United States Drug Patent 6,090,395: Claim Scope, Expiration, and Patent Landscape

United States Patent 6,090,395 is a formulation and manufacturing patent covering highly viscous hydroalcoholic compositions, including antimicrobial lotions and hand-sanitizer-type products. Its core inventive concept is the use of long-chain emulsifiers or fatty alcohol-based thickener systems to produce stable, high-viscosity alcohol-and-water compositions without relying on conventional auxiliary polymeric thickeners. The patent issued July 18, 2000, and its enforceable term has expired, subject to any applicable patent-term adjustment or terminal disclaimer. The claims therefore have historical and freedom-to-operate relevance, but do not presently create an ordinary blocking patent risk in the United States.

What does United States Patent 6,090,395 cover?

The patent covers compositions, lotions, and manufacturing methods that combine:

A major amount of a lower alcohol and, in many claims, water.
A thickener system comprising one or more emulsifiers.
Long hydrophobic groups, generally alkyl, alkenyl, aralkyl, or aralkenyl groups.
Hydrophilic groups based on ethylene oxide, propylene oxide, alcohols, polyhydric alcohols, sorbitan derivatives, or related structures.
High viscosity at 23° C.
A defined melt temperature.
In several claims, antimicrobial agents such as chlorhexidine salts, iodine, triclosan, or parachlorometaxylenol.

The claims are directed primarily to product architecture and processing conditions rather than to a single active pharmaceutical ingredient. Chlorhexidine digluconate is one specifically claimed embodiment, but the patent is not limited to chlorhexidine products.

The patent’s commercial focus is a stable, spreadable, alcohol-containing lotion or gel that remains sufficiently viscous at room temperature. Conventional hydroalcoholic systems are difficult to thicken because alcohol can disrupt polymer hydration, reduce viscosity, and destabilize emulsions. The claimed solution uses wax-like or liquid emulsifiers with long hydrocarbon chains and suitable hydrophilic groups.

What are the independent claims in US 6,090,395?

The principal independent claims are claims 1, 42, 53, 58, 62, 63, 65, 69, 73, 74, and 83 through 86.

Claim group	Claim type	Principal subject matter
1	Composition	Lower alcohol/water solvent and emulsifier-based thickener system
42	Hydroalcoholic composition	Broader hydrophobe and HLB ranges than claim 1
53	Lotion	At least two emulsifiers and antimicrobial agent
58	Lotion	Long-chain emulsifier and chlorhexidine salt
62	Hydroalcoholic lotion	Solid emulsifier, melt temperature, and long-term viscosity
63	Hydroalcoholic lotion	Hydrocarbon-chain emulsifiers and viscosity/melt requirements
65	Method	Heating, melting, combining, and cooling process
69	Method	Separate heating of thickener system and water, followed by alcohol addition
73	Method	Preparation of antimicrobial lotion with at least two emulsifiers
74	Method	Preparation of chlorhexidine-containing lotion
83	Lotion	At least 24-carbon hydrophobe and viscosity/melt limitations
84	Hydroalcoholic lotion	At least 16-carbon hydrophobe, HLB range, and viscosity
85	Hydroalcoholic composition	Broader alcohol/water ratio and at least 20,000 cP viscosity
86	Method	Process claim corresponding to claim 85

Claims 2 through 41, 43 through 52, 54 through 61, 64, 66 through 72, and 75 through 82 are dependent claims or product-by-process claims.

How broad is the scope of claim 1?

Claim 1 is broad in ingredient selection but narrow in physical-performance requirements.

A product must include all of the following:

A major amount of a solvent comprising a lower alcohol and water.
An alcohol-to-water weight ratio of approximately 60:40 to 100:0.
A thickener system at approximately 0.5% to 8% by weight.
At least one emulsifier at a minimum of approximately 0.05% by weight.
A hydrophobic group containing at least 24 carbon atoms.
A qualifying hydrophilic group.
A melt temperature above approximately 25° C.
A viscosity of at least approximately 4,000 cP at 23° C.
Measurement using a very low shear viscometer with T spindles and a heliopath adapter.

The use of “comprising” makes the claim open-ended. A product can contain additional active ingredients, emollients, preservatives, salts, silicones, polymeric thickeners, stabilizers, or therapeutic agents and still fall within the claim if every required limitation is present.

The claim does not require an antimicrobial agent. Claims 10 through 13 add antimicrobial limitations, with claim 13 specifically requiring chlorhexidine digluconate.

