United States Drug Patent RE34579: Scope, Claims, Expiration, and Selegiline Transdermal Patent Landscape

United States Reissue Patent RE34,579 covers transdermal administration of L-deprenyl, also known as selegiline, for depression and monoamine oxidase B inhibition. Its core protection combines four elements: dermal delivery, therapeutic blood levels, avoidance of skin irritation and the tyramine-related "cheese effect," and, in dependent claims, controlled delivery through a topical carrier or patch.

The patent is expired. Its historical claim scope was important to the development of transdermal selegiline, including the Emsam product, but RE34,579 does not currently block generic or other transdermal selegiline development.

What drug and delivery technology does US RE34,579 protect?

US RE34,579 protects the transdermal delivery of L-deprenyl, the levorotatory form of deprenyl. The compound is now commonly called selegiline.

The patent is directed to using the skin as the delivery route to place selegiline into systemic circulation and ultimately into the blood supply to the brain. The claims are framed around therapeutic performance rather than only the composition of the patch.

Patent element	RE34,579 scope
Active ingredient	L-deprenyl or a salt
Route	Transdermal or topical administration
Disease in independent method claim	Depression
Pharmacology	Inhibition of monoamine oxidase B
Delivery objective	Therapeutically effective concentration in the brain blood supply
Safety limitation	No skin irritation and no cheese effect
Dosage range in dependent claim	5 to 50 mg of L-deprenyl per day
Dosage form	Topical mixture, ointment, cream, or patch
Release profile	Controlled-rate migration through skin
Longest express duration	At least one day
Patch construction	Sealed pouch, impervious top layer, porous dermal-contact membrane

RE34,579 is a reissue of an earlier selegiline transdermal patent. The reissue claims include both method claims and added composition claims. The reissue format is shown by the ".Iadd." and ".Iaddend." markings in the claim text, which identify added reissue claim language in the issued patent.

What are the independent claims in US RE34579?

Claim 1: Transdermal treatment of depression

Claim 1 is the principal method claim. It requires:

A human patient with depression.
L-deprenyl or a salt of L-deprenyl.
Contact between the drug and the patient's skin.
A form that permits migration through the skin into the bloodstream.
Delivery sufficient to produce a therapeutically effective amount in the blood supply to the brain.
No skin irritation.
No cheese effect.

This is a functional claim. It does not require a particular patch design, adhesive, membrane, excipient, or chemical enhancer. A product could fall within claim 1 if it achieved the claimed therapeutic and safety results through dermal delivery, even if its physical dosage-form design differed from the patch structure described in later claims.

The principal limitation is the required therapeutic and safety outcome. Transdermal contact alone is not enough. The method must produce effective cerebral exposure without the two specified adverse effects.

Claim 7: Topical composition

Claim 7 shifts from a treatment method to a composition. It requires:

L-deprenyl or a salt as the sole therapeutically active agent;
a quantity effective after transdermal migration to inhibit monoamine oxidase B; and
at least one pharmaceutical carrier capable of permitting transdermal absorption.

The "sole therapeutically active agent" limitation narrows claim 7. A combination product containing another therapeutically active drug would have a potential noninfringement position under this claim, although other patent or regulatory issues could remain.

Claim 7 is not limited to treatment of depression. Its therapeutic requirement is monoamine oxidase B inhibition after transdermal absorption.

How do claims 2 through 6 narrow the patent scope?

Claims 2 through 6 create a delivery-system hierarchy.

Claim	Added limitation	Commercial significance
2	L-deprenyl mixed with an excipient	Covers a drug-carrier mixture rather than neat drug alone
3	Excipient provides controlled migration	Requires controlled delivery over time
4	Mixture is contained in a patch	Narrows the claim to a patch structure
5	Contact interval is at least one day	Targets once-daily or longer patch use
6	Controlled rate is 5-50 mg/day	Adds a quantitative delivery-rate limitation

Claim 6 is particularly important because it recites a broad daily delivery range rather than a single dose. A product delivering less than 5 mg/day or more than 50 mg/day could avoid literal infringement of claim 6, but it could still implicate claims 1 through 5 or other patent claims.

The claims do not require that the patch be applied to a particular anatomical site. They also do not expressly require a specific adhesive, reservoir, backing layer, rate-controlling membrane, or penetration enhancer except where claim 12 introduces a particular patch structure.

What do claims 7 through 12 protect?

Claim 7: Broad topical composition

Claim 7 covers a topical selegiline composition with a pharmaceutical carrier that allows transdermal absorption.

