Details for Patent: 4,812,313

Summary for Patent: 4,812,313

Title:	Method for lessening the incidence of anginal attacks
Abstract:	A medical bandage is disclosed comprising a reservoir containing a gelled fluid, rheological agent and a drug. A method of using the bandage for producing a beneficial effect is disclosed also.
Inventor(s):	Robert M. Gale
Assignee:	Alza Corp
Application Number:	US07/132,829
Patent Claim Types: see list of patent claims	Use;

US Patent 4,812,313: Scope, Claims, and US Landscape for Transdermal Nitroglycerin Prophylaxis via Rate-Controlled Bandage

US Patent 4,812,313 covers a specific transdermal prophylactic approach to reduce anginal attack incidence using a drug-in-adhesive/bandage system with a defined drug reservoir composition and a defined rate-controlling membrane structure. The claim scope is tightly framed around (i) method-of-use (lessening incidence of anginal attacks), (ii) the specific transdermal delivery architecture (backing, reservoir, rate controlling membrane), and (iii) defined drug delivery behavior (controlled permeability and constant/prolonged release; optional priming dose). Nitroglycerin is explicitly a preferred implementation in dependent claim 3 with numerical flux ranges.

What is being claimed, in plain terms?

Claim 1 requires all of the following, as a single method claim:

• A patient-specific prophylactic indication: “lessening the incidence of anginal attacks.”
• A topical medical bandage positioned on the skin of the at-risk patient.
• Bandage construction with three functional layers/regions:
  1. A backing member “substantially impermeable” to drug passage.
  2. A reservoir in contact with that backing, where the reservoir comprises:
     • gelled silicone fluid
     • silicon dioxide
     • a vasodilator useful as a prophylactic antianginal drug
  3. A rate controlling membrane in contact with the reservoir that:
     • is “permeable to the passage of the vasodilator”
     • “controls its rate of release from the bandage”
     • is also “in contact with the backing member” (claim language ties the membrane’s position to the backing).
• Administration step: administering the vasodilator transdermally in a prophylactically effective amount to produce the intended benefit.

Dependent claims then narrow on dose and drug identity:

• Claim 2: dose expressed as about 10 to 2000 μg/hr (general vasodilator).
• Claim 3: nitroglycerin with about 20 to 1200 μg/hr.
• Claim 4: prophylactic “priming dose” for intended effect (sequence/dosing regimen concept).
• Claim 5: prophylactic administration at a substantially constant rate over a prolonged period of time (delivery profile concept).

Claim-by-claim scope (what is in and what is out)

Claim 1: Is the core prophylactic method tied to a particular bandage composition and release-control architecture?

Yes. Claim 1 is a method claim that is inseparable from the bandage structure it requires. To practice Claim 1, a system must satisfy all structural recitations and the prophylactic use.

Essential limitations of Claim 1

• Use: lessening incidence of anginal attacks in a patient.
• Device-in-use: “medical bandage” applied to the skin.
• Layer 1: backing member substantially impermeable to drug passage.
• Layer 2: drug reservoir comprising:
  • gelled silicone fluid
  • silicon dioxide
  • vasodilator (prophylactic antianginal)
• Layer 3: rate controlling membrane that is:
  • permeable to the vasodilator
  • controls release rate
  • in contact with the backing member (positional tie)

Practical effect on infringement posture

• The claim is likely not met by:
  • oral or injectable vasodilator prophylaxis (no bandage)
  • transdermal patches with different reservoir polymers (no gelled silicone fluid plus silicon dioxide as required components)
  • systems where the rate is controlled by something other than the claimed “rate controlling membrane” structure
  • systems where backing is not “substantially impermeable” to the drug
• The claim is likely to be met by:
  • transdermal nitroglycerin patches using gelled silicone silicone matrices and silica plus a separate release-controlling membrane.

Claim 2: Does Claim 2 narrow dose numerically for any vasodilator?

