United States Patent 6,536,975: Claim Scope, Expiration, Litigation Risk, and Patent Landscape for Liquid Ampule Applicators

U.S. Patent 6,536,975 protects a single-use liquid applicator built around a frangible ampule, a hollow flexible body, opposed gripping members, and a porous dispensing element. Its broadest protection is concentrated in independent claims 1 and 17. Claim 1 covers an applicator supplied with an ampule; claim 17 covers the applicator structure without requiring the ampule to be included. Claim 28 covers a method of manufacturing the device.

The patent is a device patent, not a drug patent. It does not claim a pharmaceutical compound, formulation, therapeutic indication, dosage regimen, or biologic. Its Orange Book, Paragraph IV, biosimilar, and drug-exclusivity relevance is therefore limited. Based on the standard 20-year patent term applicable to the underlying application, the patent term has ended, with the expected expiration date falling in 2020 if the earliest nonprovisional filing date was May 17, 2000. The claims remain relevant as prior art and as a design-history reference, but they do not provide current exclusionary rights after expiration. [1, 2]

What does U.S. Patent 6,536,975 protect?

The patent protects a squeeze-operated applicator that fractures an internal ampule and delivers the released liquid through a porous outlet. The commercial concept combines liquid storage, ampule fracture, containment of glass fragments, and surface application in one disposable device.

The essential architecture is:

A hollow elongated body with open and closed ends.
A frangible ampule positioned inside the body or received by the body.
Two elongated gripping members aligned with the body’s longitudinal axis.
Inward flexure of the body when the gripping members are squeezed.
Fracture of the ampule through direct or indirect force.
A porous element closing the open end and allowing liquid to pass through.

Claim 1 is the principal combination claim. It requires the ampule to be formed of frangible material and adapted to contain liquid. Claim 17 is structurally broader in one respect because it covers an applicator adapted to receive an ampule rather than expressly requiring the ampule as part of the claimed combination.

Core claim limitations

Claim feature	Claims containing feature	Scope significance
Elongated hollow body	1, 17, 28	Establishes the housing around the ampule
Open and closed axial ends	1, 17, 28	Defines the liquid-flow path and ampule-retention structure
Frangible ampule	1, 11, 28	Required expressly in claim 1 and the manufacturing method
Ampule-receiving body	17, 28	Broadens claim 17 to an applicator sold or used without the ampule
Pair of elongated gripping members	1, 17, 28	Central operating mechanism
Gripping members positioned in longitudinal-axis planes	1, 17, 28	Narrows the geometry and may exclude transverse or radically offset handles
Inward flexure of body	1, 17, 28	Requires squeezing to deform the body and fracture the ampule
Porous dispensing element	1, 17, 28	Required liquid outlet
Flange	3, 18	Narrows attachment of the porous element
Laminate resisting ampule fragments	4, 19	Adds fragment-protection functionality
Woven or non-woven fabric	5	Narrows laminate material
Polyester fabric	6	Further narrows the laminate
Melted flange attachment	7, 20	Narrows the joining technique
Fracturing structure or tappets	8-10, 21-22	Adds discrete force-transfer components
Glass ampule	11	Narrows the ampule material
Internal ridges	12, 23	Adds ampule-positioning structure
Spatially separated handling portions	13-16, 24-27	Narrows the gripping-member configuration
Textured handling surface	16, 27	Narrowest ergonomic limitation

How broad are independent claims 1, 17, and 28?

Claim 1: applicator with ampule

Claim 1 requires the complete dispensing system. A potentially infringing product would need to include:

an elongated frangible ampule containing liquid;
a hollow body permanently receiving the ampule;
opposed gripping members;
a body that flexes inward when the members are squeezed;
ampule fracture caused by that inward flexure; and
a porous element closing the outlet.

The claim does not require glass unless dependent claim 11 is asserted. It also does not require tappets, a flange, a laminate, polyester, internal ridges, or textured grips.

The phrase “permanently receive said ampule” is important. It suggests that the ampule is intended to remain inside the applicator during normal use rather than being inserted and removed repeatedly. A reusable holder receiving replaceable ampules may present a claim-construction issue, depending on the product’s structure and operating instructions.

