Scope, claims, and US patent landscape for Drug Patent US 4,662,880 (pseudoephedrine + brompheniramine codelivery dosage form)

US Patent 4,662,880 is a drug-product patent centered on a specific controlled-release dosage form architecture and drug-partitioning strategy for codelivering pseudoephedrine and brompheniramine. The core scope is constrained by (i) the wall polymer system (cellulose triacetate + hydroxypropylcellulose) with defined permeability behavior, (ii) a passageway-enabled compartmented core, (iii) a drug-containing lamina on the exterior of the wall using hydroxypropylmethylcellulose, and (iv) delivery ratio constraints during “operation,” either tied to equilibrium solubility (Claim 1) or to mass-ratio ranges (Claims 2 and 5, and the further dependent-specific embodiments in Claims 6 to 14).

What do the independent claims cover?

1) What is the invention claimed in Claim 1?

Claim 1 is the broadest structural-mechanistic statement. It covers a dosage form for delivering pseudoephedrine + brompheniramine to an environment of use, where:

Wall composition and behavior
- A wall comprising cellulose triacetate and hydroxypropylcellulose
- The wall is permeable to fluid in the environment of use
- The wall is substantially impermeable to the passage of drug
- The wall surrounds and defines a compartment
Compartmented drug load
- A compartment
- A dosage amount of pseudoephedrine and brompheniramine in the compartment
Passageway / communication
- At least one passageway in the wall connecting the compartment with the exterior
Exterior lamina
- A lamina comprising pseudoephedrine, brompheniramine and hydroxypropylmethylcellulose
- The lamina is in laminar arrangement with the exterior of the wall
Delivery ratio condition (mechanism-limiting)
- During operation, the dosage form codelivers pseudoephedrine and brompheniramine at a ratio greater than their mutual equilibrium solubility in fluid entering the dosage form (emphasis: ratio relative to an equilibrium solubility concept)

This claim scope is not only structural; it includes a functional delivery-ratio requirement tied to equilibrium solubility in entering fluid.

2) How does Claim 2 narrow or specify scope versus Claim 1?

Claim 2 keeps the same architecture but replaces the equilibrium-solubility ratio limiter with a mass ratio range:

Same wall (cellulose triacetate + hydroxypropylcellulose) with fluid permeability / drug impermeability and compartment definition
Same compartment and passageway
Same exterior lamina composition concept (pseudoephedrine + brompheniramine + hydroxypropylmethylcellulose)
New delivery constraint:
- Compartment drugs present in a mass ratio 8:1 to 20:1
- The dosage form codelivers pseudoephedrine and brompheniramine to the environment of use in a mass ratio of 8:1 to 20:1

So Claim 2 binds delivery ratio to the same range as the initial compartment mass ratio.

3) What additional coverage appears in Claim 3 and Claim 4?

Claims 3 and 4 are limited form-of-drug refinements:

Claim 3: pseudoephedrine is present as a pharmaceutically acceptable salt
Claim 4: brompheniramine is present as a pharmaceutically acceptable salt

These are claim-scope expansions relative to “free base” concepts, but they are not specific to any single salt in the independent terms.

4) What does Claim 5 add (animal dosing + quantitative load + delivery fidelity)?

Claim 5 is a second independent claim group focused on warm-blooded animals and includes explicit dosing ranges plus delivery-ratio fidelity.

Key elements:

Same general dosage-form architecture:
- Wall of cellulose triacetate + hydroxypropylcellulose
- Compartment
- Passageway in the wall
- Exterior lamina of pseudoephedrine + brompheniramine + hydroxypropylmethylcellulose
Quantitative pseudoephedrine and brompheniramine amounts in the compartment
- 170 to 200 mg pseudoephedrine
- 10 to 20 mg brompheniramine
Quantitative amounts in the lamina (exterior)
- 55 to 65 mg pseudoephedrine
- 5 to 8 mg brompheniramine
Delivery ratio during operation
- codelivers from the compartment pseudoephedrine and brompheniramine in a mass ratio 10:1 to 15:1
- The delivered ratio corresponds to their initial ratio in the compartment

This is an explicit “ratio conservation” concept across delivery from the compartment.

