United States Patent 9,272,137: Scope, Claim Architecture, and Transdermal Iontophoresis Landscape
US 9,272,137 claims an integrated iontophoretic transdermal patch that delivers a triptan (or salt) using an electronic, two-stage delivery sequence with defined current density windows and defined plasma exposure targets. The patent’s enforceable scope is anchored on (1) the patch architecture (drug reservoir, return reservoir, electrodes, electronic circuit), (2) the two-stage regimen with specific current-density relationships during bolus vs maintenance, and (3) plasma concentration and timing thresholds framed as “therapeutically effective dosage level” and specific ng/mL targets in dependent claims.
What does claim 1 actually lock down?
Independent claim 1 is the controlling scope. It requires all elements below to be present and configured in the claimed way:
Core patch structure (must-have)
- Integrated iontophoretic transdermal patch with:
- Drug reservoir containing:
- a triptan compound or salt
- Return reservoir
- Electronic circuit in electrical connection with both reservoirs, comprising:
- Voltage source
- Active electrode
- Return electrode
- Transistor
- Electronic circuit is pre-configured for a two-stage delivery sequence.
Two-stage delivery sequence (must-have regimen)
Stage 1: First bolus stage
- Defined current density windows:
- Average current density through drug reservoir to skin: 0.05 to 0.20 mA/cm²
- Average current density through return reservoir to skin: 0.05 to 0.20 mA/cm²
- Timing coverage:
- Each current density window applies during at least 30% of the delivery time of the bolus stage.
- Exposure objective:
- During the bolus stage, the current through skin and drug reservoir is sufficient to achieve:
- therapeutically effective dosage level of at least 10 ng/mL triptan in human plasma
- Target kinetics:
- in less than one hour
Stage 2: Second maintenance stage
- Defined current density windows:
- Average current density through drug reservoir to skin: 0.01 to 0.20 mA/cm²
- Average current density through return reservoir to skin: 0.01 to 0.20 mA/cm²
- Timing coverage:
- Each current density window applies during at least 30% of the delivery time of maintenance stage.
- Relationship to bolus:
- Each maintenance current density is lower than both (i) the average current density through the drug reservoir during bolus, and (ii) the average current density through the return reservoir during bolus.
How the dependent claims expand or narrow the scope
The dependent claims do not introduce alternative independent inventive concepts; they tighten claim 1 by narrowing to particular materials, formulations, power sources, drug species, circuit variants, and performance metrics. The result is a layered infringement map: practicing any version that meets claim 1 plus additional limitations can fall under the broader independent claim alone (if claim 1 is met) or can fall under specific dependent claims (if those extras are met).
Electrode and formulation limits (material and formulation-specific)
- Claim 2: Active electrode includes zinc or zinc coating.
- Claim 3: Triptan is formulated in a flowable hydrogel.
- Claim 7-9 (drug species specificity):
- Claim 7: Tripan (or salt) selected from sumatriptan, naratriptan, and salts thereof.
- Claim 8: Tripan is sumatriptan or a salt thereof.
- Claim 9: Tripan is sumatriptan succinate.
Circuit architecture and power source variants
- Claim 4: Electronic circuit further includes a pair of control transistors with connection to two or more resistors.
- Claim 5: Voltage source is galvanic power battery source.
- Claim 6: Voltage source is lithium battery.
Activation and separation constraints
- Claim 10: Tripan compound/salt is separated from the electronic circuit prior to patch activation.
Plasma exposure and duration targets (performance lock-in)
- Claim 11: Circuit maintains a steady state concentration of triptan in plasma for at least one hour.
- Claim 12: Steady-state concentration is about 10 ng/mL or greater.
- Claim 13: Steady-state concentration is maintained for at least four hours.
Product and manufacturability constraints
- Claim 14: Shelf life of at least 6 months.
- Claim 15: Patch weighs less than about 0.1 lb.
What is the enforceable claim scope in practice?
1) The claim is regimen-defined, not just device-defined
Many transdermal patents claim patch structures. Here, the novelty leverage is the two-stage delivery sequence with:
- specific current-density bands
- defined proportional time-at-level (at least 30% of stage time)
- a kinetic target (≥10 ng/mL in < 1 hour) during bolus
- a defined current relationship (maintenance currents lower than bolus currents)
So a competitor can build a similar patch structure but avoid infringement if it:
- does not hit the defined current-density windows, or
- does not achieve the plasma target within the time window, or
- reverses/does not satisfy the maintenance < bolus relationship, or
- does not deliver with the “at least 30% of stage duration” condition.
