U.S. Patent 6,103,248: Claim Scope, Expiration, and Head-Lice Treatment Patent Landscape

U.S. Patent No. 6,103,248 protects a topical head-lice preparation and treatment regimen built around a viscous, lipophilic carrier containing a surfactant and a lice-killing agent. The central technical limitation is the carrier’s viscosity, generally 10,000 to 85,000 centipoise at 21°C, combined with washability from scalp hair.

The patent’s 20-year patent term has expired based on its 1998 filing date. The claims therefore remain relevant as prior art and for historical freedom-to-operate analysis, but they should not create current U.S. infringement liability unless an unusual patent-term adjustment, terminal-disclaimer issue, or other continuation patent preserved related rights. The patent is not an FDA exclusivity right and is not an Orange Book-listed drug patent.

What does U.S. Patent 6,103,248 cover?

The patent covers two related subject matter groups:

Composition claims directed to a topical lice preparation.
Method claims directed to applying that preparation to infested scalp hair.

The independent claims are claims 1, 10, and 19.

Claim	Type	Principal subject matter
1	Composition	Lice-killing agent in a lipophilic, surfactant-containing carrier with 10,000-85,000 cP viscosity
10	Method	Applying the preparation to dry hair and leaving it in place for at least about 15 minutes
19	Composition	Same general preparation with a narrower viscosity range beginning at 25,000 cP

Claims 2-9 and 18, 20 narrow the composition claims. Claims 11-17 narrow the treatment regimen.

The patent is therefore not limited to a particular insecticide. Its coverage is defined primarily by the carrier system, viscosity, surfactant characteristics, and use protocol.

What are the independent claims of U.S. Patent 6,103,248?

Claim 1: broad composition claim

Claim 1 requires all of the following:

A topical preparation for application to scalp hair.
A purpose or suitability for treating head lice.
A killing agent effective against head lice.
A lipophilic carrier for that agent.
A surfactant in the carrier.
A surfactant effective to permit washing the preparation from scalp hair.
Carrier viscosity of approximately 10,000-85,000 cP at 21°C.

The claim does not expressly require:

A named active ingredient.
An insecticide rather than a physical killing agent.
A specific carrier such as petrolatum, mineral oil, wax, or silicone.
A specific surfactant.
A particular percentage of active ingredient.
A particular treatment duration.
A second or third treatment.

Claim 1 is consequently the main composition claim and has the broadest viscosity range.

Claim 10: treatment-method claim

Claim 10 requires:

A first application.
Application to dry scalp hair infested with head lice.
Leaving the preparation on the hair for at least about 15 minutes.
The same killing-agent, lipophilic-carrier, surfactant, and viscosity limitations appearing in claim 1.

The method claim adds operational limitations that are absent from claim 1. A product could fall within the composition claim even if marketed with a different application protocol, while infringement of claim 10 would require performance of the claimed treatment steps.

Claim 19: narrower composition claim

Claim 19 is similar to claim 1 but raises the lower viscosity threshold from approximately 10,000 cP to approximately 25,000 cP.

Its range is approximately 25,000-85,000 cP at 21°C. This claim may capture thicker ointments, creams, and gels that fall outside the lower boundary of claim 1 only if they satisfy the other limitations.

How do the dependent claims narrow the patent scope?

Claim	Added limitation
2	Killing agent is an insecticide
3	Carrier alone kills adult head lice
4	Surfactant HLB is approximately 4-12
5	Surfactant includes hydrophilic and lipophilic surfactants
6	Surfactant is nonionic
7	Carrier viscosity is approximately 25,000-65,000 cP
8	Surfactant is approximately 10%-20% by carrier weight
9	Carrier HLB is not greater than approximately 8.5
11	Second application approximately 6-10 days after the first
12	Third application approximately 6-10 days after the second
13	Hair is totally saturated
14	Preparation remains at least about one hour
15	Preparation remains overnight
16	Treated person changes clothes
17	Hair is totally saturated; carrier kills adult lice; killing agent kills eggs
18	Surfactant HLB is approximately 4-12
20	Carrier HLB is not greater than approximately 8.5

The dependent claims create several narrower technical positions:

Physical and chemical killing: claim 3 requires the carrier itself to kill adult lice.
Ovicidal coverage: claim 17 requires the killing agent to kill lice eggs.
Washability: claims 1, 10, and 19 require a surfactant that permits removal from hair.
Rheology: claims 7 and 19 focus on higher-viscosity preparations.
Surfactant chemistry: claims 4-6, 8, 9, and 18 narrow the surfactant system by HLB, type, or concentration.
Regimen design: claims 11-17 cover repeat dosing, saturation, contact time, clothing changes, and overnight use.

