US Patent 6,465,006: Claim Scope, Expiration, Enforceability, and Transdermal Drug-Delivery Patent Landscape

US Patent 6,465,006 covers heat-assisted transdermal and near-surface drug delivery using an exothermic heater containing iron powder and water. Its independent claims reach three subject areas: heat-assisted administration, an iron-based heating apparatus, and manufacturing methods for the heater. The patent issued in 2002 and is no longer a meaningful blocking right for current U.S. commercial activity because its ordinary 20-year patent term has expired.

The strongest historical coverage was directed to disposable, oxygen-activated iron heaters placed over transdermal patches, implanted drug reservoirs, or pharmaceutical storage sites near the skin. The broadest claims face substantial vulnerability under indefiniteness, enablement, written-description, anticipation, and obviousness doctrines.

What does US Patent 6,465,006 cover?

The patent covers the use of controlled heat to increase the delivery rate, absorption, solubility, permeability, or onset of a pharmaceutical administered through or near human skin.

The claims are not limited to one drug or one transdermal patch design. They extend to:

Covered technology	Relevant claims	Scope
Heat-assisted transdermal administration	1-55	Pharmaceutical administration combined with an iron-and-water exothermic heater
Disposable exothermic heater	56-70	Chamber, air-permeable openings, iron powder, water, attachment to skin
Heater manufacturing	71-74	Mixing iron powder, activated carbon, water or alcohol, controlled evaporation, and air-permeable covering
Drug classes	54-55	Nicotine, testosterone, estradiol, nitroglycerin, clonidine, fentanyl, insulin, local anesthetics, steroids and broad therapeutic classes
Temperature-controlled delivery	24, 46-48	Approximately 37°C to 50°C, with narrower ranges of 38°C to 45°C and 39°C to 43°C
Time-controlled delivery	12, 49-52	Approximately three minutes to seven days, with narrower periods from 10 minutes to 72 hours and 20 minutes to 24 hours

The core technical theory is that heat can increase skin permeability, improve formulation solubility, accelerate release through a rate-limiting membrane, increase movement from a subcutaneous storage site, and shorten onset time.

What are the independent claims in US Patent 6,465,006?

Claim 1: heat-assisted pharmaceutical administration

Claim 1 requires a method with four material elements:

A pharmaceutical is administered through a portion of human skin.
An exothermic heating means is placed near that skin portion.
Heating occurs within a safe, pre-designed narrow temperature range for a safe, pre-designed period.
The heating means contains a predetermined amount of iron powder and water in a chamber.

A potential infringement theory would require proof of both pharmaceutical administration through or near the skin and use of an iron-and-water exothermic heater. A conventional electric heating pad would not literally satisfy the iron powder and water limitation, although doctrine-of-equivalents arguments could have been considered during the patent’s enforceable term.

Claim 1 is broad in the identity of the pharmaceutical and delivery mechanism. It does not require a particular approved drug, patch architecture, skin site, or therapeutic indication.

Claim 56: apparatus claim

Claim 56 covers a heater having:

Air-impermeable chamber walls;
A predetermined number and size of openings;
An iron powder and water heat-generating medium;
A selected quantity of material that produces heat for a predetermined time.

This claim focuses on the heater rather than the drug-delivery step. It could historically have reached an iron-oxidation warming device sold separately from a drug patch if the device had the claimed chamber, openings, composition, and controlled duration.

Claims 71 and 73: manufacturing claims

Claims 71 and 73 cover methods for producing the heater.

Claim 71 requires iron powder, activated carbon, liquid, evaporation, water addition, and a cover with selected air permeability. Claim 73 uses iron powder and water, removes part of the water by evaporation, and controls oxygen access through the covering.

These process claims are narrower than the broad delivery claims because infringement depends on the actual manufacturing sequence, composition, and chamber-control steps.

How do the dependent claims expand the patent’s technical coverage?

The dependent claims create several alternative infringement paths.

Transdermal patches and dermal drug-delivery systems

Claims 4, 6, 9, 10, 15, 18, 22, 27, and 28 cover heating associated with a dermal delivery system. The heater may:

Warm the drug formulation;
Heat a rate-limiting membrane;
Increase active-ingredient solubility;
Accelerate release from a patch;
Increase transport into systemic circulation;
Deliver drug initially into a skin or tissue storage site.

The claims do not require the heater to be physically integrated into the patch. Claim 15 expressly covers a heater disposed on the dermal drug-delivery system, while other claims can cover a heater placed proximate to a separate patch.

Implanted and injected drug reservoirs

Claims 23, 38, 39, and 40 extend the concept beyond ordinary patches. They address heating skin and surrounding tissues above an implanted or injected pharmaceutical storage site.

Claim 24 identifies a temperature range of approximately 37°C to 50°C. Claims 69 and 70 cover transport from a storage site located within approximately five centimeters of the skin surface.

This language could have implicated depot injections, implants, localized reservoirs, and other delivery systems that place drug near the skin.

Alternative delivery techniques

Claims 41-44 include iontophoretic delivery, electroporation, and high-speed delivery of a formulation onto skin. Claim 44 recites a delivery speed of at least approximately 10 meters per second.

These claims attempt to capture heat-assisted delivery across multiple physical mechanisms. Their breadth also creates greater prior-art and enablement exposure because the patent must support the full range of listed techniques and pharmaceutical formulations.

Drug and therapeutic-class coverage

Claim 54 lists specific active ingredients:

Nicotine;
Testosterone;
Estradiol;
Nitroglycerin;
Clonidine;
Dexamethasone;
Tetracaine;
Lidocaine;
Fentanyl;
Sufentanil;
Progesterone;
Insulin;
Vitamins A, C, and E;
Prilocaine; and
Bupivacaine.

Claim 55 adds broad therapeutic classes, including androgens, estrogens, analgesics, antihypertensives, antidepressants, antibiotics, anticancer agents, local anesthetics, contraceptives, antidiabetic agents, steroids, anti-allergy agents, antimigraine agents, anti-obesity agents, and smoking-cessation products.

The list does not mean that every listed drug would necessarily be enabled by the patent. A challenger could argue that the claims cover formulations and delivery conditions that the specification does not adequately teach.

What temperature and duration ranges are protected?

The relevant ranges are:

Claim	Temperature or duration
24	Approximately 37°C to 50°C
46	Below approximately 60°C
47	Approximately 38°C to 45°C
48	Approximately 39°C to 43°C
49	Approximately three minutes to seven days
50	Approximately 10 minutes to 72 hours
51	Approximately 20 minutes to 24 hours

The practical commercial center of gravity is approximately 39°C to 43°C for 20 minutes to several hours. That range is compatible with skin-contact warming systems intended to enhance topical-anesthetic or transdermal delivery without causing thermal injury.

The patent does not claim every heated transdermal system. The independent claims require an exothermic heater containing iron powder and water, or an apparatus with the specified iron-based chamber structure. A battery-powered patch heater, resistive element, ultrasound system, or microwave-assisted system would require a separate infringement analysis.

How strong are the claims under U.S. patent law?

Claim construction risks

Several terms create claim-construction issues:

"Safe, pre-designed narrow temperature range";
"Safe, pre-designed length of time";
"Proximate";
"Need to increase absorption";
"Perceived need";
"Lower than desirable effect";
"Based solely upon the effect of the drug";
"Storage site";
"Controls the need of transport," which appears to be a drafting or transcription error.

A court could construe some terms by reference to the specification and technical context. Terms such as "safe" and "proximate," however, may be challenged as indefinite if they do not provide an objective boundary for a skilled person.

Claims 13, 33-37, and 52 are especially vulnerable to indefiniteness arguments because they rely on subjective patient experience, clinical perception, or an undefined drug effect. Claim 13 also appears grammatically defective in the supplied text.

Written description and enablement

Claims 1 and 55 cover a very large number of drugs, formulations, delivery systems, and physiological mechanisms. A challenger could argue that the patent does not demonstrate possession of the entire claimed genus or teach a skilled person how to practice the full scope without undue experimentation.

The risk is highest for:

Insulin and other macromolecules;
Electroporation and iontophoretic delivery;
Implanted drug reservoirs;
High-speed formulation delivery;
Drugs whose absorption is not materially improved by moderate heating;
Formulations requiring specialized solvents or stabilizers.

The narrower heater-composition and manufacturing claims generally present a stronger enablement profile because they define more concrete physical structures and process steps.

Anticipation and obviousness

The principal prior-art combinations would likely include:

Transdermal patches and skin-heating systems;
Disposable iron-oxidation hand and body warmers;
Heat-enhanced drug-release systems;
Oxygen-controlled exothermic chambers;
Topical anesthetic delivery systems;
Implanted or subcutaneous drug reservoirs.

The central obviousness theory would be that a skilled person could combine known transdermal heat enhancement with known iron-powder disposable warmers. The patent’s strongest distinction would be the controlled integration of a specified iron-and-water medium, air-permeable chamber, temperature range, and duration with pharmaceutical delivery.

The apparatus and manufacturing claims are more vulnerable if prior art disclosed an iron-powder warming pouch with controlled oxygen access before the patent’s priority date.

When did US Patent 6,465,006 lose exclusivity?

US Patent 6,465,006 issued on October 15, 2002. Its ordinary patent term ran for 20 years from the earliest effective U.S. nonprovisional filing date under the pre-1995 and post-1995 transition rules applicable to the application history. The patent’s enforceable term has expired.

Because the patent issued in 2002, any remaining term would have depended on its filing date, patent-term adjustment, terminal disclaimers, and any applicable priority claims. Those factors affect the exact expiration date but do not change the present commercial conclusion: US 6,465,006 is expired and cannot presently block a new U.S. product under ordinary patent infringement law. Patent term is governed principally by 35 U.S.C. §154 and the application-specific file history (U.S. Patent and Trademark Office, n.d.-a).

No patent-term extension under 35 U.S.C. §156 would ordinarily be expected for a broad transdermal heater patent because the right is not directed to an approved drug product requiring the relevant regulatory review period.

What is the Orange Book status of US Patent 6,465,006?

US Patent 6,465,006 is not, by its claim structure, an Orange Book drug-substance, drug-product, or approved-method-of-use patent. It claims a heat-assisted delivery method, a heating apparatus, and heater manufacturing processes.

The FDA Orange Book is principally relevant when an NDA holder submits patents that claim an approved drug substance, drug product, or method of using the approved drug. An expired device or drug-delivery patent would not ordinarily create a current Paragraph IV barrier unless it remained properly listed and legally enforceable, which is not the case for this patent (U.S. Food and Drug Administration, n.d.-a).

An approved product using the technology could have had separate patents covering:

The active pharmaceutical ingredient;
The patch formulation;
Adhesive chemistry;
Release membranes;
The integrated heating component;
Manufacturing methods;
A specific therapeutic use.

Those patents must be assessed independently. US 6,465,006 does not establish patent protection for any particular drug.

Which commercial products are closest to the claimed technology?

The closest product category is a heat-assisted topical or transdermal delivery system using an oxygen-activated iron oxidation reaction.

Heated topical anesthetic systems

Products combining lidocaine or tetracaine with a controlled warming component are technically close to claims 54, 63-68, and 75-type commercial implementations, even where the particular product is protected by different patents. Such systems use heat to increase local skin perfusion and may accelerate onset of dermal anesthesia.

The relevant comparison is not whether a product merely warms skin. The product must be evaluated for:

Iron-powder composition;
Water content;
Air-permeable chamber;
Temperature profile;
Heating duration;
Physical association with the drug-delivery system;
Whether the heater is supplied as an integrated component or separate accessory.

Conventional transdermal patches

Nicotine, testosterone, estradiol, clonidine, fentanyl, and nitroglycerin patches are within the pharmaceutical categories identified in claims 54 and 55. A conventional patch without an iron-and-water exothermic heater would not ordinarily fall within claim 1.

A patch combined with a separate commercial warming pouch could have created historical infringement exposure if the combination met every limitation of claim 1. That exposure ended when the patent expired.

Microneedle and electrically assisted systems

Microneedle arrays, iontophoresis, electroporation, jet injection, and other enhanced-delivery platforms overlap with the patent’s functional objectives but do not necessarily practice its claimed heater structure. These technologies are more likely to be controlled by platform patents owned by microneedle, medical-device, and specialty pharmaceutical companies.

What manufacturing and intellectual-property barriers remain?

The expired patent does not remove all barriers to market entry. Current barriers may include:

Barrier	Commercial significance
Heater safety	Temperature uniformity, burn prevention, skin irritation, oxygen control
Drug formulation	Stability under heat, solubility, crystallization, evaporation, and degradation
Patch engineering	Adhesion during heating, membrane control, dose uniformity
Regulatory classification	Drug, device, combination product, or drug-delivery accessory
Manufacturing	Reproducible iron oxidation, water distribution, chamber permeability
Quality systems	Lot-to-lot heat profile and active-ingredient delivery performance
Separate patents	Patch, formulation, membrane, adhesive, active ingredient, and therapeutic-use rights
Clinical proof	Pharmacokinetic consistency, onset-time improvement, local safety

The most material surviving IP risk is likely to sit in later patents covering integrated combination products rather than in US 6,465,006 itself.

Are there Paragraph IV challenges, litigation, or settlement agreements?

US 6,465,006 is a device and delivery-method patent rather than a conventional drug patent. Paragraph IV litigation would therefore be unusual unless the patent had been listed in the Orange Book for a specific approved drug, which its claim structure does not indicate.

The supplied record does not establish a current Paragraph IV challenge, active infringement case, or settlement agreement involving US 6,465,006. Because the patent has expired, a new Paragraph IV filing directed to this patent would have no practical exclusivity value.

Any historical litigation involving a product that used a heated transdermal system would need to be separated from litigation concerning this patent. Product-level disputes can involve later patents, regulatory exclusivity, trademarks, trade secrets, or contract rights.

How does US Patent 6,465,006 compare with competing patent estates?

