Details for Patent: 5,411,738

Summary for Patent: 5,411,738

Title:	Method for treating nerve injury pain associated with shingles (herpes-zoster and post-herpetic neuralgia) by topical application of lidocaine
Abstract:	Methods and compositions are offered for reducing nerve injury pain associated with shingles (herpes-zoster and post-herpetic neuralgia), where intradermal delivery of lidocaine is maintained for a predetermined period of time. The lidocaine appears to specifically affect the damaged nerve fibers, while leaving the undamaged and normal nerve fibers with retention of response to other stimuli. Lidocaine formulations are provided which allow for the necessary dosage of the lidocaine in the dermis during the period of treatment. The formulation may be covered with an occlusive or non-occlusive dressing, which protects the lidocaine formulation from mechanical removal and enhances the transport of the lidocaine into the dermis. Long term relief is realized after maintenance of the administration of lidocaine has been terminated.
Inventor(s):	Harry Hind
Assignee:	Hind Health Care Inc
Application Number:	US08/198,223
Patent Claim Types: see list of patent claims	Use; Composition; Formulation; Delivery;

United States Patent 5,411,738: Scope, Claims, and Patent Landscape

What does US 5,411,738 claim cover?

US 5,411,738 claims a method and formulations for providing prolonged analgesia for herpes zoster or post-herpetic neuralgia (PHN) using lidocaine delivered intradermally/through the dermal layer. The patent is built around three claim pillars:

1. Therapeutic use: relief of pain specifically tied to herpes zoster or PHN.
2. Delivery and duration: intradermal or transdermal delivery with extended analgesic effect and explicit time limits.
3. Formulation composition: gel or patch with defined lidocaine concentration, vehicle composition, optional occlusive dressing, and specific excipient classes (polyols, surfactants, gelling agents).

The claims provided map to four functional scopes: (i) method of analgesia for extended time, (ii) gel/patch delivery format with duration boundaries, (iii) formulation constraints for vehicles and components, and (iv) specific compositional preferences (propylene glycol; free base; sorbitan ester surfactant; neutralized polyacrylic acid).

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What are the independent vs dependent claim structures?

Based on the claim text supplied, the claim set functions as follows:

• Claim 1 is the first method anchor.
• Claims 2 to 4 narrow Claim 1 by specifying gel/patch concentration, occlusive dressing options, and lidocaine form.
• Claim 5 is a second method anchor that is more explicit about transdermal delivery and a ≥8 hour maintenance window and effect window.
• Claims 6 to 8 narrow Claim 5 by duration ceiling and vehicle composition (polyol range; propylene glycol).
• Claim 9 is a formulation claim with defined ranges and component limitations.
• Claim 10 narrows Claim 9 by specifying lidocaine 5–10% and a specific gelling agent.

This structure creates a landscape where multiple entry points exist for infringement analysis: end products can be challenged on method, product format (gel/patch), and compositional matches.

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Claim-by-claim claim scope (with practical infringement levers)

Claim 1 (method; intradermal maintenance; extended analgesia)

Scope
A method for pain relief in a host with herpes zoster or PHN by:

• inducing analgesia for an extended period
• maintaining lidocaine intradermally at a concentration sufficient to induce analgesia at the pain site
• pain is relieved by lidocaine

Key scope levers

• Indication lock: herpes zoster or PHN.
• Delivery location: intradermal (not merely systemic).
• Concentration is functional in Claim 1 (not quantified here), setting up dependent claims to supply numeric boundaries.

Design-around risk

• A competitor that achieves intradermal delivery but uses substantially different time profiles or lidocaine formats could still be pulled in under “extended period” if the analgesia is sustained as the claim requires.

Claim 2 (gel/patch with 1–20 wt% lidocaine; vehicle for intradermal delivery)

Scope

• Maintaining comprises applying a gel or patch
• Gel/patch contains about 1 to 20 wt% lidocaine
• Vehicle provides intradermal delivery

Key scope levers

• Numeric lidocaine range.
• “Vehicle providing for intradermal delivery” is the key technology hook.

Claim 3 (occlusive dressing; porous or non-porous)

Scope

• The gel/patch includes an occlusive dressing
• Dressing is porous or non-porous

Key scope levers

• This claim covers both breathable and fully occlusive structures.
• It is not a design-around-friendly limitation; it expands coverage.

Claim 4 (lidocaine free base partial amount)

Scope

• Lidocaine is present in partial amount as the free base

Key scope levers

• Targets formulation chemistry (salt vs free base).
• “Partial amount” is a lower bar than “substantially all,” reducing the effectiveness of salt-based substitutions unless the competitor can remove free base entirely.