What technical features are essential for infringement?

A potentially accused product or regimen would need to be evaluated against each limitation, not merely against its general use for head lice.

Lipophilic carrier

The carrier must be lipophilic. Conventional candidates could include:

Petrolatum and petroleum-derived ointment bases.
Mineral oil systems.
Waxes and wax-containing creams.
Certain silicone or hydrocarbon carriers.
Other oil-dominant vehicles.

A water-based shampoo or aqueous lotion may avoid the lipophilic-carrier limitation, depending on its composition and claim construction.

Viscosity

Viscosity is a critical claim element. The patent specifies measurement at 21°C. A product’s viscosity at a different temperature, under a different shear rate, or using a different test method may not provide a reliable comparison.

The relevant bands are:

Claim 1: about 10,000-85,000 cP.
Claim 7: about 25,000-65,000 cP.
Claim 19: about 25,000-85,000 cP.

The word “about” introduces an interpretive margin, but it does not eliminate the need for a defensible viscosity measurement. Formulation changes, temperature control, shear history, batch variability, and instrument methodology can materially affect the result.

Surfactant

The surfactant must be effective to allow washing the preparation from scalp hair. Claims 4-6 and 18 narrow the scope further through:

HLB of approximately 4-12.
A mixture of hydrophilic and lipophilic surfactants.
A nonionic surfactant.
A concentration of approximately 10%-20% by weight of carrier.

A carrier may be lipophilic without satisfying the claimed washability function. Conversely, a formulation with a surfactant may still avoid a narrower claim if its HLB, surfactant type, or concentration falls outside the claimed range.

Killing agent

Claim 1 uses the functional expression “killing agent effective to kill the head lice.” Claim 2 narrows this to an insecticide. Potential killing agents could include chemical insecticides or agents that kill lice through physical mechanisms, depending on the specification and applicable claim interpretation.

Claim 17 is materially narrower because it requires the killing agent to kill lice eggs and the carrier to kill adult lice independently.

Does the patent require a particular active ingredient?

No. The claims do not identify a single active ingredient. Claim 2 specifies an insecticide, but the independent composition claims are broader than claim 2.

The patent can therefore reach formulations using different active agents if they meet the carrier, surfactant, washability, and viscosity requirements. A formulation that kills lice solely through an occlusive or physical mechanism could be relevant to claims 1, 10, or 19 if it otherwise meets the claimed limitations.

This distinction matters for products based on:

Pyrethrins or pyrethroids.
Malathion.
Spinosad.
Dimethicone or other silicone systems.
Mineral-oil or petrolatum systems.
Botanical or essential-oil ingredients.
Other physical or chemical lice-killing agents.

The active ingredient alone is not the principal claim boundary. The carrier architecture is.

What formulations are most likely to fall within the claims?

A formulation presents the highest technical risk under the expired claims when it has the following profile:

Formulation characteristic	Relevance
Oil- or hydrocarbon-dominant carrier	Supports lipophilic-carrier limitation
Viscosity between 10,000 and 85,000 cP at 21°C	Meets broad viscosity limitation
Nonionic surfactant	Supports claim 6
HLB approximately 4-12	Supports claims 4 and 18
Surfactant level approximately 10%-20%	Supports claim 8
Adult-lice killing by carrier alone	Supports claim 3
Egg-killing agent	Supports claim 17
Application to dry, saturated hair	Supports claims 10 and 13
One-hour or overnight contact time	Supports claims 14 and 15
Repeat treatment after 6-10 days	Supports claims 11 and 12

A conventional aqueous lice shampoo is less likely to satisfy the full combination. A thick, washable, oil-based lice cream or ointment is technically closer to the claim set.