What limits claim 1 in practice?

The most significant limitations are:

The minimum hydrophobe length of 24 carbon atoms.
The viscosity threshold.
The melt-temperature requirement.
The specified measurement methodology.
The absence of an auxiliary thickener for the performance test.

A formulation containing a C16 or C18 emulsifier may avoid claim 1 but could fall within claim 42, claim 53, claim 58, claim 84, or another independent claim using lower hydrophobe thresholds.

The claim is therefore best understood as a family of overlapping formulation definitions rather than a single uniform scope.

How do claims 42 through 64 expand the patent estate?

Claims 42 through 64 create alternative claim pathways that reduce reliance on the 24-carbon limitation in claim 1.

Claim 42

Claim 42 covers hydroalcoholic compositions with:

Alcohol/water ratio of approximately 60:40 to 75:25.
Hydrophobes of at least 16 carbon atoms for alkyl or alkenyl groups.
Aralkyl or aralkenyl groups of at least 20 carbon atoms.
Weight-average HLB of approximately 4 to 16.
Melt temperature above approximately 35° C.
Viscosity of at least approximately 4,000 cP.

This is materially broader than claim 1 with respect to hydrophobe length, but it imposes a narrower solvent ratio and higher melt-temperature requirement.

Claim 53

Claim 53 is directed to lotions containing at least two emulsifiers. It requires:

Each emulsifier at least approximately 0.05% by weight.
At least one emulsifier with a qualifying polyalkoxylated or polyhydric-alcohol hydrophilic group.
At least one other emulsifier with an alcoholic or polyhydroalcoholic hydrophilic group.
An antimicrobial agent.
HLB of approximately 4 to 16.
Melt temperature above approximately 35° C.
Viscosity of at least approximately 4,000 cP.

This claim targets mixed-emulsifier systems, particularly combinations of polyethoxylated alcohols with fatty alcohols or related waxy materials.

Claim 58

Claim 58 is narrower in its active-ingredient requirement because it requires a chlorhexidine salt. It covers compositions with:

A lower alcohol and water ratio of approximately 60:40 to 100:0.
Hydrophobes of at least 20 carbon atoms.
HLB of approximately 4 to 16.
Chlorhexidine salt.
Melt temperature above approximately 25° C.
Viscosity of at least approximately 4,000 cP.

A chlorhexidine formulation cannot be assessed only against claim 1. Claim 58 and dependent claims 59 through 61 provide a separate route to infringement.

Claims 62 and 63

Claims 62 and 63 focus on performance and stability:

Claim 62 requires a solid-at-room-temperature emulsifier and viscosity of at least 45,000 cP after 19 days at 23° C.
Claim 63 requires viscosity of at least 20,000 cP and a melt temperature above 35° C.
Claim 64 increases the melt-temperature requirement to above 40° C.

These claims are more difficult to satisfy than the 4,000 cP claims but may capture robust, wax-structured lotions that maintain viscosity over time.

What formulations are protected by the dependent claims?

The dependent claims cover a wide formulation platform.

Claim area	Examples of added or specified features
Stability	Less than approximately 10% separation after centrifugation
HLB	Weight-average HLB of approximately 8 to 12 or 4 to 16
Emollients	Waxes, liquids, dialkoxy dimethicones, polyether/polysiloxane copolymers
Antimicrobials	Chlorhexidine, iodine, triclosan, PCMX, hydrogen peroxide, silver compounds
Alcohol	Ethanol, isopropanol, n-propanol, or mixtures
Salts	Optional salt component
Stabilizers	Alkyl-pendant polymers and borate ion
Silicone	Polydimethylsiloxane and derivatives
Auxiliary thickeners	Polymeric thickening agents are permitted in several claims
Emulsifier systems	Polyethoxylated alcohols, fatty alcohols, sorbitan esters, polyglycerol esters
Structured systems	Mixed wax/liquid ratios from approximately 1:5 to 5:1
Processing	Melting, high-shear mixing, controlled cooling, and staged alcohol addition

Claims 28 through 37 are composition-specific alternatives. They identify combinations such as:

Polyethoxylated alcohol plus alkyl alcohol.
Polyethoxylated alkyl alcohol.
Alkyl alcohol plus polyethoxylated alkyl alcohol with a chain of at least 20 carbon atoms.
Polyhydric alcohol ester plus polyethoxylated alcohol.
Sorbitan alkyl ester plus polyethoxylated alcohol.
Polyglycerol ester, polyethoxylated alcohol, and alkyl alcohol.
All-alcohol systems with a dimethicone copolyol alkyl phosphate.

