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Patent landscape, scope, and claims summary: |
United States Patent 6,248,363: solid-carrier encapsulates hydrophilic actives with hydrophilic surfactants plus lipophilic additives
US 6,248,363 claims a broad platform for formulating hydrophilic pharmaceutical actives inside (or as part of) a solid carrier using a hydrophilic surfactant to solubilize the active, combined with a specific lipophilic additive class. The claim set is structurally wide (broad active-ingredient classes, broad carrier forms, broad delivery routes, broad surfactant subclasses, and broad mass-fraction windows), and it is also internally anchored by three functional limitations: (i) a hydrophilic active must be partially or fully solubilized in the encapsulation coat/solid carrier by (ii) an “effective solubilizing amount” of at least one hydrophilic surfactant, while (iii) the formulation also contains a lipophilic additive selected from lipophilic surfactants, triglycerides, or combinations.
A critical IP takeaway: infringement is plausibly enabled by routine excipient substitution (many HLB and ionic/non-ionic surfactants can satisfy the “effective solubilizing amount”), but enforcing the patent against a specific drug or generic would still hinge on product-specific evidence of (1) compartmental placement (encapsulation coat vs. entire solid carrier matrix) and (2) whether the formulation actually achieves partial/full solubilization of the hydrophilic active in the claimed phase. The patent’s breadth is a litigation posture asset but also a claim-construction and proof burden.
What does US 6,248,363 claim: encapsulation coat vs solid carrier matrix with hydrophilic surfactants and lipophilic additives?
Core claim architecture (representative independent claims 1 and 6)
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Claim 1 (encapsulation coat route): a solid carrier substrate with an encapsulation coat comprising:
- a therapeutically effective amount of a hydrophilic pharmaceutical active ingredient
- an effective solubilizing amount of at least one hydrophilic surfactant
- a lipophilic additive selected from lipophilic surfactants, triglycerides, or combinations
The hydrophilic surfactant amount is defined as being effective to partially or fully solubilize the pharmaceutical active ingredient in the encapsulation coat.
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Claim 6 (solid carrier route): a solid carrier that comprises, as an admixture:
- hydrophilic active
- hydrophilic surfactant (effective solubilizing amount)
- lipophilic additive (lipophilic surfactants and/or triglycerides)
The solubilization is defined as occurring in the solid carrier.
Practical enforcement hinge
- Product must exhibit a formulation where the active is solubilized by the hydrophilic surfactant in the specified location (coat vs carrier).
- The lipophilic additive requirement is not “any lipophilic excipient.” It is constrained to the claimed classes.
What is the claim scope for hydrophilic active ingredients in US 6,248,363?
Active-ingredient classes and breadth
- Claim 2 / 34: active can be a drug, nutrient, cosmeceutical, diagnostic agent, including salts, isomers, derivatives, mixtures.
- Claims 9 and 10 (and parallel dependent claims): active is defined by apparent water solubility ≥ 1 mg/mL and then an expansive list includes:
- cytokines, peptidomimetics, peptides, proteins, toxoids, serum, antibodies, vaccines, nucleosides, nucleotides, portions of genetic material, nucleic acids
- extensive therapeutic categories and long enumerated examples (e.g., acarbose, acyclovir, alendronate, atenolol, azithromycin, calcitonins, capecitabine, ciprofloxacin, cisplatin, enoxaparin, epoetin alpha, fluoxetine, ganciclovir, heparin sodium, insulin products, interferons, leuprolide acetate, metformin, octreotide, paroxetine, pregabalin, ritonavir-class items, tPA and TNFR:Fc/TNK-tPA, vancomycin, valaciclovir, warfarin sodium, and many more listed in the claim text).
Criticality
- The patent does not limit the formulation to small molecules or to any single therapeutic area.
- It is a solubilization-in-solid-excipient concept claim with broad application to hydrophilic actives.
What mass-fraction and excipient-ratio limitations narrow (or fail to narrow) infringement?
Lipophilic additive to hydrophilic surfactant ratio
- Claim 3 / 7: weight ratio of lipophilic additive : hydrophilic surfactant = ~0.10:1 to ~0.92:1.
This is a meaningful numeric limiter for proving infringement, but it is also broad enough to cover many plausible formulations.