How do the composition and method claims differ?

The composition claims target the product itself. The method claims target its use.

Issue	Composition claims	Method claim 10 and dependents
Product composition	Required	Required
Dry-hair application	Not required	Required
Minimum contact time	Not required	At least about 15 minutes
Repeat applications	Not required	Required only by claims 11 and 12
Hair saturation	Not required	Required by claim 13 and claim 17
Overnight treatment	Not required	Required by claim 15
Clothing change	Not required	Required by claim 16

A product developer could avoid the method claims by using a different regimen, but that would not necessarily avoid the composition claims. Conversely, a method performed with a nonconforming product would not satisfy the method claims.

When did U.S. Patent 6,103,248 lose exclusivity?

The patent’s ordinary term expired approximately 20 years after its U.S. nonprovisional filing date. U.S. Patent No. 6,103,248 issued in 2000, and its filing history places its ordinary expiration in approximately 2018, subject to any patent-term adjustment or disclaimer recorded in the USPTO file.

Event	Approximate timing
U.S. filing	1998
Patent issuance	2000
Ordinary 20-year expiration	Approximately 2018
Current enforceable term	Expired on the ordinary-term analysis

The patent’s expiration is separate from FDA market exclusivity. Expiration ends patent rights; it does not determine whether a product can be marketed under an OTC monograph, NDA, or other FDA pathway.

An expired patent can still affect:

Prior-art analysis.
Validity analysis for later patents.
Obviousness analysis.
Product-development history.
Freedom-to-operate reviews involving continuation or improvement patents.
Licensing and acquisition diligence.

Is U.S. Patent 6,103,248 listed in the Orange Book?

The patent is not expected to have an Orange Book listing.

The FDA Orange Book lists patents and exclusivity associated with approved prescription and certain approved nonprescription drug products submitted through the NDA framework. A patent directed to a general topical head-lice preparation does not automatically qualify for Orange Book listing. Listing depends on the approved drug application, the relationship between the patent and the approved product, and FDA listing requirements under 21 U.S.C. § 355 and 21 C.F.R. Part 314.

The patent therefore does not create an Orange Book-based Paragraph IV pathway by itself.

Are there Paragraph IV challenges to U.S. Patent 6,103,248?

No meaningful Paragraph IV pathway is apparent for this patent.

Paragraph IV certifications apply to patents listed in the FDA Orange Book for a reference listed drug. Because this patent is not an Orange Book patent associated with an approved reference product, a generic applicant would not ordinarily file a Paragraph IV certification directed to it.

Potential challenges would instead arise through:

A patent-infringement action based on an unlisted patent.
A declaratory-judgment action.
A validity challenge in district court.
An inter partes review if the patent were still within the statutory review window.
A freedom-to-operate opinion addressing expired rights or related live patents.

Because the patent has expired, a new Paragraph IV dispute directed to this patent would have no commercial exclusivity purpose.

What is the patent landscape around head-lice treatments?

The relevant landscape has several technical clusters rather than a single blocking patent.

Insecticide formulations

Older head-lice patents commonly address:

Pyrethrin and pyrethroid compositions.
Permethrin lotions and shampoos.
Malathion formulations.
Organophosphate or carbamate agents.
Synergists and resistance-management combinations.

These patents may contain active-ingredient, concentration, dosing, or formulation limitations distinct from the viscosity-centered claims of U.S. 6,103,248.

Physical-killing formulations

A separate group covers nontraditional products that kill lice through physical mechanisms, including:

Dimethicone.
Mineral oil.
Isopropyl myristate.
Occlusive hydrocarbon systems.
Dehydrating compositions.
Combinations that immobilize or suffocate lice.

These products are the closest technical comparators because they may use oil-dominant carriers and rely partly on carrier-mediated killing.

Delivery and washability systems

Other patent families focus on:

Hair saturation.
Improved spreading through dense hair.
Residence time.
Rinsability.
Surfactant combinations.
Reduction of residue or greasiness.
Aerosol, foam, gel, or mousse delivery.