These claims are narrower and may be more useful in an infringement analysis when the accused product’s ingredient list is known.

What are the method-of-manufacturing claims?

Claims 65 through 74 protect process sequences for making the compositions.

Claim 65

Claim 65 requires:

Preparing a thickener system with a qualifying long-chain emulsifier.
Combining it with a major amount of lower alcohol and water.
Heating to a temperature sufficient to melt the thickener system.
Producing a composition with a melt temperature above approximately 25° C.
Producing viscosity of at least approximately 4,000 cP.

Claim 69

Claim 69 is more process-specific. It requires:

Heating the thickener system to melt it.
Heating water above the thickener-system melt temperature.
Combining the thickener system and water.
Adding lower alcohol to the mixture.
Maintaining an alcohol/water ratio of approximately 60:40 to 75:25.
Achieving a melt temperature above approximately 35° C.
Achieving viscosity of at least approximately 4,000 cP.

Claims 70 and 71 add cooling before alcohol addition and polyethylene glycol, polypropylene glycol, or copolymer groups. Claim 68 adds high-shear mixing above the melt temperature.

Why the process claims matter

A formulation can avoid a composition claim yet still raise process-claim issues if it is manufactured using the claimed heating and staged-addition sequence. Process claims are particularly relevant to contract manufacturers because manufacturing records, batch instructions, and process validation documents can establish the required steps.

Claims 75 through 78 are product-by-process claims. Their enforceability depends on the legal treatment of process limitations and whether the resulting composition is distinguishable by its claimed production history. They generally offer less predictable enforcement value than direct composition claims.

When did US 6,090,395 lose exclusivity?

US 6,090,395 has expired based on the ordinary 20-year patent-term rule applicable to post-June 8, 1995 applications. The patent issued in 2000, so its term would ordinarily have ended approximately 20 years after the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, and any relevant priority facts. The patent is no longer an enforceable U.S. blocking right in 2025. [35 U.S.C. § 154; USPTO, n.d.-a]

The patent’s expiration does not eliminate its value as:

Prior art against later applications.
Evidence of industry disclosure.
A source of formulation and process information.
A reference for claim construction in related patent families.
A historical indicator of the assignee’s technology strategy.

What is the Orange Book status of US 6,090,395?

US 6,090,395 is not an Orange Book patent in the conventional Hatch-Waxman sense.

The claims cover topical compositions and formulation processes rather than an FDA-approved prescription drug product identified by an NDA. The patent does not claim a new molecular entity, salt, polymorph, or approved dosage form in the manner typically associated with Orange Book listings. No Paragraph IV analysis follows from the patent merely because chlorhexidine or another antimicrobial is included in certain claims.

The relevant regulatory framework is generally the FDA’s over-the-counter healthcare antiseptic framework, product-specific OTC pathways, or an NDA where a sponsor has pursued prescription approval. Alcohol hand sanitizers and topical antiseptic products may be regulated under FDA monograph rules or other FDA enforcement policies depending on the active ingredient, indication, concentration, labeling, and formulation. [FDA, 2019; FDA, 2023]

Were there Paragraph IV challenges or generic litigation?

Paragraph IV litigation is not the principal risk category for this patent. The patent is a formulation patent covering topical or OTC compositions, not an Orange Book-listed drug patent tied to a conventional ANDA product.

No litigation conclusion should be drawn solely from the claim text. A complete litigation history requires review of PACER, USPTO assignment records, district-court dockets, Federal Circuit decisions, and any continuation or foreign-family records. On the supplied record, there is no identified Paragraph IV action, settlement agreement, or judicial validity decision.

Because the patent has expired, any historical litigation would have no continuing exclusionary effect unless it produced a binding contractual or licensing obligation independent of the patent term.

Which companies challenged or licensed the patent?

The supplied information identifies no challenger, licensee, sublicensee, or settlement party. The claims themselves do not disclose licensing arrangements.

The principal commercial interest appears to have been associated with 3M and its topical antimicrobial, hand-hygiene, wound-care, and skin-protection product platforms. The patent’s claim language is consistent with technology used in high-viscosity alcohol-containing lotions and antimicrobial skin preparations. That association does not establish that every 3M product practiced the claims or that a third party licensed the patent.

