United States Patent 4,105,783: Claim Scope, Expiration, and Alpha-Hydroxy Acid Patent Landscape

U.S. Patent No. 4,105,783 covered topical treatment of dry skin using aqueous or aqueous-alcoholic reaction products formed from specified hydroxy acids and specified amine or ammonium bases. The patent issued on Aug. 8, 1978, and its original 17-year term expired on Aug. 8, 1995. It has no current exclusionary effect in the United States. The claims remain relevant as prior art and as the technical foundation for later alpha-hydroxy acid, or AHA, formulation patents.

What does U.S. Patent 4,105,783 protect?

U.S. Patent 4,105,783 protects a method of alleviating dry-skin symptoms by topically applying a non-irritating composition containing a therapeutically effective amount of a reaction product between a listed hydroxy acid or related keto acid and a listed base. The patent is generally associated with Eugene J. Van Scott, Ruey J. Yu, and Westwood Pharmaceuticals, Inc. [1]

The independent claim has five principal limitations:

Treatment of dry-skin symptoms in humans.
Topical application to affected body areas.
A non-irritating method.
A pharmaceutically acceptable vehicle.
A reaction product of one listed acid and one listed base.

The acid group includes glycolic acid, lactic acid, citric acid, malic acid, mandelic acid, tartaric acid, pyruvic acid, glucuronolactone, gluconolactone and related compounds. The base group includes ammonium hydroxide, primary, secondary and tertiary alkylamines, alkanolamines, diamines and substituted amines having alkyl or alkanol groups with one to eight carbon atoms.

The patent therefore targets a broad class of neutralized hydroxy-acid compositions rather than one commercial formulation.

What chemical products fall within the claim language?

The claimed "reaction product" most naturally encompasses salts or partially neutralized acid-base products formed in solution. Examples include:

Acid	Base	Likely product description
Glycolic acid	Ethanolamine	Monoethanolammonium glycolate or partially neutralized glycolate
Lactic acid	Triethanolamine	Triethanolammonium lactate or partially neutralized lactate
Citric acid	Ethanolamine	Ethanolamine citrate species
Glycolic acid	Ammonium hydroxide	Ammonium glycolate
Lactic acid	Diethanolamine	Diethanolammonium lactate

The claims do not require a defined stoichiometric salt, crystalline form, molecular weight, particle size or purity level. They also do not require that all acid be neutralized. The specification and dependent claims instead describe preparation in aqueous or alcoholic aqueous solution, with pH serving as a practical control.

That breadth creates two competing interpretations. A patent owner could argue that the claim covers the neutralized reaction product as present in the final topical formulation. An accused party could argue that the claim requires a chemically formed product, not merely a formulation containing free glycolic acid, lactic acid or another listed acid adjusted to a selected pH.

How many patents cover the core invention?

The central issued patent is U.S. Patent 4,105,783. Its legally important scope is now historical because the patent expired in 1995. Later AHA patents covered narrower formulations, cosmetic uses, delivery systems and combinations, but they do not revive the expired claims of the original patent.

Patent	Core subject matter	Current U.S. status
U.S. 4,105,783	Topical hydroxy-acid reaction products for dry skin	Expired
Later AHA formulation patents	Specific emulsions, concentrations, pH ranges, vehicles and cosmetic uses	Must be assessed individually
Later dermatologic-use patents	Treatment of acne, photodamage, keratoses, pigmentation and related conditions	Must be assessed individually
Later delivery and combination patents	Controlled release, encapsulation, retinoid combinations and other systems	Must be assessed individually

The relevant modern competitive question is therefore not whether a product practices U.S. Patent 4,105,783. It is whether the product practices a later unexpired patent claiming a particular formulation, use or delivery system.

What are the claim-by-claim limitations?

Claim 1: broad method claim

Claim 1 is the principal scope-bearing claim. It requires:

a human patient;
dry-skin symptom relief;
topical administration;
a non-irritating treatment;
an effective amount;
a pharmaceutically acceptable vehicle;
at least one listed acid or related compound;
at least one listed base;
preparation of the acid-base product in aqueous or alcoholic aqueous solution.

