Scope, Claim Strength, and U.S. Patent Landscape for US 6,024,981

US 6,024,981 claims hard, compressed tablets engineered for direct oral dosing that disintegrate in the mouth in ≤60 seconds (with dependent claim cutoffs at ≤90, ≤60, ≤45 seconds) while maintaining mechanical integrity (hardness ≥15 N, friability ≤2%, with dependent targets ≤1%). The claim architecture ties performance to specific formulation variables: non-direct compression filler, hydrophobic lubricant, rapidly water-soluble matrix content (≥60% of matrix), optional wicking agent, and optional particle/protective material to protect active ingredient.

What does US 6,024,981 claim in its core independent scope?

1. What is the independent composition claim and its performance envelope (Claims 1, 32)?

Claim 1 (hard, compressed, rapidly dissolvable dosage form) requires:

Dosage form type: “hard, compresed, rapidly dissolvable” for direct oral dosing
Composition:
- Active ingredient
- Matrix containing:
- non-direct compression filter (i.e., filler)
- lubricant
- Lubricant is further defined in dependent claims as hydrophobic lubricant (Claims 26-29)
Oral performance:
- “rapidly dissolve in the mouth” and liberate active ingredient
- Dissolution thresholds are made explicit through dependent claims (Claims 6-8)
Mechanical integrity:
- Friability about 2% or less (USP test)
- Hardness at least about 15 Newtons

Claim 32 (hard, compressed, rapidly dissolving tablet for direct oral dosing) adds a structured particle + matrix design:

Tablet matrix includes:
- non-direct compression filler
- wicking agent
- hydrophobic lubricant
Particles include:
- active ingredient + protective material
Quantitative constraints:
- Particles: 0.01 to 75 wt% of tablet (Claim 32)
- Matrix material: ≥60% rapidly water soluble ingredients
Performance:
- spontaneoulsy dissolve in mouth in <60 seconds and liberate particles
Mechanical integrity:
- hardness 15 to 50 N
- friability <2%
Storage: tablet “capable of being stored in bulk” (Claim 32)

Independent scope summary: The patent protects a formulation space defined by (i) disintegration speed in mouth, (ii) hardness and friability bounds, and (iii) a specific excipient system combining non-direct compression filler + (hydrophobic) lubricant, optionally wicking agent, and optionally protective particles.

2. How fast must the tablets dissolve and how is it layered across claims (Claims 6-8, 36)?

Dissolution speed is layered by dependent claim steps:

Claim	Dissolution limit	Applies to
Claim 6	about 90 seconds or less	Claim 1 base
Claim 7	about 60 seconds or less	Claim 1 base
Claim 8	about 45 seconds or less	Claim 1 base
Claim 36	less than about 45 seconds	Claim 32 base

This creates a graded infringement risk profile: a challenger must map the accused product to the exact dissolution timeframe selected by the asserted dependent claim.

3. What mechanical properties anchor the claim (hardness and friability)?

Across independent and dependent claims, the mechanical constraints are explicit:

Property	Primary limit	Dependent narrowing
Hardness	≥15 N (Claim 1)	15 to 50 N (Claim 32); 20-50 N (Claim 4); about 35 N (Claim 5); about 35 N (Claim 35)
Friability	about 2% or less (Claim 1)	≤1% (Claim 2, Claim 34); Claim 32: <2%

The patent uses a classic tablet-robustness approach: keep friability low while still driving fast mouth disintegration.

What formulation elements define the technical boundaries?

4. What is the role of “non-direct compression filler” in the claim system (Claims 1, 14-17, 33)?

The claims repeatedly require a non-direct compression filler (treated as a filler/excipient used to enable “direct compression” processing in the manufacturing method, while the filler itself is identified as “non-direct compression”).

Quantitative and particle-size constraints appear:

Presence in Claim 1 is structural: the matrix includes it.
Weight range (Claim 14): 25 to 95 wt%
Narrower ranges:
- Claim 15: 50 to 95 wt%
- Claim 16: 60 to 95 wt%
Material type (Claim 17): “non-direct compression sugar or non-direct compression sugar alcohol”
Particle size (Claim 33): average particle size ≤90 microns

These constraints matter for infringement analysis because they provide multiple numeric “switch points” that can be either met or missed depending on the excipient choice and grade.

5. How is the lubricant constrained and why is “hydrophobic lubricant” central (Claims 26-29, 32, 33)?

Lubricant is required in Claim 1 via “lubricant,” then narrowed to “hydrophobic lubricant”:

Claim 26: lubricant is hydrophobic lubricant
Claim 27: 1 to 5 wt%
Claim 28: 1 to 2.5 wt%
Claim 29: 1.5 to 2 wt%
Claim 32: matrix includes hydrophobic lubricant
Claim 33: lubricant 1.0 to 2.5 wt% (tablet basis)

The patent does not claim a single specific hydrophobic lubricant by name in the provided text. Still, the hydrophobicity requirement plus the narrow wt% ranges are likely to meaningfully reduce the practical filler/lubricant universe relative to generic fast-dissolving tablet disclosures.

6. Where do “wicking agent” and rapid water solubility thresholds land (Claims 30-31, 32, 33)?

Wicking agent appears as an additional element in Claim 32 and is constrained:

Claim 30: further comprising at least one wicking agent
Claim 31: wicking agent <5 wt%
Claim 33 (tighter): wicking agent 2 to 5 wt%

Rapidly water soluble ingredients are quantitatively defined:

Claim 32: tablet matrix has at least 60% rapidly water soluble ingredients based on total weight of matrix material

This is a key boundary: it pushes the claim away from formulations dominated by poorly soluble excipients, and toward fast-dissolution matrices.

What is protected about “particles” and “protective material” (Claims 3, 9-13, 24-25)?

7. What does the patent say about particles containing active ingredient and protective material (Claims 3, 9-13, 24-25)?

Claim 3 and Claim 32 both incorporate particles:

Particles include:
- active ingredient
- protective material
Particle wt%:
- Claim 3: 0.01 to 75 wt% of tablet
Protective material is defined by categories (Claim 10):
- “adsorbate, microgranule, a matrix or a coating”
Dependent coating specificity (Claims 11-13):
- coating (Claim 11)
- coating wt%:
- at least 5% (Claim 12)
- 5 to 75% (Claim 13)

Release profile:

Claim 24: particles can be “rapid release”
Claim 25: particles can be “sustained release”

Landscape implication: This claim structure covers not only “single-phase” fast-dissolving tablets, but also systems where active is protected and possibly released differently via particle engineering.

How broad is the claimed “active ingredient” universe (Claims 18-21)?

8. What actives are encompassed and how is loading constrained (Claims 18-21)?

Claim 18 expands actives broadly:

“systematically distributable pharmaceutical ingredients, vitamins, minerals and dietary supplements”
plus “non-systematically distributable pharmaceutical ingredients”

Claim 19 gives a long non-limiting drug class list (examples include antacids, analgesics, anti-inflammatories, antibiotics, antihistamines, beta blockers, etc.).

Loading is constrained quantitatively:

Claim 20: active ingredient >0 to 80 wt% of finished dosage form
Claim 21: active ingredient >0 to 60 wt%

This broad active scope combined with excipient constraints likely drives claim leverage for many formulations, provided performance thresholds and the filler/lubricant/wicking system are met.

What is the manufacturing and packaging scope (Claims 37-40)?

9. What does the method claim cover and what processing variants are captured (Claims 37-40)?

Claim 37 is a method of making a packaged orally disintegrable dosage form:

form mixture including:
- active ingredient
- matrix including:
  - non-direct compression filler
  - lubricant
compress to form hard, compressed, rapidly disintegrable dosage forms:
- hardness ≥15 N
- dissolve spontaneously in mouth <60 seconds
- liberate active ingredient
store tablets in bulk prior to packaging

Dependent packaging steps:

Claim 38: package in a lumen so there is at least one tablet per package
Claim 39: multiple tablets packaged in a single lumen of a single package
Claim 40: compressing step conducted using direct compression

Landscape implication: The method claim is not limited to a specific machine vendor. It focuses on ingredient selection (non-direct compression filler + lubricant), performance, and bulk storage before packaging.

Claim scope mapped to likely design-arounds

10. Where would competitors try to avoid infringement?

The claim set is unusually explicit in numeric boundaries. The most plausible avoidance routes are:

Change dissolution time target: avoid meeting the ≤60 s requirement tied to Claims 1 and 32, and/or the tighter ≤45 s thresholds.
Change mechanical spec:
- increase friability above 2% (or above 1% if a narrower dependent claim is asserted)
- reduce hardness below 15 N or adjust into/out of the 15-50 N dependent band.
Alter excipient identity and role:
- remove or replace the “non-direct compression filler” concept
- use a filler that does not fit “non-direct compression sugar/sugar alcohol” if a stricter dependent claim is asserted.
Alter hydrophobic lubricant system:
- use a lubricant not “hydrophobic”
- move outside the cited wt% bands (Claims 27-29 or 33).
Break the matrix solubility balance:
- keep matrix below ≥60% rapidly water soluble ingredients.
Remove wicking agent:
- if manufacturing uses Claim 32-dependent structure, omitting wicking agent can be a clear switch (Claim 32 includes it; Claim 1 does not).
Re-engineer particles:
- avoid particles with “protective material” in the claimed wt% and type categories.
Avoid direct compression (for method):
- if asserting Claim 40, avoid “direct compression” in manufacturing.

Relative strength inside the claim hierarchy

11. Which claims likely carry the most enforcement leverage?

Claim 1: broadest independent composition without the particle/protective material and without the wicking agent requirement. It anchors on the trio of: non-direct compression filler + lubricant, mouth dissolution ≤60 seconds (via dependent chain), and hardness and friability.
Claim 32: independent composition that adds particles + protective material and includes wicking agent plus a defined matrix solubility threshold (≥60% rapidly water soluble ingredients). It is narrower than Claim 1 but may be easier to tie to engineered particle systems.
Claim 37: method adds packaging and bulk storage and a performance requirement, plus direct compression as an extra narrowing step (Claim 40).

Inside Claim 1, dependent claims 2, 4, 5, 6-8 narrow quant specs, which can be used for both pleading and targeting product profiles.

U.S. patent landscape: how US 6,024,981 typically sits among fast-dissolving tablet art

12. What patent families and claim themes does this patent most closely overlap with?

Based on claim content alone (direct oral dosing; fast mouth disintegration; hardness/friability control; non-direct compression filler; hydrophobic lubricant; wicking agent; particles with protective coatings or microgranules), the landscape typically clusters around:

Orally disintegrating tablets (ODTs) and fast dissolving tablets:
- performance: dissolution/disintegration in mouth within ~45 to 90 seconds
- robustness: hardness and friability constraints
Direct compression formulations using fillers processed by other routes:
- “non-direct compression” excipients used to enable robust tablets made via direct compression
Matrix + lubricant + wicking agent combinations:
- hydrophobic lubricant to preserve tablet integrity
- wicking agent to accelerate water ingress
Protected active particles:
- adsorbate/microgranule/coating particles embedded in a rapidly dissolving tablet matrix
- fast vs sustained release via particle design

This matters for freedom-to-operate because many competitors can fall into one of two camps: (i) ODTs meeting dissolution speed but missing the non-direct compression filler/lubricant mechanical envelope, or (ii) tablets engineered for robustness but using different excipient logic.

What does the claim set mean for freedom-to-operate and competitive positioning?

13. Infringement mapping checklist

For any candidate product, the high-signal claim hooks to test are:

Dissolution time (≤60 seconds; also check ≤45 seconds if relevant)
Hardness (≥15 N; also check whether it falls inside 15-50 N if that independent is asserted)
Friability (≤2%; also check ≤1% where dependent claims apply)
Tablet composition architecture:
- presence of a non-direct compression filler in the claimed wt% region if dependent claims are asserted
- presence of a lubricant that is hydrophobic and within wt% bands
- matrix contains ≥60% rapidly water soluble ingredients
- optional presence of wicking agent with wt% limits
Particles:
- whether active is in particles with “protective material”
- whether protective material is a coating and within the claimed coating wt%
- whether particles are rapid or sustained release does not appear limited for infringement (Claims 24-25 are alternative dependent selections), but the particle presence is relevant.

14. Design-around strategy short list

The fastest-to-check design changes are those that shift the tablet out of numeric claim bands:

adjust dissolution profile away from ≤60 s (or ≤45 s)
adjust hardness and/or friability outside the USP ranges
swap out the hydrophobic lubricant system and/or its wt%
alter the filler grade or remove “non-direct compression sugar/sugar alcohol” characteristics
reduce rapidly water soluble ingredient fraction below 60% (matrix basis)
omit wicking agent (for Claim 32-based assertions)
avoid active-in-protective particles architecture (for Claim 32 and Claim 3-based assertions)
avoid direct compression steps (for method Claim 40-based assertions)

Key Takeaways

US 6,024,981 protects a specific ODT/fast-dissolving tablet engineering envelope combining speed (≤60 s) with robustness (hardness ≥15 N; friability ≤2%).
The claim set is built around a matrix excipient system: non-direct compression filler (often in high wt%), hydrophobic lubricant (narrow wt% bands), and optionally wicking agent.
The patent also covers particle-protected actives (adsorbate/microgranule/coating) embedded in the tablet, with release mode permitted (rapid or sustained).
The strongest leverage for enforcement typically comes from cases where a product matches the exact dissolution window and numeric mechanical specs, and uses the same excipient logic.
Competitors can design around by missing one of the required constraints: dissolution time, hardness/friability band, filler/lubricant identity and dosage, matrix solubility fraction, wicking agent presence, particle protective architecture, or direct compression in the method claim.

FAQs

Is the claim primarily about orally dissolvable tablets or protected particle actives?
It is about fast-dissolving tablets in general (Claim 1), with additional coverage for particle + protective material tablets (Claims 3 and 32).
What are the two most important performance metrics in US 6,024,981?
Mouth dissolution speed (with multiple dependent cutoffs down to ≤45 seconds) and mechanical integrity (hardness ≥15 N and friability ≤2%, with ≤1% narrowing).
Does the patent require wicking agent?
Claim 1 does not. Claim 32 does (and it constrains wicking agent to <5 wt% and also to 2-5 wt% in a dependent claim).
What excipient category is repeatedly required?
A non-direct compression filler within broad but claim-defined weight ranges, and often described as non-direct compression sugar or sugar alcohol.
What manufacturing steps are covered by the method claims?
Mixing active + matrix with the non-direct compression filler and lubricant, compressing into tablets with the hardness/dissolution requirements, storing in bulk before packaging, plus packaging format and optional direct compression.

References

[1] US 6,024,981 (claims provided in the prompt).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	6896998	⤷ Start Trial
Australia	726336	⤷ Start Trial
Canada	2284663	⤷ Start Trial
Denmark	2147669	⤷ Start Trial
Denmark	2266538	⤷ Start Trial
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Details for Patent: 6,024,981

Summary for Patent: 6,024,981