United States Drug Patent 4,793,366: Claim Scope, Expiration, FDA Status, and Nicotine-Device Patent Landscape

U.S. Patent No. 4,793,366 covers a non-pyrolytic nicotine delivery device using nicotine-bearing fluid stored in microsized reservoirs within a porous or microporous material. Its central technical concept is a passive inhalation device in which user suction causes nicotine-bearing vapor to volatilize into an airflow passageway. The patent issued on December 27, 1988, and its 17-year patent term expired on December 27, 2005. It therefore creates no current U.S. infringement barrier, Orange Book exclusivity, Paragraph IV risk, or enforceable licensing leverage.[1][2]

The claims remain commercially relevant as prior-art evidence against later patents covering porous nicotine reservoirs, inhalable nicotine devices, cigarette-like tubes, and passive vapor-generation systems.

What does U.S. Patent 4,793,366 protect?

The patent protects a structural combination rather than nicotine delivery in the abstract. An accused product would need to satisfy every limitation of an asserted claim. The core combination requires:

A housing.
An air passageway through the housing.
A material containing multiple microsized reservoirs.
Nicotine-bearing fluid in those reservoirs.
Volatilization of the fluid in response to user suction.
Release of nicotine-bearing vapor into the drawn air.
Non-pyrolytic operation.

Independent claim 1 is the broadest principal claim. Independent claim 17 narrows the device by requiring an elongated tube and a polymer material containing the reservoirs.

The patent does not require an electronic heater, battery, atomizer, aerosol-generating coil, liquid tank, or combustion source. The claims are directed to a passive or suction-responsive vapor delivery architecture.

How many independent claims does Patent 4,793,366 have?

The patent has two independent device claims: claims 1 and 17.

Claim	Independent?	Core additional limitation
1	Yes	Housing and reservoir-bearing material for non-pyrolytic nicotine vaporization
17	Yes	Elongated tubular housing and polymer material containing the reservoirs

Claim 1 is materially broader because it does not require a polymer material or elongated tube. Claim 17 requires both.

Claims 2 through 16 depend from claim 1. Claims 18 through 28 depend from claim 17 or its immediate dependent claims.

What are the key claim elements and limitations?

Housing and airflow passageway

Claims 1 and 17 require a housing that defines a passageway for air through the device. A loose nicotine-containing insert without a defined housing or airflow path would have difficulty satisfying the claims.

The housing may be:

An elongated tube;
A cigarette-paper structure;
A fibrous web;
A mouthpiece-containing assembly; or
Another structure that creates the claimed airflow passage.

Claims 2, 3, 4, 5, 21, 22, and 23 add these structural alternatives.

Microsized reservoirs

The reservoir limitation is central. The claims require a material having a plurality of microsized reservoirs containing nicotine-bearing fluid. Claim 9 and claim 25 specify a mean reservoir size of less than about 10 micrometers.

The claims do not expressly require:

A single central liquid tank;
A metered pump;
A pressurized cartridge;
A heating coil;
A ceramic wick; or
A particular reservoir geometry.

The language is broad enough to encompass a porous matrix, filament, film, cellular polymer, or similar material if the material contains multiple microscopic fluid-retention spaces.

Nicotine-bearing fluid

Claim 1 refers generally to nicotine-bearing fluid. Claim 24 narrows the nicotine to nicotine d, nicotine l, nicotine dl, nicotine salts, or combinations of those forms.

Claim 11 identifies carrier materials that include menthol, Freon, methyl salicylate, aldehydes, alcohols, esters, ethers, ketones, acetates, hydrocarbons, and combinations. Claim 28 contains a substantially similar carrier list but omits Freon.

The carrier limitation is not present in the broadest independent claims. A product could potentially fall within claim 1 or claim 17 without using one of the listed carriers, provided the product otherwise satisfies the claim language.

Suction-responsive volatilization

The claims require volatilization in response to suction supplied by the user. The claims therefore focus on the functional relationship between:

User-generated negative pressure;
Airflow through the housing;
Exposure or movement of nicotine-bearing fluid; and
Release of nicotine-bearing vapor.