The claim does not specify a concentration, precise pH, dosage frequency, application area or treatment duration. It is broad in formulation selection but narrow in therapeutic purpose.

A product containing unneutralized glycolic acid in a vehicle may present a claim-construction dispute. The strongest noninfringement position would be that no claimed acid-base reaction product is made or present. The stronger infringement position would be that the product undergoes neutralization during manufacture or formulation and contains the resulting glycolate species.

Claims 2 and 3: concentration limitations

Claims 2 and 3 narrow claim 1 by requiring the reaction product to be present at:

1% to approximately 20% by volume under claim 2;
2% to approximately 10% by volume under claim 3.

These claims raise measurement issues. The patent uses volume percentages, while modern cosmetic and pharmaceutical formulations commonly rely on weight percentages. A claim analysis would need to determine whether the claimed percentage refers to the reaction-product solution, active acid equivalent, or the final composition.

Claim 4: enumerated acid-base combinations

Claim 4 narrows the broad Markush groups by listing specific bases, including:

ammonium hydroxide;
methylamine and ethylamine;
monoethanolamine and monoisopropanolamine;
ethylenediamine and 1,2-diaminopropane;
dimethylamine and diethylamine;
diethanolamine and diisopropanolamine;
N-methylethanolamine and N-ethylethanolamine;
triethylamine and triethanolamine;
N-methyldiethanolamine and triisopropylamine.

This claim is easier to map to a formulation than claim 1 because the base must fall within the express list.

Claims 5 and 6: vehicle and pH

Claim 5 limits the vehicle to water, ethanol and propylene glycol, with stated maximum concentrations of up to 99%, 70% and 30%, respectively. Claim 6 requires a pH from 3.5 to approximately 7.5.

These limitations reflect the patent's effort to balance keratolytic activity with tolerability. The pH range is broad enough to include mildly acidic, near-neutral and some partially neutralized products.

Claims 7 through 15: formulation examples

Claims 7 through 15 are narrow composition-specific method claims. They cover particular acid/base ratios and vehicles, including:

glycolic acid and ethanolamine in water;
lactic acid and triethanolamine in water;
mineral-oil and cottonseed-oil emulsions;
petrolatum, mineral oil, spermaceti and surfactant systems;
cetyl alcohol emulsions;
propylene glycol-containing vehicles;
mixed citric, lactic and glycolic acid systems.

These claims have substantially narrower practical scope than claim 1. They are most relevant to historical products or products closely reproducing the stated recipes.

When did U.S. Patent 4,105,783 lose exclusivity?

The patent expired on Aug. 8, 1995, 17 years after issuance. The patent was issued under the pre-Uruguay Round patent term regime, under which the term generally ran for 17 years from grant rather than 20 years from the earliest effective filing date. [1, 2]

Event	Date
U.S. patent application	Feb. 17, 1976, according to public patent records
Patent issued	Aug. 8, 1978
Original term	17 years from issuance
Expiration	Aug. 8, 1995
Current enforceability	None

No current patent term extension or regulatory exclusivity can extend this patent. Patent term extension under 35 U.S.C. §156 applies to qualifying regulatory delays and was not a mechanism for reviving an already expired pre-1995 patent. [2]

What is the Orange Book status of U.S. Patent 4,105,783?

U.S. Patent 4,105,783 is not an operative Orange Book patent today. The Orange Book lists patents and exclusivity information submitted for approved drug products, not every patent covering a dermatologic or cosmetic ingredient. [3]

The patent is unlikely to have had modern Orange Book significance because:

it expired in 1995;
the claims are method claims for dry-skin treatment;
AHA products have often been marketed as cosmetics rather than approved prescription drugs;
the patent does not identify a current approved drug product or New Drug Application.

An AHA product making therapeutic claims such as treating a disease, restoring abnormal skin function or acting as a drug may fall within FDA drug regulation even if the product is sold over the counter. Product classification depends on intended use and labeling, not only on the ingredient. [4]

Are there Paragraph IV challenges to this patent?

No current Paragraph IV challenge is relevant to U.S. Patent 4,105,783 because the patent expired almost three decades ago. Paragraph IV certifications apply to patents listed in the Orange Book for an approved reference listed drug. A generic applicant may certify that an Orange Book patent is invalid, unenforceable or will not be infringed, but there is no live exclusivity period associated with this expired patent. [3, 5]

Historical generic or branded disputes involving AHA products would have depended on later patents, trademarks, regulatory status or product-specific formulation rights rather than the continuing enforceability of U.S. 4,105,783.

What patent litigation affects the patent?

There is no current infringement litigation that can be based on enforceable claims of U.S. Patent 4,105,783. The patent's expiration eliminates injunctive and damages exposure for post-expiration conduct.

For historical due diligence, the key distinction is between:

litigation involving this patent itself;
litigation involving later AHA patents;
trademark disputes involving product names;
FDA enforcement concerning drug versus cosmetic claims.

A later patent holder cannot use an unexpired continuation, improvement patent or formulation patent to extend the term of U.S. 4,105,783's broad expired claims. It can enforce only the claims of the later patent, subject to validity, infringement and prosecution-history limitations.

How strong is the patent estate for glycolic acid and lactic acid products?

The estate surrounding glycolic acid and lactic acid has historically been commercially important but is fragmented. The original patent was technically broad because it covered many acids, bases and vehicles. Its present patent strength is zero in the United States because the claims are expired.

Risk category	Assessment for U.S. 4,105,783
Core ingredient risk	None from this patent
Neutralized AHA formulation risk	None from this patent
Dry-skin method risk	None from this patent
Specific emulsion risk	None from this patent
Later formulation patents	Requires separate review
Foreign equivalents	Requires country-by-country status review
FDA classification risk	Remains relevant independently of patent status
Trademark and trade dress risk	Separate commercial issue

The most important surviving barriers may arise from proprietary manufacturing processes, supply agreements, trademarks, clinical data, packaging and regulatory positioning rather than the expired patent.

What generic launch risks exist?

A generic or private-label company can generally launch a product that practices the expired claims, assuming compliance with applicable FDA, state and international requirements. The remaining risks are product-specific.

FDA and labeling risks

A product marketed for moisturizing or improving the appearance of dry skin may be regulated as a cosmetic. A product marketed to treat a dermatologic condition may be a drug. The intended-use distinction can affect:

establishment registration;
drug listing;
current good manufacturing practices;
active and inactive ingredient treatment;
labeling;
adverse-event obligations;
OTC monograph eligibility or approval requirements.

FDA has addressed the safety and use of alpha hydroxy acids in cosmetics, including concentration, pH and sun-sensitivity considerations. FDA has also warned that AHA products can increase skin sensitivity to sunlight. [4, 6]

Later patent risks

A launch assessment should focus on whether the product uses:

a patented concentration range;
a patented pH range in combination with an AHA;
a specific emulsion or delivery system;
a combination with retinoids, hydroquinone or other active ingredients;
a patented treatment method;
encapsulated or controlled-release AHA particles;
proprietary manufacturing or stabilization techniques.

Those rights may be unexpired even though the foundational patent is not.

Does the patent have geographic coverage outside the United States?

U.S. Patent 4,105,783 has no current enforceable U.S. coverage. Foreign counterpart rights, if any, must be assessed by jurisdiction and family member. A U.S. expiration date does not establish the status of patents in Europe, Canada, Japan, China or other markets.

For international launch planning, the relevant checks are:

priority and family records;
national filing and grant dates;
local patent-term rules;
annuity payment history;
terminal disclaimers;
supplementary protection certificates;
later national patents claiming formulations or uses.

The original technology is old enough that corresponding foreign rights would generally be expected to have expired, but a definitive foreign-status conclusion requires review of each national record.

What manufacturing and intellectual-property barriers remain?

