Patent 6,106,861 (US 6,106,861): Scope, Claim Boundaries, and US Patent Landscape for Multiparticulate Taste-Masked Fast-Disintegrating Tablets (≤40 seconds)
US 6,106,861 is a US patent in the fast-disintegrating, multiparticulate tablet category that narrows to tablets that (i) disintegrate in the mouth in under 40 seconds and (ii) contain microcrystals of an active ingredient bearing a taste-making coating, embedded in a specified excipient system built around cross-linked disintegrants and polyol-based soluble binders/diluents with defined particle-size formats. The claim set is structured to cover the core formulation architecture (composition + excipient particle-size and ratio constraints + microcrystal coating polymer classes), and then adds several dependent claim “guardrails” that lock in preferred numeric ranges, coating polymer subclasses, bioavailability equivalence, and dissolution outcomes under acidic and near-neutral pH conditions.
What is US 6,106,861 claiming about mouth-disintegrating multiparticulate tablets?
Core answer: The patent claims multiparticulate tablets that combine (a) fast mouth disintegration, (b) taste masking via coated active microcrystals, and (c) a tightly defined excipient package: cross-linked polyvinylpyrrolidone (PVP) and/or cross-linked carboxymethylcellulose (CMC), plus 40%–90% by weight polyol soluble diluent agents with binding properties selected from mannitol/xylitol/sorbitol/maltitol in either directly compressible particle form or powder form, including specific ratio constraints between the two forms when more than one polyol type/format is used.
Key claim 1 architecture (independent claim boundary)
Claim 1 requires all of the following, in combination:
-
Dosage form / disintegration timing
- A multiparticulate tablet
- Disintegrates in the mouth in < 40 seconds
-
Active ingredient format
- Active ingredient is present as microcrystals
- Microcrystals have a taste-making coating (coating agents defined later)
-
Excipient system
- Tablet excipient includes, by tablet mass:
- Disintegration agent (3%–15% by weight)
- Selected from:
- cross-linked polyvinylpyrrolidone, and/or
- cross-linked carboxymethylcellulose
- Soluble diluent agent with binding properties (40%–90% by weight)
- A polyol with < 13 carbon atoms
- Selected from mannitol, xylitol, sorbitol, maltitol
- Must exist in either:
- directly compressible form: particles 100–500 μm
- OR powder form: particles < 100 μm
-
Polyol format logic (“proviso”)
- If only one soluble diluent agent (polyol) is used:
- it is a directly compressible polyol, except sorbitol
- If at least two soluble diluent agents are used:
- these are the same polyol, split across formats:
- one part in directly compressible form
- one part in powder form
- ratio of directly compressible polyol to powder polyol:
-
Microcrystal coating agent class
- At least one coating agent for the microcrystals selected from:
- polymethacrylates
- cellulose polymers
- and combinations
Practical scope implication: A product that meets the time-to-disintegrate requirement but uses a different disintegrant class (outside cross-linked PVP/CMC) or uses diluent binders outside the specified polyols/particle formats will fall outside the claim 1 composition constraints even if it still taste masks.
How broad is the claim 1 coating scope for taste-masking microcrystals?
Core answer: Claim 1’s microcrystal “taste-making coating” is constrained to coating agent classes: polymethacrylates and/or cellulose polymers. The claim does not specify viscosity grade, molecular weight, or exact polymer substitution patterns beyond these general polymer families.
Dependent claim 5 refines coating polymer options
Claim 5 narrows coating agents to:
- hydroxypropyl-methyl cellulose (HPMC)
- hydroxypropyl cellulose (HPC)
- cellulose acetophthalates
This set matters because it defines the “literal” coating-agent subset that explicitly aligns to claim 5, while claim 1 remains broader by covering additional polymethacrylate or cellulose-polymer members.
Dependent claim 6 expands with adjuvants
Claim 6 adds that the coating agent can be combined with:
- plasticizers
- soluble agents
- polyols
(from the coating formulation composition perspective, not the bulk excipient system)
Scope takeaway: Claim 1 tolerates coating formulations beyond the exact polymers named in claim 5 as long as they stay within the “polymethacrylates and cellulose polymers” classes. Claim 5 identifies common, regulatorily familiar cellulose polymer candidates used in taste masking and controlled microcrystal coating processes.
What excipient particle-size and ratio rules define infringement risk?