A product that delivers nicotine only through an electrically heated aerosolizer may not satisfy this limitation in the same way as the claimed passive device. The analysis would depend on the construction of “in response to suction” and whether the heater performs the operative volatilization rather than suction.

What formulations and materials are protected?

The dependent claims identify several protected physical forms and material classes.

Claim group	Protected formulation or structure
3, 21	Microporous polymer filaments retained in a tubular section
4, 5, 22, 23	Fibrous web or cigarette-paper housing
6, 7, 18, 19	Microporous film, including tubular film
8	Filaments
10	Microporous material
12, 13	Microporous polymer with a relatively homogeneous three-dimensional cellular microstructure
14, 20	Surface dry to the touch after loading
15, 16	Olefinic, condensation, oxidation, or specified polymer materials
19	Tubular film with an internal airflow restrictor
27	Hydrophobic polymer material

Claim 16 lists polypropylene, polyvinyl chloride, polyethylene, cellulose acetate, cellulose triacetate, polymethylpentene, polyethylene acrylic acid, polyphenylene oxide, styrene, polystyrene, and combinations.

The claims are therefore directed to a “dry” or non-leaking reservoir concept. The fluid is retained inside microscopic pores or cells rather than presented as a free liquid at the surface.

How broad is claim 1 compared with claim 17?

Claim 1 is the stronger historical coverage claim.

Issue	Claim 1	Claim 17
Housing	Required	Required
Air passageway	Required	Required
Elongated tube	Not required	Required
Polymer material	Not required	Required
Multiple microsized reservoirs	Required	Required
Nicotine-bearing fluid	Required	Required
User suction	Required	Required
Non-pyrolytic use	Required	Required
Potential coverage	Broad passive device category	Narrower tubular polymer implementation

Claim 1 can reach materials other than polymers, including films, fibers, fibrous webs, and other reservoir-bearing structures. Claim 17 excludes non-polymer implementations.

Claims 2 through 16 offer fallback positions for the claim 1 group. Claims 18 through 28 provide additional limitations for the polymer-tube group.

What products could fall within the historical claim scope?

A product would have presented the highest historical infringement risk if it combined:

A cigarette-like or tubular housing;
A defined airflow channel;
Microporous polymer filaments or film;
Nicotine liquid retained in microscopic pores;
Passive or suction-driven vapor release;
No combustion or pyrolysis; and
A mouthpiece through which the user draws air.

Potentially relevant product categories include:

Early nicotine inhalers.
Passive nicotine cigarettes.
Porous-polymer nicotine sticks.
Nicotine vapor devices using loaded polymer films.
Disposable inhalation devices with nicotine-bearing filaments.
Cigarette-paper devices containing nicotine-loaded porous inserts.

Modern electronic cigarettes typically use a liquid reservoir, wick, heater, and aerosolizer. Those products may differ materially from the claimed reservoir-bearing polymer architecture. A modern product could nevertheless have raised a historical doctrine-of-equivalents issue if its wick or porous matrix performed substantially the same function in substantially the same way with substantially the same result. That issue is academic for this patent because the patent has expired.

When did U.S. Patent 4,793,366 lose exclusivity?

The patent expired on December 27, 2005.

Event	Date
Patent issued	December 27, 1988
Applicable term	17 years from issuance for a pre-1995 U.S. patent
Patent expiration	December 27, 2005
Current enforceability	None

The patent was issued before the Uruguay Round Agreements Act changed the standard U.S. patent term to 20 years from the earliest effective nonprovisional filing date. Patents issued before June 8, 1995 generally retained the 17-year-from-issuance term, subject to statutory exceptions not relevant to the ordinary expiration analysis here.[1][3]

Expiration ends the right to exclude. It does not erase the patent as prior art or remove its value in freedom-to-operate analysis for later-filed patent applications.

What is the Orange Book status of Patent 4,793,366?

Patent 4,793,366 is not an Orange Book patent.

The Orange Book identifies patents submitted for approved drug products under FDA approval applications, principally New Drug Applications. A device patent covering a nicotine vapor delivery structure does not automatically qualify for Orange Book listing.[4]

The patent therefore has:

No Orange Book-listed product;
No FDA patent-use-code listing;
No associated Hatch-Waxman patent certification requirement;
No approved-drug exclusivity period; and
No current ability to delay an ANDA through patent litigation.

