US Patent 4,971,800: Claim Scope, Patent Expiration, FDA Status and Competitive Landscape

US Patent 4,971,800 covers topical compositions and application methods using hydroxy-terminated urethane compounds to improve the adherence of products applied to hair or skin. The patent issued on November 20, 1990, and its statutory US term has expired. It therefore does not currently create a US patent barrier to generic, cosmetic, sunscreen, insect-repellent, haircare, or topical-drug products, although separate patents, regulatory requirements, trade secrets, or foreign rights may still affect commercialization. [1][2]

What does US Patent 4,971,800 protect?

The patent protects two related subject matter categories:

A topical composition containing:
- A topical carrier; and
- A defined hydroxy-terminated urethane compound.
A method of applying that composition to hair or skin to facilitate adherence of another agent.

The patent is a platform technology patent. It does not claim a particular drug active ingredient, sunscreen active, insecticide, cosmetic active, or haircare molecule.

Independent claims 1 and 9

Claim	Category	Required elements
1	Composition	Topical composition, topical carrier, and hydroxy-terminated urethane compound within specified structural and molecular-weight limits
9	Method	Applying the claimed type of composition to hair or skin

Claim 1 is directed to the composition itself. Claim 9 is directed to conduct involving application of the composition.

Both claims use “comprising,” which generally makes them open-ended. A product can contain additional ingredients and still fall within the claim if it includes the required carrier and hydroxy-terminated urethane compound.

How broad is the hydroxy-terminated urethane limitation?

The central limitation is a Markush-style structural definition. The claim permits substantial variation in the urethane compound.

Claimed structural variables

Variable	Claimed scope
R	Alkylene or alkenylene radical with 1 to about 20 carbon atoms
R	Cycloalkylene or cycloalkenylene radical with about 5 to about 10 carbon atoms
R	Mononuclear or fused-ring arylene radical with about 6 to about 10 carbon atoms
R substitution	Lower alkyl, lower alkoxy, lower alkoxy-substituted lower alkyl, nitro, amino, or halogen substituents
R1	Same or different alkylene or alkenylene radical
m	Selected to produce an O-R1 moiety with molecular weight from about 40 to about 6,000
n and n'	Same or different integers from 0 to 30
Total compound molecular weight	Up to about 200,000 in claim 1; 220 to 200,000 in claim 9

The claim language reaches both relatively small urethane compounds and high-molecular-weight polymeric or oligomeric materials. The breadth comes from the permitted variation in R, R1, m, n, n', and the open-ended composition language.

The issued patent’s structural drawings are necessary to determine the precise placement of the terminal hydroxyl groups and urethane linkages. The supplied claim text establishes the relevant scope but does not reproduce the chemical figures.

What does “hydroxy-terminated” require?

The compound must have terminal hydroxyl functionality as specified by the patent’s structural formula. A molecule that contains hydroxyl groups internally but does not satisfy the claimed terminal arrangement may fall outside the claim.

The claim is not limited to a single molecular weight or a single commercial polymer. It covers a defined class of compounds meeting both the structural formula and molecular-weight requirements.

What do dependent claims 2 through 8 cover?

Claims 2 through 8 narrow composition claim 1 by imposing additional molecular-weight, carrier, product-category, and concentration limitations.

Claims	Limitation
2	n and n' are each 0
3	O-R1 moiety has a molecular weight of about 40 to 6,000; total compound molecular weight is about 220 to 37,000
4	O-R1 moiety has a molecular weight of about 400 to 2,000; total compound molecular weight is about 1,000 to 15,000
5	Carrier is a liquid or nonliquid carrier, gel, cream, ointment, lotion, aerosol, or emulsifier
6	Composition is a cosmetic, sunscreen, insect repellent, or haircare agent
7	Urethane compound is present at about 3 wt.% to 90 wt.%
8	Urethane compound is present at about 10 wt.% to 25 wt.%

Claim 8 is a narrower concentration range within claim 7. A product containing 10 wt.% to 25 wt.% of the claimed urethane compound could satisfy both claims if all other limitations are met.

