United States Patent 5,489,436: Scope, Claim Architecture, and US Patent Landscape

United States Drug Patent US 5,489,436 claims chewable dosage forms and methods where a medicament is taste-masked by a specific polymer blend coating. The core inventive content is the combination of (i) dimethylaminoethyl methacrylate + neutral methacrylic acid ester with (ii) cellulose acetate and/or cellulose triacetate, applied at defined blend ratios and coating-load ranges.

What does the independent claim actually cover (Claim 1)?

Claim 1 is the broadest dosage-form claim and is framed as a chewable medicament tablet where the medicament is coated with a taste-masking polymer blend that is defined by:

Claim 1 essential elements

Dosage form: “A chewable medicament tablet”
Coated medicament: the tablet contains a medicament composition coated with
Taste masking effective amount of a polymer blend that is “consisting essentially of”:
- 5 to 95 wt% of the polymer blend of:
  - dimethylaminoethyl methacrylate (DMAEMA) and
  - neutral methacrylic acid ester (NM Aester)
- 5 to 95 wt% of the polymer blend of a polymer selected from:
  - cellulose acetate, cellulose triacetate, or combinations

Interpretive levers in “consisting essentially of”

The phrase “consisting essentially of” limits the polymer blend to the recited components while allowing minor formulation impurities or non-material additives that do not materially alter the basic and novel characteristics. This is relevant for design-around (see below).

How broad is the polymer ratio and coating load (Claims 2 and 3)?

Claim 2: coating level

Polymer blend coating comprises 2 to 55% by weight of the total weight of the coated medicament composition.

Impact: This is a key practical limitation. It ties taste masking to a coating-load window that could affect dissolution, texture, and chewability. It also narrows claim coverage versus formulations that either undercoat (insufficient taste masking) or overcoat (excess inert mass).

Claim 3: polymer blend composition

The polymer blend consists essentially of:
- 10 to 90% by weight of DMAEMA and neutral methacrylic acid ester
- 10 to 90% by weight of cellulose acetate and/or cellulose triacetate
“By weight of the total weight of the polymer blend.”

Impact: Claim 1 allows 5 to 95; Claim 3 narrows to 10 to 90 ranges for the specific sub-fractions in the blend. In infringement strategy, Claim 3 can be asserted where accused products use higher loading balance within the blend.

What shapes and medicaments are included (Claims 4–7)?

Claim 4: spherical core

The medicament composition is spherical in shape.

Impact: This limits some implementations. Many taste-masking systems are done on multiparticulates or pellets; “spherical” can be contested if the core is irregular or engineered with different geometry.

Claim 5 and Claim 6: medicament list

Both claims list a large set of drugs for which taste masking is contemplated:

acetaminophen
ibuprofen
dexibuprofen lysinate
naproxen
naproxen sodium
psyllium
chlorpheniramine
astemizole
loperamide
famotidine
ranitidine
cimetidine
pseudoephedrine
salts thereof
combinations thereof

Impact: The claim set is broad on drug identity (a “gene list”), but still limited to the enumerated set and their salts and combinations.

Claim 7: excipients

Tablet additionally comprises pharmaceutically acceptable excipients.

Impact: This is a conventional dependent claim, but it helps close off arguments that a formulation lacks “tablet” completeness.

What about the process claims (Claims 8–10)?

Claim 8 defines a manufacturing route:

Coating a medicament composition with a taste-masking effective amount of the same specified polymer blend (“consisting essentially of” with the same blend ratio constraints)
Forming a chewable tablet by compressing the coated medicament composition in the presence of excipients

Claim 9 adds:

further comprising granulating the medicament to form the medicament composition

Claim 10 adds:

polymer coating comprises 2 to 55% by weight of the total weight of the coated medicament composition

Impact: Process claims are often easier to design around by altering manufacturing order or unit operations. Here, the coating + compression sequence is required, and Claim 10 anchors coating load.

What about the method-of-use claim (Claims 11–12)?

Claim 11

A method for taste masking medicaments:

coating a medicament composition with the specified polymer blend (“consisting essentially of”) with the same 5 to 95 wt% partition language for DMAEMA/NM Aester and cellulose acetate/cellulose triacetate.

Claim 12: medicament list

medicament selected from the listed set (similar to Claims 5–6, includes ibuprofen sodium and salts).

Impact: The use claim extends coverage to acts of coating those medicaments, even if the final packaged chewable tablet differs from Claim 1’s structure limits, unless the coating is outside the specified polymer system.

Where the claim set is vulnerable (practical claim boundaries)

Across the claim family, infringement hinges on satisfying all required constraints:

Material constraints (must match)

Polymer blend is limited to:
- DMAEMA + neutral methacrylic acid ester and
- cellulose acetate and/or cellulose triacetate
Blend ratios must fall in:
- 5 to 95 wt% each side in Claim 1/11 (but 10 to 90 in Claim 3)
Coating-load must fall in:
- 2 to 55 wt% (Claims 2 and 10)
For some claims:
- spherical cores (Claim 4)
- specific medicament identities (Claims 5–6, 12)
For process:
- coating then compression into a chewable tablet (Claim 8)

Common design-around vectors

Because the polymer definition is central, changes typically focus on the coating polymer system:

Replace either:
- cellulose acetate/triacetate, or
- the DMAEMA/neutral methacrylic ester system, or
Use a polymer blend where the recited components are not present within the required wt% windows, or
Use coating levels outside 2 to 55 wt% where dependent limits are asserted.

Claim coverage matrix by element

Claim	Form/Act	Key limitations that must be met	Narrowers
1	Chewable tablet	Coated medicament; polymer blend “consisting essentially of”; DMAEMA + neutral methacrylic acid ester (5-95 wt%); cellulose acetate/triacetate (5-95 wt%)	None beyond “chewable” and polymer blend definition
2	Chewable tablet	Same as Claim 1	Coating load 2-55 wt%
3	Chewable tablet	Same polymer system	Blend ratio narrowed to 10-90 / 10-90
4	Chewable tablet	Same as Claim 1	Core is spherical
5	Chewable tablet	Same as Claim 1; medicament in enumerated list	Drug list limitation
6	Chewable tablet	Same as Claim 1; medicament in enumerated list	Depends on Claim 3 (via claim dependency)
7	Chewable tablet	Same as Claim 6	Contains pharmaceutically acceptable excipients
8	Process	Coat with the specified polymer blend; compress coated composition with excipients to make chewable tablet	Requires coating then compression
9	Process	Same as Claim 8	Adds granulating before coating
10	Process	Same as Claim 8	Coating load 2-55 wt%
11	Method of taste masking	Coat with specified polymer blend	Polymer ratio constraints (5-95)
12	Method of taste masking	Same as Claim 11	Drug list limitation

US patent landscape: how this claim family maps to competitive design

Without a verified list of all related US filings in the same polymer/taste-masking space, the most business-relevant way to view the landscape is by technical adjacency and what would likely be targeted by follow-on patents.

Landscape clusters most likely competing with US 5,489,436

Other taste-masking polymer blends for chewable tablets
- Target: same outcome (taste masking) with different polymers or polymer architectures.
- Likely difference: replacing cellulose acetate/triacetate with other film-formers (e.g., other cellulose esters or acrylic copolymers), or altering the amine/methacrylate balance.
Microencapsulation or pelletization variants
- US 5,489,436 tolerates “spherical” cores in Claim 4.
- Competitors often shift pellet geometry, size distribution, or use different substrate shapes to avoid Claim 4 while keeping the taste-mask chemistry.
Coating-load and ratio optimization
- Dependent claims fix coating load (2 to 55 wt%) and blend ratio boundaries.
- Competitors often file around by using lower/higher coating loads and broader polymer blend compositions not captured by “consisting essentially of.”
Drug-specific formulations within the enumerated list
- US 5,489,436 includes a broad enumerated list of drugs.
- Competitors can still choose those same actives but change the polymer blend, coating load, or core structure.

Enforceability and claim construction pressure points

From a litigation or licensing standpoint, the highest-risk elements are:

1) “consisting essentially of” polymer blend boundary

Competitors can argue that any additional polymers materially alter taste-masking characteristics, pulling the accused product outside the “consisting essentially of” scope.

2) Weight-percent definitions

Claim 1/11 uses wt% by total weight of polymer blend, not of the coated composition.
Claim 2/10 uses wt% of coating load relative to total weight of coated medicament composition. These separate reference bases matter when comparing analytical reports.

3) “taste masking effective amount”

The phrase is often construed broadly but still ties to function. It creates a factual element but is less likely to allow easy avoidance if the polymer chemistry matches and the formulation is clearly taste-masked.

4) “spherical” (Claim 4)

This is a physical attribute. If omitted, Claim 4 coverage drops, though Claims 1–3 still remain relevant.

Business implications: what the patent is likely protecting

US 5,489,436 is best treated as a polymer-system protection patent for chewable tablets where:

taste masking relies on a defined two-part polymer blend
applied as a coating to medicament compositions
then compressed into chewables

The drug list is wide, which can support licensing across multiple brands and generics if the same coating chemistry and formulation ranges are used.

Key Takeaways

Scope is polymer-definition driven: the coating polymer system is “consisting essentially of” DMAEMA + neutral methacrylic acid ester blended with cellulose acetate/triacetate, with explicit wt% windows.
Dosage form and process coverage both exist: chewable tablets (Claims 1–7), coating + compression manufacturing (Claims 8–10), and coating methods (Claims 11–12).
Dependent claims introduce fixed constraints that can be used for both enforcement and design-around: coating load 2–55 wt%, blend ratio 10–90/10–90, spherical cores, and the enumerated drug list.
Competitive strategy typically shifts one of three levers: polymer composition outside the defined set, blend ratio outside the required wt% windows, or coating-load outside 2–55 wt%.

FAQs

Is US 5,489,436 limited to a specific drug?
No. Claims 5–6 and 12 list multiple drugs (including acetaminophen, ibuprofen, naproxen, famotidine, cimetidine, pseudoephedrine, and salts/combos), but Claim 1 and 8–11 are not limited to the drug list.
Does the patent require spherical medicament cores?
Only Claim 4 requires “spherical” medicament composition. Claims 1–3, 5–3 (as dependent) do not impose spherical geometry.
What are the coating-load constraints?
Claims 2 and 10 require the polymer coating to be 2 to 55 wt% of the total weight of the coated medicament composition.
How strict is “consisting essentially of”?
It limits the polymer blend to the recited components and excludes additional polymers that materially alter the basic and novel characteristics, while permitting only non-material additions.
Can a product escape the patent by changing manufacturing steps?
It can, at least for the process claims. Claim 8 requires coating followed by compression into chewable tablets. But dosage-form and method-of-use claims focus on the coating chemistry.

References

[1] United States Patent US 5,489,436, “Chewable medicament tablets with taste masked polymer blends,” claims text as provided in the prompt.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	2068402	⤷ Start Trial
Germany	69210124	⤷ Start Trial
European Patent Office	0523847	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,489,436

Summary for Patent: 5,489,436