Details for Patent: 5,656,296

Summary for Patent: 5,656,296

Title:	Dual control sustained release drug delivery systems and methods for preparing same
Abstract:	The present invention pertains to a dual control sustained release drug delivery system which comprises a core and a porous coating layer over the core, wherein the coated core comprises (A) a core comprising in percentages by weight of the core composition (a) a medicament present in an amount from about 60% to about 90%; (b) an edible material having a melting point from about 25° C. to about 100° C. selected from the group consisting of (i) fatty acids having an iodine value from about 1 to about 10, (ii) natural waxes, (iii) synthetic waxes, and (iv) mixtures thereof, present in an amount from about 5% to about 40%; and (B) a porous coating layer over the core comprising in percentages by weight of the coating layer composition (a) a pH-independent water-insoluble polymer present in an amount from about 40% to about 80%; and (b) a water-soluble film forming polymer present in an amount from about 20% to about 60%.
Inventor(s):	Sadath U. Khan, Phyllis Ying, Russell U. Nesbitt, Mahdi B. Fawzi, Jay Weiss
Assignee:	Warner Lambert Co LLC
Application Number:	US08/476,490
Patent Claim Types: see list of patent claims	Composition; Process; Delivery; Dosage form;

United States Patent 5,656,296 (Dual-Control Sustained-Release): Scope, Claim Coverage, and U.S. Patent Estate Risk Map

Executive summary: U.S. Patent 5,656,296 claims a dual-control sustained-release system built from (i) a high-loading medicament matrix (60–90% by weight) with a low-melting edible lipid/wax component (melting point 25–100°C; 5–40% by weight) and (ii) a porous, dual-polymer coating layer that couples a pH-independent water-insoluble acrylic-dispersion polymer (40–80%) with a water-soluble film former (20–60%). The “essentially unaffected by high-fat food consumption” limitation is anchored in the coating architecture and the specific lipid selection windows. Claim scope is strongest for tablet cores with the specified composition ranges plus the enumerated coating polymers, and narrows quickly for alternative polymer classes, omitting the specified pH-independent water-insoluble acrylic dispersions, substituting non-enumerated waxes/lipids, or shifting the medicament/lipid ratios outside the ranges. The independent claim set also captures a corresponding preparation method and a medicated composition.

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What does US Patent 5,656,296 claim for dual-control sustained-release that is “unaffected by high-fat food”?

Core answer: The patent claims a specific composition of a coated sustained-release matrix tablet and, in dependent form, specific medicaments, lipid selections, coating polymer embodiments, ratio windows, and a manufacturing method. The central invention is a porous coating layer over a molten-processed (melted) wax/lipid-containing core, where drug release is described as essentially unaffected by high-fat food.

Key claim architecture (independent claim 1)

Independent claim 1 requires all of the following:

1. Dosage form structure

   • A core plus a porous coating layer over the core.
   • The system is described as dual control sustained release and includes the functional requirement: “release of drug is essentially unaffected by high-fat food consumption.”

2. Core composition (by weight of core)

   • Medicament: about 60% to 90%
   • Edible material: about 5% to 40%, melting point 25°C to 100°C, selected from:
     • (i) fatty acids with iodine value 1–10
     • (ii) natural waxes
     • (iii) synthetic waxes
     • (iv) mixtures

3. Porous coating layer composition (by weight of coating layer)

   • (a) pH-independent water-insoluble polymer (40–80%), selected from acrylic resin dispersions consisting of enumerated polymer categories:
     • polyacrylamide
     • polyacryldextran
     • polyalkyl cyanoacrylate
     • polymethacrylate
     • methacrylic resin copolymer
     • mixtures
   • (b) water-soluble film forming polymer (20–60%) (no melt point requirement), with a generic category first and later dependent narrowing (see claim 11).

4. Coverage emphasis

   • The claim is not limited to a specific drug. It includes broad “medicament” language but later narrows to specific APIs (claim 3-4).

Claim 1 “essentially unaffected by high-fat food” limitation: how it operates in scope

This is a functional/performative limitation tied to the claimed structure/composition. In infringement analysis, it tends to be litigated as:

• a required property of the accused product, and
• potentially a construction issue (what counts as “essentially unaffected”).

Within the claim itself, the property is linked to:

• the lipid/wax edible material selection window (melting point and iodine value bounds), and
• the porous coating layer that combines pH-independent water-insoluble acrylic dispersion polymer with water-soluble film former.

If the accused formulation uses the same polymers but swaps the lipid class or ratio outside the defined windows, the “essentially unaffected” feature may become a key dispute.

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Which components in claim 1 are the main “hard limits” vs. flexible ranges?

Hard limits (high infringement friction if changed):

1. Porous coating layer must include both
   • pH-independent water-insoluble acrylic dispersion polymer (specific enumerated categories), and
   • a water-soluble film forming polymer (broad initially).
2. Core must include both
   • medicament at 60–90%, and
   • edible material at 5–40% with melting point 25–100°C and selected from enumerated lipid classes (fatty acids with iodine 1–10; natural/synthetic waxes).
3. The system must be dual-control sustained release and is described by high-fat food insensitivity.

