United States Drug Patent 4,393,871: Claims, Scope, Expiration, and Vaginal Sponge Patent Landscape

U.S. Patent No. 4,393,871 covers a vaginal sponge made from water-catalyzed foamed urethane that slowly releases a spermicide or other locally administered drug. Its principal technical limitations are the polyurethane sponge matrix, a foaming agent concentration of approximately 10% to 50% by dry weight, controlled release during vaginal use, and, in selected claims, a flattened-ball shape with a cervical recess.

The patent issued on July 19, 1983. Under the pre-1995 U.S. patent-term regime, its 17-year term from issuance ended on July 19, 2000, absent a later adjustment or unusual term event. The patent is therefore expired and cannot presently support an infringement action or block generic, OTC, or device competition. The patent also does not create current Orange Book exclusivity or biosimilar protection.

What does U.S. Patent 4,393,871 protect?

The patent protects three related subject-matter groups:

Claim group	Claims	Protected subject matter
Vaginal devices	1-11	Polyurethane vaginal sponges containing spermicide or another local drug
Manufacturing methods	12-23	Forming the sponge by mixing drug or spermicide with a water-catalyzed urethane prepolymer
Use method	24	Vaginal administration of an effective amount of drug using the device of claim 2

The core invention is a drug-loaded, flexible polyurethane foam designed for vaginal insertion, retention, and gradual release. The claims are directed to a device and its manufacturing process rather than to a new chemical entity.

The central independent device claim is claim 1. It requires:

A vaginal device adapted for insertion and removal;
A spermicide-foaming agent;
The spermicide-foaming agent at approximately 10% to 50% dry weight; and
A water-catalyzed foamed urethane polymer that slowly releases the spermicide during use.

Claim 9 provides a broader local-drug formulation. It replaces the required spermicide with a drug and a foaming agent. Claim 17 returns to a spermicide-specific manufacturing method.

How are the claims organized?

Claims 1-8: Spermicide vaginal device

Claims 1-8 focus on a spermicide-containing polyurethane sponge.

Claim 1 is the principal composition and device claim. Claims 2 and 3 add, respectively:

A second drug for local delivery; and
A non-toxic acid that lowers the device pH to approximately 4.0 to 5.0.

Claim 4 requires at least 30% dry weight spermicide-foaming agent. Claim 8 repeats substantially the same limitation, requiring at least 30% dry weight. The duplication appears to provide no meaningful additional technical scope unless the original prosecution history assigned different amendments or claim dependencies.

Claim 5 limits the spermicide-foaming agent to nonylphenoxy polyethoxyethanol. This wording is chemically broad relative to a specific ethoxylate homolog such as nonoxynol-9. Literal infringement would depend on the precise identity, average ethoxylation, nomenclature, and product composition.

Claim 6 requires a urethane polymer water-catalyzed from an isocyanate-capped hydrophilic polyoxyethylene polyol.

Claim 7 limits the device to a flattened-ball configuration with a recess contoured to fit over the cervical os.

Claims 9-11: Local drug delivery

Claim 9 is an independent device claim directed to local vaginal drug delivery. It requires:

A vaginal device;
A locally delivered drug;
A foaming agent at approximately 10% to 50% dry weight; and
A water-catalyzed foamed urethane polymer that slowly releases the drug.

Claim 10 identifies five drug classes:

Anti-infectives;
Anti-inflammatories;
Estrogenic steroids;
Progestational agents; and
Prostaglandins.

Claim 11 adds the flattened-ball and cervical-recess configuration.

The claim does not require a particular active ingredient, therapeutic indication, release rate, drug loading, or duration. Its breadth is constrained by the requirement that the product be a water-catalyzed urethane foam and that the drug be slowly released during use.

Claims 12-23: Manufacturing methods

Claims 12 and 17 are the principal process claims.

Claim 12 requires mixing:

Approximately 10% to 50% dry weight foaming agent;
A water-catalyzed, foam-forming urethane prepolymer; and
A dry local-delivery agent,

followed by foaming into a stable, flexible, sponge-like structure.

Claim 17 is narrower in subject matter but independent in form. It requires a spermicide-foaming agent mixed with the urethane prepolymer and subsequent formation of a sponge from which the spermicide is slowly released.

