Details for Patent: 6,348,210

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Summary for Patent: 6,348,210

Title:	Methods for transdermal drug administration
Abstract:	Adhesive transdermal drug delivery devices may be removed and subsequently reapplied to an area of skin if the adhesive has an initial adhesive/skin bond strength sufficient to maintain said transdermal drug delivery device on the skin to which it is applied for the entire predetermined administration period; and an adhesive/skin bond strength upon replacement on the skin after removal therefrom which is adequate to retain the device on the skin for the balance of the administration period.
Inventor(s):	Robert Martin Gale
Assignee:	Durect Corp
Application Number:	US09/438,574
Patent Claim Types: see list of patent claims	Use; Formulation; Delivery; Device;

United States Patent 6,348,210: Claim Scope, Expiration, and Transdermal Testosterone Patent Landscape

U.S. Patent No. 6,348,210 protects a method for reusing a transdermal drug-delivery device on non-scrotal skin during a prescribed administration period. Its central technical requirement is an adhesive that maintains sufficient skin adhesion both during the initial application and after the device is removed and reapplied. The dependent claims narrow the invention to non-cross-linked polyisobutylene adhesives, defined molecular-weight ranges, plasticizers, adhesion-retention thresholds, and testosterone.

The patent is directed to an adhesion and reuse method, not to testosterone itself, a testosterone dosage, or a general transdermal patch platform. Based on the patent’s filing chronology, its ordinary 20-year U.S. patent term ended in approximately 2019, subject to any applicable patent-term adjustment or terminal disclaimer recorded in the USPTO file. The patent therefore presents no current U.S. blocking right if it expired without an extension.

What does U.S. Patent 6,348,210 protect?

The independent claims protect a sequence of physical steps:

1. Apply a transdermal device containing a drug to non-scrotal skin.
2. Remove the device before the end of a predetermined administration period.
3. Reapply the same device to non-scrotal skin.
4. Use an adhesive that maintains a required bond during both the first application and the replacement application.

The invention is defined by the combination of:

• A transdermal drug-delivery device.
• An adhesive surface.
• Non-scrotal skin.
• Removal before the end of the intended administration period.
• Reapplication to the individual’s non-scrotal skin.
• Initial and replacement adhesive-bond performance.

The patent does not claim every transdermal testosterone patch. A product that uses a new patch after removal, rather than reapplying the removed device, would not literally practice the stated reuse step.

Claim 1: broadest independent method claim

Claim 1 contains the core limitation:

The adhesive must provide an initial adhesive/skin bond strength sufficient to retain the device for the entire predetermined administration period and a replacement bond strength sufficient to retain the device for the balance of that period.

This language creates several potential claim-construction issues.

Claim element	Scope implication
“Method for transdermal administration”	Requires a use method, not merely an adhesive composition or device structure
“Drug”	Broad genus covering drugs generally
“Non-scrotal skin”	Excludes application to scrotal skin
“Predetermined administration period”	Requires a defined intended period, but does not specify its duration
“Removing said device”	Requires removal before the period ends
“Reapplying said device”	Strongly suggests reuse of the same device
“Initial bond strength”	Requires measurable adhesion at first application
“Bond strength upon replacement”	Requires measurable adhesion after removal and reapplication
“Sufficient” adhesion	Functional limitation tied to retaining the device

The claim does not specify the adhesive chemistry, testosterone concentration, patch dimensions, permeation enhancer, membrane structure, backing layer, release rate, or application site other than the exclusion of scrotal skin.

How do the dependent claims narrow Patent 6,348,210?

Claims 2 through 17 progressively restrict the adhesion performance, polymer composition, plasticizer, and drug.

Adhesion limitations

Claims 2 and 3 establish an initial bond-strength range:

• Claim 2: less than 195 gm/cm.
• Claim 3: at least approximately 95 gm/cm.

Read together, claims 2 and 3 define an approximate initial bond-strength range of 95 to less than 195 gm/cm.

Claims 10 through 13 require the replacement bond strength to remain at least:

• 72% of the initial bond strength; or
• 85% of the initial bond strength.

The 85% limitation is narrower and more commercially significant because it requires limited adhesion loss after removal and reapplication.

Claims	Limitation
1	Functional initial and replacement adhesion
2	Initial bond strength below 195 gm/cm
3	Initial bond strength at least about 95 gm/cm
10, 12	Replacement bond strength at least 72% of initial strength
11, 13	Replacement bond strength at least 85% of initial strength

The claims do not state the test instrument, peel angle, peel rate, substrate preparation, dwell time, skin site, temperature, or number of replacement cycles. Those parameters would likely become important in infringement and validity disputes.

Polyisobutylene adhesive limitations

Claim 4 requires a non-cross-linked adhesive formulation. Claim 5 narrows the polymer to polyisobutylene, commonly abbreviated PIB.

Claim 6 requires a mixture of:

• Low molecular weight polyisobutylene; and
• High molecular weight polyisobutylene.

Claim 7 sets the molecular-weight ranges:

• LMW PIB: approximately 15,000 to 50,000.
• HMW PIB: approximately 990,000 to 1,600,000.

The claim text supplied states “1,6000,000” for the upper HMW PIB value. That appears to be a typographical rendering of 1,600,000. The issued patent and prosecution record control the legally operative text.

Claim 8 adds a plasticizer. Claim 9 narrows the composition to the following HMW PIB/LMW PIB/plasticizer ratio:

0.75-1.25 / 1-1.5 / 1.5-2.5

Claim 14 identifies mineral oil and polybutene as permitted plasticizers.

Claims	Adhesive composition
4	Non-cross-linked adhesive
5	PIB polymer
6	LMW PIB plus HMW PIB
7	Defined molecular-weight ranges
8	Plasticizer required
9	Defined component ratio
14	Mineral oil or polybutene plasticizer

What testosterone products fall within the patent’s claim structure?

Claims 15 through 17 narrow the drug to testosterone:

• Claim 15 depends from claim 1.
• Claim 16 depends from claim 3.
• Claim 17 depends from claim 13.

A testosterone product would need to satisfy the method limitations, not merely contain testosterone. The strongest asserted combination would require:

1. Testosterone in a transdermal device.
2. Application to non-scrotal skin.
3. Removal before the end of the intended period.
4. Reapplication of the device.
5. Initial adhesion of at least approximately 95 gm/cm.
6. Replacement adhesion of at least 85% of the initial strength.

A conventional testosterone patch applied once and discarded after a 24-hour period may not practice these claims if the product does not require or permit reapplication of the same device. A product with a fresh patch for each dosing interval would present a substantial noninfringement position against the reuse limitation.

When did U.S. Patent 6,348,210 expire?

The patent issued on February 19, 2002. Its term was governed primarily by the 20-year period measured from the relevant nonprovisional application filing date, rather than by the issue date. The patent’s filing and priority history places ordinary expiration in approximately 2019. The controlling date should be taken from the USPTO Patent Center record, including any patent-term adjustment, terminal disclaimer, continuation relationship, or other term event. (U.S. Patent and Trademark Office, n.d.-a)

Because the patent is now beyond its ordinary term, it should not create current U.S. exclusionary leverage unless an unusual term adjustment or other statutory extension applies. The patent was a method patent and was not a biologic patent eligible for patent-term restoration under the Hatch-Waxman provisions applicable to certain regulated products.

Exclusivity timeline

Event	Timing
Patent application and priority activity	Late 1990s to approximately 2000
Patent issuance	February 19, 2002
Ordinary 20-year patent term	Approximately 2019
Current status	Expected expired, subject to the official USPTO term record
FDA exclusivity	Separate from patent term and dependent on the relevant NDA

Patent expiration does not establish FDA approval status. FDA regulatory exclusivity, Orange Book listing, and patent enforceability are separate questions.

What is the Orange Book status of Patent 6,348,210?

An Orange Book listing depends on whether the patent was submitted for an approved drug application and whether the FDA accepted it as claiming the drug, a formulation, or an approved method of use. A patent number alone does not establish an Orange Book listing.

The relevant reference product for the testosterone-patch landscape is Androderm, a transdermal testosterone system approved under NDA 020489. FDA labeling identifies the product as a testosterone transdermal system for replacement therapy in males with a deficiency or absence of endogenous testosterone. (U.S. Food and Drug Administration, n.d.-a)

Patent 6,348,210 should be checked against:

• The FDA Orange Book patent-use-code listings.
• Historical Orange Book editions.
• The NDA holder’s patent submissions.
• The patent-use code associated with any listing.
• Whether the patent was delisted or expired before a later generic filing.

An expired patent may remain visible in historical Orange Book data while providing no current right to exclude. The relevant commercial question is whether the patent was listed when an ANDA applicant submitted a Paragraph IV certification.

What Paragraph IV challenges could affect this patent?

A Paragraph IV certification would assert that a listed patent is invalid, unenforceable, or not infringed by the proposed generic. For this patent, the principal noninfringement theories would be:

• The generic uses a new patch after removal rather than reapplying the same patch.
• The generic is applied to a different anatomical site that does not satisfy the claimed method.
• The adhesive does not meet the initial bond-strength range.
• The replacement bond strength is below the claimed percentage threshold.
• The adhesive is cross-linked.
• The adhesive does not contain PIB in the claimed structure or molecular-weight range.
• The product instructions do not direct the claimed removal-and-reapplication sequence.

Potential invalidity theories would focus on:

• Anticipation by earlier transdermal systems that were designed for reuse.
• Obviousness based on known PIB adhesives and routine adhesion optimization.
• Indefiniteness of “sufficient” bond strength and “predetermined administration period.”
• Enablement across the full scope of all drugs and adhesive systems covered by claim 1.
• Written-description support for the broad generic drug and non-scrotal-skin language.

The functional adhesion limitations could make anticipation more difficult if the prior art did not disclose testing after removal and reapplication. They also create evidentiary burdens because infringement testing would need a reproducible protocol.

How strong is the patent estate for reusable transdermal patches?

Patent 6,348,210 is narrower than a composition patent or a device patent. Its commercial value depends on whether the accused product’s labeling and actual use require reuse of the same patch.

Strengths

• The claim combines application, removal, and reapplication steps.
• The claim addresses a practical failure mode in transdermal systems: loss of adhesion after removal.
• Claims 10 through 13 provide quantitative replacement-adhesion thresholds.
• Claims 6 through 9 and 14 create narrower fallback positions around PIB formulations.
• Testosterone-specific claims connect the technology to an established commercial product category.

Weaknesses

• Claim 1 is a method claim with broad functional language.
• “Sufficient” adhesion is not tied to a fully specified test method.
• The reapplication step may exclude products that replace the patch instead of reusing it.
• The broad claim covers drugs beyond testosterone, but the specification must support that breadth.
• The patent’s ordinary term has ended.
• The adhesive composition claims are dependent method claims rather than standalone composition claims.

The strongest historical positions were likely claims 11, 13, and 17, because they combine testosterone with an 85% replacement-adhesion requirement. The narrowest composition position is claim 14 when read with claims 9, 8, 7, 6, 4, and 1.

What manufacturing and intellectual-property barriers did the patent create?

The patent did not appear to block ordinary manufacture of a testosterone patch solely because the patch used PIB. The risk was tied to the claimed combination of formulation and reuse behavior.

A competitor would need to control several variables:

• PIB molecular-weight distribution.
• HMW-to-LMW polymer ratio.
• Plasticizer identity and concentration.
• Adhesive coating weight.
• Peel and tack performance.
• Skin-site instructions.
• Patch-reuse instructions.
• Adhesion after removal and reapplication.

A design-around could use:

• A cross-linked adhesive.
• An acrylic or silicone adhesive.
• A new patch after removal.
• A single-use patch with no reapplication instruction.
• A formulation outside the claimed PIB molecular-weight or ratio ranges.
• A product that does not meet the claimed bond-strength thresholds.

These approaches could create separate regulatory or performance issues. A change in adhesive chemistry may affect testosterone flux, skin irritation, residual drug content, stability, or manufacturing reproducibility.

Which companies were relevant to the testosterone-patch landscape?

The commercial landscape has included the originator and generic manufacturers of testosterone transdermal systems.

Company or product group	Relevance
Watson Laboratories / Actavis / Allergan	Historical commercial association with Androderm and related testosterone products
AbbVie	Commercial presence in testosterone replacement products, including non-patch products
Generic ANDRODERM applicants	Potential ANDA applicants subject to Orange Book certifications
Other testosterone manufacturers	Competition through gels, injections, oral products, and nasal formulations

The principal competitive threat to a testosterone patch is not limited to another patch. Testosterone gels, injections, oral testosterone undecanoate, buccal systems, and nasal products compete for the same replacement-therapy market while avoiding patch-specific adhesion patents.

What litigation and settlement issues affect the patent?

The patent number alone does not establish a current litigation matter. Any historical litigation analysis must be tied to:

• The patent’s docket history.
• ANDA litigation involving NDA 020489.
• Paragraph IV notices.
• District-court complaints.
• Federal Circuit appeals.
• Settlement agreements and authorized-generic provisions.

No current enforcement value should be assigned to Patent 6,348,210 solely from its inclusion in a historical patent estate. If the patent expired in approximately 2019, later generic entry would not be blocked by this patent, although earlier litigation or settlement obligations could have affected launch timing before expiration.

A settlement involving other Androderm patents would not automatically resolve or license this patent. Each patent would require separate analysis unless the agreement expressly covered the patent family or all listed patents.

How does Patent 6,348,210 compare with other testosterone patent categories?

Patent category	Typical protected subject	Relevance to 6,348,210
Active-ingredient patent	Testosterone or derivative	Not the subject of this patent
Patch-device patent	Backing, reservoir, membrane, geometry	Not the principal subject
Adhesive-composition patent	Polymer and plasticizer composition	Partially covered through dependent method claims
Method-of-use patent	Administration protocol	Core category for 6,348,210
Formulation patent	Release profile or permeation system	Only indirectly relevant
Manufacturing patent	Coating, lamination, or assembly process	Not claimed directly
Regulatory exclusivity	NDA-based FDA protection	Separate from patent rights

This distinction matters in generic entry analysis. A generic may avoid this patent but still face a separate formulation, device, or method-of-use patent. Conversely, a patent listed for a testosterone patch may be irrelevant if the proposed generic does not practice the listed method.

What is the likely generic launch risk?

For the period before expiration, the risk depended on the generic’s proposed labeling and adhesive design.

Generic design	Risk under Patent 6,348,210
Same patch removed and reapplied	High, if adhesion thresholds are met
New patch applied after each removal	Lower, because reuse may be absent
Cross-linked acrylic adhesive	Lower under claims requiring non-cross-linked PIB
PIB formulation outside claimed ranges	Lower under composition-dependent claims
Testosterone gel	No direct claim overlap
Injectable testosterone	No direct claim overlap
Oral testosterone	No direct claim overlap
Same formulation but no reuse instruction	Reduced method-of-use exposure

The most important diligence point is the product label. Method claims are often enforced through the intended use reflected in labeling, prescribing instructions, and product design. Actual off-label reuse may present a different enforcement profile than a label-directed reuse protocol.

Key Takeaways

• U.S. Patent 6,348,210 is a transdermal-device reuse and adhesion patent.
• Claim 1 requires application, removal, and reapplication of a device on non-scrotal skin.
• The patent does not broadly claim testosterone, testosterone patches, or PIB adhesives in isolation.
• Dependent claims narrow the invention to adhesion ranges, non-cross-linked PIB, defined PIB molecular weights, plasticizers, ratios, and testosterone.
• The strongest historical claims combine testosterone with replacement adhesion of at least 85% of the initial bond strength.
• The patent’s ordinary U.S. term appears to have ended in approximately 2019.
• Generic exposure depends heavily on whether the proposed product reuses the same patch and satisfies the claimed adhesion metrics.
• Orange Book listing, Paragraph IV litigation, and settlement coverage must be verified from the relevant NDA and USPTO records rather than inferred from the patent number.
• The patent is no longer an apparent current U.S. barrier if the official USPTO record confirms expiration without an extension.

FAQs

Does Patent 6,348,210 cover all testosterone transdermal patches?

No. It covers a method requiring removal and reapplication of the same transdermal device, together with specified adhesion performance. A single-use testosterone patch may fall outside the claims.

Does the patent cover scrotal testosterone administration?

No. Every independent method claim supplied requires application to non-scrotal skin. Scrotal administration is outside that express limitation.

Can a generic avoid the patent by changing the adhesive polymer?

Potentially. A product using an adhesive outside the claimed non-cross-linked PIB limitations may avoid the narrower dependent claims. It would still need to avoid the broader functional method claim.

Are the bond-strength values enough to determine infringement?

No. The values require a reproducible test protocol. The parties would need to address the test method, peel conditions, skin substrate, dwell time, and replacement procedure.

Does patent expiration eliminate FDA exclusivity?

No. Patent expiration and FDA exclusivity are separate rights. An expired patent cannot ordinarily block launch, but FDA regulatory exclusivity or another unexpired patent may still affect approval or commercial entry.

References

1. U.S. Food and Drug Administration. (n.d.-a). Drugs@FDA: FDA-approved drugs, Androderm, NDA 020489. https://www.accessdata.fda.gov/scripts/cder/daf/

2. U.S. Food and Drug Administration. (n.d.-b). Approved drug products with therapeutic equivalence evaluations. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

3. U.S. Patent and Trademark Office. (n.d.-a). Patent Center. https://patentcenter.uspto.gov/

4. U.S. Patent No. 6,348,210. (2002). Transdermal drug delivery device with improved adhesion. United States Patent and Trademark Office.

5. U.S. Patent and Trademark Office. (n.d.-b). Patent term adjustment and patent term calculation. https://www.uspto.gov/patents/laws/patent-term-calculator

Drugs Protected by US Patent 6,348,210

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate