U.S. Patent 6,729,786: Claim Scope, Expiration, Infringement Risk, and Patent Landscape

U.S. Patent No. 6,729,786 covers a disposable liquid applicator that combines a frangible liquid ampoule with a colorant-containing porous element. The core commercial concept is a breakable reservoir that releases liquid through dyed foam, felt, or another porous medium before the liquid reaches an application pad or surface.

The broadest protection is in claim 1. Claim 17 is a narrower combination claim requiring both a colorant-containing porous plug and a porous application pad. The patent is a device patent, not a drug patent. It does not create Orange Book listing rights, FDA drug exclusivity, or biosimilar protections.

The patent issued in 2004. Its ordinary 20-year term would have ended no later than 2024, measured from the earliest effective nonprovisional filing date, subject to any patent-term adjustment, terminal disclaimer, or other USPTO term record under 35 U.S.C. § 154.

What does U.S. Patent 6,729,786 claim?

The claims cover five technical elements:

A liquid-containing ampoule.
A frangible structure capable of being broken.
A hollow body that houses the ampoule.
A porous element containing colorant.
A liquid path through the porous element after ampoule fracture.

Claim 1 is the principal independent claim:

A liquid applicator comprising at least one frangible ampoule, a hollow body receiving the ampoule, and a porous colorant-containing element positioned so that liquid flows through it after the ampoule is fractured and picks up colorant.

The claim is directed to the apparatus, not to a particular drug, cosmetic, antiseptic, solvent, or other liquid.

What is the protected inventive combination?

The claim does not protect an ampoule alone, a sponge alone, or a colored liquid alone. It requires the interaction of those components.

A product is within the literal scope of claim 1 if it has:

Claim limitation	Scope
Frangible ampoule	Any breakable ampoule structure, not limited to glass
Liquid contents	Any liquid intended for application to a surface
Hollow body	Any body defining an internal chamber receiving the ampoule
Porous colorant element	A pad, plug, foam, felt, or comparable porous material
Fluid communication	Liquid must flow through the porous element
Color transfer	Colorant must transfer into the liquid after fracture

The claim does not expressly require a particular breakage mechanism, application surface, liquid volume, ampoule geometry, color intensity, or manufacturing process.

How broad is claim 1 of U.S. Patent 6,729,786?

Claim 1 is relatively broad at the component level but narrower at the functional-interaction level. It reaches many physical designs, but every accused product must use a porous colorant-bearing element through which the released liquid flows.

Broad limitations

The following language expands the potential scope:

"at least one ampoule"
"frangible material"
"desired liquid"
"surface"
"porous element"
"contains colorant"
"hollow body"
"internal chamber"

The use of "at least one" permits one or multiple ampoules. Claim 8 confirms that two ampoules are within the contemplated scope, but claim 1 is not limited to two.

"Frangible material" is broader than glass. Claims 5, 6, and 7 narrow the scope to glass, vial-type, and elongated glass ampoules.

"Porous element" is also broad. Claims 2, 3, and 9 identify pads, plugs, foam, and felt as examples rather than necessarily exhaustive categories.

Functional limitations

The most important limitation is the required fluid path. The porous element must be positioned so that:

the ampoule is fractured;
liquid exits the ampoule;
the liquid flows through the porous colorant element; and
colorant transfers into the liquid.

A product in which colorant is pre-mixed into the ampoule liquid may fall outside the literal wording if the colorant-containing porous element does not transfer colorant into the liquid. A product in which the liquid bypasses the colorant-bearing porous element also presents a noninfringement position.

The phrase "such that" connects the structure to the required result. It is likely to be treated as a functional limitation rather than as a purely aspirational statement.

What do dependent claims 2 through 16 protect?

Claims 2 through 16 narrow claim 1 through specific materials, configurations, and colorant characteristics.