Claim 17: applicator adapted to receive an ampule

Claim 17 is likely the most commercially significant claim because it does not expressly require the ampule to be present in the claimed article. It covers an empty or preassembled applicator shaped to receive a fracturable ampule, provided the remaining structural and functional limitations are met.

The claim still requires:

opposed longitudinal gripping members;
inward body flexure caused by squeezing;
fracture-capable operation; and
a porous outlet through which liquid can flow after ampule fracture.

An applicator using a removable ampule, a preloaded ampule, or a kit containing separate applicator and ampule components would require separate analysis. Claim 17 is not limited to glass ampules or pharmaceutical liquids.

Claim 28: manufacturing method

Claim 28 requires:

providing the flexible hollow body;
coupling the pair of wing-like gripping members to the body; and
coupling a porous element to close the open end.

The method also requires that the gripping members flex the body inwardly to exert fracturing force against the ampule. A manufacturer that produces an applicator but does not perform every claimed coupling step may avoid literal infringement of claim 28, although equivalent manufacturing operations could still raise infringement issues under the doctrine of equivalents.

The method claim is narrower operationally than a pure apparatus claim because infringement depends on the acts performed during manufacture. It may be more useful against a domestic manufacturer than against a foreign supplier whose products are imported, where 35 U.S.C. § 271(a), § 271(g), or other importation theories would require separate analysis. [3]

What claim limitations create the principal infringement risks?

The patent’s claim scope is defined less by the liquid or intended use than by the mechanical relationship among the body, grips, ampule, and porous element.

Longitudinal gripping geometry

The gripping members must be substantially positioned in planes defined by the body’s longitudinal axis. A product with side buttons, a transverse lever, a rotating actuator, or a top-mounted plunger may avoid this limitation if its force path does not satisfy the claimed geometry.

The words “substantially positioned” introduce some flexibility, but the claim still requires a longitudinally oriented arrangement. The specification and prosecution history would be relevant to determine how much angular or spatial deviation is permitted.

Flexure-based ampule fracture

The claims require the gripping members to flex the body inwardly. A device that fractures the ampule using a separate blade, piston, spring-loaded striker, screw mechanism, or external crushing collar may not meet this limitation literally.

A product can remain within the claim even if it uses tappets or another intermediate structure. Claims 8-10 and 21-22 expressly identify that configuration, but independent claims 1 and 17 already cover the basic inward-flexure mechanism without requiring tappets.

Porous dispensing element

The outlet must be porous and must permit liquid to flow through it after fracture. A nonporous nozzle, slit valve, open tube, absorbent swab without a separate porous closure, or capillary outlet could require claim-by-claim analysis.

The claims do not limit the porous element to a particular pore size, polymer, foam, fabric, felt, sponge, or absorbent composition. Dependent claims 4-7 and 19-20 add fabric and melt-bonding limitations but do not narrow the broad porous-element requirement in the independent claims.

Ampule-fragment protection

Claims 4 and 19 add a laminate secured directly to the flange to resist puncture by ampule fragments. Claims 5 and 6 narrow the laminate to woven or non-woven fabric, including polyester fabric. Claim 7 requires melting the laminate material and flange together.

These limitations may be commercially important even though they are not required by the broadest claims. A product using a separate protective screen, a molded retaining grid, a thick porous plug, or a non-laminated filter may fall outside claims 4-7 and 19-20 while still implicating claims 1 or 17.

How do the dependent claims divide the patent’s technical scope?

The dependent claims create five principal fallback groups.

Outlet and fragment-control claims

Claims 3-7 and 18-20 cover the flange, laminated porous element, fabric, polyester, and melt-bonded attachment. These claims target the interface where liquid exits and where ampule fragments could damage the applicator or contact the user.

Fracture-mechanism claims

Claims 8-10 and 21-22 cover an intermediate structure between the body and gripping members. Claims 10 and 22 specifically require first and second diametrically opposed tappets.

The tappet claims are narrower than the independent claims but may be easier to compare against a product using visible opposed force-transfer projections.

Ampule-material claim

Claim 11 limits the ampule to glass. This limitation excludes plastic, polymer, ceramic, and other frangible materials unless the product also contains a glass ampule.

Ampule-positioning claim

Claims 12 and 23 require multiple inwardly projecting ridges on the inner circumference of the hollow body. These ridges maintain ampule position relative to the open end.

A product using ribs, retainers, elastomeric rings, adhesive, friction fit, end stops, or a molded cradle may not meet the ridge limitation, although the broader ampule-retention concept remains relevant to claim 1 or 17.

Grip-ergonomics claims

Claims 13-16 and 24-27 cover spatially separated handling portions, parallel orientation, longitudinal-axis positioning, and textured surfaces. These claims are narrow and likely provide limited standalone protection unless the accused product replicates the claimed grip arrangement closely.

When does U.S. Patent 6,536,975 lose exclusivity?

The patent’s standard term is 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and applicable continuity rules. The patent issued on March 25, 2003, but the issue date does not control the ordinary expiration date. [1, 4]

Event	Date or assessment
Patent	U.S. Patent 6,536,975
Title	Liquid applicator
Issue date	March 25, 2003
Earliest filing date used for standard-term analysis	May 17, 2000
Expected standard expiration	May 17, 2020
Current practical status	Expired by completion of statutory term
Post-expiration enforcement	No ordinary patent injunction or damages claim for conduct occurring after expiration

A terminal disclaimer or patent-term adjustment could change the precise calculation. The operative date is the expiration date recorded in USPTO Patent Center and the official patent record, not the issue date. [1, 2]

What is the Orange Book status of U.S. Patent 6,536,975?

U.S. Patent 6,536,975 is not an Orange Book drug patent. FDA Orange Book listings generally concern patents claiming the approved drug substance, drug product, or method of using the approved drug. A standalone applicator housing, ampule-fracture mechanism, or porous dispensing device ordinarily does not qualify as an Orange Book-listed patent for an NDA. [5]

Regulatory issue	Relevance to Patent 6,536,975
Orange Book listing	None indicated for the device patent
Paragraph IV challenge	Not applicable to this patent standing alone
ANDA approval block	None under this device patent
New chemical entity exclusivity	Not applicable
New clinical investigation exclusivity	Not applicable
Biologic exclusivity	Not applicable
Biosimilar litigation	Not applicable
FDA device pathway	Depends on the complete applicator and intended use
Drug-device combination product	Possible if the applicator is supplied with a regulated drug

If the applicator is sold with a drug, FDA may regulate the complete product as a combination product. That regulatory classification does not convert the applicator patent into an Orange Book patent.

Which companies are challenging U.S. Patent 6,536,975?

Paragraph IV challengers are not the relevant competitive category for this patent because it is not an Orange Book-listed drug patent. Generic-drug companies could manufacture or market an applicator after patent expiration without filing a Paragraph IV certification against this patent.

A litigation search would need to distinguish:

patent infringement suits involving the applicator;
product-liability actions involving glass fragments or leakage;
trade-secret or contract disputes;
trademark litigation concerning product names; and
FDA enforcement involving the associated liquid or drug.

The claims supplied do not identify a pending case, settlement, covenant not to sue, license, or inter partes review. No litigation or settlement term can be inferred from the claim language itself. USPTO Patent Center and PACER are the controlling sources for prosecution and federal litigation records. [2, 6]

How strong is the patent estate for the applicator?

The estate is structurally coherent but narrow in several important respects.

Strengths

Claims 1 and 17 capture the central combination of ampule, flexible body, opposed grips, inward flexure, and porous outlet.
Claim 17 reaches an applicator adapted to receive an ampule even when the ampule is not included.
The patent addresses both the product and its manufacture.
Dependent claims cover practical commercial details, including fragment protection, tappets, ampule retention, and grip texture.

Weaknesses

The claims are highly mechanical and may be avoided through a different fracture mechanism.
The longitudinal-plane limitation restricts design freedom only in a specific geometric configuration.
The porous outlet requirement excludes many nozzle-based or nonporous delivery systems.
Claims 4-7 and 19-20 are narrow and depend on specific laminate and attachment techniques.
The patent term has ended, eliminating current exclusionary value.

For present-day product development, the patent is most relevant as an expired reference that may signal the likely prior-art field. A new patent estate would need claims directed to a distinct mechanical architecture, a drug-specific formulation or use, a manufacturing process, or a new safety feature rather than a direct repetition of the expired combination.

What manufacturing and intellectual-property barriers remain?

Patent expiration does not remove non-patent barriers. Commercial entry may still depend on:

validated ampule-fracture performance;
control of glass particle generation;
leakage and seal integrity;
sterilization compatibility;
extractables and leachables;
biocompatibility of the porous element;
consistent liquid dose delivery;
manufacturing tolerances for the body and tappets;
packaging and shelf-life validation; and
FDA classification of the final drug-device or device product.

The expired patent may also be relevant to freedom-to-operate analysis for later patents claiming improvements. A later patent could cover a particular polymer, filter laminate, sterile package, ampule coating, fracture-control geometry, or applicator-drug combination even though it cannot restore the expired claims of Patent 6,536,975.

How does this patent compare with drug, formulation, and method-of-use patents?

Patent category	Patent 6,536,975	Commercial consequence
Active pharmaceutical ingredient	Not claimed	No compound exclusivity
Drug formulation	Not claimed	No composition exclusivity
Method of treatment	Not claimed	No therapeutic-use exclusivity
Manufacturing method	Claimed in claim 28	Covers specified applicator assembly steps
Delivery device	Claimed	Main technical subject
Container closure	Partially implicated	Porous outlet and flange are claimed
Drug-device combination	Not expressly claimed	Could be covered by later patents
Biosimilar or generic barrier	None after expiration	No direct regulatory barrier

The patent therefore had product-design relevance rather than traditional pharmaceutical exclusivity value. Revenue exposure would have depended on sales of applicators or combination products using the patented mechanical design, not on protected drug sales.

Key Takeaways

U.S. Patent 6,536,975 covers a squeeze-actuated applicator that fractures an internal ampule and dispenses liquid through a porous element.
Claims 1 and 17 are the principal apparatus claims; claim 17 is broader because it covers an applicator adapted to receive an ampule.
Claim 28 covers manufacture of the applicator through specified body, grip, and porous-element coupling steps.
The strongest technical limitations are the opposed longitudinal gripping members, inward body flexure, ampule fracture, and porous outlet.
Dependent claims add flange attachment, fabric or polyester laminates, melt bonding, tappets, glass ampules, internal ridges, and textured grips.
The patent is a device patent, not an Orange Book drug patent.
Paragraph IV, ANDA, biosimilar, and biologic-exclusivity mechanisms do not directly apply.
The standard patent term has expired, with May 17, 2020, the expected expiration date based on the underlying filing-date analysis.
Current product risk should focus on later improvement patents, FDA requirements, product liability, manufacturing validation, and combination-product regulation.
A new commercial design can generally avoid the expired claims by using a different fracture mechanism, outlet architecture, ampule-retention system, or grip geometry.

FAQs About U.S. Patent 6,536,975

Does Patent 6,536,975 cover the liquid inside the ampule?

No. The claims cover the applicator structure and manufacturing method. They do not claim a pharmaceutical compound, liquid formulation, concentration, or therapeutic indication.

Can a company sell a glass ampule applicator after the patent expires?

Yes, expiration removes the patent exclusion for conduct occurring after the expiration date. The product must still comply with applicable FDA, quality, safety, labeling, packaging, and product-liability requirements.

Does using a porous swab avoid the patent?

Not automatically. The analysis depends on whether the swab or porous element closes the body’s open end and permits liquid to flow through it, as required by the relevant claim.

Are tappets required for infringement?

No. Tappets are required only by dependent claims 10 and 22. Claims 1 and 17 cover the broader inward-flexure and fracture arrangement without expressly requiring tappets.

Can a later patent protect an improved version of this applicator?

Yes. A later patent may protect a novel improvement, such as a different fracture-control mechanism, sterile packaging arrangement, filter laminate, polymer construction, ampule coating, or drug-device combination, subject to novelty, nonobviousness, enablement, and other statutory requirements.

References

United States Patent and Trademark Office. (2003). U.S. Patent No. 6,536,975, Liquid applicator.
United States Patent and Trademark Office. (n.d.). Patent Center. https://patentcenter.uspto.gov/
35 U.S.C. § 271.
35 U.S.C. § 154.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
Administrative Office of the United States Courts. (n.d.). PACER: Public Access to Court Electronic Records. https://pacer.uscourts.gov/

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2002243289	⤷ Start Trial
Australia	4328902	⤷ Start Trial
Canada	2428099	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,536,975

Summary for Patent: 6,536,975