Active loading in the coat and carrier
- Claim 4 / 5: active ingredient in encapsulation coat = ~1.96 wt% to 28.57 wt%.
- Claim 8: active ingredient in solid carrier = ~4.6 wt% to 50.0 wt%.
Where these numbers matter most
- These windows allow strong coverage for “high loading” solid systems.
- But if a competitor’s product has significantly lower or higher active fractions, infringement risk drops sharply because these are quantitative, not purely functional, limitations.
Which surfactants and HLB thresholds are claimed in US 6,248,363?
Non-ionic hydrophilic surfactant with HLB ≥ 10
- Claim 15 / 41: non-ionic hydrophilic surfactant HLB ≥ about 10.
- Claim 16 / 42 (non-ionic list examples):
- alkylglucosides, alkylmaltosides, alkylthioglucosides
- lauryl macrogolglycerides
- polyoxyethylene alkyl ethers, polyoxyethylene alkylphenols
- PEG fatty acid esters, PEG glycerol fatty acid esters
- polyoxyethylene sorbitan fatty acid esters, polyoxyethylene-polyoxypropylene block copolymers
- polyglycerol fatty acid esters, polyoxyethylene glycerides
- polyoxyethylene sterols/derivatives
- tocopherol polyethylene glycol succinates, sugar esters/ethers
- sucroglycerides
- and “mixtures thereof”
Ionic hydrophilic surfactant
- Claim 17 / 43: at least one ionic surfactant.
- Claim 18 / 44 (ionic list examples):
- alkyl ammonium salts
- bile acids and salts, analogues, derivatives
- amino acid/carnitine/peptide/polypeptide fatty-acid derivatives
- acyl lactylates
- tartaric acid esters of mono/diglycerides (diacetylated forms, mono/diglyceride esters)
- succinylated monoglycerides, citric acid esters
- alginate salts; propylene glycol alginate
- lecithins, hydrogenated lecithins; lysolecithin
- lysophospholipids, phospholipids
- sodium docusate
- salts of alkyl sulfates; salts of fatty acids
Criticality
- By embedding explicit HLB and surfactant taxonomy, the patent supports arguments that common excipient classes satisfy “hydrophilic surfactant.”
- Enforcing against a real product still requires matching the surfactant subclass and demonstrating the “effective solubilizing amount” function.
What lipophilic additive categories are covered: lipophilic surfactants vs triglycerides?
Lipophilic additive selection
- Claim 1/6: lipophilic additive is from:
- lipophilic surfactants
- triglycerides
- combinations
Lipophilic surfactants list
- Claim 24/47/“lipophilic additive selected from lipophilic surfactants”
- Claim 25/48: includes alcohols, polyoxyethylene alkyl ethers (note: overlap in surfactant taxonomy), fatty acids, bile acids, glycerol fatty acid esters, acetylated glycerides, lower alcohol fatty acid esters, PEG fatty acid esters, propylene glycol diglycerides, sorbitan esters, polyglycerol/fatty acid esters, sugar esters/ethers, sucroglycerides, polyoxyethylene vegetable oils, hydrogenated vegetable oils, reaction mixtures, and mixtures.
Triglyceride list
- Claim 26/49: triglycerides including vegetable oils, fish oils, animal fats, hydrogenated and partially hydrogenated vegetable oils, synthetic/modified/fractionated triglycerides.
Criticality
- These lists are broad and cover common excipient families used to improve wetting, dispersion, and drug solubilization in solid dosage and multiparticulates.
- The ratio limitation (lipophilic additive : hydrophilic surfactant) is the numeric guardrail; category match is otherwise wide.
What solid-carrier forms and coatings are claimed in US 6,248,363?
Substrate definition
- Claim 19: substrate is powder or multiparticulate.
- Claim 20: substrate can be an additive, active ingredient, or mixture.
- Claim 21: example additive types: solubilizer, enzyme inhibitor, anti-adherent, anticoagulant, antifoaming, antioxidant, binder, bufferant, chelating agent, coagulant, colorants/opaquants, coolant, cryoprotectants, diluent/filler, disintegrant/super disintegrant, hydrogen bonding agent, flavorant/desensitizer, ion-exchange resin, plasticizer, preservative, solvent, sweetener, thickener.
Multiparticulate and particulate shape
- Claim 22: multiparticulates include granule, pellet, bead, spherule, beadlet, microcapsule, millisphere, nonocapsule, nonosphere, microsphere, platelet, tablet, capsule.
Solid carrier geometry
- Claim 23 / 45: includes beads, beadlets, granules, spherules, pellets, microcapsules, microspheres, nanospheres, films, wafers, sprinkles, implants, troches, lozenges, platelets, nanocapsules, strips.
Coatings and release-related variants
- Claim 27 / 50: solid carrier can be enteric coated, fast-disintegration coated, seal coated, film coated, barrier coated, compress coated, or enzyme-degradable coating.
- Claim 28 / 51: encapsulated, extruded, compressed, pelletized, coated, mixed, granulated, crystallized, lyophilized, or molded.
Dosage form and administration
- Claim 29 / 52: capsule, tablet, ovule, suppository, wafer, chewable tablet, buccal/sublingual/quick-dissolve/effervescent, granule/pellet/bead/pill/sachet/sprinkle/film/dry syrup/reconstitutable solid/suspension/lozenge/troche/implant/powder/triturate/platelet/strip.
- Claim 30 / 53: immediate, pulsatile, controlled, extended, delayed, targeted, targeted delayed release.
- Claim 31 / 54: oral, nasal, ocular, urethral, buccal, transmucosal, vaginal, topical, rectal delivery.
- Claims 32-33 / 55-56: method of administering dosage forms to mammal including human.
Criticality
- The patent’s structural scope is not limited to a specific dosage architecture.
- It is compatible with immediate-release and targeted-release platforms, as long as the claimed excipient-phase solubilization relationship exists.
How could the claim language create both strong coverage and litigation friction?
Coverage strength
- Broad definition of hydrophilic active: accepts a wide enumerated list and uses solubility threshold.
- Excipient category breadth: includes many non-ionic and ionic hydrophilic surfactants; includes triglycerides and many lipophilic excipient families.
- Dosage and carrier breadth: supports many solid dosage archetypes and coating technologies.
- Quantitative windows: active loading and ratio windows expand potential product match.
Litigation friction points
- Functional “solubilize in the coat/carrier”: infringement proof may require product-specific analytical evidence that the active is actually solubilized (not merely dispersed) by the surfactant in the claimed compartment.
- Encapsulation coat vs solid carrier admixture: if a product does not have an “encapsulation coat” structure, the enforcement focus shifts to claim 6-style admixture coverage. Claiming both helps, but product structure matters.
- HLB and surfactant subclass: many products will use surfactants, but matching HLB ≥ 10 (for non-ionic dependent claims) may not be automatic.
- Numerical ratio and loading: if a competitor formulates outside 0.10:1 to 0.92:1 (lipophilic additive : hydrophilic surfactant) or outside active loading windows, the claim may narrow materially.
How strong is the patent estate for US 6,248,363 against generic and reformulation threats?
Key question for commercial risk
US 6,248,363 is an “excipient-phase architecture + solubilization” patent. That places it in a category that can block:
- new product launches using similar solid carriers and excipient systems,
- generics that attempt to keep the same solid architecture without engineering around solubilization and ratio/active-loading windows.
What an engineered product could do to reduce risk
- Adjust excipient composition to break the ratio or active loading windows.
- Use surfactants that do not meet the claimed hydrophilic surfactant constraints (or use no surfactant in an amount that meets the claimed “effective solubilizing amount”).
- Create a formulation where hydrophilic active is not “solubilized in the encapsulation coat/solid carrier” as claimed, but instead remains in a different physical state (e.g., precipitated/solvated elsewhere).
- Avoid encapsulation-coat geometry and ensure that any claimed “solubilized in the solid carrier” limitation is not met (still requires close claim-construction).
Business impact
Because the claims span broad active categories and broad dosage forms, the patent can create non-trivial licensing leverage for reformulation platforms. The likely battleground is not whether the target uses solid dosage, but whether it replicates:
- the hydrophilic surfactant solubilization role,
- the lipophilic additive type,
- and the claimed quantitative windows.