Claims	Added limitation	Commercial significance
2	Porous pad	Covers a pad-shaped colorant element
3	Porous plug	Covers a plug positioned in the fluid path
4	Fracturing mechanism	Requires an integrated ampoule-breaking structure
5	Glass ampoule	Limits the ampoule to glass
6	Vial-type ampoule	Narrows ampoule geometry
7	Elongated glass ampoule	Covers a particular glass configuration
8	Two ampoules	Covers dual-ampoule embodiments
9	Foam or felt	Narrows porous media
10	Colorant changes hue	Requires a hue change
11	Colorant adds hue	Requires addition of color
12	Tint, dye, pigment, or paint	Identifies colorant categories
13	Dye	Narrows claim 12 to dye
14	FD&C Green No. 3	Specific colorant formulation
15	Porous element imbibed with colorant	Colorant incorporated into the porous material
16	Colorant located on porous-element surface	Surface-coated or surface-deposited colorant

Claims 10 and 11 appear to distinguish between changing an existing hue and adding hue to an otherwise uncolored liquid. Their practical value depends on the specification's definitions and examples.

Claim 14 is technically narrow because it requires FD&C Green No. 3. That limitation could be avoided by using another approved dye, pigment, or tint, subject to the doctrine of equivalents and the patent's prosecution history.

What does claim 17 add?

Claim 17 is an independent combination claim that requires:

a frangible ampoule;
a hollow body;
a porous plug containing colorant; and
a porous pad secured to the body and closing an open end.

The colored liquid must flow through the porous pad after passing through the colorant-containing plug.

This claim is narrower than claim 1 because it requires two distinct porous components:

an internal colorant-bearing plug; and
an external application pad.

A product using only a colored porous pad may avoid claim 17 while potentially remaining within claim 1. Conversely, a product with an internal dyed plug and an external pad faces a stronger literal-infringement risk under claim 17.

What is the scope of claims 18 and 19?

Claim 18 depends from claim 17 and recites a method of making the porous plug:

mixing isopropyl alcohol, water, and dye;
saturating the porous plug with the mixture; and
allowing the plug to dry.

Claim 19 narrows the dye to FD&C Green No. 3.

These claims raise a claim-category issue because they depend from an apparatus claim while adding manufacturing steps. The scope may be treated as a product-by-process limitation or may face indefiniteness and statutory-classification arguments under 35 U.S.C. § 112. The enforceable effect would depend on the patent's exact claim format, specification, prosecution history, and judicial construction.

For a competitor, the most direct design-around is to use:

a different dye-loading process;
a pre-colored porous material;
a colorant placed directly in the ampoule;
a nonporous colorant carrier; or
a different colorant that avoids claim 19.

When does U.S. Patent 6,729,786 lose exclusivity?

The ordinary U.S. patent term is 20 years from the earliest effective nonprovisional filing date, not 20 years from the issue date. Because the patent issued in 2004, its ordinary term would have ended by 2024 at the latest, absent patent-term adjustment or another unusual term event (35 U.S.C. § 154).

Event	Timing
Patent issued	2004
Ordinary 20-year term endpoint	No later than 2024 based on issue-date ceiling
Current commercial status	Likely expired unless a USPTO term adjustment extended the term
Regulatory exclusivity	None apparent from the device claims
Orange Book exclusivity	Not applicable

The exact expiration date requires the patent's earliest effective filing date and USPTO patent-term calculation. The claims alone cannot establish those dates.

A patent expiration analysis must also check:

patent-term adjustment;
terminal disclaimers;
reexamination certificates;
maintenance-fee status;
disclaimer filings; and
continuation or divisional patents.

Expiration of this patent would not necessarily eliminate related protection if a continuation or separate family member contains still-pending or later-expiring claims.

Is U.S. Patent 6,729,786 an Orange Book drug patent?

No. The claims cover a mechanical liquid applicator. They do not claim:

an active pharmaceutical ingredient;
a drug composition;
a dosage regimen;
a therapeutic method;
a drug formulation; or
a drug-device combination identified for an approved drug product.

The FDA Orange Book lists approved drug products and certain patent and exclusivity information submitted under 21 C.F.R. § 314.53. A standalone applicator patent ordinarily does not qualify as an Orange Book-listed drug patent.

The relevant FDA pathway would depend on the liquid and intended use. Possible regulatory categories could include a general consumer product, cosmetic, medical device, combination product, or drug-delivery accessory. The patent itself does not determine FDA classification.

What generic-entry or biosimilar risks exist?

There is no conventional generic-drug or biosimilar risk created by these claims.

Risk category	Applicability
ANDA Paragraph IV challenge	Not applicable to the device claims
505(b)(2) drug application	Relevant only if the liquid is a drug and the applicator is part of the drug product
Biosimilar application	Not applicable
Device substantial-equivalence pathway	Potentially relevant depending on intended use
Consumer-product competition	Directly relevant
Trade-secret manufacturing risk	Potentially relevant for dye-loading and assembly processes

A competitor could commercialize an equivalent application concept after patent expiration without facing this patent, although other patents, trademarks, design patents, regulatory requirements, or contractual restrictions could remain relevant.

What patents protect comparable ampoule applicators?

The relevant patent landscape is broader than this patent and generally divides into six technology groups:

Breakable-ampoule applicators

These patents claim a frangible reservoir inside a handle, tube, swab, brush, sponge, or pad. The principal issues are ampoule placement, fracture mechanics, liquid release, and leak prevention.

Dual-chamber delivery systems

These systems keep two liquids separate until use. Relevant claims commonly cover mixing chambers, breakable seals, valves, membranes, and staged release.

Color-indicating applicators

These patents use a dye or pigment to show that liquid has been released or applied. The color may be in the liquid, a porous filter, a swab, or a downstream indicator.

Porous-media metering systems

These claims focus on foam, felt, plugs, wicks, membranes, or pads that meter liquid flow. The strongest prior art may disclose fluid passage through porous material even without colorant.

Integrated fracture mechanisms

These systems use a cap, button, plunger, twist mechanism, snap feature, or internal projection to break the ampoule.

Manufacturing and impregnation processes

These patents cover loading porous media with dye, solvent mixtures, active ingredients, preservatives, or other functional materials.

The most important prior-art combination is a breakable ampoule positioned upstream of a porous filter, plug, wick, or pad. A separate reference disclosing dye-impregnated porous material could be combined with an ampoule applicator reference in an obviousness challenge under 35 U.S.C. § 103.

How strong is the patent estate?

The claim estate is concentrated rather than extensive.

Estate characteristic	Assessment
Core independent claims	Claims 1 and 17
Broadest concept	Ampoule plus porous colorant-transfer element
Narrowest claims	Claims 14 and 19, requiring FD&C Green No. 3
Composition protection	None apparent
Method-of-use protection	None apparent
Manufacturing protection	Limited to claim 18's process language
Drug-product protection	None apparent
Design-around availability	High
Current blocking value	Likely low if the patent has expired

Claim 1 has the highest historical enforcement value because it does not require glass, a specific dye, a particular ampoule shape, or a specific application pad. Claim 17 is narrower but may be easier to prove against a product with the same plug-and-pad architecture.

The principal validity pressure points would likely include:

anticipation based on earlier ampoule applicators;
obviousness based on combining breakable-reservoir and porous-indicator references;
definiteness of functional phrases such as "such that";
written-description support for broad porous-element and colorant categories;
enablement across all liquids, dyes, porous materials, and applicator geometries; and
the mixed apparatus/process structure of claims 18 and 19.

What licensing, litigation, or settlement issues affect the patent?

The claim text does not establish any license, assignment, litigation, consent judgment, or settlement agreement. Those issues must be determined from USPTO assignment records, Patent Center documents, PACER litigation records, and any relevant Federal Circuit or district-court opinions.

For transaction diligence, the critical records are:

USPTO assignment and ownership history.
Patent Center prosecution history.
Patent-term adjustment and terminal-disclaimer data.
Maintenance-fee records.
Continuation and divisional applications.
Federal court infringement and validity cases.
International family members.
Any license, covenant-not-to-sue, or settlement agreement.

Because the patent claims a physical delivery article, geographic coverage is limited to U.S. activity. Foreign counterparts require separate review. A U.S. patent does not block manufacture and sale outside the United States, although importation into the United States can implicate 35 U.S.C. § 271.

What generic launch scenarios are possible?

For a product using this architecture, the principal scenarios are:

Scenario	Patent consequence
Same architecture launched after confirmed expiration	This patent should not block launch
Launch before confirmed expiration	Review literal infringement and patent-term adjustment
Ampoule with colorant preloaded in liquid	Potential design-around of color-transfer limitation
Colored porous pad without internal plug	Potentially outside claim 17; claim 1 requires analysis
Nonporous colorant carrier	Potentially outside the porous-element limitation
Different dye	Avoids claims 14 and 19, but not necessarily claim 1
Dual-liquid system with no colorant transfer	May avoid the central claim combination
Manufacture overseas and import into the U.S.	U.S. infringement exposure may remain under § 271

Key Takeaways

U.S. Patent 6,729,786 claims a breakable liquid ampoule combined with a porous colorant-transfer element.
Claim 1 is the broadest claim and does not require glass, two ampoules, a specific dye, or a separate application pad.
Claim 17 is narrower and requires both a colorant-containing porous plug and a porous pad.
Claims 14 and 19 are limited to FD&C Green No. 3.
Claim 18's apparatus-plus-manufacturing language creates potential claim-construction and validity issues.
The patent is a device patent, not an Orange Book drug patent.
ANDA Paragraph IV and biosimilar frameworks do not directly apply.
The ordinary patent term would have ended by 2024 at the latest, subject to USPTO term adjustments and related family rights.
The architecture has substantial design-around flexibility.
Current blocking risk depends primarily on the verified USPTO term record and any continuation patents, not on the 19 claims alone.

FAQs

Can a competitor use the same ampoule applicator after patent expiration?

Yes, provided no unexpired continuation, reissued patent, design patent, trademark, or separate third-party patent covers the product.

Does using FD&C Green No. 3 create special patent risk?

It creates risk under claims 14 and 19 only if the other inherited limitations are present. The dye itself is not monopolized by these claims.

Is a colored applicator pad alone covered?

Not necessarily. Claim 1 requires a frangible ampoule and fluid flow through a porous colorant-containing element. Claim 17 separately requires a porous plug and a porous pad.

Could a pre-colored liquid avoid the patent?

Potentially. If the liquid is colored before entering the applicator and no porous element transfers colorant into the liquid, the product may avoid the central color-transfer limitation.

Are foreign versions of this patent automatically enforceable in Europe or Asia?

No. Foreign enforcement depends on separately granted national or regional patents, their expiration dates, claim scope, maintenance status, and local law.

References

U.S. Patent No. 6,729,786, claims 1-19. United States Patent and Trademark Office.
35 U.S.C. § 154. Patent term.
35 U.S.C. § 271. Patent infringement.
35 U.S.C. § 102. Conditions for patentability; novelty.
35 U.S.C. § 103. Conditions for patentability; non-obvious subject matter.
35 U.S.C. § 112. Specification and claim requirements.
U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations. Orange Book.
21 C.F.R. § 314.53. Submission of patent information.
United States Patent and Trademark Office. Patent Center and patent-term adjustment records.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2004220817	⤷ Start Trial
Brazil	PI0408318	⤷ Start Trial
Canada	2519176	⤷ Start Trial
European Patent Office	1610961	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,729,786

Summary for Patent: 6,729,786