2) Infringement can be staged: meet claim 1, then dependents for coverage breadth
A patch that uses different electrodes/materials or different hydrogel can still meet claim 1 if the independent elements are met. Conversely, if a patch meets claim 1 but also uses zinc electrodes, hydrogel formulation, specific power sources, and specific triptan species, it can land under multiple dependent claims.
3) Claim 10 adds an integration constraint that matters for commercial variants
If a competitor integrates the drug with electronics (no separation prior to activation), they can potentially avoid claim 10 while still meeting claim 1.
Where does the competitive “design-around” risk concentrate?
A. Current density bands and proportional time windows
Claim 1’s most explicit numerical boundaries are the average current densities and the duration share (“at least 30% of delivery time” during each stage). These are the easiest levers for claim charts and the highest-risk for design-arounds.
Key infringement-sensitive numeric elements from claim 1:
| Element |
Bolus stage requirement |
Maintenance stage requirement |
| Drug-side current density (avg) |
0.05 to 0.20 mA/cm² |
0.01 to 0.20 mA/cm² |
| Return-side current density (avg) |
0.05 to 0.20 mA/cm² |
0.01 to 0.20 mA/cm² |
| Time-at-level threshold |
≥30% of bolus delivery time |
≥30% of maintenance delivery time |
| Bolus outcome |
≥10 ng/mL plasma in < 1 hour |
steady-state maintenance (via dependent claims) |
| Maintenance vs bolus relationship |
n/a |
maintenance current densities must be lower than bolus current densities (on both sides) |
B. Plasma threshold and time-to-≥10 ng/mL
Claim 1 ties delivery parameters to a functional outcome: ≥10 ng/mL plasma within < 1 hour. If a competitor targets a lower Cmax or slower onset, or uses a different dose strategy that does not reach that plasma level in that time window, they have a plausible risk reduction.
The dependents also create reinforcement:
- Claim 11: steady state for ≥1 hour
- Claim 12: steady state ≥ about 10 ng/mL
- Claim 13: steady state for ≥4 hours
C. The “two-stage” topology
The claim requires two-stage delivery sequence with current levels in each stage and the maintenance being lower than bolus. Any single-stage iontophoretic scheme or staged scheme that does not comply with the lower maintenance current constraint can avoid claim 1.
What is the patent’s “triptan coverage” and why it matters for freedom-to-operate?
Tripan genus + species narrowing
- Claim 1 covers “a triptan compound or a salt thereof.”
- Claim 7 narrows to sumatriptan, naratriptan, and salts thereof.
- Claims 8 and 9 further specify sumatriptan and sumatriptan succinate.
For an FTO view, the practical coverage axis is:
- If your compound is outside triptans or outside the listed species, your risk drops for the dependent claims but not necessarily the independent claim if the compound is still a triptan (which claim 1 says it is).
- If your compound is a triptan but not sumatriptan/naratriptan, you still need to assess claim 1 only; claim 7-9 likely do not apply.
What does the electronic circuit limitation exclude?
Claim 1 requires:
- a transistor within the electronics
- voltage source, active electrode, return electrode
- the electronics are “pre-configured” to execute the two-stage regimen
Claim 4 further requires additional architecture:
- pair of control transistors
- connection to two or more resistors
This does not necessarily exclude basic circuits if a transistor is present, but it can exclude “non-transistor” controllers, analog-only constant-current drivers without transistor switching/control, or circuit designs that do not meet the “pre-configured two-stage” requirement.
How strong is the landscape position versus older transdermal iontophoresis approaches?
Based on the claim content alone, the differentiation is the combination of:
- triptan in transdermal iontophoresis
- two-stage bolus/maintenance regimen
- numeric current-density ranges and time distribution constraints
- explicit plasma exposure and onset kinetics (≥10 ng/mL in < 1 hour)
- a defined steady-state concentration strategy (reinforced by dependents)
- device packaging constraints (shelf life, weight)
- optional zinc electrode and hydrogel formulation
In practical terms, any earlier art that covers “iontophoretic delivery of ionizable drugs” will not automatically anticipate unless it:
- uses triptans (or salts), and
- uses a two-stage bolus/maintenance current scheme with these average current-density bands, and
- achieves the specified plasma outcomes, or explicitly discloses equivalent ranges and functional outcomes.
Without the file history and cited references, this analysis treats those as non-assumptive and focuses on claim-based scope.
