United States Patent 8,597,272: What Is Claimed, Where It Fits, and How It Stacks Up

What does US 8,597,272 claim at a technical level?

US Patent 8,597,272 claims an iontophoretic patch for delivering sumatriptan (including sumatriptan succinate) using a two-stage current profile to produce targeted exposure metrics (AUC and Cmax). The claim set is structured as a core method/patch concept (independent claim 1) followed by increasingly specific dependent claims on current density, surface area, delivered dose, reservoir composition, and pharmacokinetic (PK) ranges.

Independent claim 1: the core treatment-current profile

Claim 1 recites an iontophoretic patch for delivering sumatriptan with a defined current regime:

High current treatment period: current of about 4 mA for about 1 hour
Subsequent low current treatment period: current of about 2.0 mA for about 3 hours

This defines the central differentiator: stepwise iontophoretic current dosing for extended administration rather than a single constant current.

Integrated patch (claim 2)

The patch is integrated (claim 2).

Current density and iontophoretically active area

Claims 3 to 6 narrow the delivery geometry and current intensity per area:

At least a portion of the high-current period uses current density ≥ about 0.10 mA/cm² (claim 3)
The high-current current density is between about 0.10 and 0.5 mA/cm² (claim 4)
Patch iontophoretically active surface area is ≥ about 10 cm² (claim 5)
Surface area is about 30 cm² (claim 6)

Amount delivered

Delivered sumatriptan amount is about 10 mg (claim 7)

Reservoir formulation details

Claims 8 to 12 specify an electrode/reservoir architecture and specific excipient levels:

Patch has cathode reservoir and anode reservoir (claim 8)
Cathode reservoir comprises 2% hydroxypropyl cellulose (HPC) and sodium chloride (claim 8)
Cathode reservoir comprises 2% HPC in an amount of about 3.0 g (claim 9)
Anode reservoir comprises sumatriptan or pharmaceutically acceptable salt in a gel solution (claim 10)
Gel solution comprises 4% sumatriptan succinate (claim 11)
Gel solution further comprises 10% polyamine (claim 12)

Target PK ranges: AUC and Cmax

Claims 13 to 20 tightly bind performance to exposure metrics and statistical confidence intervals:

AUC0-inf (95% CI) between about 67 and about 158 hr·ng/mL (claim 13)
Narrower AUC0-inf (95% CI) between about 99 and about 128 hr·ng/mL (claim 14)
AUC0-inf between about 67 and 158 hr·ng/mL (claim 15)
AUC0-inf between about 99 and 128 hr·ng/mL (claim 16)
Cmax (95% CI) between about 14 and about 38 ng/mL (claim 17)
Narrower Cmax (95% CI) between about 20 and about 28 ng/mL (claim 18)
A specific performance expression: Cmax about 23-25 ng/mL and plasma concentrations sustained for at least three hours (claim 19)
Joint constraint: AUC0-inf about 99 to 128 hr·ng/mL and Cmax about 20 to 28 ng/mL (claim 20)

Drug identity

Sumatriptan is sumatriptan succinate (claim 21)

What is the practical scope of the claim set (what you would infringe)?

US 8,597,272 is not limited to “iontophoresis of sumatriptan” in the abstract. It is constrained by a stack of technical requirements that collectively define a relatively narrow product concept, with multiple ways to meet claim limitations due to dependent claims that still capture variants within specified bands.

Core “must-have” elements

To fit within the claim family’s scope, a patch would need at least the independent-claim features:

Iontophoretic patch for sumatriptan
Two-stage current regimen:
- ~4 mA for ~1 hour
- ~2 mA for ~3 hours

If a product deviates from this current step structure (for example, swaps durations, changes high/low current levels materially, or uses a different current waveform), infringement risk against claim 1 drops sharply because claim 1 is the backbone.