**Flexible elements (range-based):

• Medicament loading (60–90%)
• Lipid/wax loading (5–40%)
• Lipid melting point (25–100°C)
• Coating polymer proportions (40–80% insoluble acrylic; 20–60% soluble film former)
• Core:coating ratio is later explicitly defined in claim 13.

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What specific dependent claims narrow coverage (medicament, edible material, polymers, ratios)?

Medicament-specific narrowing (claims 3–4)

• Claim 3: medicament selected from procainamide hydrochloride and sodium meclofenamate
• Claim 4: medicament is procainamide hydrochloride

Scope effect: If the accused product uses either enumerated API and also meets the structural/composition windows, infringement risk rises. If the API is outside this set, claim 1 still covers it, but it becomes more difficult to litigate “essentially unaffected by high-fat food” because the patent’s practical enablement and performance evidence often depends on the known examples/drug contexts (not provided in the excerpt).

Edible material selection narrowing (claims 5–7)

• Claim 5: edible material 5–30% (subset of 5–40%)
• Claim 6: edible material selected from:
  • carnauba wax
  • hydrogenated vegetable oils
  • stearic acid
• Claim 7: edible material is carnauba wax

Scope effect: The more specific the lipid, the narrower the claim coverage; substitutes like cocoa butter, glycerides with different melting profiles, or other edible fats without fitting the listed categories can move outside.

Coating polymer narrowing (claims 8–12)

• Claim 8: pH-independent water-insoluble polymer 50–75% (subset of 40–80%)
• Claim 9: pH-independent water-insoluble polymer is methacrylic resin copolymer
• Claim 10: water-soluble film forming polymer 25–50% (subset of 20–60%)
• Claim 11: water-soluble film forming polymer is cellulose derivative, selected from:
  • hydroxypropylcellulose
  • hydroxypropylmethylcellulose
  • hydroxypropylmethylcellulose phthalate
  • sodium carboxymethylcellulose
  • mixtures
• Claim 12: water-soluble film forming polymer is hydroxypropyl cellulose

Scope effect: Substituting away from cellulose derivatives (for the soluble film former) can avoid dependent claims 11-12 but may still land in independent claim 1 if the soluble film former still falls within “water-soluble film forming polymer” (not restricted in claim 1).

Core:coating ratio narrowing (claim 13)

• Claim 13: weight ratio core composition:coating layer composition = 94:6 to 98:2

Scope effect: This matters when accused formulations differ in tablet core mass fraction or coating thickness distribution. A large formulation design change in core-to-coating ratio can eliminate infringement of the dependent claims.

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What method claims cover manufacturing of the dual-control system? (Claim 14)

Executive answer: Claim 14 covers a process sequence for making dual-control sustained-release coated systems with the same composition constraints as claim 1.

Claim 14 step-by-step scope

1. Providing ingredients

   • Same core composition windows and classes (medicament 60–90%; edible lipid/wax 5–40% melting 25–100°C and listed classes)
   • Same coating composition windows and classes (insoluble pH-independent acrylic dispersion 40–80%; soluble film former 20–60%)

2. Melting edible material and admixing medicament

   • Melt step uses edible material from core (step 1(A)(b))
   • Medicament is admixed into molten mixture

3. Cooling, milling, and compressing

   • Cool and mill molten mixture
   • Compress milled mixture to form tablet cores

4. Preparing porous coating layer suspension

   • Add coating ingredients from step 1(B) in water

5. Coating

   • Coat tablet cores with porous coating layer suspension

Process-specific risk: An accused manufacturer that uses a different manufacturing route (for example, granulation/solvent deposition, hot-melt but different cooling/milling steps, fluid-bed coating with different vehicle composition) may avoid claim 14 even if the final product matches claim 1, unless product-by-process theories are asserted.

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What “medicated sustained release composition” coverage exists (Claim 15)?

Executive answer: Claim 15 claims a medicated sustained release composition that includes:

• pharmaceutically acceptable carrier, and
• a therapeutically effective amount of the claim-1 drug delivery system,
• and repeats the core and coating composition requirements.

Scope effect: Claim 15 functions as an additional hook for formulations where the claimed delivery system is present within a broader composition context.

Note the excerpt ends mid-sentence for the coating layer description in claim 15; the intent is clearly to incorporate the claim-1 coating requirements. The practical scope is still directed to including a therapeutically effective amount of the same dual-control coated core system.

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How does claim scope compare across “structure”, “composition”, and “functional performance”?

Structure

• Core + porous coating are mandatory.
• A non-coated sustained-release matrix likely fails claim 1 and all dependents.

Composition

• The core and coating each have defined components and percentage ranges.
• The lipid selection has an explicit melting point window and a defined set of lipid classes.
• The coating’s insoluble polymer is restricted to specific acrylic dispersion families.

Functional performance

• “essentially unaffected by high-fat food consumption” is a limiting requirement.
• For product infringement, performance evidence typically becomes critical:
  • dissolution and food-effect studies,
  • comparative release profiles under fed vs fasted conditions,
  • and sometimes mechanistic correlation to coating porosity and polymer behavior.

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What would an at-risk competitor formulation need to have to fall within this estate?

Likely within scope (high probability based on claim text)

A coated sustained-release tablet system with:

• Core
  • medicament 60–90%
  • edible lipid/wax 5–40% with melting point 25–100°C and selected from the listed classes (including iodine value-bounded fatty acids)
• Coating
  • porous coating comprising:
    • pH-independent water-insoluble acrylic dispersion polymer (polyacrylamide / polyacryldextran / polyalkyl cyanoacrylate / polymethacrylate / methacrylic resin copolymer) at 40–80%
    • plus a water-soluble film former 20–60% (cellulose derivatives if asserting dependents 11-12)

High-risk design changes that could defeat scope

• Replacing the insoluble acrylic dispersion polymer with a different insoluble polymer class (Eudragit-type non-acrylic, ethylcellulose-only, PEG-based matrices, silicone-based barriers without matching “pH-independent water-insoluble polymer selected from … acrylic resin dispersions consisting of …”)
• Changing lipid component to something that does not meet:
  • melting point 25–100°C, and/or
  • listed lipid categories (including iodine value requirement for fatty acids)
• Shifting proportions outside the defined ranges
• Removing the porous coating layer or changing from porous to non-porous barrier.

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What does this imply for freedom-to-operate in the U.S. (composition, method, and product)

Executive answer: The patent estate presented here is internally cohesive across:

• product claims (system and medicated composition),
• and a specific product-by-process-like manufacturing method (claim 14).

A design-around needs to address all three dimensions:

1. product structure and composition (claim 1),
2. method steps (claim 14), and
3. meditated composition embodiment (claim 15).

If a competitor matches claim 1’s composition and structure but uses a different manufacturing process, it can still face product infringement unless the method is the only disputed claim basis.

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Patent landscape beyond the single patent: what other patents typically intersect this theme?

Executive answer: Based on the limited information provided (the single U.S. patent claim set excerpt), the landscape cannot be fully mapped without bibliographic and citation data. No further patent numbers, assignees, family members, related continuations, or citing/cited patents are included in the prompt.

What can be derived from the claim content is the likely intersection set for similar technologies:

• food-effect resistant sustained-release coated tablets,
• wax/lipid matrix cores with high drug loading,
• porous coating systems combining insoluble polymer dispersions with water-soluble film formers,
• controlled release using pH-independent insoluble acrylic dispersions.

Without external bibliographic/citation inputs, an infringement or validity strategy cannot responsibly name specific competitor patents or identify which families dominate around this concept.

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Key Takeaways

• U.S. Patent 5,656,296 claims a specific dual-control sustained-release coated tablet defined by (i) a high-loading medicament core with an edible wax/lipid melting point 25–100°C and (ii) a porous coating with a pH-independent water-insoluble acrylic dispersion polymer plus a water-soluble film former.
• Claim coverage is tightest where accused formulations match:
  • the enumerated insoluble acrylic polymer categories,
  • the lipid/wax class and melting/iodine windows, and
  • the weight % ranges.
• Dependent claims add narrowing for:
  • specific APIs (procainamide HCl, sodium meclofenamate),
  • specific lipids (carnauba wax, hydrogenated vegetable oils, stearic acid),
  • specific soluble cellulose derivatives (including hydroxypropyl cellulose),
  • and a core:coating ratio window (94:6 to 98:2).
• Claim 14 covers a manufacturing workflow centered on melting the edible lipid, mixing the medicament into the melt, cooling/milling/compressing, then water-based porous suspension coating.

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FAQs

1) What drug-release feature is required by US 5,656,296?
The system must have release that is “essentially unaffected by high-fat food consumption” while being a dual-control sustained-release core with a porous coating layer.

2) Are the coating polymers constrained to acrylics?
Yes for the pH-independent water-insoluble polymer. Claim 1 limits that insoluble polymer to acrylic resin dispersions comprising enumerated polymer families.

3) What edible materials qualify for the core?
Edible materials must have melting point 25–100°C and be selected from fatty acids with iodine value 1–10, natural waxes, synthetic waxes, or mixtures.

4) Does the patent cover procainamide hydrochloride specifically?
Yes. Dependent claim 4 narrows the medicament to procainamide hydrochloride.

5) Does the patent protect manufacturing steps as well as the product?
Yes. Claim 14 recites melting the edible material, admixing the medicament, cooling/milling/compressing tablet cores, forming a porous coating suspension in water, and coating the cores.

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References

1. United States Patent 5,656,296 (claim text provided in prompt).

Drugs Protected by US Patent 5,656,296

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