United States Patent 7,150,881: Claim Scope, Validity, and Transdermal Drug-Delivery Patent Landscape

U.S. Patent 7,150,881 protects a solvent-free or substantially solvent-free transdermal matrix made from hydrophobic acrylic polymer and a low-molecular-weight liquid drug. The core commercial relevance is selegiline, the active ingredient in the Emsam transdermal system. Claims 1 and 8 are the independent claims; claims 9 and 10 narrow the invention to selegiline.

The patent’s strongest technical limitation is not the acrylic adhesive alone. It is the combination of: (1) a hydrophobic acrylic polymer, (2) a therapeutically effective quantity of a low-molecular-weight drug that is liquid at or near room temperature, (3) drying at a defined processing temperature, and (4) substantial absence of water and specified non-drug liquids after processing.

The patent term appears to have run from a 2001 priority period into 2021, subject to the patent’s actual term adjustment, terminal disclaimers, and USPTO term calculation. As a result, the patent is no longer a primary blocking right for new U.S. commercial launches unless an unusual surviving term issue applies. Its historical importance is greater than its current exclusionary value.

What does U.S. Patent 7,150,881 cover?

U.S. Patent 7,150,881 covers a dried transdermal delivery matrix in which a hydrophobic acrylic polymer carries a low-molecular-weight drug that remains liquid at approximately room temperature.

The independent claims can be reduced to the following elements:

Element	Claim 1	Claim 8
Transdermal delivery system	Yes	Yes
Dried at a predetermined processing temperature	Yes	Yes
Hydrophobic acrylic polymer	One or more	One
Therapeutically effective drug quantity	Yes	Yes
Low-molecular-weight liquid drug	At least one drug	The drug
Substantially free of water	Yes	Yes
Substantially free of specified non-drug liquids	Yes	Yes
Claims expressly directed to selegiline	Through claim 9	Through claim 10
Required acrylic polymer substructures	Added in claims 2-5	Not expressly required
Drug concentration of 3% to 35%	Claim 7	No corresponding limitation

The invention is directed to a matrix that does not depend on residual water or a conventional liquid solvent to process or deliver the drug. The low-molecular-weight liquid drug itself remains in the dried matrix and can perform part of the formulation role normally performed by a solvent or plasticizer.

What are the independent claims in Patent 7,150,881?

Claim 1: broad polymer-and-drug composition claim

Claim 1 requires:

A transdermal delivery system.
Drying at a predetermined processing temperature.
One or more hydrophobic acrylic polymers.
A therapeutically effective amount of one or more drugs.
At least one drug with low molecular weight and liquid physical state at or around room temperature.
Substantial absence of water.
Substantial absence of other liquids meeting the specified boiling-point relationship.

Claim 1 is broad because it does not require selegiline, a particular acrylic copolymer, a particular drug loading, or a particular patch architecture. It can potentially reach systems containing multiple drugs, provided at least one drug satisfies the low-molecular-weight and liquid-state limitations.

Claim 8: alternative single-polymer, single-drug claim

Claim 8 is similar but narrower in certain respects. It requires:

A hydrophobic acrylic polymer rather than one or more polymers.
A drug that is both low molecular weight and liquid near room temperature.
The same drying and solvent-exclusion framework.
A post-processing system that is free of water and specified liquids other than the drug.

Claim 8 may be easier to analyze in a product comparison because it focuses on one hydrophobic acrylic polymer and one qualifying drug. It does not, however, require the additional polymer classes and formulation percentages recited in claims 2-7.

How do claims 2 through 7 narrow the patent scope?

The dependent claims impose a progressively narrower polymer and composition structure.