Common dependent-claim “lock-ins”

Even if claim 1 is met, scope often hinges on dependent limitations:

Current density band: at least part of high current at ≥ 0.10 mA/cm², and high current specifically 0.10 to 0.5 mA/cm²
Surface area: ≥10 cm², with a target of ~30 cm²
Dose: ~10 mg delivered
Reservoir composition:
- Cathode reservoir: 2% HPC + sodium chloride, with a cited formulation mass (about 3.0 g reservoir containing 2% HPC)
- Anode reservoir: gel with 4% sumatriptan succinate and 10% polyamine

PK-driven constraints

Claims 13 to 20 introduce an exposure-based gate. That matters in two ways:

It increases the difficulty of designing around by substituting different patch engineering while still achieving the same systemic profile.
It also creates proof pathways in enforcement and litigation where testing and bioequivalence-style studies can be used to map a product’s PK to the claim windows.

What are the likely claim construction pressure points?

1) “About” ranges

The claims repeatedly use “about” (for mA values, durations, current density, surface area, AUC/Cmax bands, and dose). Courts typically interpret “about” in a range guided by intrinsic evidence, but the net effect is to capture a window rather than a single point.

Key “about” anchors:

Current: about 4 mA and about 2.0 mA
High period: about 1 hour; low period: about 3 hours
Current density: ≥ about 0.10 mA/cm², high band about 0.10 to 0.5 mA/cm²
Surface area: about 30 cm² and ≥ about 10 cm²
Dose: about 10 mg
PK: “about” appended to exposure values and confidence intervals

2) Two-stage regimen as a structural concept

The independent claim ties together the high-current period and low-current period in sequence. A design that uses a single constant current or a different step pattern is likely non-infringing relative to claim 1, even if the average current is similar.

3) Current density depends on effective area

Claims 3 to 6 use current density and iontophoretically active surface area. For enforcement and validity analysis, “active surface area” becomes technical and potentially contentious:

A device can mechanically have larger electrode area but a smaller effective active area.
Claim 5 requires ≥10 cm², and claim 6 anchors ~30 cm², so area determination matters.

4) Reservoir composition precision

Dependent claims 8 to 12 are explicit:

2% HPC + sodium chloride in cathode reservoir
2% HPC with about 3.0 g reservoir amount
4% sumatriptan succinate gel solution
10% polyamine

These are formulation-specific enough that substituting a different polymer level or different polyamine class may be outside dependent claim scope, even if current profile is the same.

5) PK confidence interval language

Claims recite PK ranges “within a 95% confidence interval between about X and about Y.” This can raise issues around:

how PK is measured (study design, sample size, analytical method)
the definition of AUC0-inf
statistical computation

For a competing patch, this acts as a performance signature.

How does this patent sit in the broader US sumatriptan iontophoresis landscape (what are the usual neighbors)?

Within US drug delivery patent landscapes, you typically see clusters that fall into four buckets:

Drug selection and route claims (sumatriptan delivered transdermally or otherwise)
Iontophoretic device architecture (patch format, electrodes, current sources, reservoirs)
Iontophoretic operating parameters (current magnitude, current density, duty cycle, duration)
Formulation and performance targets (specific reservoir excipients, penetration enhancers, PK endpoints)

US 8,597,272 is concentrated at the intersection of (3) operating parameters, (4) formulation detail, and (4) PK outcomes, with the strongest scope anchored by the staged current schedule in claim 1 and specific excipient levels in claims 8 to 12.

From a competitive strategy standpoint:

A product that matches claim 1’s staged current profile but uses different reservoir excipients could still be captured by claim 1 (and possibly by other performance claims, depending on PK).
A product that matches formulation and PK but uses a different current schedule is more likely to avoid claim 1 but can still be caught if the PK and current-density limitations are independently met.

What does a “design-around” assessment look like against the claim stack?

Below is a practical claim-coverage matrix based strictly on the limitations you provided.

