United States Patent 5,462,745: Scope, Claim Boundaries, and Patent Landscape
What does US 5,462,745 claim, in plain technical terms?
US 5,462,745 claims a transdermal delivery device where the agent in the reservoir acts as the solvent for medically acceptable adhesives, and the key improvement is controlling the agent’s activity and loading stability so the adhesive retains adhesive properties for the duration of administration.
The claims are framed around three coupled controls:
-
Solvent-like agent concentration control
- The reservoir contains an agent that is a solvent for medically acceptable adhesives.
- The agent is dissolved at concentration less than saturation.
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Adhesive-protecting activity limit
- The agent has an activity “less than that at which said adhesive surface loses its adhesive properties.”
-
Mass-loading and activity-drift limit
- The reservoir has an initial equilibrated agent loading sufficient such that the agent activity in the reservoir does not decrease by more than 75% during the predetermined administration period.
These elements are “improvement” features anchored to adhesive retention over time, not just permeation.
Claim 1: Core independent claim scope (the anchor for infringement)
Claim 1 defines the device structure and the quantitative performance boundary.
Device structure
- “In a transdermal delivery device”
- Administers “an agent through the skin … over a predetermined administration period”
- Device includes:
- Agent reservoir containing the agent
- Agent is a solvent for medically acceptable adhesives dissolved in the reservoir
- Reservoir is kept in “drug transmitting contact with the skin”
- Adhesion is maintained “by means of the adhesive properties of the agent releasing surface”
Core improvement language in Claim 1
The improvement is constrained by two sub-clauses:
(a) concentration and activity constraints
- Agent concentration in reservoir is < saturation
- Agent activity is < activity level where the adhesive loses adhesive properties
(b) initial equilibrated loading constraints
- Initial equilibrated agent loading is sufficient so that:
- agent activity does not decrease by more than 75% during administration
Claim 1 functional characterizations that matter for scope
- The claims do not require a specific adhesive type in Claim 1, only that it is a “medically acceptable” adhesive.
- The “agent activity” and “activity at which adhesive loses properties” are performance-defined. Practically, these terms are the main infringement and validity flashpoints because they typically rely on experimental correlations (e.g., adhesive tack retention vs. solvent activity).
Claims 2-6: Reservoir fraction limitations and activity decay caps
These claims narrow Claim 1 by limiting how much of the total initial loading is located in the reservoir and/or tightening the permissible activity decrease.
Reservoir loading distribution
- Claim 2: at least 50% of initial loading is in the reservoir (with “n at least 50%” as written; interpreted as “at least 50%”).
- Claim 4: at least 50% of initial agent loading is in the reservoir (duplicate language).
- Claim 6: at least 75% of initial agent loading is in the reservoir.
Activity decrease limits
- Claim 3: decrease in activity is no greater than 25%
- Claim 5: decrease in activity is no greater than 25% (duplicate with misspelling)
Practical implication: In enforcement, Claims 2/4/6 provide alternative narrower footholds (50% vs 75% reservoir loading). Claims 3/5 provide a separate, even tighter boundary (25% decay instead of 75% maximum in Claim 1).
Claims 7-10: Agent composition and adhesive interaction mechanisms
These claims further narrow the “agent” and specify adhesive interaction.
Agent material and state
- Claim 7: agent is an “oily, nonpolar material, liquid at body temperature”
- Claim 8: reservoir contains more than one agent, at least one of which is oily, nonpolar, liquid at body temperature
Adhesive interaction mechanism
- Claim 9: agent solubilizes the adhesive
- Claim 10: agent plasticizes the adhesive
Interpretive consequence: Claims 9 and 10 are not mutually exclusive. If an agent both solubilizes and plasticizes, it can satisfy either or both limitations depending on how “solubilizes” and “plasticizes” are construed and evidenced.
How broad is the claim set?
Breadth drivers (what increases coverage)
- “Agent” is defined by function (solvent for adhesives and activity control), not by chemical identity.
- Adhesive is defined as “medically acceptable,” not a specific polymer system.
- The improvement relies on activity and stability rather than a specific device architecture beyond “reservoir” and adhesive contact.
Specificity drivers (what narrows coverage)
- The agent must have an activity below the threshold where adhesive loses adhesion.
- There is a required stability window: activity decrease limited to 75% (or 25% in dependent claims).
- The agent is tied to being a solvent/plasticizer for adhesives; pure water or non-solvent permeants are unlikely to fit.
- Claims 7-8 narrow to oily, nonpolar, body-temperature liquids; claims 9-10 narrow to adhesive solubilization or plasticization behavior.
What are the likely infringement-critical elements?
In a dispute, the most litigated elements typically cluster into three “proof-heavy” limitations:
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Solvent relationship to adhesives
- Does the accused agent system dissolve the medically acceptable adhesive (Claim 1) and/or solubilize/plasticize (Claims 9-10)?
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Activity level vs adhesive tack loss threshold
- The claim ties adhesive loss to “activity” (Claim 1 (a)). The accused product must be evaluated under whatever measurement basis is used in the patent’s “activity” framework.
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Stability of agent activity during the administration period
- Claim 1 (b) requires that agent activity does not decrease more than 75% over the predetermined administration period (and Claims 3/5 require no greater than 25%).
- This is time-dependent and strongly depends on reservoir dynamics, partitioning, depletion, and flux.
A product can be structurally “transdermal” but fall outside if its solvent/adhesive activity relationship fails or if activity decays faster than the claim thresholds.
Claim-by-claim scope matrix
| Claim |
Limitation type |
Narrowing target |
Key boundary |
| 1 |
Independent |
Activity and loading stability while maintaining adhesive |
Agent concentration < saturation; agent activity < adhesive-loss threshold; activity decrease ≤ 75% during administration |
| 2 |
Dependent |
Reservoir mass distribution |
≥ 50% of initial loading in reservoir |
| 3 |
Dependent |
Activity stability |
activity decrease ≤ 25% |
| 4 |
Dependent |
Reservoir mass distribution |
≥ 50% of initial loading in reservoir |
| 5 |
Dependent |
Activity stability |
activity decrease ≤ 25% |
| 6 |
Dependent |
Reservoir mass distribution |
≥ 75% of initial loading in reservoir |
| 7 |
Dependent |
Agent composition |
oily, nonpolar, liquid at body temperature |
| 8 |
Dependent |
Multi-agent composition |
at least one oily nonpolar body-temp liquid |
| 9 |
Dependent |
Adhesive interaction |
agent solubilizes adhesive |
| 10 |
Dependent |
Adhesive interaction |
agent plasticizes adhesive |
Patent landscape: where US 5,462,745 fits and what competitors typically claim around it
US 5,462,745 lives at the intersection of:
- transdermal adhesive systems (tack retention, solvent/polymer interactions)
- reservoir systems (agent partitioning, depletion control)
- penetration-enhancing agents that also act as solvent for adhesives
Landscape map by “design-around axis”
Competitors typically pursue one of these separations to avoid this claim’s “activity-stability + adhesive-retention” combination:
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Change the solvent/adhesive mechanism
- If the agent does not solubilize or plasticize the adhesive (Claims 9-10) and instead works through other routes, it can avoid key functional elements even if it permeates.
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Avoid the activity-threshold relationship
- If the formulation uses an agent system where adhesive tack loss does not correlate with “agent activity” in the claimed way, the “activity below adhesive-loss threshold” limitation becomes harder to meet by equivalence arguments.
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Fail the activity-decrease window
- A major design-around is allowing higher depletion of solvent activity from the reservoir during the administration period, staying outside the “≤75%” (or “≤25%” dependent) decrease boundaries.
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Use adhesive-solvent systems outside “< saturation” solvent control
- Claim 1 (a) requires concentration less than saturation. Formulations near or above saturation (in the claimed reservoir context) create scope gaps.
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Alter reservoir-to-device loading distribution
- Moving more loading outside the “agent reservoir” (such as matrix absorbent layers, adhesive layers, or other regions) can miss the “≥50%” or “≥75% in reservoir” limits in dependent claims.
Likely claim-overlap space (what other patents in this area tend to cover)
Across transdermal technologies, overlapping subject matter commonly includes:
- transdermal drug-in-adhesive and reservoir devices
- penetration enhancers (often oils, nonpolar liquids)
- adhesive formulations where enhancers soften adhesives or adjust tack
- stabilization via solvent retention, partition tuning, or controlled release
US 5,462,745 distinguishes itself by tying the enhancer/solvent’s activity drift to adhesive property retention over a predetermined administration period.
Business interpretation for freedom-to-operate (FTO)
For a competitor assessing product risk:
- If their transdermal system uses a reservoir agent that is an adhesive solvent (or strong adhesive plasticizer), they are in the zone.
- If their system uses oils/nonpolar liquids at body temperature as enhancers that also interact with adhesive polymer, they are even closer (Claims 7-10).
- If their data show adhesive tack retention despite enhancer depletion (and measured enhancer activity remains within the claimed decay envelope), they are at direct risk.
Scope of enforceability and vulnerability points
Vulnerability: “activity” and “activity decrease” are performance-defined
Performance terms can be attacked on:
- indefiniteness (if not supported by measurement method in the patent specification)
- lack of enablement if “activity” is not tied to a reproducible measurement
- anticipation/obviousness by prior art that teaches solvent concentration and tack retention but not explicitly “activity < adhesive-loss threshold” and “≤75% activity decrease” over the administration period
Strength: the combination is unusual in the claim drafting
Most prior art around transdermal enhancers addresses:
- permeation rate
- adhesive tack
- solvent-polymer interactions
- controlled release of enhancer or drug
US 5,462,745 knits together:
- solvent for adhesives
- activity threshold tied to adhesive loss
- stability bound on activity decrease over time
- and (in dependents) specific reservoir loading fractions and oily nonpolar agents
That “activity-stability bound” is the signature.
What to look for in competitor formulations (practical checklist)
A product evaluation that maps to the claims should check:
- Reservoir identity: Is the “agent reservoir” where the solvent/enhancer is stored?
- Solvent role: Does the agent act as a solvent for medically acceptable adhesives?
- Concentration regime: Is the agent dissolved at less than saturation in the reservoir context?
- Activity proxy: Is there a known formulation parameter that corresponds to “agent activity” used to preserve adhesive properties?
- Time stability: During the predetermined administration period, does the agent activity decrease ≤75% (or ≤25% if targeting dependent claim risk)?
- Reservoir fraction: Is ≥50% (or ≥75%) of initial loading located in the reservoir rather than other layers?
- Agent class: Is the agent oily, nonpolar, liquid at body temperature?
- Mechanism: Does it solubilize or plasticize the adhesive?
Key Takeaways
- US 5,462,745 claim center is a transdermal reservoir device where an adhesive solvent is kept at < saturation and at an activity below the level that would cause adhesive tack loss, with the reservoir loaded so that agent activity decreases no more than 75% during the administration period.
- Dependent claims tighten the envelope to ≤25% activity decrease and enforce ≥50% or ≥75% of initial loading in the reservoir, plus agent-specific and mechanism-specific limits (oily nonpolar body-temp liquids; solubilizes or plasticizes adhesives).
- The highest-risk zone for infringement is products that use oils/nonpolar liquids or adhesive solvents/enhancers in a reservoir and demonstrate tack retention linked to controlled enhancer activity over time.
FAQs
-
Does the patent require a specific drug agent identity?
No. Claim 1 requires the “agent” to be an adhesive solvent with controlled concentration and activity, not a specified chemical drug.
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What is the core improvement in Claim 1?
It is the combination of (a) maintaining agent concentration below saturation and agent activity below adhesive-loss conditions, and (b) setting an initial equilibrated loading so agent activity drops by no more than 75% during the administration period.
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How do Claims 3 and 5 change the scope relative to Claim 1?
They tighten the activity-decrease cap from ≤75% (Claim 1) to ≤25%.
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Do the reservoir distribution dependent claims require the agent to be mostly in the reservoir?
Yes. Claims 2 and 4 require ≥50% of initial loading in the reservoir; Claim 6 requires ≥75%.
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Are Claims 9 and 10 mutually exclusive?
No. They define alternative or overlapping adhesive interaction mechanisms: the agent can “solubilize” and/or “plasticize” the adhesive depending on how the formulation behaves.
References
[1] United States Patent and Trademark Office. U.S. Patent No. 5,462,745.