Which dependencies expand claim coverage vs which dependencies narrow it?
Expanding dependencies
- Active ingredient categories (claims 2, 10-14, 34-40) widen the types of products covered.
- Solid carrier geometry and dosage form variations (claims 19-23, 27-31, 45-54) support many product formats.
Narrowing dependencies
- Ratio (claims 3, 7, 57).
- Active loading in coat and carrier (claims 4-5, 8, 57).
- Solubility threshold for hydrophilic active (claim 9, 35; and downstream dependencies).
- Non-ionic HLB ≥ 10 (claims 15, 41) and specific non-ionic lists (claims 16, 42).
- Ionic surfactant lists (claims 17-18, 43-44).
- Lipophilic additive subclass narrowing to lipophilic surfactants (claims 24, 47, 48) or triglycerides (claims 26, 49).
Key claim map (quick reference)
| Claim cluster |
Limitation type |
Numeric/structural trigger |
Coverage effect |
| Claim 1 vs 6 |
Structural placement |
Encapsulation coat (claim 1) vs solid carrier admixture (claim 6) |
Enables two enforcement theories |
| Claims 3 and 7 |
Ratio |
Lipophilic additive : hydrophilic surfactant = ~0.10:1 to ~0.92:1 |
Numeric narrowing |
| Claims 4-5 |
Active loading in coat |
Active in encapsulation coat = ~1.96 wt% to 28.57 wt% |
Numeric narrowing |
| Claim 8 and 57 |
Active loading in carrier |
Active in solid carrier = ~4.6 wt% to 50.0 wt% |
Numeric narrowing |
| Claim 9 / 35 |
Active solubility |
Apparent water solubility ≥ ~1 mg/mL |
Active filter |
| Claims 15-16 and 41-42 |
Surfactant subclass |
Non-ionic, HLB ≥ ~10 |
Narrowing but still broad in list |
| Claims 17-18 and 43-44 |
Surfactant subclass |
Ionic surfactant lists |
Broad but listed |
| Claims 24-26 and 47-49 |
Lipophilic additive subclass |
Lipophilic surfactants or triglycerides |
Category constraints |
| Claims 27-31 and 50-54 |
Carrier and dosage |
Coatings, release profiles, routes |
Broad architecture |
Key Takeaways
- US 6,248,363 is a platform patent for solid-carrier formulations of hydrophilic actives using hydrophilic surfactants as solubilizers plus lipophilic additives (lipophilic surfactants and/or triglycerides).
- The claim set is broad in active-ingredient class, dosage form, carrier geometry, and release/route, but it includes meaningful numeric constraints: active loading windows and a lipophilic additive : hydrophilic surfactant ratio.
- Practical infringement pivots on product-specific proof that the active is partially or fully solubilized by the hydrophilic surfactant in the claimed compartment (encapsulation coat or solid carrier).
- The most direct litigation exposure for competitors is likely reformulations that use similar solid-carrier architectures and common surfactant/lipid excipient families in falling ratio and loading ranges.
FAQs
1) Does US 6,248,363 require a specific active pharmaceutical ingredient (API)?
No. It applies to hydrophilic actives generally, constrained by an apparent water solubility threshold and broad lists of drug/nutrient/cosmeceutical/diagnostic categories.
2) What is the key quantitative limiter in US 6,248,363?
The lipophilic additive to hydrophilic surfactant weight ratio of approximately 0.10:1 to 0.92:1, plus active loading windows in coat and/or solid carrier.
3) How does claim 1 differ from claim 6 for infringement analysis?
Claim 1 requires the solubilized active to be in an encapsulation coat on a substrate; claim 6 covers an admixture within the solid carrier where the active is solubilized in the solid carrier.
4) Can a product with a different release profile avoid the patent?
Release profile alone is not enough to avoid coverage because the patent lists immediate, controlled, delayed, targeted, and other release formats and multiple routes. Avoiding coverage requires breaking claimed excipient-phase solubilization and ratio/loading limits.
5) Does the patent cover only triglycerides?
No. Triglycerides are one lipophilic additive option. The lipophilic additive can also be lipophilic surfactants or mixtures with triglycerides, subject to the ratio window.
References
- U.S. Patent No. 6,248,363.
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