United States Patent 5,834,010: Claim Scope, Expiration, Orange Book Status and Patent Landscape

U.S. Patent No. 5,834,010 covers transdermal delivery systems that use triacetin to enhance skin penetration of basic drugs with a pKa of approximately 8.0 or higher. Its commercial center of gravity is oxybutynin transdermal patches, particularly acrylic-adhesive matrix systems containing triacetin and, in narrower claims, glycerin.

The patent issued on November 10, 1998. Its statutory patent term has expired. The patent therefore does not presently block manufacture, sale, or use of a product that practices the disclosed triacetin-oxybutynin patch technology, although separate patents, regulatory exclusivities, trademarks, trade secrets, or third-party rights may affect a specific product.

What technology does U.S. Patent 5,834,010 protect?

The patent protects a transdermal matrix patch and a method of using that patch. The core combination has four technical elements:

A biocompatible polymer layer.
A pressure-sensitive adhesive matrix.
A basic, percutaneously absorbable drug with a pKa of about 8.0 or greater.
Triacetin as the permeation enhancer.

The patent claims both the patch itself and application of the patch to skin. The broadest independent claims are claim 1, directed to a method, and claim 13, directed to the matrix patch.

Claim group	Claim type	Principal subject matter
1-12	Method claims	Applying a triacetin-containing matrix patch to enhance transdermal penetration
13-24	Product claims	Matrix patch containing the drug, adhesive polymer and triacetin
2, 14	Drug Markush claims	Listed basic drugs, including oxybutynin
3, 15	Broad concentration claims	0.1% to 50% triacetin by weight
5, 17	Intermediate concentration claims	1% to 40% triacetin by weight
9, 21	Narrow concentration claims	2% to 20% triacetin by weight
10, 22	Excipient claims	Glycerin as a skin-irritation-reducing agent
11-12, 23-24	Structural claims	Polymer layer laminated to or overlaid with an adhesive

The patent does not claim triacetin generally, oxybutynin generally, or every transdermal oxybutynin formulation. Infringement requires the claimed combination or its equivalent.

How broad are the independent claims?

Claim 1: method of enhancing transdermal penetration

Claim 1 requires applying a matrix patch containing:

A pressure-sensitive adhesive selected from specified polymer classes.
A basic drug with a pKa of approximately 8.0 or higher.
An effective amount of triacetin.

The listed adhesive classes include acrylics, vinyl acetates, rubbers, ethylene-vinyl acetate copolymers, polysiloxanes, polyacrylates, polyurethanes, plasticized polyether block amides, plasticized styrene-rubber block copolymers and mixtures.

The claim is broad because it does not require:

Oxybutynin specifically.
A particular oxybutynin salt.
A particular patch size.
A specified drug loading.
A specified delivery rate.
A specified wear time.
A numerical triacetin concentration.
Glycerin.
A particular backing layer or release liner.

The claim is narrower than a generic “triacetin transdermal enhancer” claim because the drug must be basic and have a pKa of about 8.0 or greater. The drug must also be percutaneously absorbable.

Claim 13: matrix patch

Claim 13 contains substantially the same chemical and structural limitations as claim 1 but is directed to the patch rather than the act of applying it.

This distinction matters commercially. A product claim can potentially reach manufacture, importation, sale or offer for sale of a patch. A method claim principally reaches performance of the claimed administration method. A patch manufacturer would generally face greater exposure from a valid product claim than from a method claim that requires a particular use.

What drugs fall within the claimed Markush group?

Claims 2 and 14 identify the following drugs:

Oxybutynin
Scopolamine
Fluoxetine
Epinephrine
Morphine
Hydromorphone
Atropine
Cocaine
Buprenorphine
Chlorpromazine
Imipramine
Desipramine
Methylphenidate
Methamphetamine
Lidocaine
Procaine
Pindolol
Nadolol
Carisoprodol

The claims also refer to acid-addition salts of the listed drugs.

The Markush language narrows claims 2 and 14 to the specified group. It does not necessarily narrow independent claims 1 and 13 to that group. A drug outside the Markush list could still fall within claim 1 or 13 if it satisfies the independent limitations, including the pKa and transdermal-absorption requirements.

The commercial significance of the list is uneven. Oxybutynin is the principal product-relevant embodiment. Several listed drugs are not established commercial transdermal products in the same patch format, and their inclusion expands the patent’s technical scope more than its demonstrated market scope.