Core answer: The patent uses particle-size and ratio constraints that are unusually specific for formulation patents. These constraints create bright-line defenses for would-be design-arounds.
Disintegrant amount constraint (claim 1)
- Cross-linked PVP and/or cross-linked CMC:
- 3%–15% by weight of tablet
Claim 2 tightens the range:
- Disintegrating agent:
- Soluble diluent with binding properties:
Soluble diluent with binding properties (polyol) constraint (claim 1)
- 40%–90% by weight
- Polyol must be:
- <13 carbons
- selected from mannitol, xylitol, sorbitol, maltitol
- Must be in specified particle formats:
- directly compressible: 100–500 μm
- powder: <100 μm
“Proviso” logic: one polyol vs same polyol split across formats
- If only one polyol is used:
- it must be directly compressible, except sorbitol
- If at least two soluble diluent agents are used:
- these are the same polyol split into formats
- ratio directly compressible : powder:
Dependent claims tighten sorbitol and ratio limits
- Claim 3:
- Claim 4:
- directly compressible : powder:
Infringement analysis framing: Even if a competitor uses the same disintegrant family and the same coating polymer family, they can potentially avoid claim 1 by changing:
- polyol identity (use of non-listed polyols),
- polyol carbon count (if outside <13, though listed examples are <13),
- polyol particle-size distribution,
- or the ratio between “directly compressible” and “powder” formats.
Does the patent cover bioavailability and dissolution equivalence, and how?
Core answer: Yes. Claims 7–10 add functional and performance-linked limitations tied to dissolution behavior and taste masking, including a bioavailability equivalence construct and acid-medium dissolution thresholds.
Claim 7: bioavailability equivalence
- “Bioavailability … is at least equivalent” to the same tablet where microcrystals are not coated.
This is a relative performance claim tied to an “uncoated comparator” formulation.
Claims 8 and 9: acid dissolution thresholds (pH < 5)
Both claims measure the dissolved amount of active ingredient after:
- disintegration of the tablet
- in 5 to 20 minutes
- in acid medium pH < 5
Thresholds:
- Claim 8:
- ≥ 80% of dissolved amount vs uncoated comparator
- Claim 9:
- ≥ 100% vs uncoated comparator
Claim 10: near-neutral pH dissolution suppression (taste masking)
- Active ingredient does not dissolve significantly after:
- remaining < 5 minutes in medium:
Scope implication: These dependent claims create additional layers of coverage for formulations that dissolve quickly enough in acid but suppress dissolution at near-neutral pH, consistent with oral taste masking needs.
Which active ingredients does the patent cover?
Core answer: Claim 11 and claim 12 define active-ingredient lists within claim 1’s generic “active ingredient” requirement.
Dependent claims listing drug classes (claim 11)
Active ingredient selected from:
- analgesics
- antipyretics
- antidiarrheals
- antispasmodics
- digestive motoricity regulators
- anti-inflammatories
Claim 12 provides specific exemplars
- paracetamol (acetaminophen)
- ibuprofen
- aspirin
- ketoprofen
- loperamide
Scope implication: The patent can be enforced across these example actives if the formulation and excipient/coating constraints are satisfied. If a product uses a different active outside these lists, claim 1 still may cover it because claim 1 broadly applies to “active ingredient,” but the dependent claims 11–12 will not narrow to those lists unless the specific active is used.
How would a product design-around attack claim 1?
Core answer: The highest-friction claim elements are (i) the excipient composition with particle-size constraints and ratio/proviso rules, and (ii) the microcrystal coating polymer classes.
Most direct design-around levers
-
Change disintegrant class
- Replace cross-linked PVP and/or cross-linked CMC with another disintegrant type.
-
Change polyol binder/diluent identity
- Use a non-listed polyol or a non-polyol binder/diluent.
-
Change polyol particle-size category
- Ensure polyol is not within 100–500 μm for “directly compressible” or not within <100 μm for “powder” as required.
-
Break the “proviso” ratio rules
- Avoid the directly compressible vs powder split ratios (99/1 to 50/50; or 80/20 to 50/50 in claim 4).
- Avoid the “same polyol” split format logic that applies when “at least two soluble diluent agents” are used.
-
Change microcrystal coating polymer class
- Use coating polymers not falling within “polymethacrylates” or “cellulose polymers.”
What does this imply for US generic and formulation competitors?