Does Patent 4,793,366 create Paragraph IV risk?

No. Paragraph IV applies to an ANDA applicant challenging patents listed for an approved drug product. Patent 4,793,366 is an expired device patent and is not an Orange Book-listed drug patent.

A generic nicotine product could not receive a Paragraph IV notice based on this patent alone. The patent also could not support a 30-month stay under the Hatch-Waxman framework.[5]

The relevant regulatory pathway would depend on the product:

Product type	Likely FDA framework
Nicotine gum, patch, lozenge, nasal spray, or inhaler for cessation	Drug product, typically NDA or applicable OTC pathway
Electronic nicotine-delivery system	Tobacco product pathway under the Tobacco Control Act
Combination device delivering nicotine as a therapeutic drug	Drug-device combination pathway
Passive nicotine inhaler marketed for cessation	FDA drug review, depending on intended use and formulation

FDA authorization to market a tobacco product is not the same as approval as a smoking-cessation drug. FDA has separately regulated nicotine-replacement therapies and electronic nicotine-delivery products.[6][7]

Does biosimilar risk apply?

No. Biosimilar law is irrelevant to this patent.

The claims cover a nicotine delivery device and nicotine-bearing fluid. Nicotine is a small-molecule active ingredient, not a biologic subject to the Biologics Price Competition and Innovation Act. Any competitive risk would arise from generic drugs, authorized generics, alternative nicotine-replacement products, or competing tobacco products, not biosimilars.

What is the current patent strength of Patent 4,793,366?

Its current enforceability is zero because the patent expired. Its historical claim strength can be assessed as follows:

Factor	Assessment
Independent-claim breadth	Moderate to broad for passive nicotine devices
Structural specificity	Moderate; claim 1 allows several material forms
Functional limitations	Significant; suction-responsive volatilization is required
Polymer coverage	Stronger in claims 12-16 and 17-28
Product relevance	Highest for passive porous-matrix devices
Electronic-cigarette coverage	Fact-dependent and generally less direct
Current enforcement value	None
Prior-art value	Material for later porous nicotine delivery claims

The strongest claim limitation is the combination of microsized fluid reservoirs and suction-responsive volatilization. The weakest commercial fit is for products that rely on a conventional liquid tank and electrically heated wick rather than nicotine fluid retained in the claimed microsized reservoirs.

What patent landscape surrounds this technology?

The relevant landscape has four technical segments.

Passive nicotine inhalers

These patents generally claim cigarette-like tubes, mouthpieces, airflow channels, and nicotine-bearing inserts. Patent 4,793,366 is most closely aligned with this segment.

Porous-matrix delivery systems

This group includes patents directed to microporous polymers, cellular materials, loaded filaments, films, wicks, and controlled release from microscopic pores. Patent 4,793,366 is important because it expressly combines pore structure with nicotine vapor release.

Electronic nicotine-delivery systems

Later patents commonly focus on:

Resistive heating elements;
Liquid reservoirs;
Wicking structures;
Airflow sensors;
Battery control;
Aerosol temperature;
Nicotine salt formulations; and
Cartridge and pod interfaces.

Those claims may avoid direct overlap with Patent 4,793,366 by requiring electrical heating or by defining a reservoir as a bulk chamber rather than a microsized porous matrix.

Pharmaceutical nicotine-replacement products

Drug patents in this segment tend to claim dosage forms, nicotine salts, transdermal systems, nasal delivery, oral formulations, dose control, or cessation methods. They do not necessarily implicate the structural device claims of Patent 4,793,366.

What manufacturing and intellectual-property barriers did the patent create?

The historical manufacturing barrier was not merely the presence of nicotine. It was the integration of:

A microporous material;
Controlled pore size;
Uniform fluid loading;
Surface dryness after loading;
Controlled nicotine release;
Acceptable airflow resistance; and
A mouthpiece or cigarette-like housing.

Manufacturers would have needed to control fluid retention without blocking airflow. They also would have needed to avoid leakage, inconsistent dosing, excessive pressure drop, and premature evaporation.