Yes. Claim 2 narrows Claim 1 with a delivery amount range:

• About 10 to 2000 μg/hr of the vasodilator.

Scope impact

• It does not mandate nitroglycerin.
• It constrains the prophylactic regimen to within that approximate flux/rate expression.

Claim 3: Does Claim 3 lock in nitroglycerin and a narrower delivery range?

Yes. Claim 3 makes nitroglycerin explicit:

• Vasodilator = nitroglycerin
• Administered at about 20 to 1200 μg/hr

Scope impact

• A nitric oxide donor other than nitroglycerin likely falls outside Claim 3, though it could still fall under Claim 1/2 if it meets the “vasodilator useful as a prophylactic antianginal drug” language and the Claim 1 structural requirements.

Claim 4: Is a “priming dose” required as a regimen element?

Claim 4 narrows Claim 1 by adding that the vasodilator is administered in a:

• prophylactic priming dose for intended effect.

Scope impact

• This is a regimen feature. A product using only steady-state prophylaxis with no priming step would avoid Claim 4, even if it meets Claim 1 and Claim 5.

Claim 5: Does Claim 5 require a delivery profile of constant rate over a prolonged period?

Yes. Claim 5 narrows Claim 1 by adding:

• prophylactically effective amount at a substantially constant rate over a prolonged period of time

Scope impact

• A patch that delivers in a pulse-and-chase fashion, rapidly ramps and then decays sharply, or releases largely in an initial burst would likely avoid Claim 5, even if it remains structurally similar.

Structural map of the claimed bandage (useful for freedom-to-operate design filters)

The claim language can be translated into a compliance checklist for competitive patches:

Claimed bandage element	Claim language	Competitive design flags
Backing member	“substantially impermeable to the passage of drug”	Non-drug barrier backs, breathable backs with drug bleed risk
Reservoir composition	“gelled silicone fluid, silicon dioxide, and a vasodilator”	Other reservoir matrices (hydrocolloids, acrylates without silicone gel, non-silica excipients)
Rate controlling membrane	“permeable…controls its rate of release…in contact with backing”	Release control via different mechanisms (diffusion through reservoir only, no discrete membrane, multi-layer structures not satisfying contact/positioning as claimed)
Release behavior	Constant rate over prolonged period (Claim 5)	Pulsed dosing, ramp-up only, fast then fall-off release
Dosage rate	10-2000 μg/hr (Claim 2) / 20-1200 μg/hr for nitroglycerin (Claim 3)	Rate outside ranges (noting “about” gives flexibility, but boundary crossing can matter)
Regimen	priming dose (Claim 4)	No priming step

Patent landscape in the United States (strategy-relevant view)

Because the user-provided text contains only the claim set and no bibliographic data (assignee, filing date, publication date, continuation status, maintenance/expiration state), a complete, citation-backed US landscape cannot be produced to Bloomberg-style specificity without risking fabrication.

Accordingly, the actionable landscape analysis below is framed strictly as claim-driven competitive mapping rather than document-by-document citation.

Where does 4,812,313 sit in the design space?

This patent is positioned at the intersection of:

• Transdermal nitroglycerin delivery for angina prophylaxis
• Silicone-based gel matrices with silica
• Discrete release control via a rate controlling membrane
• Regimen control (constant prolonged delivery; optional priming dose)

Most likely infringement/design-around pressure points

A competitor attempting to enter the US market with a similar prophylactic transdermal vasodilator would typically face one or more of these risks:

1. Silicone gel + silica reservoir
   • If a patch’s reservoir omits silica or uses a different gel system, it can avoid the strict “reservoir comprising” recitation.
2. Discrete rate controlling membrane
   • If the release rate is controlled by matrix diffusion without a separate membrane layer, or if the membrane is not positioned to satisfy “in contact with the backing member,” claim 1 can be avoided.
3. Backing impermeability
   • If the backing permits drug passage above “substantially impermeable,” it can fail a required limitation.
4. Dosing rate windows
   • Claim 3’s nitroglycerin range (20-1200 μg/hr) provides a measurable boundary for potential rate adjustments.
5. Delivery profile
   • Claim 5’s “substantially constant rate over a prolonged period” is a regimen limitation. A patch designed with controlled initial delivery that tapers could reduce exposure to Claim 5.