U.S. 6,103,248 is distinguished by its defined viscosity range and surfactant-enabled removal from scalp hair.

Ovicidal and repeat-treatment regimens

Method patents may address:

A first treatment followed by a second application after egg-hatching.
A third application.
Contact times ranging from minutes to overnight.
Treatment of clothing, bedding, combs, and household surfaces.
Simultaneous treatment of adult lice and nits.

Claims 11, 12, and 17 place U.S. 6,103,248 within this regimen-focused segment.

How strong was the patent estate?

The patent had meaningful technical breadth during its term, but its current commercial strength is low because the patent has expired.

Historical strengths

The independent claims did not depend on a single branded active ingredient.
The claims captured both chemical and potentially physical lice-killing systems.
The viscosity range was broad enough to cover many thick topical vehicles.
The method claims added practical treatment instructions.
The carrier, surfactant, and washability limitations could reach formulations that were not conventional shampoos.

Historical weaknesses

The claims required a lipophilic carrier.
The viscosity limitation created a measurable design-around route.
The surfactant had to facilitate washout.
Aqueous or low-viscosity products could avoid the claims.
Narrow dependent claims could be defeated by changing HLB, surfactant type, concentration, or treatment protocol.
Functional language such as “effective to kill” and “effective to allow” could generate proof disputes.
The patent did not claim a specific commercial active ingredient across the independent claims.

Current strength

Factor	Current assessment
Enforceability of 6,103,248	None after expiration
Orange Book leverage	None apparent
Paragraph IV leverage	None apparent
Prior-art value	Potentially significant
Relevance to later formulation patents	High
Need to review continuations	Yes, for complete family clearance
Blocking value for a new product	None from the expired patent itself

Which companies could face competitive overlap?

The relevant commercial competitors are manufacturers of:

Permethrin products.
Pyrethrin and piperonyl-butoxide products.
Malathion products.
Spinosad products.
Benzyl alcohol products.
Ivermectin lotions.
Dimethicone and mineral-oil products.
OTC physical lice treatments.
Prescription and nonprescription lice shampoos, lotions, creams, and gels.

Overlap should be assessed at the formulation level. A company marketing a thick oil-based lice treatment may have technical overlap with the historical claims, but that overlap does not create present infringement liability under an expired patent.

The principal current risk is a later patent covering:

A specific active ingredient.
A specific excipient combination.
A particular viscosity or rheology profile.
A dosing schedule.
An improved delivery vehicle.
A manufacturing process.
A commercial product’s approved formulation.

What patent litigation affects U.S. Patent 6,103,248?

The supplied claim set does not establish a litigation history. The patent’s expiration also reduces the likelihood of current enforcement activity involving the patent itself.

A complete litigation review would normally examine:

USPTO Patent Examination Data System records.
PACER district-court dockets.
PTAB proceedings.
Federal Circuit decisions.
Assignment and maintenance records.
Continuation and divisional applications.
Terminal disclaimers.
Reexamination certificates.
Patent-term-adjustment records.

No current litigation consequence should be attributed to U.S. 6,103,248 without a verified docket or USPTO record.

What geographic coverage does the patent provide?

U.S. Patent 6,103,248 provides rights only in the United States. It does not directly cover:

Canada.
Europe.
Japan.
China.
Australia.
Other jurisdictions.

International protection would require corresponding national or regional applications claiming priority to the same disclosure. Separate foreign patents may have different claims, expiration dates, maintenance status, and litigation histories.

A global product launch therefore requires a family-level review, not reliance on the U.S. patent number.

What manufacturing activities could be relevant?

The issued claims are directed primarily to the formulation and treatment method, not to a manufacturing process. Manufacturing risk would arise if the production process necessarily results in a product satisfying the composition limitations.

Relevant manufacturing controls include:

Carrier composition.
Surfactant identity and concentration.
Mixing sequence.
Temperature during manufacture.
Cooling profile.
Particle or droplet dispersion.
Final viscosity at 21°C.
Batch-release testing.
Product stability over shelf life.

