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Patent landscape, scope, and claims: |
Executive summary
- US Patent 5,227,169 claims a laminated transdermal composite (patch/skin-contact device) for sustained delivery, defined by: (i) a substantially impermeable backing layer, (ii) a reservoir on skin via an adhesive polymer layer, (iii) a permeation enhancer consisting essentially of specific sorbitan esters with tightly defined substituent classes (with dependent coverage adding specific species like sorbitan monooleate and sorbitan monolaurate, plus an added C1–C4 alcohol alternative), and (iv) broad coverage for pharmacologically active agents including pindolol and steroid drugs (estradiol, progesterone, norethindrone acetate).
- The claims fall into two claim “families”:
- Basic laminated composite with sorbitan-ester permeation enhancer (claims 1-12 and 14-19, plus formulation vehicle options).
- Laminated composite with multi-layer peel/seal architecture (claims 13, 20, 26-27) that includes peelable/impermable peel layers, a permanent heat seal, and a peelable heat seal broken on removal of a second peelable layer, enabling controlled activation/handling of actives.
Because the prompt provides only the claim set (not publication history, assignee, or file wrapper documents), this analysis is limited to scope mapping and landscape inference grounded in claim language, not to verified prosecution/licensing outcomes.
US Patent 5,227,169 landscape: what patents protect laminated transdermal composites using sorbitan esters?
US 5,227,169 is structurally anchored in a transdermal laminated system with a defined permeation enhancer class: sorbitan esters of a specified general formula with substituent constraints on chain length and hydroxyl/esterification status. The independent claim architecture also requires a backing that is substantially impermeable and a reservoir layer that is adhered to skin by an adhesive polymer.
What permeation enhancer scope does US 5,227,169 cover?
Core: “permeation enhancer which consists essentially of” sorbitan esters.
Key sorbitan ester structural parameters (independent-claim level)
The claims require:
- Sorbitan ester with structural formula (as shown in the claims)
- R1 = –O(CO)R′
- R′ selected from:
- saturated / mono-unsaturated / di-unsaturated / tri-unsaturated aliphatic hydrocarbon substituents
- 7 to 21 carbon atoms
- optionally containing 1 to 3 hydroxyl groups
- R2 and R3 independently selected from:
- hydroxyl and/or –O(CO)R′ (esterified hydroxyl positions)
“Consists essentially of” affects add-on ingredients
“Consists essentially of” means the enhancer is primarily the specified sorbitan ester structure, while allowing only those additional ingredients that do not materially affect the basic and novel characteristics of the claimed permeation enhancer. That phrasing typically narrows design-arounds vs “comprises.”
Dependent narrowing: specific species
- Sorbitan monooleate and sorbitan monolaurate are explicitly called out in dependent claims (e.g., claim 4, 10, 17, 23, 27).
Alternative branch: sorbitan ester plus C1–C4 alcohol
Claims 7 and 11 (and the corresponding sealed-device version in claim 20/26 variants) expand to:
- sorbitan ester in combination with a C1–C4 aliphatic alcohol
- Explicit alcohol list: ethanol, n-propanol, isopropanol, t-butanol, and mixtures.
Practical implication: if an accused patch uses a sorbitan ester outside the stated structural boundaries or relies on a different enhancer class, it can fall outside the “consists essentially of” limitation. If it uses the same sorbitan ester species, adding alcohol can still land inside the claimed enhancer system, depending on whether the claim uses “consists essentially of” and whether the alcohol is part of the specifically recited alternative.
Which drugs and therapeutic categories are explicitly claimed?
US 5,227,169 explicitly covers:
- Pindolol (claim 5 and claim 12)
- Steroid drugs (claims 14-19, 18, 24-25, and sealed variants 20-27), including:
- estradiol
- progesterone
- norethindrone acetate
- mixtures
Claim scope for “pharmacologically active agent” beyond pindolol/steroids
The independent claims use “pharmacologically active agent” and separately define a steroid subset. Based on literal language, the broadest independent claims do not limit to pindolol/steroids; they only provide dependent narrowing where specified. That means in a dispute, the active-ingredient coverage could be broader than the explicitly listed examples if a court treats “pharmacologically active agent” as inclusive.
What laminated patch architecture is required?
Universal elements (independent claim “basic laminated composite”)
Across claims 1 and 7:
- Backing layer: “substantially impermeable” to the pharmacologically active agent
- Reservoir layer:
- includes an adhesive polymer
- basal surface is adapted to be adhered to skin
- contains “therapeutically effective amount” of the active
- Permeation enhancer:
- sorbitan ester class, “consists essentially of …”
- The claims do not require a separate membrane in the basic versions.
Distinct architecture in sealed/peel-system independent claim (claim 13 and mirrored steroid version in claim 26)
Claim 13 adds:
- Active-agent-permeable membrane between backing and reservoir
- Reservoir periphery smaller than backing and membrane, so backing/membrane extend outward
- First peelable active agent formulation-impermeable layer underlying reservoir and outward portion
- Adhesive layer underlying and covering first peelable layer and outward portion
- Second peelable formulation-impermeable layer underlying and covering adhesive layer
- Permanent heat seal about reservoir periphery between backing and membrane
- Peelable heat seal underlying permanent heat seal between backing and first peelable layer
- A peel-strength relationship:
- peel strengths between adhesive and first/second peelable layers are greater than force to break peelable heat seal
- Mechanism on use:
- when second peelable layer is removed, peelable heat seal breaks
- first peelable layer and underlying adhesive portion are removed with it
Practical implication: infringement of claim 13/26 type requires a specific multi-peel activation/heat-seal mechanism. A patch without those peelable layers and heat seals can avoid those claims even if it uses the same sorbitan enhancer and adhesive/reservoir architecture.
How broad are the “adhesive polymer” and “vehicle” limitations?
Adhesive polymer class (dependent claims 2, 8, 15, 21)
The adhesive polymer is limited to:
- polysiloxanes
- polyacrylates
- polyurethanes
- tacky rubbers
This is not “any adhesive.” It narrows to these polymer categories.
Inert vehicle option (claims 6, 19, 25)
Dependent claims add:
- reservoir layer further includes “a pharmaceutically acceptable inert vehicle.”
This can broaden formulations that otherwise meet the base structure. It also supports that US 5,227,169 contemplates standard transdermal reservoir solvent/vehicle systems, so design-arounds must still track enhancer and adhesive/reservoir structure more than vehicle choice.
What are the independent claim “design zones” and how can they be segmented for freedom-to-operate?
Claim zone A: Basic laminated composite with sorbitan ester enhancer (claims 1 and 7)
Required chain of elements
- substantially impermeable backing
- reservoir adhered via adhesive polymer
- therapeutically effective active agent in reservoir
- permeation enhancer: sorbitan ester (consists essentially of) with structural constraints
- optionally: C1–C4 alcohol in claim 7 dependent branch
Scope leverage for attackers/defenders
- Strong for plaintiffs where accused products use the same enhancer architecture.
- Weaker for plaintiffs against products that use:
- a different enhancer scaffold (e.g., terpene-based, fatty acid derivatives not in sorbitan ester form, etc.)
- sorbitan esters outside the carbon-length or esterification/hydroxyl constraints
- adhesive polymer outside the specified categories
- Also avoidsable if the patch includes a different layer configuration not matching “basic” claim (if claim 13/26 architecture is missing, that affects the peel-claims but not claim 1/7).
Claim zone B: Sealed/peel-layer laminated composite (claims 13 and 26)
Required additional elements
- membrane and multi-layer peel architecture
- heat-seal system
- peel strength relationship and removal sequencing logic
This is a more complex “mechanism and construction” set. If a product lacks the peel/heat-seal activation scheme, it is outside the peel claims even if it uses sorbitan esters.
Claim zone C: Drug-specific dependent narrowing
- pindolol (claims 5 and 12)
- steroids list (claims 18 and 24-27)
These dependent claims make it easier to map coverage for those specific APIs, but they do not constrain the broad “pharmacologically active agent” category in claim 1/7.
How long is the exclusivity tail and when would US 5,227,169 expire?
No expiration data can be computed from the prompt alone because patent term depends on:
- filing date
- patent grant date and any patent term adjustment
- whether there are terminal disclaimers
- whether the patent is part of a family with later continuing claims affecting term
The claim text alone cannot yield the enforceable expiration date, and producing an expiration timeline without the file date risks accuracy failure.
How does claim scope map to likely competing transdermal patents and “sorbitan ester enhancer” equivalents?
Which claim elements are most likely to be copied vs engineered around?
Most copyable
- laminated transdermal structure: impermeable backing + reservoir adhered to skin
- using a sorbitan ester enhancer species such as monooleate/monolaurate
- using polysiloxane/polyacrylate/polyurethane/tacky rubber adhesive polymers
- adding inert vehicles
Most engineer-aroundable
- the “consists essentially of” enhancer definition: switching enhancer class or using sorbitan ester chemistry outside the constrained parameter space (R′ chain length 7-21 and R2/R3 patterns)
- removing or altering the peel/heat-seal architecture needed for claim 13/26
- changing adhesive polymer chemistry away from the listed polymer categories
How do the “with C1–C4 alcohol” branches change risk?
If a product uses:
- sorbitan ester in the claimed class and
- includes C1–C4 aliphatic alcohol as an enhancer adjunct,
then risk increases under claims 7/11 and the corresponding sealed composite options.
If a product uses:
- sorbitan esters but omits the alcohol,
then the claim 7/11 branches may not apply, but claims 1/4/5/6 and steroid analogs still may.
What does the claim set imply about patent strength for litigation?
Strength drivers
- Narrow and specific enhancer chemistry defined by structural formula constraints.
- Explicit “sorbitan monooleate / sorbitan monolaurate” dependent claims create concrete infringement anchors.
- Sealed/peel system claims (13 and 26) define a fairly specific device activation architecture, which can be compelling if an accused patch has a similar multi-layer peel design.
Strength reducers (scope vulnerabilities)
- “Consists essentially of” creates a potential argument space over whether any co-enhancers materially affect the basic and novel characteristics.
- “Substantially impermeable” and “reservoir/permeation enhancer” functional language can invite claim construction fights.
- The adhesive polymer limitation to specified polymer classes may allow design-around by selecting different adhesive compositions.
Orange Book status and FDA regulatory linkage
No FDA product identifiers, NDA/ANDA/BLA references, or Orange Book listings are provided in the prompt. This analysis therefore cannot map 5,227,169 to specific listed drug products or exclusivity blocks.
Key claim-by-claim scope checklist (for infringement mapping)
Claims 1 and 7 (basic laminated composite)
- Impermeable backing (required)
- Adhesive polymer reservoir with basal surface adhered to skin (required)
- Active amount (required)
- Permeation enhancer:
- claim 1: sorbitan ester class only
- claim 7: sorbitan ester class plus C1–C4 alcohol (alternative branch)
- R′ = 7–21 carbon aliphatic substituent (optionally 1–3 hydroxyls)
- R2 and R3 = hydroxyl and/or esterified hydroxyl positions
Claims 2, 8, 15, 21 (adhesive polymer subset)
- polysiloxanes / polyacrylates / polyurethanes / tacky rubbers
Claims 3-4, 9-10, 16-17, 22-23 (sorbitan ester narrowing)
- R′ = 11–21 carbon substituents (optionally 1–3 hydroxyls)
- R2 and R3 both hydroxyl (dependent)
- sorbitan monooleate or sorbitan monolaurate
Claims 5 and 12 (pindolol)
- Active ingredient is pindolol
Claims 6, 19, 25 (vehicle)
- reservoir includes pharmaceutically acceptable inert vehicle
Claims 13 and 26 (sealed/peel layered composite)
All claim 1/7-type enhancer and reservoir/backing concepts plus:
- active-agent-permeable membrane
- multi-peel layers and adhesive layer layout
- permanent heat seal and peelable heat seal sequence
- peel strength relationship controlling activation by removing second peelable layer
Claims 14-18 and 20-27 (steroid version)
- steroid list as specified in dependent claims
- same enhancer and adhesive limitations
- sealed/peel architecture mirrored in claims 26-27
Key Takeaways
- US 5,227,169’s enforceable concept is a transdermal laminated patch defined by (i) a sorbitan ester permeation enhancer with tightly constrained structural parameters and (ii) an adhesive-polymer reservoir adhered to skin against a substantially impermeable backing.
- The claim set contains two distinct technology “zones”: basic laminated composites (enhancer + reservoir + backing) and multi-layer peel/heat-seal activation composites (claim 13/26) that add a specific device activation mechanism.
- Dependent claims materially increase infringement precision for sorbitan monooleate/monolaurate, specified adhesive polymer classes, and pindolol/steroid actives.
- A product can avoid risk by changing either the enhancer chemistry (outside the sorbitan ester structural bounds or altering the “consists essentially of” profile) or the device architecture (removing the peel/heat-seal mechanism required for the sealed claims).
FAQs
- What does “permeation enhancer consists essentially of a sorbitan ester” limit compared with “comprises”?
- Do claims 1 and 7 cover transdermal patches that omit an active-agent-permeable membrane?
- Can a product use sorbitan monooleate but with an adhesive polymer outside polysiloxanes/polyacrylates/polyurethanes/tacky rubbers and avoid dependent claims?
- How critical is the peel-strength relationship in claims 13 and 26 for infringement analysis?
- If a formulation includes sorbitan ester plus a C1–C4 alcohol, does that automatically place it within claim 7 (or claim 20/26 variants)?
References
- US Patent 5,227,169, “Laminated composite for administering a pharmacologically active agent through a selected area of skin over a sustained time period,” claim set as provided in prompt.
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