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Claim 5 (method; transdermal delivery; ≥8 hours; no anesthesia; effect ≥8 hours)

Scope A method for pain relief in herpes zoster or PHN by:

• applying to skin surface at pain site a gel or patch comprising about 1 to 20 wt% lidocaine
• vehicle is for transdermal delivery to dermal layer
• maintain gel/patch for at least 8 hours
• induces analgesia “but not anesthesia”
• pain is relieved for at least about 8 hours by lidocaine

Key scope levers

• Transdermal to dermal layer: distinguishes it from purely intradermal manufacturing claims.
• Maintenance time: ≥8 hours.
• Pharmacology boundary: “analgesia, but not anesthesia.”
• Outcome duration: pain relief for at least ~8 hours.

Design-around risk

• Products intended for “numbing” (anesthesia/complete sensory block) move toward the boundary.
• Products with shorter wear time but similar initial analgesia fall outside the explicit ≥8 hour maintenance/effect.

Claim 6 (duration ceiling: >8 hours and ≤~24 hours)

Scope

• Gel/patch maintained greater than 8 hours and not more than about 24 hours

Key scope levers

• If a competitor uses a wear period outside that range, Claim 6 may not read cleanly, but other claims (especially Claim 5) can still capture the core concept depending on interpretation of “at least 8 hours.”

Claim 7 (vehicle polyol: 70–90 wt%)

Scope

• vehicle comprises about 70 to 90 wt% of a polyol vehicle

Key scope levers

• Vehicle composition requirement.
• This claim narrows by solvent system.

Claim 8 (polyol: propylene glycol)

Scope

• polyol is propylene glycol

Key scope levers

• Strong formulation specificity.

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Claim 9 (formulation: gel for herpes zoster/PHN pain)

Scope A gel formulation comprising:

• 70–90 wt% propylene glycol
• 1–20 wt% lidocaine
• 2–20 wt% non-ionic surfactant comprising physiologically acceptable sorbitan esters
• 0.1–5 wt% physiologically acceptable gelling agent
• not more than about 10 wt% physiologically acceptable excipients (total)

Key scope levers

• Component classes and ranges are tightly defined.
• Strong constraint on “not more than 10 wt% total excipients” limits formulation freedom.

Claim 10 (lidocaine 5–10%; gelling agent: neutralized polyacrylic acid)

Scope

• lidocaine: about 5 to 10%
• gelling agent: neutralized polyacrylic acid

Key scope levers

• Pulls the formulation into a specific gel matrix chemistry.

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What is the practical “center of gravity” for enforcement?

Across the claims, enforcement focus concentrates on products that match all of the following:

1. Indication: used for herpes zoster or PHN pain.
2. Drug: lidocaine.
3. Dose range: about 1–20 wt% (with tighter 5–10% in Claim 10 for some gel embodiments).
4. Delivery: vehicle capable of intradermal delivery (Claims 1–3) and/or transdermal delivery to the dermal layer (Claim 5).
5. Duration: maintenance of at least 8 hours and analgesic effect of at least about 8 hours; Claim 6 further constrains to >8 hours and ≤ about 24 hours.
6. Vehicle/excipient profile: high propylene glycol fraction and specific surfactant and gelling agent packages (Claims 7–10).

A competitor that matches the drug dose and delivery but uses a fundamentally different solvent system or gel rheology can fall outside claims 7–10, but can still face risk under method claims 1–6 depending on wear time and delivery location.

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How does the patent allocate claim scope across products (gel vs patch)?

• Claims 1–4 and 2–4 explicitly cover gel or patch for intradermal maintenance.
• Claim 5 also covers gel or patch for transdermal delivery, but makes duration and effect explicit.
• Claim 9–10 focus on gel formulation only (not patch).

So product format matters:

• Patches are most directly implicated by method claims (Claims 1–6).
• Gels are implicated by both method claims and the dedicated formulation claims (Claims 9–10), which are narrower and can be used as higher-confidence infringement targets if formulation specs are known.

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What does “analgesia but not anesthesia” practically do to scope?

The language is a pharmacodynamic boundary. In a litigation or challenge context, it supports an argument that the claimed invention targets pain relief without driving toward a sensory-blocking outcome.

From a scope perspective:

• It narrows embodiments that produce frank dermal anesthesia rather than analgesia.
• It does not define a numerical threshold, so infringement disputes would likely hinge on clinical or instrumental outcomes rather than composition alone.

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Patent landscape: what other patent families typically overlap?

The provided record does not include citation lists, assignee history, prosecution events, or related patent numbers. With only the claims text, the landscape can only be mapped at the level of technical claim themes that commonly recur around lidocaine for PHN/zoster and prolonged-contact dermal delivery.

Below is a theme map of what 5,411,738 sits among, and what competitors typically litigate or design around in this space.

1) Lidocaine for PHN is a known therapeutic use category

US 5,411,738 locks the method to herpes zoster and PHN pain. In that neighborhood, patents often cover:

• indication-specific topical lidocaine dosing regimens
• wear-time prolongation strategies
• delivery technology (adhesive patches, gels, occlusive systems)

Overlap risk
Other lidocaine topical formulations for PHN that maintain ≥8 hours with similar concentrations can collide under method claims.