The expired patent does not prevent manufacture of glycolate, lactate or related AHA formulations. Manufacturing barriers may still arise from:

control of neutralization heat;
pH and free-acid management;
emulsion stability;
preservative compatibility;
odor and color control;
raw-material specifications;
microbial control;
packaging compatibility;
validated claims support;
proprietary commercial processes.

A formulation that uses the same acid, base and vehicle categories described in the patent is not, by that fact alone, infringing any current U.S. patent. The commercial product may still infringe a later patent if it uses a newer formulation architecture or treatment combination.

How does this patent compare with later AHA patents?

U.S. Patent 4,105,783 is broader at the ingredient and method level but older and expired. Later AHA patents are typically narrower but may remain commercially relevant because they claim specific combinations or performance characteristics.

Issue	U.S. 4,105,783	Later AHA patents
Claim focus	Broad acid-base reaction products for dry skin	Specific formulation, use or delivery
Claim format	Method claims with Markush groups	Often composition, method or system claims
pH limitation	Broad, 3.5 to about 7.5 in claim 6	Often narrower and product-specific
Vehicle coverage	Broad in claim 1; specified in dependent claims	Usually defined by exact excipients or ratios
Legal status	Expired Aug. 8, 1995	Varies by patent
Launch relevance	Prior art only	Potentially material
Biosimilar relevance	None	None unless tied to a biologic product

Key Takeaways

U.S. Patent 4,105,783 covered topical dry-skin treatment with neutralized or partially neutralized hydroxy-acid products.
Claim 1 is broad across acid classes, bases and pharmaceutical vehicles, but it is limited to human dry-skin treatment and a non-irritating topical method.
Claims 2 through 6 add concentration, listed-base, vehicle and pH limitations.
Claims 7 through 15 protect narrow formulation examples involving glycolic acid, lactic acid, citric acid, ethanolamine and triethanolamine.
The patent issued Aug. 8, 1978, and expired Aug. 8, 1995.
There is no current Paragraph IV, Orange Book or infringement risk attributable to the expired claims.
Modern launch risk comes from later AHA patents, FDA drug-versus-cosmetic classification, labeling, manufacturing controls and commercial rights.
The patent has no biosimilar relevance because it concerns small-molecule topical formulations rather than a biologic.
Foreign patent status cannot be inferred solely from the U.S. expiration date.

FAQs

Can a company sell glycolic acid or lactic acid moisturizer products today?

Yes, the expired U.S. patent does not block sale of products practicing its claims. FDA classification, labeling, safety and any later patents remain separate issues.

Does neutralizing glycolic acid with ethanolamine create a new patented product?

It may create the type of reaction product described by U.S. Patent 4,105,783, but that patent is expired. A later patent could still claim a particular ethanolamine glycolate formulation or use.

Are the formulation recipes in claims 7 through 15 still proprietary?

Not by virtue of U.S. Patent 4,105,783. The claims expired with the patent. Trade-secret protection could apply only to nonpublic manufacturing information independently maintained as confidential.

Can an AHA cosmetic avoid drug regulation by omitting the word "treat"?

Not necessarily. FDA assesses intended use from the full labeling, advertising and promotional context. Claims directed to treating or preventing a disease or abnormal condition can support drug classification. [4]

Does this patent establish that all alpha-hydroxy acid products are safe?

No. The patent describes particular compositions and a non-irritating treatment objective. It does not replace current safety evaluation, stability testing, labeling review or FDA requirements.

References

United States Patent and Trademark Office. (1978). U.S. Patent No. 4,105,783, Treatment of dry skin.
United States Code. (2024). 35 U.S.C. §§ 154, 156.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). Cosmetics and the law: Products, ingredients and labeling.
United States Code. (2024). 21 U.S.C. § 355(j)(2)(A)(vii)(IV).
U.S. Food and Drug Administration. (2005). Alpha hydroxy acids. FDA.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2858377	⤷ Start Trial
Australia	519802	⤷ Start Trial
Belgium	858404	⤷ Start Trial
Canada	1115211	⤷ Start Trial
Cyprus	1245	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,105,783

Summary for Patent: 4,105,783