5) What do Claims 6 to 9 do (tight numeric embodiments)?

These claims are direct “composition-within-Claim-5” embodiments:

Claim 6: compartment comprises 180 mg pseudoephedrine hydrochloride
Claim 7: compartment comprises 10 mg brompheniramine maleate
Claim 8: lamina comprises 60 mg pseudoephedrine hydrochloride
Claim 9: lamina comprises 6 mg brompheniramine maleate

Together, Claims 6 to 9 lock both the salt identities and the exact quantitative amounts for one specific animal dosage configuration.

6) What does Claim 10 add (a second animal dosing band)?

Claim 10 is another warm-blooded animal independent claim group with a different numeric dosing band:

Wall, compartment, passageway, and exterior lamina architecture remains the same in form.
Compartment dosing ranges
- 80 to 110 mg pseudoephedrine
- 3 to 8 mg brompheniramine
Lamina dosing ranges
- 25 to 35 mg pseudoephedrine
- 2 to 5 mg brompheniramine
Delivery ratio
- codelivers from the compartment pseudoephedrine and brompheniramine in a mass ratio 10:1 to 15:1
- ratio corresponds to initial compartment ratio

Claim 10 therefore preserves the delivery-ratio constraint while shifting total dose bands.

7) What do Claims 11 to 14 do (tight numeric embodiments for Claim 10)?

Direct numeric and salt embodiments:

Claim 11: compartment comprises 90 mg pseudoephedrine hydrochloride
Claim 12: compartment comprises 3 mg brompheniramine maleate
Claim 13: lamina comprises 30 mg pseudoephedrine hydrochloride
Claim 14: lamina comprises 3 mg brompheniramine maleate

This is the “second locked configuration” inside the Claim 10 band.

Claim scope map: what must a practicing product include to infringe?

Core structural elements required across the main claims

Element	Claim language constraint	Practical infringement implication
Wall polymer system	Wall comprises cellulose triacetate + hydroxypropylcellulose	A different film system is likely out of scope
Wall permeability behavior	permeable to fluid, substantially impermeable to drug	Requires similar selective transport characteristics
Compartment inside wall	compartment within wall	Needs internal drug-containing core
Passageway	at least one passageway connecting compartment with exterior	Blocks-only diffusion designs may avoid scope unless they still have defined passageways
Exterior drug lamina	lamina on exterior comprising pseudoephedrine + brompheniramine + hydroxypropylmethylcellulose	Exterior layer must contain both actives and polymer
Delivery ratio condition	Claim 1: ratio greater than mutual equilibrium solubility; Claims 2/5/10: ratio 8:1 to 20:1 or 10:1 to 15:1 with “corresponds to initial ratio”	Infringement is partly performance-defined

Quantitative narrowing layers

Claim band	Target context	Quantitative constraints
Claim 2	environment of use (non-animal-specific wording)	compartment mass ratio and delivered ratio: 8:1 to 20:1
Claim 5	warm-blooded animal	compartment: 170-200 mg pseudoephedrine, 10-20 mg brompheniramine; lamina: 55-65 mg, 5-8 mg; delivered ratio: 10:1 to 15:1
Claims 6-9	specific animal embodiment	exact loads: 180 mg + 10 mg in compartment; 60 mg + 6 mg in lamina (salt forms specified)
Claim 10	warm-blooded animal (different dose band)	compartment: 80-110 mg pseudoephedrine, 3-8 mg brompheniramine; lamina: 25-35 mg, 2-5 mg; delivered ratio: 10:1 to 15:1
Claims 11-14	specific animal embodiment	exact loads: 90 mg + 3 mg compartment; 30 mg + 3 mg lamina (salt forms specified)

Functional-mechanistic constraints that change the freedom-to-operate shape

Delivery ratio relative to equilibrium solubility (Claim 1)

Claim 1 includes a performance condition: delivery ratio “greater than” the mutual equilibrium solubility of the two actives in fluid entering the dosage form.

This creates a higher evidentiary burden for a challenger and makes infringement turn on:

fluid environment used for defining “mutual equilibrium solubility”
experimental or theoretical method for equilibrium solubility in the relevant entering fluid
measured delivered ratio during operation

In practice, competitors often design around by:

using different exterior layer compositions so the delivered ratio trends toward solubility-limited behavior
using different polymer transport properties so the delivered ratio is not “greater than” equilibrium expectations

Ratio conservation (Claims 5 and 10)

Claims 5 and 10 require that delivered ratios (from the compartment) correspond to initial ratios in the compartment in the range 10:1 to 15:1. This constraint is tighter than merely achieving a ratio at a single time point.

Design-around implications:

products that “blend” compartment and exterior lamina contributions in a way that shifts the delivered ratio away from initial compartment composition may be outside
products that use different compartment-to-lamina release timing can change what portion of delivery is attributed to the compartment

Mass-ratio mapping (Claim 2)

Claim 2 ties both:

compartment initial mass ratio
delivered mass ratio to the same 8:1 to 20:1 band

This is a simpler, more direct constraint for enforcement than equilibrium-based language.

Patent landscape analysis: what adjacent claim themes typically appear around this type of dosage architecture?

Without adding external documents, the landscape analysis below uses claim-level inference from the structure of US 4,662,880. The patent landscape risk for this patent typically clusters around these technical axes:

1) Cellulose-based controlled-release membranes with selective permeability

US 4,662,880 requires a two-polymer wall: cellulose triacetate + hydroxypropylcellulose, with:

fluid permeability
drug impermeability

Adjacent families in this space usually claim variations on:

polymer ratios
degrees of substitution
alternative cellulose esters/ethers
plasticizers or pore-formers that tune passage of small molecules versus macromolecules

Infringement sensitivity: high for the specific polymer pair; medium for permeability behavior if the claim construction treats “substantially impermeable” broadly.

2) Compartmented core plus exterior lamina for two-phase codelivery

The architecture is uncommon in the sense that it uses both:

a compartment containing both actives
an exterior lamina containing both actives

Adjacent patents often swap:

which layer contains which actives
whether the lamina contains one drug or both
whether the exterior layer is coated onto the exterior surface of the wall versus positioned in an intermediate layer

Infringement sensitivity: high for requiring the lamina to comprise pseudoephedrine + brompheniramine + hydroxypropylmethylcellulose in laminar arrangement with the exterior of the wall.

3) Passageway-defined communication between compartment and exterior

The “at least one passageway” limitation can be a key design-around point:

systems that rely purely on diffusion through the wall may avoid the literal requirement
systems that use microperforations, channels, or engineered pores may still fall within the passageway concept depending on claim interpretation

Infringement sensitivity: medium to high, depending on how “passageway” is construed.

4) Ratio-controlled codelivery for pseudoephedrine + antihistamine combinations

This patent focuses on ratio targets that are unusual to see in simple combination formulations. Claims constrain:

ratio bands (8:1 to 20:1 and 10:1 to 15:1)
salt forms in dependent claims for particular embodiments
ratio relative to equilibrium solubility in Claim 1

Adjacent patents frequently claim different ratio strategies, such as:

fixed dose ratio tablets
immediate release plus delayed release (where the in vivo ratio varies over time)
ratio control through separate release kinetics rather than transport selectivity

Infringement sensitivity: high, because ratio language appears directly in the claim.

Practical scope boundaries and “likely non-infringing” design lanes (from claim text)

Likely outside scope

Dosage forms that use a wall that is not made from cellulose triacetate + hydroxypropylcellulose.
Dosage forms where the exterior lamina lacks hydroxypropylmethylcellulose or does not contain both pseudoephedrine and brompheniramine.
Dosage forms that do not include a compartment surrounded by the wall.
Dosage forms without a defined passageway connecting compartment to exterior.
Formulations that deliver codelivered ratios not falling inside:
- 8:1 to 20:1 (Claim 2) or
- 10:1 to 15:1 with the “corresponds to initial ratio in the compartment” requirement (Claims 5 and 10)
Animal dosing products that fall outside the specific quantitative bands in Claims 5 and 10 may still be at risk under broader claims depending on claim interpretation, but exact embodiments in Claims 6 to 9 and 11 to 14 are narrow.

Likely within scope

Products that replicate the two-layer drug loading (compartment + exterior lamina) and the exact cellulose wall system.
Products that match both ratio constraints and use the same salt forms in the specific dependent embodiments.

Claim-by-claim infringement checklist (condensed)

Claims 1 and 2 (environment of use)

A product is at risk if it has:

Wall of cellulose triacetate + hydroxypropylcellulose with fluid permeable / drug substantially impermeable behavior.
Compartment containing both pseudoephedrine and brompheniramine.
Passageway in wall connecting compartment to exterior.
Exterior lamina containing both drugs + hydroxypropylmethylcellulose in a laminar arrangement.
Delivery ratio during operation satisfies:
- Claim 1: delivered ratio > mutual equilibrium solubility ratio (relative performance)
- Claim 2: delivered mass ratio 8:1 to 20:1, consistent with compartment initial mass ratio

Claims 3 and 4

Risk increases if pseudoephedrine is a pharmaceutically acceptable salt and/or brompheniramine is a pharmaceutically acceptable salt.

Claims 5 to 14 (warm-blooded animals)

All of the above, plus:

animal context
compartment and lamina dosage ranges (Claim 5 and Claim 10)
exact loads and salt identities (Claims 6-9 and 11-14)
delivered ratio 10:1 to 15:1 corresponding to initial compartment ratio

Key takeaways

US 4,662,880 claims a layered, compartmented controlled-release dosage form with a highly specific cellulose polymer wall (cellulose triacetate + hydroxypropylcellulose) and an exterior drug lamina (hydroxypropylmethylcellulose).
The invention is performance constrained through codelivery ratio limits: > mutual equilibrium solubility (Claim 1) and strict delivered-to-initial ratio bands (8:1 to 20:1 in Claim 2 and 10:1 to 15:1 in Claims 5 and 10).
The animal claims split into two dosing bands (Claim 5 vs Claim 10) with locked dependent embodiments (Claims 6-9 and 11-14) that specify exact pseudoephedrine hydrochloride and brompheniramine maleate loads.
Freedom-to-operate risk is driven most by matching the polymer system + architecture and meeting the delivery-ratio constraints, not just using pseudoephedrine and brompheniramine together.

FAQs

1) Does US 4,662,880 protect any pseudoephedrine + brompheniramine combination product?

No. The claims require a specific dosage-form architecture: a cellulose triacetate/hydroxypropylcellulose wall with drug-impermeability behavior, a compartment, at least one passageway, and a hydroxypropylmethylcellulose exterior lamina containing both actives, plus ratio-related delivery constraints.

2) What is the most design-sensitive limitation in the independent claims?

The ratio constraints during “operation” are central: equilibrium-solubility-based delivery ratio in Claim 1 and mass-ratio delivery bands in Claims 2, 5, and 10.

3) Do Claims 6 to 9 and Claims 11 to 14 cover only specific salt forms and exact doses?

Yes. They specify exact loads (e.g., 180 mg pseudoephedrine hydrochloride and 10 mg brompheniramine maleate in the compartment; 60 mg and 6 mg in the lamina for Claims 6 to 9) and similarly exact loads for Claims 11 to 14.

4) Are the animal claims separate from the environment-of-use claims?

They are drafted as different independent claim sets: Claims 5 and 10 explicitly cover warm-blooded animal delivery with dose ranges and ratio conservation language.

5) If a competitor matches the architecture but not the delivery ratio, is it outside scope?

Based on the claim text, yes for at least those independent claim mappings that explicitly require delivered mass ratios (Claims 2, 5, 10) or equilibrium-related delivery ratios (Claim 1).

References

[1] United States Patent 4,662,880 (claims as provided in prompt).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	63059	⤷ Start Trial
Australia	601708	⤷ Start Trial
Australia	6740687	⤷ Start Trial
Canada	1255563	⤷ Start Trial
Germany	3769678	⤷ Start Trial
European Patent Office	0237159	⤷ Start Trial
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Summary for Patent: 4,662,880