The dependent process claims add:

Isocyanate-capped hydrophilic polyoxyethylene polyol;
Nonylphenoxy polyethoxyethanol;
At least 30% dry-weight spermicide;
A second local-delivery drug;
Acidification to a pH of approximately 4.0 to 5.5; and
The flattened-ball cervical-recess design.

These process claims could have been relevant to a competing manufacturer even if the final product differed in shape. They are now expired.

What formulations are protected by U.S. Patent 4,393,871?

The patent covers formulations with the following architecture:

Formulation element	Scope
Matrix	Water-catalyzed foamed urethane polymer
Polymer precursor	In selected claims, isocyanate-capped hydrophilic polyoxyethylene polyol
Active or functional agent	Spermicide, other vaginal drug, or both
Foaming-agent concentration	Approximately 10% to 50% dry weight
Narrow concentration	At least 30% dry weight in claims 4, 8, and 20
pH option	Approximately 4.0-5.0 or 4.0-5.5
Release profile	Slow release during vaginal use
Physical form	Optional flattened ball with cervical recess

The broadest practical product concept is a locally drug-loaded polyurethane vaginal sponge. The patent does not cover every vaginal insert, every spermicide formulation, or every controlled-release vaginal dosage form. A product based on a non-urethane matrix, a non-foamed polymer, a tablet, gel, ring, film, capsule, or bioadhesive system would generally fall outside the literal core of these claims.

How broad is the nonylphenoxy polyethoxyethanol limitation?

Claim 5 and claim 19 identify nonylphenoxy polyethoxyethanol as the spermicide. This is a class description rather than a highly precise single-molecule definition because commercial nonylphenol ethoxylates can contain distributions of ethoxylation levels.

The claim is narrower than claim 1 because it requires the specified chemical class. It is also potentially vulnerable to claim-construction disputes over:

The number of oxyethylene units;
Whether the claim covers a distribution of homologs;
Whether a commercial nonoxynol product satisfies the chemical identity;
Whether the material functions as both spermicide and foaming agent; and
Whether the formulation contains the claimed amount on a dry-weight basis.

A competing product using a chemically distinct surfactant or a non-foaming active would not necessarily satisfy this limitation. That distinction would have mattered during the patent term, but it has no current enforcement effect because the patent expired.

What is the significance of the slow-release limitation?

The device claims require that the polymer release the active agent slowly during use. This is both a technical limitation and a potential infringement issue.

The patent does not specify:

A numerical release rate;
A required release duration;
A pharmacokinetic threshold;
A required percentage released;
A dissolution test; or
A specific in-vitro assay.

That lack of numerical precision could create claim-construction disputes. The limitation would likely be evaluated through the product’s composition, physical structure, water uptake, release testing, and intended vaginal performance. A product that contains the same components but releases the active immediately may argue that it does not meet the slow-release limitation.

The phrase also limits the claims against products that merely contain drug in a polyurethane foam without demonstrating sustained or gradual vaginal release.

When did U.S. Patent 4,393,871 lose exclusivity?

Event	Date or status
Patent issued	July 19, 1983
Statutory term under pre-1995 law	17 years from issuance
Expected expiration	July 19, 2000
Current enforceability	Expired
Orange Book exclusivity	None
Biosimilar exclusivity	Not applicable
Current Paragraph IV exposure	None for this expired patent

The patent was governed by the pre-1995 U.S. patent term generally calculated as 17 years from grant. The current 20-year-from-earliest-effective-filing-date rule does not ordinarily apply to a patent issued from an application filed before June 8, 1995, unless the transition rules produce a different result. The USPTO patent record should be treated as the controlling source for the final legal-status entry and any term adjustment or disclaimer information.[1][2]

Expiration removes the exclusionary right. It does not erase the patent’s historical relevance, prosecution history, technical disclosures, or potential prior-art effect against later patent applications.

What is the Orange Book status of U.S. Patent 4,393,871?

U.S. Patent 4,393,871 is not an Orange Book drug patent. The Orange Book lists patents submitted for approved drug products under the Federal Food, Drug, and Cosmetic Act. A polyurethane vaginal sponge containing a spermicide or other local drug is primarily a drug-device combination or vaginal delivery product, not a conventional small-molecule prescription drug listing.

The patent therefore does not provide:

An Orange Book patent listing;
A 30-month stay;
Hatch-Waxman patent certification rights;
A current regulatory exclusivity period; or
A listed patent barrier against an ANDA applicant.

If a later product received FDA approval as a drug, device, or combination product, the relevant patents would depend on that product’s approval pathway and FDA listing records rather than on this expired patent.[3][4]

Were Paragraph IV challenges or settlements associated with this patent?

A Paragraph IV certification is generally relevant to an unexpired Orange Book-listed patent. U.S. Patent 4,393,871 expired in 2000 and was not a current Orange Book barrier after expiration.

Accordingly:

A present Paragraph IV challenge cannot create a new litigation stay based on this patent.
A later generic or OTC competitor cannot be blocked by this patent.
Any historical challenge would have had to occur before expiration and in connection with a listed drug product.
The patent itself does not establish a settlement, reverse-payment agreement, or launch license.

A patent assignment or product acquisition would not, by itself, prove a license agreement. License terms would typically appear in separate contractual records, SEC filings, court documents, or transaction disclosures.

What patent litigation affects U.S. Patent 4,393,871?

The patent’s expiration eliminates current infringement litigation risk based on the patent. Historical litigation, if any, would have concerned the patent during its enforceable term and could have involved:

Whether a competing vaginal sponge used a water-catalyzed polyurethane;
Whether the active concentration fell within the 10%-50% range;
Whether the product slowly released the active;
Whether the product included the claimed cervical recess;
Whether a manufacturer practiced the claimed foaming process; and
Whether the claims were anticipated or obvious over earlier contraceptive sponges, polyurethane foams, surfactants, and vaginal drug-delivery systems.

No current freedom-to-operate conclusion should rely on this patent as an enforceable right. Its principal present value is historical and technical.

How strong was the patent estate?

The patent had meaningful claim coverage during its term because it combined composition, device, process, and use claims. Its strongest features were:

Coverage of both spermicide and broader local-drug embodiments;
Alternative device and manufacturing claims;
A defined dry-weight loading range;
Specific polyurethane chemistry;
Optional pH control;
Cervical placement geometry; and
Slow-release functionality.

Its weaknesses included:

Repeated and overlapping claim language;
Functional release limitations without numerical testing criteria;
Potential ambiguity in chemical nomenclature;
Broad drug-class language in claim 10;
Possible written-description and enablement issues for the full range of claimed drugs; and
Dependence on a particular foam chemistry that could be designed around.

The claims would have been stronger against products closely replicating the claimed polyurethane sponge and loading range. They would have been weaker against non-urethane delivery systems, non-foamed vaginal products, alternative dosage forms, and products using a different controlled-release mechanism.

How does this patent compare with competing vaginal delivery technologies?

Technology	Typical dosage form	Relationship to Patent 4,393,871
Polyurethane contraceptive sponge	Drug-loaded foam	Directly aligned with the patent’s core concept
Vaginal gel	Semisolid gel	Generally outside the polyurethane sponge claims
Vaginal tablet	Compressed solid	Generally outside the foam claims
Vaginal ring	Elastomeric ring	Outside the flattened sponge architecture
Vaginal film	Thin polymeric film	Usually outside the claimed sponge structure
Vaginal insert	Solid or polymeric insert	Depends on whether it uses the claimed foamed urethane
Bioadhesive system	Mucoadhesive polymer	Usually outside unless it uses the claimed matrix

The patent’s commercial concept is closest to contraceptive vaginal sponges containing nonoxynol-type spermicide. It is less relevant to modern vaginal rings, inserts, films, tablets, gels, and nanoparticle or mucoadhesive delivery systems.

What generic launch risks exist?

There is no current generic launch risk created by this patent because it expired more than two decades ago. A competitor evaluating a modern vaginal product should instead assess:

Later patents on the active ingredient or formulation;
Device patents covering geometry, applicators, or retention systems;
Manufacturing patents covering foam formation or drug loading;
Regulatory exclusivity for the approved product;
Trade-secret protection for processing conditions;
Trademark and trade-dress rights; and
Product liability and quality-system requirements.

A product that reproduces the historical technology can launch without a license from the owner of U.S. Patent 4,393,871, subject to other unexpired rights and applicable FDA requirements.

Does the patent create biosimilar risk?

No. Biosimilar provisions apply to biological products, not to a polyurethane vaginal sponge containing a spermicide or conventional locally delivered drug. The relevant competitive pathways would be generic drug, OTC monograph, 505(b)(2), device, or combination-product pathways, depending on the active ingredient and FDA classification.

What manufacturing and intellectual-property barriers remain?

The expired patent does not remove all barriers. A commercial product may still require:

Validated polyurethane mixing and foaming conditions;
Control of residual isocyanates;
Uniform drug distribution;
Reproducible pore size and density;
Release-rate testing;
Microbiological controls;
Biocompatibility testing;
Packaging and shelf-life studies;
Vaginal irritation and sensitization testing; and
FDA classification and labeling compliance.

Manufacturing know-how can remain commercially valuable even after patent expiration if it is maintained as a trade secret. Regulatory data, product specifications, supplier relationships, and quality systems can also create practical barriers without extending the patent term.

What geographic coverage does the patent provide?

The patent provided rights only in the United States. It did not automatically cover Canada, Europe, Japan, or other markets. Foreign protection would require separate national or regional patents, such as European, Canadian, or Japanese counterparts.

Because the U.S. patent expired in 2000, it provides no current territorial exclusion in the United States. Foreign counterparts would need separate status analysis, but any counterpart with a comparable early-1980s filing history would ordinarily also be expired.

Key Takeaways

U.S. Patent 4,393,871 covers drug-loaded, water-catalyzed foamed polyurethane vaginal sponges.
The principal limitations are a 10%-50% dry-weight foaming-agent range, slow release, and a vaginally insertable/removable sponge.
Dependent claims add nonylphenoxy polyethoxyethanol, pH control, specific polyurethane chemistry, drug classes, and a cervical recess.
Claims 12-23 extend coverage to manufacturing methods.
Claim 24 covers vaginal administration using the device of claim 2.
The patent issued July 19, 1983, and its expected 17-year term ended July 19, 2000.
It is not a current Orange Book patent and creates no present Paragraph IV or biosimilar risk.
Its current value is historical, technical, and prior-art related rather than exclusionary.
Modern competitors must examine later patents, FDA requirements, trade secrets, manufacturing know-how, and product-specific regulatory rights.

Frequently Asked Questions

Can a company make a polyurethane vaginal sponge without licensing U.S. Patent 4,393,871?

Yes. The patent’s term expired in 2000. A license is not required for this expired U.S. patent, although later patents and other intellectual-property rights must be reviewed.

Does using nonoxynol-9 infringe the patent today?

No current infringement action can be based on this expired patent. During its term, the analysis would have depended on whether the commercial nonoxynol product met the applicable chemical, concentration, polyurethane, and slow-release limitations.

Is the Today Sponge protected by U.S. Patent 4,393,871?

The claims are technically consistent with a contraceptive polyurethane sponge containing a nonoxynol-type spermicide. Patent coverage of a commercial product must be determined from the product’s formulation, manufacturing process, ownership history, and other patents, not from this patent alone.

Could a vaginal ring infringe U.S. Patent 4,393,871?

A conventional vaginal ring would generally not meet the claimed foamed urethane sponge limitations. A ring using a materially different polymer structure would ordinarily be outside the principal claim architecture.

Does patent expiration eliminate FDA approval requirements?

No. Patent expiration removes the patent barrier but does not remove FDA requirements for safety, effectiveness, manufacturing quality, labeling, or product classification.

References

U.S. Patent and Trademark Office. (1983). U.S. Patent No. 4,393,871, Vaginal device. https://patents.google.com/patent/US4393871
U.S. Patent and Trademark Office. (n.d.). Patent term adjustment and patent term provisions. https://www.uspto.gov/patents/laws/patent-term-calculator
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, commonly known as the 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.). Drug-device combination products. https://www.fda.gov/combination-products/about-combination-products
U.S. Code, 35 U.S.C. § 154. (2024). Contents and term of patent; provisional rights. https://www.law.cornell.edu/uscode/text/35/154

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	3746778	⤷ Start Trial
Australia	522989	⤷ Start Trial
Australia	549236	⤷ Start Trial
Australia	6426780	⤷ Start Trial
Canada	1122900	⤷ Start Trial
Canada	1163886	⤷ Start Trial
Germany	2862302	⤷ Start Trial
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Details for Patent: 4,393,871

Summary for Patent: 4,393,871