies that the device system should route:
- therapeutic drug transport preferentially through the anode,
- while limiting CPS ionic migration to skin.
Landscape interpretation: the presence of an anion exchange membrane (claim 14) likely supports this.
What would a claim chart look like for common electrotransport architectures?
Scenario A: fentanyl at anode, CPS (CPC chloride) antimicrobial catholyte, polymer housing (PET or PP)
This aligns strongly with:
- device claim 1 (CPS antimicrobial catholyte in polymer housing)
- device dependents 6–8 (drug free cathode, fentanyl anode)
- dependents 10–13 (CPC chloride and concentration)
- dependent 5 if PET/PP is used
- process claims 15, 16, 20, 21 if no CPS or no cathode drug is delivered
Scenario B: CPS-free cathode but antimicrobial via different preservative
- Avoids the “cetylpyridinium salt” limitation in claim 1 and claim 15.
- Likely avoids direct infringement across the set, though broader electrotransport patents may still apply (not analyzed here).
Scenario C: CPS in cathode but polymer housing is not “compatible”
- Could fall outside dependent claim 5 but may still be asserted under claim 1 if “compatible” is interpreted broadly enough.
- Product teams should treat polymer-CPS interaction as a claim-critical variable.
Key takeaways
- US 6,181,963 is focused on electrotransport devices that use cetylpyridinium salt in the cathodic reservoir aqueous medium as an antimicrobial agent, with a polymeric housing compatible with that CPS.
- Independent protection spans both device (claim 1) and process/selectivity (claim 15) and covers manufacturing of the cathode medium (claim 23).
- The most enforceable “fences” in dependent claims are:
- pH windows (claims 2–3),
- polymer species (claim 5),
- CPC chloride identity (claims 9–10, 20),
- CPS concentration ranges (claims 11–13, 18–19),
- and selective transport limitations (claim 15) plus optional anion exchange membrane (claim 14).
- Landscape-wise, the likely competitive threat zone for follow-on entrants is devices that adopt the same architecture: CPS-containing antimicrobial catholyte paired with PET/PP-compatible polymer housing, especially when the therapeutic drug is delivered from the anode and unwanted cathode ionic migration is suppressed.
FAQs
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Does claim 1 require fentanyl specifically?
No. Claim 1 requires an electrotransport device with a CPS-containing cathodic reservoir. Fentanyl is required only in dependent claims (notably claims 8 and 16/22).
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Is cetylpyridinium chloride required to infringe?
Not for claim 1. Claim 10 and claim 20 restrict the CPS to cetylpyridinium chloride, but claim 1 covers “cetylpyridinium salt” broadly.
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What is the strongest narrowing limitation in the independent process claim?
Claim 15 requires that cetylpyridinium ions are not transdermally delivered from the cathodic reservoir while the drug is delivered from the anodic reservoir.
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Can the cathodic reservoir contain drug?
Yes under claim 1 (it can include a drug and/or electrolyte salt). Claim 6 narrows to “substantially drug free” cathode reservoir.
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Do the patent claims cover manufacturing the device, not just use?
Yes. Claim 23 is a manufacturing/preparation process for placing the CPS-containing medium into the cathodic reservoir, and several dependent claims restrict that preparation further.
References (cited sources)
[1] United States Patent 6,181,963. “Transdermal electrotransport drug delivery device and process.” (Claim set provided in prompt).