A manufacturer could potentially design around the expired patent by using a non-lipophilic carrier, a viscosity outside the claimed range, or a different washability system. Those changes may affect product performance and could implicate later patents.

What generic launch risks exist?

There is no current generic-launch barrier from U.S. Patent 6,103,248.

A competing product would instead face:

FDA pathway requirements.
Active-ingredient and labeling requirements.
Product-specific patents issued after 1998.
Formulation patents held by current manufacturers.
Method-of-use patents with unexpired terms.
Trade-secret restrictions involving manufacturing.
Trademark and trade-dress issues.
Clinical or performance claims requiring substantiation.

For an OTC product, the key regulatory question is whether the active ingredient and labeling fit an applicable FDA monograph or require an NDA. For a prescription product, the relevant pathway may involve an ANDA, 505(b)(2) application, or other FDA submission depending on the reference product and formulation.

How does U.S. Patent 6,103,248 compare with modern lice-treatment patents?

Attribute	U.S. 6,103,248	Later product-focused patents
Primary focus	Viscous lipophilic carrier and washability	Specific actives, delivery systems, or formulations
Active ingredient	Generally unspecified	Often expressly identified
Physical killing	Captured through carrier limitation and dependent claims	Often claimed directly
Viscosity	Central limitation	May be absent or narrowly defined
Treatment regimen	15-minute minimum, repeat dosing, saturation, overnight use	Often product-specific
Regulatory linkage	No apparent Orange Book role	May be linked to an NDA
Current enforceability	Expired	Depends on individual patent
Design-around options	Change carrier, viscosity, surfactant, or regimen	Often narrower and product-specific

Key Takeaways

U.S. Patent 6,103,248 covers a lice-treatment formulation with a lipophilic carrier, surfactant, and specified viscosity range.
Claims 1 and 19 are composition claims; claim 10 and claims 11-18 are treatment-regimen claims.
The patent does not depend on a single named insecticide.
The most important limitations are lipophilicity, washability, viscosity, surfactant characteristics, and treatment protocol.
The ordinary U.S. patent term expired approximately in 2018.
The patent is not an FDA exclusivity right and is not expected to provide Orange Book or Paragraph IV leverage.
Current commercial risk lies in later patents covering specific lice-treatment products, active ingredients, formulations, delivery systems, or methods.
The patent remains relevant as historical prior art and as a technical reference for formulation design.
A complete freedom-to-operate review must examine continuations, foreign counterparts, later improvement patents, assignments, and litigation records.

FAQs

Can a dimethicone lice product infringe U.S. Patent 6,103,248?

It could have fallen within the claim language if it used a lipophilic carrier, the claimed viscosity range, a washability-promoting surfactant, and a qualifying lice-killing agent. The expired status of the patent eliminates current infringement exposure under this patent.

Does the patent cover nit combing?

No. The claims address topical preparations and application regimens. They do not expressly claim mechanical removal with a nit comb.

Does claim 17 require the carrier and killing agent to perform different functions?

Yes. Claim 17 requires the carrier by itself to kill adult lice and the killing agent to kill lice eggs. A formulation that relies on one agent for both functions may face a claim-construction issue unless the carrier independently satisfies the adult-lice limitation.

Can a formulation avoid the patent by using a viscosity below 10,000 centipoise?

A product with viscosity materially below the claimed lower boundary would not satisfy the viscosity limitation of claims 1, 10, or 19. The product would still require review against other live patents.

Does FDA approval extend the patent term?

No. FDA approval and patent term are separate legal regimes. Regulatory exclusivity may restrict certain FDA submissions, but it does not extend an expired patent.

References

United States Patent and Trademark Office. (2000). U.S. Patent No. 6,103,248, Topical preparation for treating head lice. U.S. Department of Commerce.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
U.S. Food and Drug Administration. (2024). 21 C.F.R. Part 314: Applications for FDA approval to market a new drug. U.S. Department of Health and Human Services.
United States Code. (2024). 35 U.S.C. § 154: Contents and term of patent; provisional rights. U.S. Code.
United States Code. (2024). 21 U.S.C. § 355: New drugs. U.S. Code.

Summary for Patent: 6,103,248