2) Delivery and wear-time are the main technical battleground

The patent’s strongest differentiators are:

• maintenance time ≥8 hours
• analgesia lasting ≥8 hours
• delivery to dermal/intradermal layers via specific vehicles

Competitors typically counter with:

• shorter wear time
• different delivery kinetics
• different target layers (e.g., focusing on stratum corneum rather than dermal layer)

3) Vehicle composition and gel matrix constraints

Claims 7–10 narrow formulation to:

• propylene glycol 70–90 wt%
• non-ionic surfactant sorbitan esters 2–20 wt%
• neutralized polyacrylic acid at 0.1–5 wt%

In the landscape, many alternative topical systems use:

• different polyols or solvent blends
• different surfactant families
• different polymer gel matrices

These swaps can reduce or remove infringement under formulation claims, but method claims still remain a risk if the delivery and wear-time are matched.

4) Salt vs free base chemistry

Claim 4 requires partial presence of lidocaine free base. In many lidocaine topical patents, lidocaine is formulated as a salt (commonly lidocaine hydrochloride) to improve solubility. This claim targets those alternatives.

Competitors design around by:

• excluding free base entirely
• using lidocaine in a salt form only
• reformulating to remove free base residuals

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What does the claim set imply for freedom-to-operate screening?

Using the claims as a checklist, an FTO screen for a topical lidocaine product targeting PHN would need to verify:

• Concentration: 1–20 wt% in the applied gel/patch.
• Wear time: at least 8 hours, and whether a product is positioned to last >8 but ≤24 hours.
• Intended effect: analgesia rather than anesthesia.
• Delivery: whether the formulation is engineered to achieve dermal/intradermal drug levels rather than only surface/local effects.
• Vehicle: whether the solvent system is predominantly polyol, specifically propylene glycol at 70–90 wt%.
• Surfactant package: sorbitan esters at 2–20 wt%.
• Gel matrix: neutralized polyacrylic acid at 0.1–5 wt% (if gel is targeted).
• Lidocaine form: whether any portion is the free base (not only lidocaine salt).

If any one of the narrow formulation parameters is missing, formulation claims 9–10 may not read. But method claims 1–6 can still attach if the product delivers prolonged dermal/intradermal analgesia in the same wear-time window.

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Where are the strongest claim “hooks” for infringement arguments?

1. Wear-time + effect duration (Claims 5–6): explicit ≥8 hour maintenance and ≥8 hour pain relief.
2. Delivery target (Claims 1 and 5): intradermal maintenance vs transdermal delivery to dermal layer.
3. Composition pack for gel (Claims 9–10): propylene glycol + sorbitan ester surfactant + neutralized polyacrylic acid.
4. Free base requirement (Claim 4): “partial amount as the free base.”

These hooks reduce reliance on broad expert interpretation of “extended period” (though that still exists in Claim 1) by anchoring scope to concrete ranges and time outcomes.

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Key Takeaways

• US 5,411,738 is centered on topical lidocaine for herpes zoster and post-herpetic neuralgia, with prolonged analgesia driven by gel/patch wear of at least 8 hours and sustained pain relief.
• The core enforcement pathway runs through method claims (intradermal maintenance; transdermal delivery to dermal layer; wear-time and analgesia duration) and can extend into narrow formulation claims for gels (propylene glycol 70–90 wt%, sorbitan ester surfactants 2–20 wt%, neutralized polyacrylic acid gel matrix).
• The claim set contains multiple “selective narrowing” features that support both broad and precise infringement theories: lidocaine 1–20 wt%, optional occlusive dressing, free base presence, and in gel embodiments, a tightly bounded polymer/surfactant/solvent package.

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FAQs

1) Does US 5,411,738 cover both gels and patches?

Yes. The method claims (Claims 1–6) cover gel or patch. The dedicated formulation claims (Claims 9–10) are gel formulations.

2) What lidocaine concentration range is claimed?

Claims 2 and 5 state about 1 to 20 wt% lidocaine in the gel or patch. Claims 9 and 10 align with that range and narrow further in Claim 10 to about 5 to 10%.

3) Is the required treatment duration exactly 8 hours?

Claim 5 requires maintaining the gel/patch for at least 8 hours and provides pain relief for at least about 8 hours. Claim 6 further constrains embodiments to greater than 8 hours and not more than about 24 hours.

4) What delivery layer is required for the main method claims?

Claim 1 focuses on intradermal maintenance. Claim 5 specifies transdermal delivery to the dermal layer.

5) Which claims are most formulation-specific?

Claims 9 and 10. They specify solvent level (propylene glycol 70–90 wt%), lidocaine range, surfactant class (sorbitan esters), gelling agent type (neutralized polyacrylic acid), and an excipient cap.

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References

1. United States Patent 5,411,738, “Methods and gel formulations for relief of pain associated with herpes zoster and post-herpetic neuralgia using lidocaine,” claims text as provided in the prompt.

Drugs Protected by US Patent 5,411,738

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 5,411,738

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	161735
Canada	1338779
Germany	69031879
Denmark	0388306