Details for Patent: 4,801,461

Summary for Patent: 4,801,461

Title:	Pseudoephedrine dosage form
Abstract:	A dosage form is disclosed for delivering the beneficial drug pseudoephedrine to a biological environment of use.
Inventor(s):	Larry G. Hamel, Felix A. Landrau, George V. Guittard, Patrick S. L. Wong
Assignee:	Alza Corp
Application Number:	US07/007,879
Patent Claim Types: see list of patent claims	Composition; Compound; Delivery; Dosage form;

Scope and claims analysis for US Patent 4,801,461 (pseudoephedrine osmotic dosage form)
US 4,801,461 is an osmotic-controlled dosage-form patent built around a two-part delivery architecture: (i) a compartment containing pseudoephedrine and (ii) a cellulose-acetate/hydroxypropylcellulose semipermeable wall with a passageway plus an exterior lamina that delivers pseudoephedrine immediately and then shifts to metered release from the compartment. Claim scope is dominated by specific material ranges (cellulose acetate acetyl content; hydroxypropylcellulose wt%), dose splits (lamina vs compartment pseudoephedrine mass windows), and structural features (lamina location, wall permeability, passageway). The patent landscape is likely constrained to other pseudoephedrine osmotic systems and cellulose-acetate/hydroxypropylcellulose osmotic membranes that replicate these elements; design-arounds that change polymer class, remove the lamina-first step, or change the release mechanism away from osmotic metered delivery reduce direct claim coverage.

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What does US 4,801,461 claim about pseudoephedrine dosage forms?

Core answer: It claims an osmotic dosage form for pseudoephedrine where pseudoephedrine is delivered immediately from an exterior lamina and then at a metered release rate from an internal compartment through a permeable cellulose-acetate-based wall having a passageway.

Claim 1 architecture (the “independent” backbone)

Claim 1 is the main, broadest structure. It requires, in combination:

1. Dosage form for delivering pseudoephedrine to an environment of use
2. Compartment
3. Pseudoephedrine dosage in the compartment: about 160 to 200 mg (or therapeutically acceptable salts)
4. Wall composition and properties
   • Wall comprises at least in part:
     • 70 to 85 wt% cellulose acetate with acetyl content 35% to 43.5%
     • 15 to 30 wt% hydroxypropylcellulose
   • Wall is permeable to passage of external fluid
   • Wall “aids in protecting” pseudoephedrine from premature exposure
5. Passageway in the wall connecting compartment to exterior
6. Exterior lamina over/adjacent to exterior of the wall in laminar arrangement
   • Lamina pseudoephedrine amount: 55 to 65 mg
7. Operational requirement
   • When in operation, dosage form administers pseudoephedrine:
     • immediately from the lamina
     • and at a metered release rate per unit time from the compartment

This is a combination claim: changing any one element can avoid literal infringement, even if the overall concept remains similar.

Claim 1 key technical levers (what defines infringement risk)

• Polymer identity + proportions
  • cellulose acetate (70–85 wt%) with acetyl content 35–43.5%
  • hydroxypropylcellulose (15–30 wt%)
• Geometry/function
  • semipermeable wall + passageway
• Two-stage dosing
  • immediate lamina dose (55–65 mg) + compartment dose (160–200 mg)
• Metered osmotic delivery
  • operational “metered release from compartment” requirement

Dependent claims 2–6 in Claim 1 chain

• Claim 2: pseudoephedrine is pseudoephedrine hydrochloride
• Claim 3: compartment includes 10–30 mg osmagent
• Claim 4: compartment comprises 180 mg pseudoephedrine (specific example within Claim 1 range)
• Claim 5: compartment includes 2–9 mg hydroxypropylmethylcellulose
• Claim 6: compartment includes 10–30 mg microcrystalline cellulose

These claims narrow within Claim 1’s architecture by specifying salts and excipient types/amounts.

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How do Claim 7–11 alter dose splitting and scope?

Core answer: Claim 7 is another osmotic two-stage claim, with different compartment and lamina dose ranges and the same cellulose acetate/hydroxypropylcellulose wall concept plus wall permeability and passageway.

Claim 7 independent structure differs by dose windows

Claim 7 requires:

• Compartment pseudoephedrine amount: about 80 to 115 mg
• Wall composition: same 70–85 wt% cellulose acetate (acetyl content 35–43.5%) and 15–30 wt% hydroxypropylcellulose
• Lamina pseudoephedrine amount: 25 to 35 mg
• Immediate administration from lamina + metered release from compartment
• Same wall features: permeable wall, passageway connecting compartment to exterior

Dependent claims 8–11

• Claim 8: pseudoephedrine is pseudoephedrine hydrochloride
• Claim 9: compartment includes 10–30 mg osmagent
• Claim 10: compartment includes 2–9 mg hydroxypropylmethylcellulose
• Claim 11: compartment includes 10–30 mg microcrystalline cellulose

Scope impact: Claim 7 captures a lower-total-dose embodiment versus Claim 1, keeping the same polymer and structural framework. In enforcement, this means an accused product could fall into Claim 7 even if it misses Claim 1 dose ranges.

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What animal-dosage claims (12–18) cover beyond human-style “environment of use”?

Core answer: Claims 12–18 shift from “environment of use” broadly to delivery to a warm-blooded animal, with a more explicitly recited therapeutic composition and some additional lamina/passsageway specificity.

Claim 12 (warm-blooded animal) recites specific internal composition

Requirements:

• Dosage form for warm-blooded animal
• Wall comprises:
  • cellulose acetate and/or cellulose triacetate (for physical/chemical integrity)
  • hydroxypropylcellulose
• Wall surrounds compartment and includes passageway (pore-like, generally)
• Therapeutic composition in compartment includes:
  • about 180 mg pseudoephedrine hydrochloride
  • about 23 mg sodium chloride
  • about 7.5 mg hydroxypropylmethylcellulose

This claim expands permissible wall cellulose backbone to cellulose triacetate (explicitly includes cellulose triacetate as well as cellulose acetate) and adds a specific formulation for the compartment.

Claims 13–14

• Claim 13: composition comprises poly(vinylpyrrolidone) and magnesium stearate
• Claim 14: lamina includes 60 mg pseudoephedrine hydrochloride on exterior surface of wall

Claims 15–17 (another animal composition and lamina dose)

Claim 15 again uses cellulose acetate/triacetate + hydroxypropylcellulose wall and passageway, and requires compartment composition:

• about 90 mg pseudoephedrine hydrochloride
• about 11.7 mg sodium chloride
• about 3.7 mg hydroxypropylmethylcellulose

Claim 16: composition comprises poly(vinylpyrrolidone) and magnesium stearate.
Claim 17: lamina includes about 30 mg pseudoephedrine hydrochloride.

Claim 18 (passageway is a pore)

Claim 18 further narrows passageway structure: “passageway is a pore.”

Scope impact: Claims 12–18 are narrower in some ways (specific compartment composition and lamina amount) but broader in polymer identity (cellulose acetate and cellulose triacetate both expressly covered). They also reflect that the patent anticipates multiple dose strengths for animals.

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What do Claims 19–20 add on cellulose acetate vs triacetate?

• Claim 19: cellulose acetate is cellulose triacetate (as part of Claim 1 feature)
• Claim 20: cellulose acetate is cellulose triacetate (as part of Claim 7 feature)

These dependents close potential loopholes in polymer identity, making it harder for a competitor to argue that triacetate falls outside Claim 1/7 when triacetate is substituted into the “cellulose acetate” portion.

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How strong is the patent estate’s claim coverage based on these features?

Core answer: The claim strength is high where products replicate the same osmotic two-stage system with the same polymer system (cellulose acetate with defined acetyl content plus hydroxypropylcellulose in defined ranges) and the same mass split between lamina and compartment, plus a wall with a passageway.

Key “literal infringement” checkpoints

A challenger/design-around is likely to win if it:

• changes polymer chemistry outside the defined ranges
• removes or materially changes the lamina-first immediate delivery step
• eliminates the passageway concept as a structural requirement (or uses a fundamentally different release interface)
• changes dosing beyond the lamina and compartment windows
• uses a release mechanism that is not metered osmotic release from the compartment

Key “likely covered” product attributes

Products that look like classic osmotic tablets with:

• semipermeable cellulose acetate/hydroxypropylcellulose membrane (with acetyl content constraint)
• osmotic agent inside the compartment
• a leaving orifice (passageway/pore)
• an overcoat/lamina containing drug on the exterior
• initial burst from the lamina followed by controlled release from internal compartment

are at the highest risk.

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Where do other patents in the pseudoephedrine osmotic space typically crowd in?

Core answer: US 4,801,461’s likely overlap zone is other patents that claim (i) osmotic controlled-release pseudoephedrine formulations, (ii) semipermeable membranes based on cellulose acetate derivatives, (iii) lamina-assisted immediate release over osmotic cores, and (iv) delivery system for pseudoephedrine salts (especially HCl) in different dose strengths.

Landscape clustering by claim element

1. Membrane/material claims
   • cellulose acetate derivatives (including triacetate)
   • hydroxypropylcellulose co-polymers/blends
2. Mechanical interface claims
   • passageways, pores, or drilled orifices
3. Drug placement claims
   • lamina vs core split dosing
4. Pseudoephedrine-salt formulation claims
   • pseudoephedrine HCl
   • osmagent types
   • excipients like hydroxypropylmethylcellulose, microcrystalline cellulose
5. Animal vs human
   • warm-blooded animal embodiments with specified sodium chloride and binder/plasticizer systems

In enforcement, the most durable overlap tends to be around the membrane and the two-stage placement, because these are distinguishing and repeatable.

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When does the patent lose exclusivity in the US?

Core answer: For US utility patents, exclusivity ends at 20 years from the earliest non-provisional effective filing date (subject to adjustment). Without the patent’s filing history in the prompt, the exclusivity end date cannot be determined from the claim text alone.

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What generic entry risks exist for pseudoephedrine osmotic systems?

Core answer: For any competitor targeting pseudoephedrine controlled release via osmotic delivery, the generic “risk” is strongest for:

• products matching the two-stage lamina + compartment dosing architecture, and
• products using cellulose acetate/hydroxypropylcellulose semipermeable wall compositions within the given wt% and acetyl content windows, and
• products with a wall passageway/pore concept.

If a generic uses a different coating system that provides immediate release by a different mechanism (for example, dissolvable coatings released by simple diffusion with no metered osmotic delivery core), the risk reduces even if the dose is similar.

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What would a design-around look like under this specific claim set?

Core answer: The best-known design-around vectors relative to these claims are:

• Membrane change: move away from cellulose acetate with acetyl content constraint and/or hydroxypropylcellulose 15–30 wt% blend.
• Eliminate lamina immediate dose: remove the laminar pseudoephedrine exterior layer; use only internal drug for controlled release.
• Change release mechanism: replace “metered release rate per unit time from compartment” osmotic metered release with a different controlled-release mechanism not tied to the described wall/permeation/passageway system.
• Dose split shift: move pseudoephedrine quantities outside 55–65 mg lamina and 160–200 mg compartment (Claim 1) or 25–35 mg lamina and 80–115 mg compartment (Claim 7).
• Passageway alteration: implement a fundamentally different interface from a wall passageway/pore that does not satisfy the structural requirement.

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Key Takeaways

• US 4,801,461 is centered on a pseudoephedrine osmotic dosage form with an exterior lamina for immediate delivery and an internal compartment for metered release.
• The claim scope is tightly defined by cellulose acetate acetyl content (35%–43.5%), cellulose acetate wt% (70%–85%), and hydroxypropylcellulose wt% (15%–30%), plus a wall passageway/pore.
• Enforcement risk is highest when an accused product replicates the same two-stage dose split and the same semipermeable wall material system.
• Animal claims (12–18) add specific pseudoephedrine HCl + sodium chloride + hydroxypropylmethylcellulose amounts, while explicitly keeping cellulose triacetate within the wall scope.
• Design-arounds are most effective by changing membrane polymer system, removing the lamina-first dose mechanism, altering the release mechanism, or moving outside the defined dose ranges.

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FAQs

1) Can a product using cellulose triacetate still infringe if it does not meet the acetyl content range?
Claims 19–20 attempt to pull triacetate into the cellulose acetate feature set for Claim 1 and Claim 7, but acetyl content requirements in Claim 1/7 still control the literal language where those independent claims are asserted.

2) What claim element is most likely to be used to distinguish competitors: lamina-first burst or osmotic metered release?
Both. The independent claims require immediate delivery from lamina and metered release from compartment, with structural support from the permeable wall and passageway.

3) Do the warm-blooded animal claims broaden or narrow protection versus the “environment of use” claims?
They narrow via specific compartment compositions and lamina amounts, but broaden via explicit inclusion of cellulose triacetate in the wall composition.

4) If a competitor uses the same excipients like hydroxypropylmethylcellulose and microcrystalline cellulose, do they automatically fall into scope?
No. Excipient matches do not overcome differences in the membrane polymer ranges, dose splits, lamina arrangement, and passageway structure required by the independent claims.

5) Which claim would typically be targeted in a freedom-to-operate assessment first?
Claim 1 and Claim 7 because they are the primary two-stage osmotic architecture claims with quantitative polymer and dose-range limitations.

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References

No external sources were cited because the prompt provides only the claim text of US 4,801,461 and does not include prosecution history, assignee, filing dates, or any other patent documents to cite.

Drugs Protected by US Patent 4,801,461

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

International Family Members for US Patent 4,801,461

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	1286229
Germany	3774264
European Patent Office	0279976
Japan	H0825872
Japan	S63258409
Mexico	9203560