Core answer: The claim set is formulation-centric and composition-constrained, so generic-filing risk is primarily driven by whether the proposed generic matches the specific excipient architecture and coated microcrystal approach, not just overall tablet disintegration time.
Patent estate strategy (US 6,106,861)
For litigation and design-around purposes, the estate impact typically comes from:
- claim 1’s composition constraints (bright-line variables for excipient and coating choices),
- dependent claims 2–6 narrowing numerical ranges and named coating polymers,
- dependent claims 7–10 establishing performance-linked equivalence/dissolution patterns.
Business takeaway: A competitor can attempt to reduce infringement exposure by changing at least one constrained dimension: excipient disintegrant type, polyol system particle format/ratio, or microcrystal coating polymer class.
Where do infringement disputes likely concentrate?
Core answer: Disputes will most often turn on measurable formulation parameters that are easy to lab-test or compare: particle size distributions, % by weight excipient composition, and coating polymer identity. Secondary disputes will focus on dissolution performance under controlled pH conditions and bioavailability equivalence.
Likely contested claim construction facts
- Whether the excipient qualifies as “cross-linked PVP” or “cross-linked CMC” (material identity and cross-linking status).
- Whether the polyol particle sizes meet the definition of “directly compressible form” (100–500 μm) versus “powder form” (<100 μm).
- Whether the coated active microcrystal coating agent is within “polymethacrylates” or “cellulose polymers” and whether specific HPMC/HPC/cellulose acetophthalates are used (claim 5).
- Dissolution comparisons at:
- acid pH < 5 for 5–20 minutes
- near neutral pH 7.0 ± 0.5 for <5 minutes
- Whether the “bioavailability at least equivalent” standard can be met relative to an uncoated comparator.
What is the US regulatory and Orange Book relevance of US 6,106,861?
Core answer: Whether US 6,106,861 appears in the FDA Orange Book depends on whether it is listed for a specific approved NDA/ANDA and whether the formulation described corresponds to an approved product. Without the specific listed drug(s) and Orange Book entry(s), the practical Orange Book status (listed patent, expiration, exclusivity tie) cannot be stated from the provided information.
Key Takeaways
- US 6,106,861 is a tightly drafted formulation patent centered on multiparticulate fast-disintegrating tablets (<40 seconds) using microcrystals with taste-masking coatings made from polymethacrylates and/or cellulose polymers.
- The independent claim 1 is constrained by a specific excipient design: 3%–15% cross-linked PVP/CMC disintegrants plus 40%–90% polyol soluble diluents/binders selected from mannitol, xylitol, sorbitol, maltitol, with hard-defined particle-size categories and ratio/proviso logic between directly compressible and powder forms.
- Dependent claims narrow numerical ranges (claim 2, claim 3, claim 4), specify coating polymers (claim 5), add coating formulation adjuncts (claim 6), and impose performance-linked limitations on dissolution and comparative bioavailability (claims 7–10).
- A competitive design-around most effectively targets one or more of the claim’s “hard” constraints: excipient disintegrant class, polyol identity and particle-size/ratiometrics, or coating polymer class.
FAQs
1. Does US 6,106,861 require the tablet to be dissolvable in acid but not in near-neutral pH?
Yes. Claims 8–10 impose dissolution behavior in acid pH <5 over 5–20 minutes and reduced significant dissolution in pH 7.0 ± 0.5 over <5 minutes.
2. Can a formulation with the same active and disintegration time avoid infringement by changing polyol particle size?
It can. Claim 1 ties infringement to polyol presence in either “directly compressible form” (100–500 μm) or powder form (<100 μm) and to specific ratio/proviso rules.
3. Are HPMC and HPC explicitly covered for microcrystal taste masking?
Yes. Claim 5 lists HPMC and HPC (and cellulose acetophthalates) as coating agents.
4. Does the patent cover any active ingredient or only the listed drugs (paracetamol, ibuprofen, aspirin, ketoprofen, loperamide)?
Claim 1 covers “active ingredient” generally. Claims 11–12 list drug classes and specific exemplars, but they are dependent.
5. What is the most litigation-sensitive measurable parameter in claim 1?
The polyol system’s particle-size definitions and the directly compressible-to-powder ratio constraints, because they are explicitly numerically defined and tied to the proviso logic.
References (APA)
No external sources were cited because the prompt provided only the claim text and not the prosecution history, assignee, filing/publication identifiers, related family members, or Orange Book listings for specific products.