What formulations are protected by the patent?

The narrowest and most commercially relevant formulation path is:

Oxybutynin.
Acrylic copolymer pressure-sensitive adhesive.
Triacetin at 2% to 20% by weight.
Glycerin as a skin-irritation-reducing agent.
Matrix patch architecture.

Claims 19-22 progressively narrow the formulation to oxybutynin, acrylic copolymer, 2% to 20% triacetin and glycerin.

Formulation characteristic	Covered by narrow claims?
Oxybutynin	Yes
Another listed basic drug	No under claims 19-22, potentially yes under claims 1-18
Acrylic copolymer adhesive	Yes
Triacetin at 2%-20% by weight	Yes
Triacetin below 2% or above 20%	Not under claims 9 or 21, potentially under broader claims
Glycerin	Yes under claims 10 and 22
Non-glycerin irritation reducer	Potentially under claims 6 and 18
Reservoir system without the claimed matrix structure	Generally outside the express matrix claims
Patch with no triacetin	Outside the claims
Patch using a different permeation enhancer instead of triacetin	Outside the claims unless triacetin is also present

The phrase “consisting essentially of triacetin” is important. It generally permits components that do not materially alter the basic and novel characteristics of the claimed enhancer system, while excluding an additional enhancer or component that materially changes those characteristics. The scope would depend on the specification, prosecution history and technical evidence.

How do the concentration limitations affect claim scope?

The concentration claims create a nested hierarchy:

Claim	Triacetin range
1, 13	Effective amount, no numerical range
3, 15	About 0.1% to about 50%
5, 17	About 1% to about 40%
9, 21	About 2% to about 20%

A formulation containing 10% triacetin can fall within all four concentration tiers, assuming the other limitations are met. A formulation containing 0.5% triacetin may fall within claims 3 and 15 but not claims 5, 9, 17 or 21. A formulation containing 45% triacetin may fall within claims 3 and 15 but not the narrower 1%-40% and 2%-20% claims.

“About” introduces some tolerance around the numerical endpoints. The scope would depend on claim construction, technical context and prosecution history. It does not convert the ranges into unlimited concentration claims.

What are the principal claim-construction issues?

“Basic drug having a pKa of about 8.0 or greater”

The claim requires a basic drug with a pKa at or around 8.0 or above. Questions may arise over:

Which ionization constant is used for drugs with multiple basic centers.
Whether pKa is measured in water, a buffer or another specified medium.
Whether the relevant value is for the free base or an acid-addition salt.
How much variation is permitted by “about.”

A product using a drug with a pKa materially below 8.0 would have a substantial noninfringement position under the express limitation.

“Effective amount”

The claims do not state a single minimum triacetin amount in the independent claims. The amount must be sufficient to enhance transdermal penetration in the claimed system. Claims 3, 5, 9, 15, 17 and 21 add numerical ranges but retain the “about” qualification.

“Matrix patch”

The claims require the drug and enhancer to be associated with a polymer layer or adhesive matrix. A conventional reservoir patch, where liquid or gel drug solution is separated from the adhesive by a membrane, may present a stronger noninfringement position if it lacks the claimed matrix arrangement.

“Pressure-sensitive adhesive”

The polymer must function as the claimed biocompatible pressure-sensitive adhesive. Merely using a polymer somewhere in a patch may not satisfy the limitation if the polymer does not perform the required adhesive or matrix function.

When did U.S. Patent 5,834,010 lose exclusivity?

The patent issued November 10, 1998, and its ordinary 20-year term ran from the applicable nonprovisional filing date. Public patent records identify the patent as expired. The expiration occurred before the present date, so the patent no longer supplies an enforceable exclusionary right against new commercial entrants.

Event	Date or status
Patent issued	November 10, 1998
Patent number	U.S. 5,834,010
Technology	Triacetin-enhanced transdermal delivery
Principal commercial embodiment	Oxybutynin matrix patch
Current patent status	Expired
Current ability to block a generic solely under this patent	None after expiration

Patent expiration does not eliminate other possible barriers. A later continuation, divisional, formulation patent, manufacturing patent, trademark right or regulatory exclusivity must be assessed separately. A later patent cannot extend the term of U.S. Patent 5,834,010 itself.

What is the Orange Book status of U.S. Patent 5,834,010?

The patent is associated with the oxybutynin transdermal product marketed as Oxytrol. The relevant regulatory product is an oxybutynin transdermal system delivering approximately 3.9 mg of oxybutynin per day, according to the FDA product labeling.[2]

Historically, the patent was relevant to the FDA-listed oxybutynin transdermal product. Its current practical Orange Book significance is limited because the patent has expired. An expired Orange Book patent does not independently prevent an ANDA applicant from entering after satisfying applicable FDA requirements.

The Orange Book analysis must distinguish:

Patent listing: whether a patent was submitted and listed for an approved product.
Patent term: whether the patent remains unexpired.
Regulatory exclusivity: whether a separate exclusivity period remains.
Enforceability: whether the patent can support a current infringement action.

Those concepts are not interchangeable. The patent’s historical association with Oxytrol does not create current patent exclusivity.

What Paragraph IV challenges and generic-entry risks existed?

A Paragraph IV certification would have been relevant while the patent was listed and unexpired for an ANDA referencing the covered oxybutynin transdermal product. The applicant could have alleged that the patent was invalid, unenforceable or would not be infringed.

Because the patent is expired, it no longer creates a meaningful Paragraph IV barrier to a new generic launch. The commercial questions instead shift to:

FDA approval of the transdermal generic.
Demonstration of pharmaceutical equivalence.
Adhesion and wear performance.
Drug delivery-rate consistency.
Skin irritation.
Residual patent claims in later oxybutynin patents.
Product-specific exclusivities or labeling restrictions.

For an ANDA applicant, the principal technical risk is likely product development and regulatory approval rather than U.S. Patent 5,834,010.

Which companies are relevant to the competitive landscape?

The original patent estate is associated with Noven Pharmaceuticals, the developer of transdermal drug delivery systems later used in oxybutynin products. Noven became part of Hisamitsu Pharmaceutical through its acquisition, but corporate ownership does not extend the expired patent term.

The relevant competitive set includes:

The Oxytrol brand and its successor commercial rights holders.
FDA-approved generic oxybutynin transdermal system manufacturers.
Developers of oral oxybutynin products.
Developers of alternative overactive-bladder therapies, including other anticholinergic and beta-3 agonist products.
Manufacturers using different transdermal enhancers or patch architectures.

The patent does not cover oral oxybutynin, oxybutynin extended-release tablets, non-triacetin patches, or unrelated overactive-bladder drugs.

What patent litigation and settlement issues affect the patent?

No current enforcement value remains under U.S. Patent 5,834,010 because the patent has expired. Historical litigation or settlement agreements could still matter for understanding market entry timing, but they do not revive the patent.

A complete litigation review would need to separate:

Cases involving U.S. Patent 5,834,010 directly.
Cases involving later oxybutynin or patch patents.
ANDA litigation under the Hatch-Waxman framework.
Patent settlements that included launch dates or licenses.
Non-patent disputes involving trademarks, manufacturing or regulatory matters.

The supplied claim set alone does not establish that a particular generic manufacturer infringed, challenged or settled this patent.

How strong was the patent estate?

The patent was technically strong against a product that copied the full commercial configuration: oxybutynin, acrylic adhesive, triacetin within the claimed range and the claimed matrix structure.

Its strength was lower against designs that changed one material limitation, such as:

Using another permeation enhancer.
Omitting triacetin.
Selecting a drug outside the claimed pKa range.
Using a non-matrix reservoir system.
Using a concentration outside the narrower dependent ranges.
Using a different adhesive architecture.
Demonstrating that triacetin did not materially enhance penetration in the accused product.

The patent also carried potential validity pressure because its claims span a broad genus of drugs, polymer systems and concentration ranges. Possible attack theories would include anticipation, obviousness, written-description support, enablement and indefiniteness concerning “about,” “effective amount,” pKa and “consisting essentially of.” Those theories no longer have commercial significance against the expired patent except in historical litigation analysis.

Does the patent create biosimilar risk?

No. Biosimilar regulation applies to biological products, not oxybutynin or the small-molecule transdermal products covered by this patent. The relevant competitive pathway is generic drug approval, generally through an ANDA, not a biosimilar application under the Public Health Service Act.

What manufacturing and geographic barriers remain?