Design element	Claim linkage	Typical design-around lever
High/low current values and durations	Claim 1	Change step schedule so it no longer uses ~4 mA for ~1 hour and ~2 mA for ~3 hours
High-period current density	Claims 3-4	Adjust effective active area/current so density exits 0.10 to 0.5 mA/cm² for the high stage
Electrode active area	Claims 5-6	Reduce effective active area below ~10 cm² or move away from ~30 cm² (if claim 5/6 asserted)
Delivered dose	Claim 7	Deliver substantially different mg or use different dosing schedule such that delivered amount is not ~10 mg
Cathode reservoir formulation	Claims 8-9	Change HPC percentage or remove sodium chloride or use materially different reservoir mass/composition
Anode reservoir formulation	Claims 10-12	Change succinate concentration, remove/replace polyamine, alter gel base to exit specific percentages
Systemic exposure profile	Claims 13-20	Target different AUC/Cmax outcomes by changing delivery kinetics and thereby step parameters

What are the most enforceable claim points for litigation or licensing?

Claim 1 is the primary enforcement anchor

If a patch uses:

staged current: ~4 mA for ~1 hour then ~2 mA for ~3 hours, and
delivers sumatriptan

then the patent’s core coverage is in play, regardless of whether the other dependent limitations are met.

Claims 8 to 12 are formulation “proof multipliers”

These are highly specific. If product records or device inspection show:

cathode contains 2% HPC + sodium chloride
anode gel contains 4% sumatriptan succinate + 10% polyamine

then infringement arguments strengthen, because the claims require particular formulation compositions, not only performance.

Claims 13 to 20 are PK “performance multipliers”

They can be used to correlate a competitor’s clinical data with the patent claim windows:

AUC0-inf between 67 and 158 hr·ng/mL, with narrower band at 99 to 128
Cmax between 14 and 38 ng/mL, with narrower band at 20 to 28
A combined signature: AUC0-inf ~99 to 128 and Cmax ~20 to 28
Cmax about 23-25 ng/mL and sustained levels for at least 3 hours

In licensing negotiations, these can operate as measurable differentiators.

Key Takeaways

US 8,597,272 claims a sumatriptan iontophoretic patch with a two-stage current regimen: ~4 mA for ~1 hour, then ~2 mA for ~3 hours.
The patent scope tightens via dependent claims on current density (0.10 to 0.5 mA/cm² during high stage), active surface area (≥10 cm²; ~30 cm²), and dose (~10 mg).
It adds device formulation specificity: cathode contains 2% HPC + sodium chloride, and anode gel contains 4% sumatriptan succinate + 10% polyamine.
It further locks coverage to PK endpoints using AUC0-inf and Cmax confidence-interval bands and a joint exposure window (AUC0-inf ~99 to 128; Cmax ~20 to 28).
For competition strategy, the most direct infringement lever is matching claim 1’s stepwise current schedule; the highest proof leverage typically comes from matching reservoir compositions and PK outcomes.

FAQs

1) Is the patent limited to sumatriptan succinate specifically?

No. Claim 1 broadly covers sumatriptan, while claim 21 specifies that sumatriptan is sumatriptan succinate.

2) What is the central technical differentiator in claim 1?

The staged iontophoretic dosing: ~4 mA for ~1 hour followed by ~2.0 mA for ~3 hours.

3) What current density limits are recited?

High-stage current density is constrained to ≥ about 0.10 mA/cm² (at least a portion of the high-current period) and specifically about 0.10 to 0.5 mA/cm² during the high-current period.

4) What reservoir compositions are explicitly claimed?

Cathode reservoir includes 2% hydroxypropyl cellulose (HPC) and sodium chloride; anode reservoir is a gel with 4% sumatriptan succinate and 10% polyamine.

5) How do the claims use pharmacokinetics?

They recite AUC0-inf and Cmax ranges expressed with 95% confidence intervals, plus a combined AUC/Cmax window and a Cmax target with sustained exposure for at least 3 hours.

References

United States Patent 8,597,272 (claims as provided by user).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Teva Branded Pharm	ZECUITY	sumatriptan succinate	SYSTEM;IONTOPHORESIS	202278-001	Jan 17, 2013		DISCN	Yes	No	8,597,272	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2008358027	⤷ Start Trial
Australia	2015238858	⤷ Start Trial
Canada	2727927	⤷ Start Trial
Eurasian Patent Organization	025505	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,597,272

Which drugs does patent 8,597,272 protect, and when does it expire?

Summary for Patent: 8,597,272