Claims 5 and 6 do not limit the carrier or product category to one specific commercial formulation. The listed forms and uses operate as narrowing examples within the broader composition claim.

What do method claims 10 through 16 cover?

Claims 10 through 16 mirror the composition claims but require application to hair or skin.

Claims	Limitation
10	n and n' are each 0
11	O-R1 moiety has a molecular weight of about 40 to 6,000; total compound molecular weight is about 220 to 37,000
12	O-R1 moiety has a molecular weight of about 400 to 2,000; total compound molecular weight is about 1,000 to 15,000
13	Carrier is a liquid or nonliquid carrier, gel, cream, ointment, lotion, aerosol, or emulsifier
14	Composition is a cosmetic, sunscreen, insect repellent, or pharmaceutically active agent
15	Urethane compound is present at about 3 wt.% to 90 wt.%
16	Urethane compound is present at about 10 wt.% to 25 wt.%

The method claims are potentially broader in commercial application than the composition claims because claim 14 expressly includes a pharmaceutically active agent. A formulation manufacturer and a party applying the formulation could have presented separate infringement questions while the patent was enforceable.

What is the practical infringement scope of the independent claims?

A product would generally need to satisfy each of the following elements to fall within claim 1:

It is a locally administrable topical composition.
It contains a topical carrier.
It contains a compound meeting the claimed hydroxy-terminated urethane structure.
The compound satisfies the specified R, R1, m, n, n', and molecular-weight limitations.

For claim 9, the additional conduct requirement is application to hair or skin.

The claims do not require:

A named active pharmaceutical ingredient.
A particular disease indication.
A specific dosage form.
A particular release profile.
A particular penetration-enhancement mechanism.
A specific commercial brand.
A specific manufacturing process.
A specific carrier concentration in the independent claims.
A particular route other than topical application to hair or skin.

The claims are therefore broad at the formulation-platform level but narrow at the chemical-structure level. A formulation that uses a different adhesion polymer, a nonurethane polymer, or a urethane compound outside the claimed structural and molecular-weight ranges would not necessarily fall within the claims.

When did US Patent 4,971,800 lose exclusivity?

US Patent 4,971,800 issued on November 20, 1990. Because it was filed before the modern 20-year-from-earliest-effective-filing-date regime, its ordinary US term was generally 17 years from grant, subject to statutory exceptions such as a terminal disclaimer. On that basis, the patent term ended on November 20, 2007. [1][2]

Event	Date
US patent grant	November 20, 1990
Ordinary pre-1995 patent term	17 years from grant
Expected statutory expiration	November 20, 2007
Current US enforceability	Expired

The patent cannot now be used to block a US product launch based on conduct occurring after expiration. A party also does not need a Paragraph IV certification against an expired patent merely because the patent once covered a formulation technology.

What is the Orange Book status of US Patent 4,971,800?

US Patent 4,971,800 is not an Orange Book drug patent in the ordinary sense.

The patent claims a topical formulation platform rather than an FDA-approved drug product. Its claims do not identify a specific active ingredient, approved dosage form, or approved drug product for listing in the Orange Book. FDA Orange Book patent listings are associated with approved drug products and submitted patent information under the Hatch-Waxman framework. [3]

Regulatory implications by product category

Product type	Likely US regulatory framework	Relevance of Patent 4,971,800
Topical prescription drug	FDA drug approval pathway	Patent itself is expired and is not an Orange Book barrier
OTC sunscreen	FDA OTC monograph or approved application, depending on product	Regulatory compliance remains separate from patent rights
Insect repellent	EPA pesticide registration in many cases	Patent does not replace EPA requirements
Cosmetic or haircare product	FDA cosmetic framework, generally without premarket approval	Patent expiration removes this patent-based exclusion
Generic topical drug	ANDA or other applicable FDA pathway	No current Paragraph IV challenge is needed against this expired patent

The expired patent may still appear in technical literature or historical patent searches, but it should not be treated as an active Orange Book-listed patent.

What Paragraph IV challenges and litigation affect this patent?

A Paragraph IV certification is an ANDA mechanism used when a generic applicant asserts that a listed patent is invalid, unenforceable, or not infringed. It is relevant to patents listed for an approved drug product, not to an expired standalone formulation patent with no identified Orange Book listing. [3]

No current Paragraph IV pathway is apparent for US Patent 4,971,800. The patent expired in 2007, so it cannot support a current Hatch-Waxman 30-month stay or a new infringement action based solely on ordinary post-expiration commercial activity.

The supplied record does not identify:

A patent litigation case involving US 4,971,800.
A Paragraph IV notice letter.
A generic settlement agreement.
A covenant not to sue.
A terminal disclaimer.
A post-grant validity proceeding.
A listed drug product associated with the patent.

Any historical litigation analysis would require separate court-docket and assignment-record evidence. The patent’s expiration independently resolves the present US exclusionary-rights issue.

How strong was the patent estate, and how strong is it now?

Historical strength

The patent had meaningful breadth during its enforceable term because:

Claims 1 and 9 covered both compositions and application methods.
The claimed urethane class permitted variation in the central organic radicals.
The claims covered multiple topical carriers.
The claims reached cosmetics, sunscreens, insect repellents, haircare products, and pharmaceutical applications.
Independent claims did not impose a narrow concentration range.
The claims did not depend on one active ingredient.

The main technical vulnerability would have been proving that the accused material matched the structural formula and molecular-weight limitations. Product-by-product chemical analysis would have been important.

Current strength

The patent has no remaining US exclusionary strength because its ordinary term ended in 2007. Its remaining commercial value is limited to:

Historical disclosure.
Prior-art value.
Technical know-how that may not be fully disclosed in the patent.
Potential foreign rights, if any existed and remain unexpired.
Patent-family members with distinct claims, if any were granted and remain enforceable.

The patent itself does not claim manufacturing methods. It therefore does not independently create a manufacturing-process barrier.

What formulation patents are relevant around this technology?

A modern freedom-to-operate analysis would separate the expired claims from potentially active rights in four categories.

Polymer and excipient patents

Later patents may claim:

Specific hydroxy-terminated polyurethane structures.
Particular polyurethane molecular-weight distributions.
Crosslinked or branched urethane systems.
Adhesion-promoting polymers with defined functional groups.
Polymer blends with silicones, acrylics, cellulose derivatives, or other film formers.

Formulation patents

Separate patents may cover:

Sunscreen formulations containing a particular UV filter combination.
Hair products using a specified film-forming polymer.
Aerosol compositions.
Emulsion systems.
Water-resistant topical products.
Controlled-release or residence-time formulations.

Method-of-use patents

Later rights could target:

Improving residence time on skin.
Increasing water resistance.
Enhancing delivery of a named active.
Treating a particular dermatological condition.
Applying the composition in a defined sequence or dosage.

US 4,971,800 does not prevent these later claims from existing, but its expired disclosure may be relevant prior art against later patentability.

Manufacturing and process rights

The patent does not claim a synthesis process. Active process patents may instead cover:

Preparation of particular diisocyanate or polyol intermediates.
Catalyst systems.
Solvent-free polymerization.
Molecular-weight control.
Purification methods.
Scale-up and batch-control processes.

Trade secrets may also affect commercial sourcing even where no active patent blocks use of the finished compound.

How does US Patent 4,971,800 compare with a modern topical drug patent?

Issue	US 4,971,800	Modern topical drug patent
Claimed subject matter	Urethane-containing topical platform	Often a specific active, formulation, device, or method
Active ingredient	Not specified	Usually identified
Regulatory linkage	No apparent Orange Book product linkage	Often linked to an approved drug
Claim format	Composition and method	Composition, method, dosage, device, or manufacturing claims
Patent status	Expired in 2007	May remain active depending on filing date and extensions
Generic challenge	No current Paragraph IV need	Paragraph IV may be central
Biosimilar relevance	None	Relevant only to biologic products
Manufacturing coverage	Not claimed in supplied claims	May be separately claimed
Current US market barrier	None from this patent	Potentially significant

What generic launch risks exist?