The material claims could have increased design-around costs where a manufacturer used microporous polymer filaments or films. A design based on a separate liquid chamber and electrically heated atomizer would have had a clearer path around the literal material limitations.

What litigation and licensing issues affect the patent?

No current infringement litigation can be based on Patent 4,793,366 because the patent expired in 2005. The patent cannot support:

A new exclusionary lawsuit;
A preliminary injunction;
A damages claim for post-expiration conduct;
A Paragraph IV challenge;
An Orange Book listing; or
A current royalty demand based solely on patent rights.

The patent may still appear in prosecution histories, validity analyses, prior-art searches, or historical licensing files. Any settlement or license signed during the patent term would require review of its contractual terms, because contractual obligations can raise issues distinct from the expired patent right.

How does Patent 4,793,366 compare with modern nicotine-device patents?

Category	Patent 4,793,366	Modern electronic nicotine patents
Energy source	User suction	Battery or other heater
Nicotine storage	Microsized reservoirs in material	Tank, cartridge, pod, wick, or capsule
Vapor generation	Volatilization in response to suction	Heated aerosol generation
Main claim focus	Porous material and airflow housing	Heater, control circuit, sensor, cartridge, formulation
Device form	Tube, filament, film, cigarette-paper structure	Pod, tank, disposable, closed cartridge
Current patent status	Expired	Varies by patent and jurisdiction
FDA context	Historical device concept	Tobacco-product or drug-device regulation depending on claims and marketing

Key Takeaways

U.S. Patent 4,793,366 covers passive, non-pyrolytic nicotine delivery through a housing containing nicotine-loaded microsized reservoirs.
Claims 1 and 17 are the two independent claims.
Claim 1 is broader; claim 17 requires an elongated tube and polymer reservoir material.
Dependent claims cover microporous films, filaments, cigarette paper, hydrophobic materials, specified polymers, carrier fluids, and sub-10-micrometer reservoirs.
The patent expired on December 27, 2005.
It has no current Orange Book, Paragraph IV, biosimilar, or enforceable U.S. patent-exclusion effect.
Its remaining value is historical and analytical, particularly as prior art against porous nicotine-delivery and passive inhaler patents.
Modern electronic cigarettes often differ because they use electrically heated liquid reservoirs rather than suction-responsive nicotine-loaded porous materials.

FAQs

Can a company commercialize a nicotine inhaler covered by Patent 4,793,366?

Yes, the expired patent does not block commercialization. Separate unexpired patents, FDA requirements, tobacco-product requirements, trademarks, and formulation rights may still apply.

Does the patent cover nicotine salts?

Claim 24 expressly includes nicotine salts, but the patent’s expiration means that coverage has no current exclusionary effect in the United States.

Does a nicotine wick in an electronic cigarette infringe the patent?

Not automatically. The product would need to satisfy all relevant limitations, including microsized reservoirs containing nicotine-bearing fluid and volatilization in response to user suction. The expired status eliminates current infringement exposure from this patent.

Are foreign counterparts of Patent 4,793,366 still enforceable?

The U.S. patent does not establish the status of foreign counterparts. Patent rights are territorial, and each foreign application would have its own filing, grant, maintenance, and expiration history.

Can Patent 4,793,366 be cited against a later nicotine-device patent?

Yes. An expired patent can remain relevant prior art. Its claims, specification, drawings, and disclosure may be used in novelty, obviousness, claim-construction, and freedom-to-operate analyses.

References

United States Patent No. 4,793,366, Nicotine dispensing device (U.S. Patent and Trademark Office, Dec. 27, 1988).
U.S. Patent and Trademark Office. (n.d.). Patent Center. https://patentcenter.uspto.gov/
35 U.S.C. § 154. Patent term.
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
21 U.S.C. § 355(j). Abbreviated applications for new drugs.
U.S. Food and Drug Administration. (n.d.). Nicotine replacement therapy products. https://www.fda.gov/drugs/information-drug-class/nicotine-replacement-therapy-products
U.S. Food and Drug Administration. (n.d.). Tobacco products: Marketing and advertising. https://www.fda.gov/tobacco-products/compliance-enforcement-training/marketing-and-advertising-tobacco-products

Details for Patent: 4,793,366

Summary for Patent: 4,793,366