How strong was the patent estate?

The patent had meaningful breadth but several technical vulnerabilities.

Strengths

Multiple independent composition and method claims.
Broad “comprising” language.
Coverage of several emulsifier classes.
Alternative hydrophobe thresholds from 16 to 24 carbon atoms.
Coverage of both antimicrobial and non-antimicrobial compositions.
Functional viscosity and melt-temperature limitations tied to a defined test method.
Claims directed to both final products and manufacturing sequences.

Vulnerabilities

Many limitations depend on test results rather than structural identity.
“Major amount,” “stable,” “capable of forming,” and related terms can require construction.
HLB values may vary by supplier, analytical method, and commercial grade.
The very low shear heliopath method may create reproducibility and claim-construction issues.
The genus of covered emulsifiers is broad relative to the narrow performance window.
Conventional fatty alcohol, wax, sorbitan ester, and polyethoxylated-alcohol technology may provide substantial prior-art pressure.
Claims requiring particular viscosity or melt temperature can be avoided through formulation tuning.
The patent’s expiration removes present enforcement leverage.

The strongest historical claims were likely the narrower claims that combined a specific antimicrobial, defined emulsifier system, and measurable viscosity or melt requirement. The broadest claims were more exposed to prior-art and enablement arguments.

How does this patent compare with competing thickening technologies?

Technology	Compatibility with hydroalcoholic systems	Typical patent issue	Relationship to US 6,090,395
Carbomer and crosslinked acrylates	Often reduced by high alcohol content; may require neutralization	Polymer identity, neutralization, rheology	Potential design-around or separate patent estate
Cellulose derivatives	Variable alcohol tolerance and clarity	Polymer substitution and concentration	Generally outside the emulsifier-centered core
Fumed silica	Can provide alcohol-compatible thickening but may feel tacky or dry	Particle treatment and dispersion	Usually structurally distinct
Polymeric associative thickeners	Can provide high viscosity at lower loading	Polymer architecture and solvent compatibility	May avoid fatty-emulsifier limitations
Fatty alcohol/emulsifier systems	Strong fit with the claimed architecture	Chain length, HLB, ratios, processing	Directly within the patent’s core
Waxes and structured lipids	Can raise melt temperature and viscosity	Wax identity, crystalline structure	Potentially within claims 62, 63, 83, and 84
Silicone-based rheology modifiers	May improve spreadability and sensory profile	Silicone structure and copolymer chemistry	Often relevant to dependent claim 9 or claim 22

The patent’s technical distinction is the achievement of high room-temperature viscosity through a melted, crystallizable emulsifier network rather than through a conventional water-swollen polymer alone.

What generic launch risks existed?

During the patent term, a competing manufacturer faced several potential design-around routes:

Use an alcohol/water ratio outside the claimed range.
Use hydrophobes below the applicable carbon-chain threshold.
Use a polymeric thickener without a qualifying long-chain emulsifier.
Keep viscosity below the claimed threshold.
Use a formulation with a melt temperature below the claim requirement.
Use an alternative antimicrobial or omit the antimicrobial where the claim requires one.
Employ a different manufacturing sequence.
Use an emulsifier with a hydrophilic group outside the claimed categories.

These routes could create performance tradeoffs. Lowering chain length or changing HLB may reduce viscosity, alter sensory properties, increase phase separation, or impair product stability.

The current generic-entry risk is effectively zero from this patent because the patent term has expired. Competitors remain exposed to later patents covering specific formulations, dispensing systems, active ingredients, packaging, manufacturing controls, or branded product features.

What geographic coverage did the patent provide?

US 6,090,395 provided protection only in the United States. Any foreign protection would have required separate national or regional applications. U.S. claims could not block manufacture, sale, or use solely outside the United States, although U.S. importation and commercial distribution could create infringement issues during the patent term under 35 U.S.C. § 271. [35 U.S.C. § 271]

The practical geographic landscape therefore depended on related filings in jurisdictions such as Europe, Canada, Japan, and Australia. Expiration of the U.S. patent does not establish expiration of any foreign counterpart.

What manufacturing and intellectual-property barriers remain?