Competitive product archetypes likely to collide

• Nitroglycerin patches that:
  • use silicone-based drug reservoirs containing silica
  • use a separate polymeric rate-controlling membrane
  • target prophylactic reduction of anginal attacks
  • provide controlled sustained delivery

Archetypes likely to reduce collision risk

• Different reservoir chemistry (no silica, or non-silicone gel matrix)
• Different rate-control mechanism (no discrete membrane; release governed primarily by matrix diffusion or engineered nanochannels within the reservoir)
• Different regimen (no priming; or non-constant release)
• Different dosing expression that systematically keeps nitroglycerin delivery outside 20-1200 μg/hr while still delivering therapeutically (note: “about” may limit simple numeric design-around, but large shifts can matter)

Business implications for R&D and investment screening

Claim-driven “must-match” features

A transdermal prophylactic vasodilator program seeking to be risk-robust against 4,812,313 should plan around at least one core structural or regimen limitation:

• reservoir composition (gelled silicone fluid + silicon dioxide)
• discrete rate controlling membrane with the claimed positional relationships
• steady constant prolonged release requirement (Claim 5)
• priming dose requirement (Claim 4)
• nitroglycerin delivery rate window (Claim 3)

Dosing and regimen engineering has the highest leverage if the chemistry is fixed

If a company already uses a silicone-silica reservoir and a membrane-controlled system, the fastest mitigation path is often regimen and delivery profile:

• avoid a “priming dose” regimen (Claim 4 exposure)
• avoid “substantially constant rate” prolonged delivery (Claim 5 exposure)
• consider maintaining nitroglycerin delivery outside Claim 3’s window where feasible

Key Takeaways

• US Patent 4,812,313 claims a method to lessen anginal attack incidence using a specific transdermal bandage architecture: impermeable backing + silicone-silica drug reservoir + permeable rate controlling membrane.
• The strongest practical boundaries are Claim 1 structure, then Claim 3’s nitroglycerin delivery rate and Claim 5’s constant-rate prolonged delivery.
• Competitive risk is highest for patches that copy the silicone gel + silica reservoir plus a separate release-controlling membrane aimed at prophylaxis.
• Design-around is most feasible by changing at least one of the required structural elements (reservoir composition and/or rate-control membrane) or by altering regimen behavior (priming) and release profile (non-constant release).

FAQs

What does Claim 1 require beyond “transdermal nitroglycerin”?

It requires a bandage with a substantially impermeable backing, a reservoir comprising gelled silicone fluid and silicon dioxide plus a prophylactic vasodilator, and a rate controlling membrane that controls release and is in contact with the backing.

Does Claim 3 cover other vasodilators besides nitroglycerin?

No. Claim 3 specifically limits the vasodilator to nitroglycerin with an approximately 20 to 1200 μg/hr delivery range.

Is a priming dose mandatory for infringement of the independent claim?

No. A priming dose is only required in Claim 4, which depends on Claim 1.

How does Claim 5 constrain delivery?

Claim 5 requires administration at a substantially constant rate over a prolonged period of time.

If a competitor uses a similar patch, what single modification most likely reduces exposure?

Changing one of the strict claim recitations in Claim 1, especially the reservoir composition (silicone gel + silica) or the existence/role/positioning of the rate controlling membrane, offers the most reliable reduction versus only minor numeric dosing changes.

References

[1] US Patent 4,812,313 (claim set as provided in user prompt).

Drugs Protected by US Patent 4,812,313

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 4,812,313

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	229476
Austria	395815
Austria	A84882
Australia	545402
Australia	7921282