Patent landscape: how to map likely infringement and licensing pressure
1) High-risk practice profiles (most likely to read on claim 1)
- Iontophoretic transdermal delivery of sumatriptan or other triptan (or salt)
- Two-stage current programming with:
- bolus: 0.05 to 0.20 mA/cm² average at least 30% of bolus stage time
- maintenance: 0.01 to 0.20 mA/cm² average at least 30% of maintenance stage time
- maintenance currents lower than bolus currents on both drug-side and return-side
- Bolus delivers ≥10 ng/mL in < 1 hour
2) Medium-risk profiles (may avoid claim 1 but could still hit dependents)
- Meets claim 1 device and regimen but varies:
- electrode material (could avoid claim 2)
- hydrogel vs another carrier (could avoid claim 3)
- battery type or circuit component count (could avoid claims 4-6)
- drug separation approach (could avoid claim 10)
- plasma steady-state duration or level (could avoid claims 11-13)
- shelf life or weight targets (could avoid claims 14-15)
3) Lower-risk profiles (likely avoid the independent claim)
- Single-stage iontophoresis or non-bolus/maintenance scheme
- Current densities outside the bolus and maintenance windows
- Maintenance not strictly lower than bolus (on both current paths)
- Plasma onset does not reach the defined ≥10 ng/mL in < 1 hour
Claim-by-claim scope map (quick reference)
| Claim |
Scope hook |
Scope impact on competitors |
| 1 |
Device architecture + two-stage regimen + current density windows + ≥10 ng/mL in <1 hour |
Primary infringement gate |
| 2 |
Zinc electrode/coating |
Narrows to specific materials |
| 3 |
Flowable hydrogel formulation |
Narrows to specific formulation class |
| 4 |
Two additional control transistors + resistors |
Narrows to specific electronics design |
| 5 |
Galvanic power battery source |
Narrows to specific power category |
| 6 |
Lithium battery |
Narrow subset of claim 5 |
| 7 |
Tripan species limited to sumatriptan/naratriptan and salts |
Narrows to species |
| 8 |
Sumatriptan or salt |
Narrow subset of claim 7 |
| 9 |
Sumatriptan succinate |
Narrowest drug identity |
| 10 |
Drug separated from electronic circuit before activation |
Narrows to integration/activation approach |
| 11 |
Steady state for ≥1 hour |
Narrows to pharmacokinetic outcome |
| 12 |
Steady state ≥ about 10 ng/mL |
Narrows to minimum concentration |
| 13 |
Steady state for ≥4 hours |
Narrows to duration of exposure |
| 14 |
Shelf life ≥6 months |
Narrows to product spec |
| 15 |
Weight <0.1 lb |
Narrows to product spec |
Key Takeaways
- US 9,272,137’s enforceable scope is centered on two-stage iontophoretic current programming plus functional plasma outcomes: ≥10 ng/mL within <1 hour during the bolus stage (claim 1).
- The claim sets explicit average current-density ranges for both drug-side and return-side pathways, with a minimum 30% time-at-level condition and a strict maintenance current lower than bolus relationship (claim 1).
- Dependent claims tighten scope via zinc electrodes, flowable hydrogel, specific battery types, specific triptan species (sumatriptan/naratriptan; sumatriptan succinate), drug/electronics separation before activation, steady-state concentration for ≥1 to ≥4 hours, and product shelf life and weight.
- In the transdermal iontophoresis space, the highest risk designs are those that match the bolus/maintenance regimen plus plasma onset threshold; designs that change only formulation or packaging may still fall under claim 1.
FAQs
-
What part of claim 1 is most likely to drive infringement analysis?
The numeric bolus and maintenance current-density windows, the 30% of delivery time condition, and the functional plasma threshold of ≥10 ng/mL in <1 hour.
-
Can a design avoid the patent by changing only the drug formulation?
It can avoid dependent claims (like the hydrogel in claim 3), but it still risks claim 1 if the two-stage regimen and plasma targets are met.
-
Does using lithium batteries automatically create infringement?
Lithium is relevant to dependent claim 6, but claim 1 can still be implicated regardless of battery type as long as the circuit includes the required elements and regimen.
-
If maintenance current equals bolus current, is it still within the claim?
No. Claim 1 requires maintenance current densities to be lower than both bolus current densities on both pathways.
-
Which triptan salts are explicitly covered in the dependent claims?
The dependent claims explicitly include sumatriptan succinate (claim 9) and salts in general for the species-limited provisions (claims 7-9).
References
[1] US Patent 9,272,137, “Integrated iontophoretic transdermal patch for delivery of triptan compounds.”