Claim	Added limitation	Practical effect
2	Acrylic polymer includes a C4-C12 alkyl acrylate	Covers hydrophobic soft-monomer structures such as certain butyl, 2-ethylhexyl, or related acrylates
3	Also includes a C1-C4 alkyl acrylate hardening monomer	Requires a harder acrylic component, such as a lower-alkyl acrylate
4	Also includes a functionalizing monomer	Requires a monomer introducing functional groups, such as carboxyl, hydroxyl, or similar functionality
5	Also includes a cross-linking agent	Adds network formation or curing chemistry
6	At least one drug has molecular weight below about 300	Creates a numerical molecular-weight boundary
7	Drug content is about 3% to 35%	Adds a formulation concentration range

Claims 2-5 are composition-focused. They are relevant when a product’s adhesive is identified by monomer composition, cross-linking chemistry, or supplier technical documentation.

Claim 6 is important because “low molecular weight” in claims 1 and 8 is otherwise qualitative. The word “about” creates an interpretive margin around 300 molecular-weight units, but a drug substantially above that threshold would face a stronger noninfringement position under claim 6. It would not necessarily avoid claims 1, 8, 9, or 10.

Claim 7 is a concentration claim. A product containing less than approximately 3% or more than approximately 35% drug may avoid claim 7 while still falling within the independent claims.

What does the boiling-point limitation require?

The boiling-point language is a central claim limitation.

The claimed system must be substantially free of water and liquids other than the qualifying low-molecular-weight drug where those other liquids:

Have boiling points below the predetermined processing temperature; and
Have boiling points equal to or greater than the boiling points of the relevant low-molecular-weight drugs.

The limitation is designed to distinguish a formulation that retains the drug during processing from one that uses a separate volatile carrier or solvent with a comparable or higher boiling point.

A product analysis should establish:

The actual drying or coating temperature.
Whether the temperature is constant or changes during processing.
The identity of every liquid present before drying.
The boiling point of each liquid at the relevant pressure.
Whether water or residual solvents remain after processing.
Whether the drug evaporates, degrades, or remains in the adhesive.
The analytical method used to measure residual solvents and drug content.

The term “substantially free” is fact-dependent. It does not necessarily mean absolute zero. Residual solvent levels, analytical detection limits, manufacturing tolerances, and the role of the liquid in the finished product would be relevant to claim construction and infringement analysis.

What drug is specifically covered by Patent 7,150,881?

Claims 9 and 10 specifically identify selegiline.

Claim	Selegiline limitation	Parent claim structure
9	The drug includes selegiline	Depends on claim 1
10	The drug comprises selegiline	Depends on claim 8

Selegiline is a low-molecular-weight monoamine oxidase inhibitor. In transdermal use, it is delivered through the skin from an adhesive matrix. The selegiline claims do not cover every selegiline patch. They require the structural and processing limitations inherited from claims 1 or 8.

A selegiline product using a hydrophobic acrylic adhesive may still avoid claims 9 and 10 if it contains:

Water or a qualifying non-drug liquid in the finished matrix.
A non-acrylic adhesive system.
A drug form or formulation that does not satisfy the low-molecular-weight liquid limitation.
A manufacturing process or finished composition inconsistent with the claimed drying conditions.
A polymer system outside the hydrophobic acrylic requirement.

The absence of literal infringement would not automatically eliminate a doctrine-of-equivalents theory, although the solvent-exclusion and drying limitations could create prosecution-history and claim-scope barriers.

What formulation patents are relevant to selegiline transdermal systems?

The relevant patent estate is broader than Patent 7,150,881. A complete freedom-to-operate review should separate four technical groups.

Selegiline transdermal delivery patents

These patents generally address:

Delivery of selegiline through skin.
Adhesive matrix construction.
Selegiline dose and flux.
Patch size and wear duration.
Reduction of oral gastrointestinal or hepatic exposure.
Transdermal treatment of depressive disorders.

The historic Emsam estate included patents directed to transdermal selegiline and associated delivery systems. The key commercial product is Emsam, originally developed through Somerset Pharmaceuticals and later commercialized by Bristol-Myers Squibb and other rights holders.