Patent expiry does not remove all barriers to commercial entry. Relevant barriers may include:

Process validation for heating and cooling fatty emulsifier systems.
Control of crystallization and batch-to-batch viscosity.
Compatibility with chlorhexidine, iodine, triclosan, or other actives.
Flammability controls for ethanol and isopropanol.
Preservative efficacy and antimicrobial performance.
Stability testing over the product shelf life.
Packaging compatibility and dispensing performance.
FDA labeling and active-ingredient requirements.
Trade secrets relating to mixing order, shear rate, cooling profile, and raw-material specifications.

The process disclosed in claims 69 and 86 indicates that order of addition and temperature control may materially affect the final rheology. These process variables can remain commercially important even after patent expiration.

What is the commercial exposure associated with this patent?

The patent could historically have affected products in several categories:

Alcohol-based hand sanitizing lotions.
Surgical or healthcare antiseptic preparations.
Chlorhexidine skin-preparation lotions.
Wound-care and first-aid compositions.
Emollient-containing antimicrobial gels.
High-viscosity ethanol or isopropanol lotions.
Topical therapeutic or cosmetic hydroalcoholic products.

The patent itself does not provide revenue figures, product sales, market share, or royalty data. It therefore cannot support a reliable estimate of revenue exposure or licensing value. Its commercial relevance must be assessed through identified products, historical sales, and evidence that those products practiced one or more claims.

Key Takeaways

US 6,090,395 is a formulation and manufacturing patent for high-viscosity hydroalcoholic compositions.
Its central technology uses long-chain emulsifiers, fatty alcohols, polyethoxylated materials, sorbitan derivatives, and related thickener systems.
The independent claims cover compositions, lotions, and manufacturing methods.
Important claim limitations include alcohol/water ratio, hydrophobe chain length, HLB, melt temperature, viscosity, and specified rheology testing.
Chlorhexidine-containing products are addressed through claims 13, 58, 74, and related dependent claims.
The patent is not an ordinary Orange Book patent and does not create a conventional Paragraph IV pathway.
The U.S. patent term has expired under the ordinary post-1995 20-year framework.
No challenger, licensee, settlement, or litigation party is identified in the supplied record.
Current U.S. generic-entry risk from this patent is effectively eliminated by expiration.
Later patents covering specific actives, formulations, packages, manufacturing processes, or dispensing systems remain relevant.

FAQs

Does US 6,090,395 cover ordinary alcohol hand sanitizer gel?

Not necessarily. A conventional carbomer-thickened alcohol gel may avoid the patent’s emulsifier, hydrophobe, melt-temperature, or viscosity limitations. A product-by-product formulation and rheology analysis is required.

Does a formulation containing chlorhexidine automatically infringe this patent?

No. Chlorhexidine alone is insufficient. The formulation must also satisfy the applicable independent claim, including the solvent ratio, qualifying emulsifier, hydrophobe, HLB, viscosity, and melt-temperature requirements.

Can a competitor use the same emulsifiers after the patent expired?

Yes, in the United States, subject to other unexpired patents, regulatory requirements, trade secrets, trademarks, and contractual restrictions.

Are claims 65 through 74 relevant to contract manufacturers?

Yes. Those claims target heating, melting, water combination, alcohol addition, cooling, and high-shear processing steps. They were relevant during the patent term if a manufacturer performed every required step.

Does expiration of the U.S. patent eliminate foreign patent risk?

No. U.S. expiration does not establish the status of foreign counterparts. Each jurisdiction requires a separate patent-family and legal-status review.

References

United States Patent No. 6,090,395. (2000). Hydroalcoholic compositions. U.S. Patent and Trademark Office.
U.S. Patent and Trademark Office. (n.d.-a). Patent term adjustment and patent term. https://www.uspto.gov
U.S. Food and Drug Administration. (2019). Safety and effectiveness of health care antiseptic products; topical antimicrobial drug products for over-the-counter human use. Federal Register.
U.S. Food and Drug Administration. (2023). Temporary policy for preparation of certain alcohol-based hand sanitizer products during the public health emergency. https://www.fda.gov
35 U.S.C. § 154. Patent term.
35 U.S.C. § 271. Infringement of patent.
Manual of Patent Examining Procedure § 2111. Claim interpretation. U.S. Patent and Trademark Office.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	6103496	⤷ Start Trial
Australia	715468	⤷ Start Trial
Canada	2224702	⤷ Start Trial
Germany	69630221	⤷ Start Trial
European Patent Office	0833606	⤷ Start Trial
European Patent Office	1407761	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,090,395

Summary for Patent: 6,090,395