Patent estate type	Typical protected subject matter	Relationship to US 6,465,006
Active-ingredient patents	New chemical entity or salt	Usually unrelated to the heater
Transdermal formulation patents	Solvent, enhancer, matrix, adhesive, drug loading	Potentially overlapping commercial product, but distinct legal rights
Patch architecture patents	Membrane, reservoir, backing, multilayer construction	May be practiced with or without the claimed heater
Integrated heated-patch patents	Heater and pharmaceutical product combination	Closest later-generation competitive estate
Microneedle patents	Solid, hollow, coated, or dissolving needles	Alternative delivery mechanism
Iontophoresis patents	Electrical transport through skin	Functional overlap, structural difference
Disposable warmer patents	Iron oxidation, moisture, oxygen control, chamber design	Closest prior-art and competitive technology
Method-of-use patents	Heating for a specific drug or indication	Potentially narrower than the broad claims here

The expired patent was strongest as a platform concept. A current competitor would focus its freedom-to-operate review on later patents covering the specific drug product, patch construction, heating architecture, and manufacturing process.

What generic-entry risks exist?

For a generic or follow-on transdermal product, US 6,465,006 creates no current U.S. patent-entry risk. The relevant risks are:

Active-ingredient patent term;
Orange Book-listed formulation or method patents;
Later combination-product patents;
Device patents covering the heater;
Regulatory requirements for a drug-device combination;
Clinical or pharmacokinetic differences caused by heat;
Trade-secret restrictions involving heater composition or manufacturing.

A generic applicant using a non-iron heater, such as a resistive element or battery-powered warming layer, would have a stronger technical distinction from the expired claims. An applicant using an iron-powder and water pouch would still not face this expired patent, but it could encounter later patents covering the same commercial implementation.

Key Takeaways

US Patent 6,465,006 covers heat-enhanced pharmaceutical absorption through skin and near-surface tissue.
The core limitations are an exothermic heater containing iron powder and water, controlled temperature, controlled duration, and pharmaceutical delivery through or near skin.
Independent claims cover the delivery method, heater apparatus, and heater manufacturing process.
The patent reaches transdermal patches, implanted or injected reservoirs, topical anesthetics, iontophoresis, electroporation, and other delivery systems through dependent claims.
Claims using "safe," "pre-designed," "proximate," and patient-perception standards have material indefiniteness and claim-construction risks.
The broad drug and delivery-system coverage creates written-description and enablement vulnerabilities.
The patent issued on October 15, 2002, and its enforceable U.S. term has expired.
It is not, by claim type, a conventional Orange Book drug patent.
No current Paragraph IV barrier, active exclusivity right, or new-product blocking position should be attributed to this patent.
Current commercial risk is more likely to arise from later patents covering heated patches, drug formulations, membranes, adhesives, integrated combination products, or heater manufacturing.

Frequently Asked Questions

Can a company still sell a transdermal patch with an iron-powder heater?

Yes. US Patent 6,465,006 is expired. The company must still assess later patents covering the specific patch, heater, formulation, and manufacturing process.

Does US Patent 6,465,006 cover all heat-assisted drug delivery?

No. The claims are tied to specified iron-powder and water exothermic structures in the independent claims. Other heating technologies may fall outside the literal scope.

Did the patent protect fentanyl or nicotine themselves?

No. The patent identified fentanyl and nicotine as pharmaceutical examples within a heat-assisted delivery method. It did not create composition-of-matter rights in those drugs.

Is an iron-oxidation warming pouch a medical device under FDA law?

Its classification depends on its intended use and whether it is marketed as part of a drug-delivery system. An integrated heated drug product may be regulated as a combination product rather than as a standalone consumer warmer (U.S. Food and Drug Administration, n.d.-b).

Can expired US Patent 6,465,006 support a new patent application?

The expired patent can remain prior art against later applications. A later patent would need a novel and nonobvious improvement, such as a distinct heater architecture, formulation, control algorithm, manufacturing process, or clinical use.

References

Congress. (2024). 35 U.S.C. §§ 102, 103, 112, 154, 156, and 271. https://uscode.house.gov/

U.S. Food and Drug Administration. (n.d.-a). 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

U.S. Food and Drug Administration. (n.d.-b). Rationale for assigning combination products to a lead center. https://www.fda.gov/combination-products

U.S. Patent and Trademark Office. (n.d.-a). Patent term adjustment. https://www.uspto.gov/patents/laws/patent-term-adjustment

U.S. Patent No. 6,465,006. (2002). Method and apparatus for facilitating the absorption of pharmaceuticals through human skin. U.S. Patent and Trademark Office.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	320233	⤷ Start Trial
Austria	489949	⤷ Start Trial
Australia	2002336585	⤷ Start Trial
Australia	5924199	⤷ Start Trial
Australia	6406299	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,465,006

Summary for Patent: 6,465,006