Claim 8: 5-50 mg/day composition

Claim 8 adds the same general delivery range recited in claim 6. It is a composition claim, not a method claim.

Claims 9 and 10: Ointment and cream formulations

Claims 9 and 10 cover two alternative carrier formats:

an ointment base; and
a cream base.

These claims are narrower than claim 7. They would not reach every transdermal composition, because the carrier must be an ointment or cream base.

Claim 11: Patch composition

Claim 11 requires incorporation into a transdermal patch structure. A simple topical cream would not meet this limitation.

Claim 12: Sealed-pouch patch

Claim 12 requires a patch having:

a sealed pouch;
a top layer impervious to the composition; and
a bottom membrane that is slowly porous to L-deprenyl and permits dermal contact.

This claim is the most structurally specific claim in the provided set. It is directed to a reservoir-type patch rather than every possible transdermal patch. A matrix patch, gel patch, microneedle system, or iontophoretic device would require separate analysis and would not automatically satisfy the literal sealed-pouch and porous-membrane limitations.

When did US RE34579 expire?

RE34,579 is expired and has no current blocking effect in the United States.

The patent is a reissue of US Patent No. 4,868,218. The underlying patent issued on September 19, 1989. For a pre-June 8, 1995 patent, the operative term was generally 17 years from grant under the pre-URAA patent-term regime. On that basis, the underlying term ended on September 19, 2006, absent a recorded terminal disclaimer or other term adjustment. The reissue did not create a new full patent term. (U.S. Patent No. RE34,579; U.S. Patent No. 4,868,218.)

Event	Date
Underlying patent issued	September 19, 1989
Reissue patent issued	June 7, 1994
Expected underlying patent expiration	September 19, 2006
Current status	Expired

The practical consequence is that the claim analysis is historical for freedom-to-operate purposes. A company does not need a license to practice the expired claims in the United States, although later patents, trade secrets, regulatory requirements, and foreign rights may still matter.

Was RE34579 an Orange Book patent for Emsam?

RE34,579 is not a current Orange Book barrier to Emsam or generic selegiline transdermal products.

Emsam is the selegiline transdermal system approved by the FDA for major depressive disorder. The FDA-approved product uses a transdermal patch and delivers selegiline systemically. The product labeling identifies the product, its dosage strengths, administration instructions, contraindications, and tyramine-related dietary restrictions. (U.S. Food and Drug Administration, 2006.)

The relevant commercial product was developed after the original patent family had already been issued. Later patents relating to transdermal delivery systems, patch construction, formulations, manufacturing, and product performance were more likely to have regulatory and commercial significance than the original broad RE34,579 claims.

Regulatory issue	RE34,579 position
FDA approval	Not an approval patent; it is a patent document
Emsam indication	Major depressive disorder
Orange Book relevance today	No live patent term
Current Paragraph IV threat from RE34,579	None based on the expired patent
Regulatory exclusivity	Separate from patent rights and expired patent term
Biosimilar pathway	Not applicable; selegiline is a small molecule

Orange Book listing and patent enforceability are separate questions. An expired patent cannot support a current injunction or damages claim for post-expiration activity, regardless of whether it was historically associated with a branded product.

What Paragraph IV challenges and generic entry risks applied to transdermal selegiline?

A Paragraph IV certification is relevant only to an unexpired listed patent. RE34,579 itself cannot support a present Paragraph IV litigation strategy because its term has ended.

For generic transdermal selegiline, the relevant risks historically included:

Formulation patents. A generic patch could implicate patents covering adhesives, membranes, reservoirs, matrix systems, solvents, and penetration enhancers.
Patch-construction patents. Claims directed to pouch design, backing layers, release membranes, or drug loading could create product-specific risk.
Method-of-use patents. Patents covering depression treatment, dosing schedules, or reduced tyramine interaction could affect labeling and skinny-label strategies.
Regulatory exclusivity. FDA exclusivity could delay approval independently of patent expiration.
Clinical and pharmaceutical equivalence. A generic must demonstrate appropriate delivery performance, stability, adhesion, and bioequivalence or satisfy the applicable FDA abbreviated approval requirements.
Manufacturing barriers. Reproducible transdermal flux, patch adhesion, uniform drug loading, and control of residual solvents can create practical barriers even when no enforceable patent remains.

The core generic-launch scenarios are therefore:

Scenario	Effect of RE34,579
Patch copies the historical Emsam concept	No current risk from RE34,579
Patch uses a different matrix or carrier	No current risk from RE34,579
Product relies on a later unexpired patent	Potential risk from the later patent
Product uses a different indication	RE34,579 depression limitation may not apply, but composition claims must be assessed separately
Product is an oral or injectable selegiline product	Outside the transdermal claims
Product uses another active ingredient	Outside the literal active-ingredient scope

How strong were the claims of RE34579?

Historical strengths

The patent had several features that could make it commercially valuable when unexpired:

Claim 1 was not limited to a particular patch architecture.
The invention was tied to transdermal delivery of a known active ingredient for a specific therapeutic purpose.
The claims addressed the clinical problem of obtaining brain exposure without skin irritation or the cheese effect.
Dependent claims covered controlled release and one-day administration.
Composition claims extended protection beyond use of the method.

The broadest historical protection came from claim 1 and claim 7. Claims 4 through 6 and 11 through 12 were narrower but better aligned with a commercial patch product.

Vulnerabilities

The principal weaknesses were claim construction and proof of performance.

Functional limitations

Claim 1 requires a therapeutically effective amount in the blood supply to the brain and absence of skin irritation and cheese effect. These limitations can create proof issues. An accused product might dispute whether:

the delivered amount reaches the required level;
the amount is effective in the brain;
observed skin effects qualify as "skin irritation"; or
a clinical response constitutes a cheese effect.

Enablement and written-description issues

A broad claim covering transdermal selegiline across multiple carriers, patch designs, doses, and release profiles could face enablement or written-description scrutiny if the specification did not support the full breadth. Those issues would have mattered during the enforceable term, particularly against later patch systems using materially different technologies.

Prior-art exposure

The invention used a known monoamine oxidase inhibitor and a known delivery route. Patentability depended on the claimed combination, the demonstrated ability to achieve effective brain exposure, and the asserted avoidance of skin irritation and the cheese effect. Prior art concerning selegiline, transdermal drug delivery, and controlled-release patches would have been central to validity analysis.

Claim differentiation

The presence of specific patch and dosage limitations in dependent claims could support an argument that claim 1 was broader than a patch delivering 5-50 mg/day. It could also create prosecution-history and claim-construction issues if the applicant relied on those limitations to obtain allowance.

Because the patent is expired, these validity questions have limited current commercial value except in historical litigation review, prosecution analysis, or assessment of later patent-family strategy.

What later patents were more relevant to the Emsam patent estate?

The commercial selegiline transdermal estate included later patents directed to patch technology and product implementation. Publicly associated Emsam patent materials have included patents such as US 5,288,497 and US 5,427,798, although the legal relevance of each patent depends on its claims, expiration date, listing history, and any terminal disclaimer. These later patents should not be treated as interchangeable with RE34,579.

Patent category	Typical protected subject matter	Relevance to generic entry
Original transdermal method	Transdermal selegiline treatment	Historical platform protection
Controlled-release formulation	Carrier, rate control, drug flux	Product-design risk
Reservoir patch	Pouch, membrane, backing layer	Patch-construction risk
Matrix patch	Drug dispersed through polymer matrix	Alternative delivery-system risk
Adhesion technology	Skin adhesion and release characteristics	Manufacturing and product-performance risk
Method of use	Depression dosing or administration	Labeling and litigation risk
Manufacturing process	Loading, sealing, coating, packaging	Process and supply-chain risk

The existence of a later patent does not establish current enforceability. Each patent requires a separate review of its issued claims, maintenance status, term, terminal disclaimers, Orange Book listing, and litigation history.

Which companies were commercially involved in transdermal selegiline?

The principal branded product was Emsam. Somerset Pharmaceuticals developed and commercialized the product, and later commercial rights were associated with larger pharmaceutical companies through corporate transactions and product portfolios. Generic competition developed after the relevant patent and regulatory barriers declined.

The competitive landscape includes:

branded Emsam;
generic selegiline transdermal systems;
oral selegiline products, which do not practice the transdermal claims;
other antidepressants;
other monoamine oxidase inhibitors, including tranylcypromine and phenelzine; and
selective serotonin and norepinephrine reuptake inhibitors.

Transdermal selegiline had a differentiated safety and administration profile, but the product also carried dietary and drug-interaction restrictions at higher doses. Those clinical restrictions affected commercial substitution and prescribing.

How does RE34579 compare with oral selegiline patents?

RE34,579 is route-specific. Its claims require migration through the skin. They do not cover ordinary oral tablets, capsules, or sublingual dosage forms.

Product or route	Potential RE34,579 coverage
Transdermal selegiline patch	Historically within core scope
Selegiline cream or ointment	Potentially within composition claims 7, 9, or 10
Oral selegiline tablet	Outside the transdermal route limitations
Injectable selegiline	Outside the claimed route
Another MAO-B inhibitor	Outside the L-deprenyl limitation
Transdermal combination product	May avoid claim 7's sole-active-agent limitation, subject to claim 1 and other claims

The distinction matters because selegiline's active ingredient does not by itself establish infringement. The route, formulation, dosage, and therapeutic use must be mapped to the claim limitations.

What geographic rights did RE34579 create?

US RE34,579 created rights only in the United States. Corresponding foreign applications or patents would require separate analysis. Patent expiration in the United States did not automatically determine the status of foreign counterparts.

For international commercial planning, a company would need to distinguish:

US patent term;
European and national European rights;
Japanese, Canadian, and Australian rights;
supplementary protection certificates or patent-term extensions;
local generic approval rules; and
country-specific patent-linkage systems.

No foreign right can be inferred solely from the US reissue number.

What is the current freedom-to-operate position for transdermal selegiline?

RE34,579 presents no current US patent barrier because its term has expired. A new transdermal selegiline product would not require a license under the expired patent.

The meaningful current FTO questions concern later rights, including:

unexpired formulation patents;
patch-device patents;
manufacturing patents;
trademarks and trade dress;
regulatory exclusivity;
patent listings for any reference product; and
rights in jurisdictions where related patents had different terms.

A design that uses an ointment, cream, matrix patch, reservoir patch, or alternative carrier is not currently restricted by RE34,579 itself. The patent's historical claim architecture remains relevant as prior art and as a template for analyzing later selegiline transdermal claims.

Key Takeaways

US RE34,579 covers transdermal L-deprenyl, or selegiline, for depression and related topical compositions.
Claim 1 is the broadest method claim and focuses on effective brain exposure without skin irritation or the cheese effect.
Claims 2 through 6 narrow the invention to excipients, controlled delivery, patches, one-day use, and 5-50 mg/day delivery.
Claims 7 through 12 cover topical compositions, ointments, creams, patches, and a sealed-pouch porous-membrane patch.
RE34,579 is a reissue of US 4,868,218.
The underlying patent term ended in 2006 under the pre-URAA 17-year-from-grant regime.
The patent has no current US enforcement value and cannot independently support a present Paragraph IV challenge or generic-entry block.
Biosimilar analysis is not applicable because selegiline is a small-molecule drug.
Current FTO work must focus on later formulation, patch, manufacturing, method-of-use, and regulatory rights.
Transdermal selegiline claims do not reach oral or injectable selegiline products.

FAQs About US RE34579 and Transdermal Selegiline

Does US RE34579 cover all selegiline products?

No. It is directed to transdermal or topical L-deprenyl. Oral and injectable selegiline products do not meet the claimed dermal-delivery limitations.

Can an expired patent still block FDA approval of a generic selegiline patch?

No. An expired patent cannot block approval or support an infringement action. FDA approval may still require resolution of later listed patents, regulatory exclusivity, and product-specific requirements.

Does a selegiline cream infringe the original patent claims?

Historically, a selegiline cream could have implicated composition claims 7 and 10 if it satisfied all limitations. RE34,579 is now expired in the United States.

Is Emsam a biologic subject to biosimilar competition?

No. Emsam contains selegiline, a chemically synthesized small molecule. Generic-drug pathways, not biosimilar pathways, govern competition.

Does claim 6 cover a patch delivering less than 5 mg of selegiline per day?

No, not literally. Claim 6 expressly requires a controlled rate between 5 and 50 mg/day. A lower-dose patch could still require analysis under broader claims, but it would not satisfy the express numerical limitation of claim 6.

References

U.S. Patent No. RE34,579. (1994). Transdermal delivery of deprenyl. United States Patent and Trademark Office.
U.S. Patent No. 4,868,218. (1989). Transdermal delivery of deprenyl. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2006). Emsam (selegiline transdermal system) prescribing information. FDA.
U.S. Patent No. 5,288,497. (1994). Transdermal delivery system for selegiline. United States Patent and Trademark Office.
U.S. Patent No. 5,427,798. (1995). Transdermal delivery of selegiline. United States Patent and Trademark Office.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	3502289	⤷ Start Trial
Australia	628340	⤷ Start Trial
Canada	1329132	⤷ Start Trial
China	1038385	⤷ Start Trial
China	1048320	⤷ Start Trial
European Patent Office	0406488	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: RE34579

Summary for Patent: RE34579