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Patent landscape, scope, and claims: |
Patent 4,857,330 (US) Chlorpheniramine Dosage Form with Cellulose Acylate Wall and Mannitol-Controlled Release: Claim Scope and US Patent Landscape
United States Patent 4,857,330 claims an oral (or other body-fluid) dosage form for chlorpheniramine that uses a cellulose acylate/diacylate/triacylate wall permeable to exterior fluid but substantially impermeable to chlorpheniramine, enclosing a compartment with chlorpheniramine plus mannitol where mannitol concentration is 1.5 to 6x chlorpheniramine, and one or more passageways that dispense chlorpheniramine to the environment at an even rate over time. Dependent claims narrow to pharmaceutically acceptable salts (including chlorpheniramine maleate), specific cellulose triacylate (cellulose triacetate), 2 to 24 mg chlorpheniramine per unit, and an outermost layer structure and GI tract use.
What does US Patent 4,857,330 claim cover: dosage form architecture, rate control, and excipient ratios?
Core claim (claim 1) is a structural-function combination with five required elements:
- Dosage form for delivering chlorpheniramine to a biological environment of use (the claim is not limited to oral by claim 1, but claim 9 does specify GI/oral).
- A wall:
- Wall material must be a member selected from:
- cellulose acylate
- cellulose diacylate
- cellulose triacylate
- Wall is:
- permeable to exterior fluid
- substantially impermeable to chlorpheniramine
- Wall surrounds and forms a compartment.
- A compartment containing a dosage unit amount of:
- chlorpheniramine
- mannitol
- A quantitative composition relationship:
- mannitol concentration is from 1.5 to 6 times greater than chlorpheniramine.
- At least one passageway through the wall connecting the compartment to the exterior:
- enables dispensing at a substantially even rate to the environment over time.
Claim 1 scope implications (what the patent forces and what it leaves open)
- The patent’s “center of gravity” is the combination of wall selectivity + passageway metering + mannitol concentration window.
- It does not limit:
- particle size, crystal form, or manufacturing process in the text you provided;
- the number, geometry, or placement of passageways (only “at least one” and connection is required);
- whether the dosage unit is a single compartment or multi-compartment architecture (claim 1 requires a compartment; it does not expressly bar multiple compartments if at least one meets the claim language).
- It does not specify whether the mannitol is present as a solid, melt, mixture, or granulate; it only requires the presence and a concentration relationship relative to chlorpheniramine.
How does the cellulose acylate wall limit design-arounds for competing chlorpheniramine delivery?
The wall must be:
- drawn from a defined cellulose acylate family (acylate/diacylate/triacylate),
- fluid-permeable to exterior fluid,
- chlorpheniramine-impermeable “substantially,” and
- arranged as a surrounding barrier that forms a compartment.
Dependent narrowing: cellulose triacetate (claim 5)
Claim 5 narrows claim 1 by requiring the cellulose triacylate to be cellulose triacetate.
Design-around effect
- If a competitor uses cellulose esters outside the acylate/diacylate/triacylate set, they can avoid claim 1.
- If they use another cellulose triacylate other than triacetate (example type, not specified in the claim), they may still fall within claim 1 (triacylate is allowed) but avoid claim 5.
How is mannitol used to control chlorpheniramine release in claim 1, and how tight is the window?
Claim 1 forces a ratio constraint:
- mannitol concentration = 1.5 to 6x chlorpheniramine concentration.
This is a composition control that can drive both infringement and formulation validity:
- If the competitor’s formulation places mannitol outside the 1.5–6x range, it can avoid the claim even if the rest of the dosage architecture matches.
- If a competitor uses mannitol but with a different ratio, the core claim 1 may not be met.
Related dependent claims (amount, salts)
- Claim 6: 2 to 24 mg chlorpheniramine per dosage unit (limits unit strength).
- Claims 2–4: salt form and specific chlorpheniramine maleate.
These do not alter the ratio requirement, but they tighten infringement positions for salt-formulation competitors.
What do the passageways require for “substantially even rate” dispensing: metering versus diffusion?
Claim 1 requires at least one passageway in the wall:
- connecting the compartment to the exterior,
- enabling chlorpheniramine to be dispensed at a substantially even rate over time.
Scope impact
- The claim reads like a hybrid of barrier diffusion selectivity (cellulose wall impermeable to chlorpheniramine) and controlled release through one or more ports (passageways).
- It does not limit:
- passageway length or diameter,
- whether passageways are formed by a manufacturing process, pre-existing voids, laser channels, or other means.
- But the “even rate over time” is a functional requirement that would typically be evaluated against performance data if litigation turns on whether the design achieves “substantially even” release.
Is oral GI delivery required in US 4,857,330 or just optional?
Claim 1 is drafted broadly to a “biological environment of use” and does not limit route.
- Claim 9 explicitly sets:
- environment of use = gastrointestinal tract
- dosage form adapted for oral admittance into the GI tract.
Infringement consequence
- A product that meets claims 1–8 but is not adapted for GI/oral use could still infringe claim 1 depending on how “environment of use” is construed for the product’s intended use.
- A GI/oral product that meets all other claim limitations is directed into claim 9.
How strong is the claim coverage against chlorpheniramine salt formulations (maleate) and triacetate walls?
Salt coverage (claims 2–4)
- Claim 2: chlorpheniramine can be any pharmaceutically acceptable salt.
- Claim 4: chlorpheniramine can be chlorpheniramine maleate.
Scope effect
- Claim 1 already requires “chlorpheniramine.” Claim 2 makes explicit that salts are included. That supports coverage of commercial salt forms without requiring a narrow salt limitation.
- Claim 4 is narrower and would capture maleate-specific embodiments if the rest of claim 1 elements are met.
Wall material narrowing (claim 5)
- If a competitor uses cellulose triacetate specifically, it aligns with claim 5 but also generally aligns with claim 1 because triacetate is a type of cellulose triacylate.
What formulations are protected by the “outermost layer” limitations (claims 7–8)?
Claims 7 and 8 add a structural layering requirement:
- Claim 7: dosage form has an outermost layer comprising chlorpheniramine.
- Claim 8: outermost layer comprises 1 to 15 mg chlorpheniramine.
Scope effect
- If a competitor places chlorpheniramine only within the compartment (inner reservoir) and does not place it in an outermost layer, claims 7–8 may not read even if claim 1 does.
- But claim 1 itself does not state chlorpheniramine must be in an outermost layer. So claims 7–8 function as fallback dependent limitations, not necessarily essential for claim 1 infringement.
What is the practical infringement map: which product changes avoid claim 1?
A product will likely avoid claim 1 if it breaks any one required limitation:
- Wall material not within cellulose acylate/diacylate/triacylate set, or wall not substantially impermeable to chlorpheniramine.
- No compartment formed by such a wall or no passageway connecting compartment to exterior.
- No mannitol, or mannitol concentration outside 1.5–6x chlorpheniramine concentration.
- No dispensing at a substantially even rate over time through passageways.
- If relying on dependent claim constraints to avoid narrower claims:
- not a pharmaceutically acceptable salt (for claim 2, typically easier to avoid if using free base only, though claim 1 still covers chlorpheniramine generally),
- not maleate (for claim 4),
- not triacetate (for claim 5),
- chlorpheniramine amount not within 2–24 mg (claim 6),
- no outermost layer with chlorpheniramine and/or outside 1–15 mg (claims 7–8),
- not adapted for oral GI use (claim 9).
US patent landscape: what else typically sits around 4,857,330 in the same chlorpheniramine controlled-release space?
The claim set you provided is specific, but without a cited list of related patents, an Orange Book record, or prosecution history, a complete landscape cannot be constructed from your prompt alone. Under your constraints, an analysis that names specific neighboring US patents, assignees, and expiration dates would risk fabrication.
What can be stated from claim language alone is the likely type of surrounding patent families you would expect to coexist in US practice for this delivery concept:
- controlled-release chlorpheniramine dosage forms (extended-release antihistamines),
- semipermeable or selective membranes using cellulose ester matrices,
- capsule/tablet release modulation using osmotic or ported architectures with passageways,
- excipient-modulated release using sugar alcohols like mannitol as a release/solubility/porosity mediator,
- salt-form-specific claims (chlorpheniramine maleate) and unit-dose-strength claims,
- GI-adapted oral release systems.
But the specific “who, what patent numbers, and what dates” cannot be reliably produced from the information in your message.
Key takeaway
US 4,857,330 claim 1 is a defined, multi-constraint claim covering chlorpheniramine controlled release using a cellulose ester wall that is permeable to exterior fluid but substantially impermeable to chlorpheniramine, a mannitol-containing compartment with a 1.5–6x concentration ratio relative to chlorpheniramine, and at least one passageway producing substantially even release over time.
Dependent claims further narrow by salt form (including maleate), cellulose triacetate, unit dose (2–24 mg), outermost-layer chlorpheniramine and its mg range (1–15 mg), and GI/oral adaptation.
Key Takeaways
- Claim 1 is architecture-driven: cellulose acylate/diacylate/triacylate wall + impermeability to chlorpheniramine + compartment + passageway.
- Formulation ratio is mandatory: mannitol concentration must be 1.5 to 6x chlorpheniramine.
- Release behavior is claimed functionally: “substantially even rate” over time through the passageway.
- Dependent claims tighten product specifics: maleate salt, cellulose triacetate, 2–24 mg unit dose, and outermost-layer drug loading (1–15 mg), plus GI/oral route.
FAQs
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Does US 4,857,330 require passageway geometry or number of passageways?
Claim 1 requires “at least one passageway,” without geometry/number limitations in the provided claim text.
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Is mannitol required for infringement of claim 1?
Yes. Claim 1 requires chlorpheniramine and mannitol in the compartment plus the 1.5–6x concentration relationship.
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If the drug is chlorpheniramine free base, does the patent still apply?
Claim 1 covers chlorpheniramine generally; claim 2 clarifies that pharmaceutically acceptable salts are included.
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Is oral GI delivery required to practice the claimed invention?
Claim 9 specifies GI/oral adaptation, but claim 1 itself is drafted to a broader “biological environment of use.”
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Can a product avoid dependent claims 7–8 by putting chlorpheniramine only in the compartment?
Yes, if the product lacks an outermost layer comprising chlorpheniramine and thus does not meet the outermost-layer limitations.
References
- United States Patent 4,857,330. (Claims as provided in prompt text).
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