Acrylic adhesive and matrix patents

Patent 7,150,881 is principally in this category. It is directed to the physical and chemical design of the matrix rather than to selegiline pharmacology alone.

Potentially relevant adhesive features include:

C4-C12 alkyl acrylate monomers.
C1-C4 alkyl acrylate hardening monomers.
Functional monomers.
Cross-linking agents.
Drug loading between approximately 3% and 35%.
Solvent-free or low-residual-solvent processing.

Method-of-use patents

Separate patents may claim use of transdermal selegiline for:

Major depressive disorder.
Specific dosing regimens.
Dietary restriction requirements at particular patch strengths.
Treatment of patients with selected psychiatric or neurological conditions.

Method-of-use claims can remain commercially relevant even after composition patents expire, although their enforcement depends on labeling, induced infringement, prescribing behavior, and the specific approved indication.

Manufacturing and process patents

Manufacturing rights may cover:

Coating an adhesive-drug mixture onto a backing layer.
Drying conditions.
Lamination.
Release-liner removal.
Control of selegiline content and degradation products.
Packaging to limit oxidation or volatilization.
Continuous-roll production.

Patent 7,150,881 has process language embedded in the product definition. A manufacturer may therefore need process records to determine whether a finished patch falls within the claims.

When did Patent 7,150,881 lose exclusivity?

The patent’s ordinary U.S. term would be measured from its earliest effective nonprovisional filing date, not from the 2006 grant date. The patent’s priority history appears to place the ordinary term in the 2021 period, rather than 2026.

Event	Approximate timing
Earliest priority period	2001
U.S. patent application period	2002
Patent grant	December 2006
Ordinary 20-year term endpoint	2021, subject to USPTO adjustment
Current status for commercial blocking purposes	Historical, with no ordinary unexpired term expected

The grant date does not add 20 years to the patent. Patent-term adjustment, patent-term extension, terminal disclaimers, and any disclaimer filings must be checked against the USPTO patent record for an exact expiration date. Patent 7,150,881 does not appear to be the principal current barrier to a U.S. generic selegiline patch launch.

FDA regulatory exclusivity is separate from patent protection. FDA exclusivity may expire earlier or later than a patent, but it does not revive an expired patent.

What is the Orange Book status of Patent 7,150,881?

The Orange Book question must be separated from the patent’s technical relevance.

FDA Orange Book listings are product-specific. A patent must be submitted and accepted for listing against a particular approved drug product and dosage form. A patent covering a manufacturing process or a broad formulation concept may not be listed unless it meets FDA’s listing criteria for the relevant NDA.

For Emsam, the historically important Orange Book patents are the patents listed against the Emsam NDA, including patents directed to transdermal selegiline and delivery technology. Patent 7,150,881 should not be treated as an Orange Book barrier solely because it mentions selegiline or covers a transdermal matrix.

The current Orange Book record should be used to determine:

Whether Patent 7,150,881 was ever listed against Emsam.
Whether the listing was withdrawn or delisted.
The listed patent expiration date.
Whether the patent was submitted as a drug substance, drug product, or method-of-use patent.
Whether any pediatric exclusivity or patent-term extension affected the listing.

The Orange Book does not determine the full private patent landscape. Unlisted patents may still support infringement litigation, subject to ordinary patent-law requirements.

Which companies challenged or competed with Emsam?

The relevant competitive group has included:

Company or category	Role
Somerset Pharmaceuticals	Original development and commercialization history for selegiline transdermal therapy
Bristol-Myers Squibb	Commercial rights and marketing history for Emsam
Mylan and related entities	Generic transdermal selegiline development and commercialization activity
FDA-approved generic manufacturers	Potential or actual ANDA-based competition after applicable barriers expired
Other transdermal technology suppliers	Potential adhesive, backing, coating, and manufacturing competitors

A Paragraph IV challenge would target listed patents identified in the Orange Book for the reference product. It would not automatically target every patent in the broader patent family or every patent potentially relevant to manufacturing. The filing of an ANDA with a Paragraph IV certification can trigger patent litigation under 21 U.S.C. § 355(j)(5)(B)(iii), but the case must be tied to a listed patent and the statutory notice process.

No reliable conclusion should be drawn that Patent 7,150,881 itself generated a Paragraph IV case without confirming the specific ANDA, notice letter, and litigation docket.

What litigation and settlement issues affect selegiline transdermal products?

The principal litigation risks historically would have involved:

Whether the generic patch used the claimed hydrophobic acrylic matrix.
Whether the drug remained liquid at room temperature.
Whether processing removed water and other specified liquids.
Whether the generic’s adhesive composition met the dependent monomer limitations.
Whether the product contained 3% to 35% drug.
Whether a generic label induced infringement of method-of-use claims.
Whether the asserted patent was listed and enforceable.

A settlement agreement could include:

A licensed entry date.
A launch date earlier than patent expiration.
Authorized-generic rights.
Royalty or supply terms.
No-challenge provisions.
Restrictions on manufacturing sites or product strengths.

Settlement terms are not necessarily public. They should be distinguished from court judgments, consent decrees, and FDA approval dates. An FDA approval does not prove that all patent disputes have been resolved.

How strong is the patent estate for Patent 7,150,881?

Strengths

The patent has several potentially meaningful claim features:

It captures the combination of polymer, drug state, and processing outcome.
The claims can reach the finished patch, not only a manufacturing step.
Claims 9 and 10 identify selegiline directly.
The solvent-exclusion limitation can distinguish conventional adhesive formulations.
Claims 2-5 provide narrower positions around acrylic chemistry.

Weaknesses

The principal vulnerabilities are technical and temporal:

The claims depend on a complex boiling-point relationship.
“Substantially free” can create factual disputes.
“Low molecular weight” and “liquid at or about room temperature” require product-specific evidence.
Product-by-process language may limit the scope if the drying step is treated as a meaningful claim requirement.
Acrylic adhesive systems are widely used and may create prior-art pressure.
The patent’s ordinary term appears to have ended in 2021.
A patent-specific claim win would not necessarily block a product using a different adhesive or solvent architecture.

Commercial assessment

Factor	Assessment
Historical relevance to Emsam	High
Current blocking value	Low if the patent expired as expected
Ease of detecting infringement	Moderate to difficult
Dependence on formulation records	High
Relevance to generic product design	Moderate historically; limited prospectively
Design-around potential	Meaningful
Risk from independent claims	Higher than from claims 2-7
Risk from selegiline claims	Product-specific and dependent on claims 1 or 8

What generic launch scenarios existed for transdermal selegiline?

Scenario 1: Launch after patent and regulatory barriers

This is the lowest-risk scenario. The generic product matches the reference product’s therapeutic concept but enters after listed patents and FDA exclusivity expire.

Scenario 2: Paragraph IV launch

A generic applicant may certify that listed patents are invalid, unenforceable, or not infringed. Risk depends on whether the reference-product patents are still listed and whether the innovator files suit within the statutory period.

Scenario 3: Formulation design-around

A manufacturer can reduce risk by using:

A non-acrylic adhesive.
A different polymer composition.
A drug form that does not meet the liquid-state limitation.
A formulation containing a permitted non-drug component, if the resulting product falls outside the boiling-point limitation.
A different drug-loading range.
A process that does not satisfy the claimed drying framework.

Each design-around must be tested against the independent claims. Avoiding claim 7 does not avoid claim 1. Avoiding claims 2-5 does not avoid claims 1 or 8.

Scenario 4: Alternative selegiline dosage form

Oral, buccal, implantable, or other dosage forms may fall outside the transdermal-system claims, but they may implicate separate selegiline composition, method-of-use, or manufacturing patents.

How does Patent 7,150,881 compare with broader transdermal drug patents?

Patent 7,150,881 is narrower than a patent claiming transdermal delivery of a drug generally, but broader than a patent limited to a specific patch size, backing layer, release liner, or drug concentration.

Patent type	Relative scope	Relevance to Patent 7,150,881
Broad transdermal drug-delivery platform	Potentially broader	Could dominate or overlap the claimed matrix
Selegiline-specific transdermal patent	Narrower drug focus	May overlap claims 9 and 10
Acrylic adhesive composition patent	Different technical focus	May overlap claims 2-5
Manufacturing-process patent	Process-centered	May overlap the drying limitation
Method-of-use patent	Therapeutic-use focus	Separate infringement theory
Patch construction patent	Physical-device focus	May cover backing, liner, or multilayer structure not claimed here

Geographic protection is limited by jurisdiction. U.S. Patent 7,150,881 does not establish rights in Europe, Canada, Japan, or other markets. Foreign counterparts must be reviewed independently for filing, grant, lapse, opposition, and expiration status.

Key Takeaways

U.S. Patent 7,150,881 claims a dried hydrophobic acrylic transdermal matrix containing a low-molecular-weight liquid drug.
Claims 1 and 8 are the principal independent claims.
Claims 9 and 10 specifically cover selegiline, but only within the inherited limitations of claims 1 and 8.
The key infringement issues are polymer identity, drug physical state, processing temperature, boiling points, residual water and solvents, and final drug loading.
Claims 2-5 narrow the acrylic polymer to specified monomer and cross-linking structures.
Claim 7 covers approximately 3% to 35% drug content but does not define the scope of the independent claims.
The patent’s ordinary term appears to have ended in the 2021 period, subject to the USPTO’s final term calculation.
Orange Book listing must be verified against the specific Emsam NDA; patent coverage and Orange Book status are separate questions.
The patent remains relevant for historical Emsam and generic-development analysis, but it is unlikely to be the principal current U.S. launch barrier if expired.
A freedom-to-operate review must include selegiline transdermal patents, adhesive patents, method-of-use patents, manufacturing patents, and any listed Orange Book patents.

FAQs

Does Patent 7,150,881 cover every selegiline patch?

No. The patch must also satisfy the hydrophobic acrylic polymer, drying, low-molecular-weight liquid-drug, and water or solvent-exclusion limitations inherited from claims 1 or 8.

Can a selegiline patch avoid claim 9 by using a drug concentration below 3%?

Possibly, but only claim 7 expressly requires the 3%-35% range. Claims 1 and 8 do not contain that concentration limitation.

Does use of a silicone adhesive avoid Patent 7,150,881?

A silicone adhesive would not literally satisfy the hydrophobic acrylic polymer limitation. It could, however, implicate separate transdermal, selegiline, method-of-use, or device patents.

Does an FDA-approved generic prove that Patent 7,150,881 was invalid?

No. FDA approval addresses regulatory requirements. It does not adjudicate patent validity, infringement, enforceability, or the complete patent estate.

Are foreign patents equivalent to U.S. Patent 7,150,881?

Not necessarily. Foreign counterparts may have different claims, prosecution amendments, term dates, opposition outcomes, and legal standards. Each jurisdiction requires separate analysis.

References

United States Patent and Trademark Office. (2006). U.S. Patent No. 7,150,881, transdermal delivery system. U.S. Department of Commerce.
United States Code. (2024). 35 U.S.C. § 154: Contents and term of patent; provisional rights.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs, Emsam (selegiline transdermal system). U.S. Department of Health and Human Services.
U.S. Food and Drug Administration. (2006). Emsam prescribing information: Selegiline transdermal system. U.S. Department of Health and Human Services.
Hatch-Waxman Amendments, 21 U.S.C. § 355(j).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0887075	⤷ Start Trial
European Patent Office	1561461	⤷ Start Trial
Japan	H1160475	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,150,881

Summary for Patent: 7,150,881