The patent was a United States patent. Its expiration removes the U.S. patent barrier created by this document. Foreign counterparts, if any, had separate terms and separate validity outcomes. A U.S. freedom-to-operate analysis therefore cannot be extended automatically to Canada, Europe, Japan or other jurisdictions.

Manufacturing barriers may still arise from:

Trade-secret adhesive processing.
Controlled drug loading.
Uniform triacetin distribution.
Coating and drying conditions.
Patch adhesion and crystallization control.
Stability of oxybutynin in the adhesive.
Skin-irritation performance.
Scale-up and quality-control requirements.

Those are technical and commercial barriers, not continuing rights under U.S. Patent 5,834,010.

What is the revenue exposure associated with this patent?

The patent’s historical revenue exposure was tied principally to oxybutynin transdermal products. No current revenue stream can be attributed to exclusivity under the patent because the patent has expired.

The relevant commercial product characteristics are:

Metric	Oxytrol-related characteristic
Active ingredient	Oxybutynin
Dosage form	Transdermal system
Typical delivery rate	Approximately 3.9 mg/day
Therapeutic area	Overactive bladder
Patent relevance	Historical protection for triacetin-containing transdermal technology
Current patent contribution	None from U.S. Patent 5,834,010 alone

Current revenue exposure depends on brand retention, generic penetration, reimbursement, over-the-counter distribution and any later intellectual-property rights.

Key Takeaways

U.S. Patent 5,834,010 covers triacetin-enhanced transdermal delivery of basic drugs with a pKa of approximately 8.0 or greater.
Claims 1 and 13 are the broad independent method and patch claims.
Oxybutynin is the principal commercial embodiment.
The narrowest claims require oxybutynin, an acrylic copolymer adhesive, 2% to 20% triacetin and, in claims 10 and 22, glycerin.
The patent does not cover all oxybutynin products or all transdermal patches.
The patent has expired and no longer independently blocks generic entry.
Paragraph IV issues are historical rather than a current barrier under this patent.
The patent is irrelevant to biosimilar competition because oxybutynin is a small molecule.
Later patents, foreign rights, manufacturing know-how and FDA requirements remain separate issues.

FAQs

Can a generic use triacetin in an oxybutynin patch today?

Yes, U.S. Patent 5,834,010 is expired. A generic must still assess later patents and satisfy FDA requirements.

Does the patent cover an oxybutynin patch that uses a reservoir instead of a matrix?

Not necessarily. The asserted product would need to satisfy the matrix and polymer-layer limitations of the relevant claim.

Is glycerin required in every covered oxybutynin patch?

No. Glycerin is required only by the narrower claims 10 and 22. The broader claims do not require glycerin.

Does a 1% triacetin formulation fall within the patent?

It may fall within the 0.1% to 50% claims, subject to the other limitations. It is outside the express 2% to 20% claims unless claim construction treats the boundary differently.

Does expiration of this patent eliminate all intellectual-property risk for Oxytrol-style products?

No. It eliminates the blocking effect of this patent only. Later patents, foreign patents, trademarks, trade secrets and regulatory requirements require separate analysis.

References

United States Patent and Trademark Office. (1998). U.S. Patent No. 5,834,010: Transdermal delivery of drugs using triacetin as a permeation enhancer. U.S. Department of Commerce. https://patents.google.com/patent/US5834010
U.S. Food and Drug Administration. (2013). Oxytrol: Oxybutynin transdermal system prescribing information. https://www.accessdata.fda.gov
U.S. Food and Drug Administration. (2024). 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. (2013). FDA approves first over-the-counter treatment for overactive bladder. https://www.fda.gov/news-events/press-announcements/fda-approves-first-over-counter-treatment-overactive-bladder
United States Patent and Trademark Office. (2024). Manual of patent examining procedure, Chapter 2700: Patent term. U.S. Department of Commerce. https://www.uspto.gov/web/offices/pac/mpep/mpep-2700.html

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0871420	⤷ Start Trial	CA 2005 00010	Denmark	⤷ Start Trial
European Patent Office	0871420	⤷ Start Trial	05C0008	France	⤷ Start Trial
Argentina	001721	⤷ Start Trial
Austria	205694	⤷ Start Trial
Australia	5446796	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,834,010

Summary for Patent: 5,834,010