Details for Patent: 6,117,894

Scope and claims of US Patent 6,117,894

US 6,117,894 claims pharmaceutical compositions and stabilized suspensions that combine (i) one or more actives defined by structural “formula (I)” and/or “formula (II)” and (ii) a “stability improving amount” of a pharmaceutically acceptable acid. The acid package is defined two ways:

1. Stabilization by acid identity (citric, glutamic, succinic, ethanesulfonic, acetic, tartaric, ascorbic, methanesulfonic, fumaric, adipic, malic; and mixtures).
2. Stabilization by acid amount/pH target (composition contacted with water to yield pH 2 to 6, with specific weight-ratio ranges of acid to composition in multiple dependent claims).

The claims also add formulation mechanics that constrain infringement to certain dosage forms and unit operations: solid dosage forms with granulated active particles (claim 7 et seq.), suspensions with granulated active particles (claim 10 et seq.), and a paste embodiment with wetting agent and thickener (claim 14 et seq.). There is also a specific suspension claim set focused on “stabilized pharmaceutical suspension” defined by active identity, liquid, and stabilizing pH range (claims 21–23). A related process claim states that the acid can be added during granulation (claim 24).

Claim-by-claim scope (what is actually protected)

Core composition concept (formula (II) + acid)

• Claim 1: A pharmaceutical composition with active agent = a compound of formula (II) plus a stability improving amount of a pharmaceutically acceptable acid.

  • Scope anchor: “formula (II)” is the essential active requirement; acid is required but not quantity-bound in claim 1 beyond functional “stability improving amount.”

• Claim 3: Formula (II) + citric acid.

• Claim 4: Formula (II) + ascorbic acid.

  • Scope anchor: narrows to specific acid species for formula (II) embodiment.

Breadth via “at least one compound selected from formula (I) and formula (II)” + acid

• Claim 2: Composition with active agent = at least one compound selected from:

  • a compound of formula (I) and
  • a compound of formula (II)
    plus a stability-improving amount of a pharmaceutically acceptable acid chosen from the enumerated list.
  • Scope anchor: allows either (I), (II), or both.

• Claim 9 and Claim 15: depend from claims in this family by selecting acid identity from the same enumerated list.

Acid amount and pH-mechanics for compositions contacted with water

• Claim 5: Composition with active agent = compound of formula (II) plus acid quantity such that when contacted with water:

  • pH is between 2 and 6
  • and the weight ratio of acid to pharmaceutical composition is 0.01 to 0.5.
  • Scope anchor: moves from functional “stability improving amount” to explicit acid quantity and pH.

• Claim 6: narrows ratio to 0.03 to 0.2.

• Claim 7: Composition with active agent = at least one of formula (I) and formula (II), plus acid quantity such that:

  • upon contact with water, pH 2 to 6
  • and the composition is a solid dosage form
  • and active particles are granulated in the presence of a granulating agent to form granulated active solid particles.
  • Scope anchor: locks infringement to (a) solid dosage form, (b) granulation, and (c) pH target on reconstitution/contact with water.

• Claim 9: selects acid identity from the enumerated list in the claim 7 context.

• Claim 10: Similar active set and pH-on-contact-with-water definition, but the composition is a suspension of solid particles in a liquid, where active particles are granulated prior to forming the suspension.

  • Scope anchor: suspension dosage form plus pre-suspension granulation.

• Claim 11: narrows liquid to water.

• Claim 12: Suspension of solid particles of formula (II) in a liquid with acid giving pH 2 to 6 (functional) where the suspension pH is within that range.

• Claim 13: narrows pH to 3 to 5.

Paste formulation with acid + wetting/thickener system

• