Details for Patent: 6,022,562

US Patent 6,022,562: Scope, Claim Architecture, and US Landscape Impact

United States Patent 6,022,562 is a composition-and-process family built around reservoir-type oral microcapsules whose defining technical core is a dual-polymer, non-hydrosoluble sustained-release coating system intended to reside in the small intestine for 5 to 24 hours. Claim scope is anchored by (i) coating composition thresholds, (ii) particle size bands, (iii) residence-time functional limits, and (iv) exclusion of acetylsalicylic acid (ASA) for the covered active principle set.

What does the patent claim, in one technical sentence?

The patent claims oral reservoir microcapsules where each active-principle (AP) particle is coated with a coating film comprising: (a) an insoluble, film-forming cellulose derivative polymer P1 (primarily ethylcellulose or cellulose acetate) at 50 to 90 wt% of coating dry matter, (b) a nitrogen-containing polymer P2 (primarily polyacrylamide / polyvinylpyrrolidone / poly-N-vinylamide / poly-N-vinyl-lactam) at 2 to 25 wt%, (c) a plasticizer (typically castor oil or glycerol esters, phthalates, citrates, sebacates, cetylalcohol esters, castor oil/cutin-derived) at 2 to 20 wt%, and (d) a surface-active and/or lubricating agent (fatty acid salts and/or sorbitan ethoxylates/castor oil ethoxylates and/or metal stearates such as Mg/Ca/Zn stearate) at 2 to 20 wt%, with particle size 50 to 1000 µm and small-intestine residence ≥5 hours (preferably 7 hours; also 8 to 24 hours band) enabling absorption/release during residence. (Claim 1 and Claim 14).

How is the claim set structured (and what is actually limiting)?

The independent technical “heart” is Claim 1, followed by dependent claims that tighten composition, AP categories, specific AP examples, and tablet/galenical/method uses. Claim 8-10 recite the manufacturing process at a functional unit-operation level. Claims 11-13 and 14 are downstream use claims centered on vehicle/reservoir microcapsules.

Core independent scope: Claim 1

Claim 1 defines the covered product in terms of:

1. Microcapsule type

   • “Microcapsules of reservoir kind” for oral administration.
   • AP exclusion: “with the exclusion of acetylsalicylic acid (ASA).”
   • AP can be medicinal and/or nutritional.

2. Per-particle architecture

   • “particles of AP each coated with at least one coating film” containing the four component groups:
     • P1 (insoluble film-forming polymer, non-hydrosoluble cellulose derivative)
     • P2 (nitrogen-containing polymer)
     • Plasticizer
     • Surface-active and/or lubricating agent

3. Coating dry-matter composition ranges

   • P1: 50-90 wt% (preferably 50-80)
   • P2: 2-25 wt% (preferably 5-15)
   • Plasticizer: 2-20 wt% (preferably 4-15)
   • Surface-active/lubricant: 2-20 wt% (preferably 4-15)

4. Particle size

   • 50 to 1000 µm
   • preferred: 100 to 750 µm
   • more preferred: 100 to 500 µm

5. Residence-time functional limitation

   • designed to remain in small intestine:
     • at least about 5 hours, preferably at least about 7 hours
     • more preferably about 8 to about 24 hours
   • and to “permit so the absorption of the AP during at least part of their residence.”

Downstream independent-like method claim: Claim 14

Claim 14 is an additional “use as a vehicle” method claim with a tighter particle-size band (explicitly including 200 to 500 µm as the “even more preferably” band) and the same residence-time and coating composition framing (“particles of AP each coated with at least one coating film of specific composition”).

What are the hard quantitative limits (where design-arounds are likely to be tested)?

Coating composition limits (Claim 1)

Particle size limits (Claim 1 and Claim 14)

Small intestine residence-time functional limitation (Claim 1 and Claim 14)

• designed to remain in small intestine for:
  • ≥ about 5 hours, preferably ≥ about 7 hours
  • even more preferably 8 to 24 hours
• and to release/permit absorption “during at least part” of residence.

Which microcapsule compositions are explicitly pinned down (dependent claims)?

Claim 2: AP loading

• AP amount 55-95 wt% (preferably 70-85 wt%).

Claim 3: Example coating recipe window

This is the most concrete dependent claim:

• 60 to 80% ethylcellulose
• 5 to 10% polyvinylpyrrolidone
• 5 to 10% castor oil
• 2 to 8% magnesium stearate

This claim narrows P1 to ethylcellulose and pins P2 to PVP with specific plasticizer and lubricant.

Claim 4: Anti-agglomerant addition

• Add 0.5 to 5 wt% (preferably 1.5 to 3 wt%) of an anti-agglomerating agent:
  • talc, colloidal silica, or a mixture.

Which active principles are covered (scope and exclusion)?

AP families (Claim 5)

AP covers broad therapeutic and nutritional categories, including:

• antiulcer, antidiabetic, anticoagulant/antithrombic, hypolipaemic, antiarrhythmic, vasodilatory/antianginal/antihypertensive/vasoprotective
• fertility enhancers, labor inducers and inhibitors, contraceptive
• antibiotic/antifungal/antiviral/anticancer/anti-inflammatory/analgesic/antiepileptic/antiparkinsonian/neuroleptic/hypnotic/anxiolytic/psychostimulatory
• antimigraine, antidepressant, antitussive, antihistamine/antiallergic

Specific named actives (Claim 6)

Claim 6 enumerates many compounds (representative set below exactly as claim lists):

• Pentoxifyllin, prazosin, acyclovir, nifedipin, diltiazem, naproxen, ibuprofen, flurbiprofen, ketoprofen
• indomethacin, diclofenac, fentiazac
• oestradiol valerate
• metoprolol, sulpiride, captopril, cimetidin
• zidovudin, nicardipine, terfenadine, atenolol, salbutamol
• carbamazepin, ranitidine, enalapril, simvastatin, fluoxetin, alprazolam
• famotidin, ganciclovir, famciclovir, spironolacton
• 5-ASA
• quinidin, perindopril
• morphin, pentazocin
• paracetamol, omeprazol, metoclopramid

Exclusion: acetylsalicylic acid (ASA) is excluded from Claim 1’s microcapsule definition.

Nutritional supplements (Claim 7)

AP can be nutritional/dietary supplements including:

• vitamins, amino acids, trace elements, antioxidants, and mixtures.

What does the process coverage cover (and where can it be narrow)?

Claim 8: Process for producing microcapsules

Claim 8 recites an essential sequence:

a. Select/make AP microparticles with particle size 50-1000 µm (pref. 100-750; more pref. 100-500)
b. Prepare coating composition by mixing:

• polymer P1, polymer P2, plasticizer, and surface-active/lubricating agent in a solvent system
  c. Apply coating to AP particles:
• applying coating composition/solvent system mixture to particles of AP
  d. Dry microcapsules
  e. Optionally mix with anti-agglomerant

Claim 9: Solvent system list

Solvents selected from:

• ketones, esters, chlorinated solvents, alcohols (preferably aliphatic, alkanes)
• preferred 1 to 6 carbons
• “particularly preferred”: acetone, methyl ethyl ketone, methanol, ethanol, isopropanol, methylene chloride

Claim 10: Coating application method

Applying coating composition/solvent system mixture by spraying onto moving articles, preferably:

• mechanical stirring or fluidization

Claim 11-13: Use in dosage forms and therapy

• Claim 11: “Method of preparation of pharmaceutical forms” where improvement is use of microcapsules (tablets crumbled, powders, gelatin capsules).
• Claim 12: Galenical system containing microcapsules.
• Claim 13: Method for treating/preventing diseases/pains using microcapsules.

How broad is the protection vs how easy is it to design around?

Where the scope is broad

1. AP identity is not limited to specific drugs in Claim 1, only to the broad “AP families” and explicit exclusions (ASA).
2. The coating requirement is functional and compositional, but P1 includes “at least one” non-hydrosoluble cellulose derivative with ethylcellulose/cellulose acetate as preferred options.
3. P2 includes multiple nitrogen-containing polymer options.

Where the scope is narrow

1. Four-part coating composition with strict wt% ranges: P1 must dominate at 50-90 wt%, P2 must be 2-25 wt%, and both plasticizer and surfactant/lubricant are each constrained at 2-20 wt%.
2. Particle size is constrained to 50-1000 µm, with a tighter band preferred and an even tighter band in Claim 14.
3. Residence-time is not just a formulation goal but a design limitation tied to small intestine duration.

Practical design-attack points (claim-based, not hypothetical)

A competitor can aim to avoid Claim 1 by failing at least one of the required claim elements:

• change coating solids composition so one component is outside the specified wt% ranges
• replace the cellulose derivative P1 with a polymer that is not a “non-hydrosoluble cellulose derivative” in the claim meaning
• exclude the specified nitrogen-containing polymer class for P2 (polyacrylamide/PVP/poly-N-vinylamide/poly-N-vinyl-lactam)
• remove or substitute plasticizer class outside claim definitions
• remove or substitute surface-active/lubricant class outside claim definitions
• change particle size band outside 50-1000 µm (or outside 100-750 and 100-500 depending on which dependent preferences are implicated in infringement argumentation)
• fail the “designed to remain in the small intestine” functional requirement

US patent landscape: where this sits relative to formulation and controlled-release microencapsulation IP

This patent is a representative example of a controlled-release oral microencapsulation approach anchored on:

• water-insoluble cellulose derivatives (ethylcellulose/cellulose acetate) as matrix-forming film
• polymeric permeability modulation via a nitrogen-containing polymer (P2)
• plasticization to control film properties
• lubricants/surfactants to manage processing and possibly surface wetting
• micron-range particle sizing and an oral intestinal residency claim theme (5-24 hours)

From a landscape perspective, the claims are structured to cover a broad set of actives while keeping the inventive contribution focused on the coating system and the intended small intestine residence and release/absorption.

Because the patent text provided contains only the claims (not the prosecution history, priority data, specification disclosures, or citations), the competitive landscape can only be mapped at the level of claim architecture and technical feature sets, not at the level of which specific third-party patents are closest.

Key takeaways

• Claim 1 is the operative boundary: oral reservoir microcapsules with per-particle P1/P2/plasticizer/lubricant coating composition defined by tight wt% windows plus 50-1000 µm particle size and small intestine residence ≥5 to 24 hours.
• Claim 3 provides a concrete formulation snapshot: ethylcellulose + PVP + castor oil + magnesium stearate in specified ranges.
• AP scope is broad across drug classes and nutritional supplements, but ASA is excluded.
• Process claims 8-10 cover microparticle preparation with defined solvent classes and spraying onto moving particles (spray/coating and drying sequence).

FAQs

1) Is this a method-of-treatment patent or a formulation patent?
It is primarily a formulation and microcapsule construction patent (Claim 1 and dependent product claims), with additional downstream use claims (Claims 11-13 and Claim 14) that use the microcapsules as a vehicle.

2) What is the most limiting feature for infringement?
The most limiting feature is the combination of specific coating composition ranges (P1/P2/plasticizer/lubricant), plus particle size and the small intestine residence-time design limitation.

3) Does it cover acetylsalicylic acid?
No. Claim 1 expressly excludes acetylsalicylic acid (ASA).

4) Are there specific exemplar actives covered?
Yes. Claim 6 enumerates many named drugs, and Claim 5 also defines broad therapeutic families. Claim 1 itself is broader but still tied to the claimed reservoir microcapsule construction.

5) What exact dependent formulation is called out?
Claim 3 specifies: ethylcellulose (60-80%), polyvinylpyrrolidone (5-10%), castor oil (5-10%), and magnesium stearate (2-8%).

References

1. US Patent 6,022,562 (claims as provided).