US Patent 4,971,800 presents no current generic-launch risk by itself. A company can commercialize a topical product using a compound within the historical claim scope without infringing this expired patent.

The relevant remaining risks are external to this patent:

Later patents covering the same or a related urethane compound.
Formulation patents directed to a specific active ingredient.
Method-of-use patents for a dermatological or pharmaceutical indication.
Active patents covering a sunscreen, insect repellent, or drug active.
Process patents covering commercial manufacture.
Foreign patents in jurisdictions where a corresponding right remained active.
Regulatory exclusivity or approval requirements unrelated to patent term.
Trade-secret restrictions involving proprietary manufacturing or formulation know-how.

For an ANDA product, an applicant would ordinarily review current Orange Book listings for the reference product, not rely solely on the status of this historical patent. [3]

What licensing deals or commercial rights are associated with the patent?

No licensing agreement, assignment, royalty arrangement, or commercial partnership is identified in the supplied claim record. The patent’s expiration also means that an exclusive US license cannot restore the expired patent rights.

A historical license could still matter for:

Confidential know-how.
Technical data.
Foreign patent rights.
Contractual restrictions unrelated to patent enforceability.
Improvements covered by later patents.

No such rights can be attributed to US Patent 4,971,800 from the claims alone.

What is the geographic coverage of this patent?

US Patent 4,971,800 provided rights only in the United States. A US patent does not establish protection in Canada, Europe, Japan, China, or other jurisdictions.

Foreign coverage would require confirmation of:

International or PCT filings.
National-stage applications.
Foreign grants.
Expiration dates.
Maintenance status.
Terminal disclaimers or local term adjustments.

The expired US right cannot be used to restrict manufacture, sale, use, or importation in the United States today.

Key Takeaways

US Patent 4,971,800 is a topical formulation-platform patent covering hydroxy-terminated urethane compounds.
Independent claims 1 and 9 cover compositions and methods, respectively.
The claims span cosmetics, sunscreens, insect repellents, haircare products, and pharmaceutical topical applications.
The compound definition is broad in its permitted organic radicals, polymer length, and molecular weight.
The claims do not identify a specific drug active ingredient or approved drug product.
The patent issued November 20, 1990, and its ordinary US term ended November 20, 2007.
It is not an effective current US patent barrier and does not create a current Paragraph IV or Orange Book risk.
No biosimilar issue applies because the patent does not cover a biologic.
Current commercialization risk must be assessed against later formulation, active-ingredient, method-of-use, manufacturing, and foreign patents.
The patent does not claim a manufacturing process in the supplied claims.

FAQs About US Patent 4,971,800

Can a company use the urethane compounds claimed in US 4,971,800 today?

Yes, in the United States, the patent’s term expired in 2007. Use may still implicate later patents, regulatory requirements, or foreign rights.

Does US Patent 4,971,800 cover sunscreen products?

Yes. Claim 6 expressly identifies sunscreens, and claim 14 includes pharmaceutical active-agent compositions. The patent covers the specified urethane-containing composition, not every sunscreen product.

Does the patent cover a specific topical drug?

No. The claims do not identify a particular active ingredient, approved drug, indication, or brand.

Is a Paragraph IV certification required for this patent?

No current Paragraph IV certification is required against an expired patent that is not being used as an active Orange Book-listed patent.

Can this patent block a polyurethane-based topical formulation outside the United States?

The US patent cannot. Foreign blocking rights would depend on separate patents and their local expiration and maintenance status.

Does the patent protect the manufacture of the claimed urethane compounds?

Not under the supplied claims. The claims cover compositions and application methods, not a synthesis or manufacturing process.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	115553	⤷ Start Trial
Canada	1331861	⤷ Start Trial
Germany	3852437	⤷ Start Trial
European Patent Office	0299758	⤷ Start Trial
Spain	2065912	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,971,800

Summary for Patent: 4,971,800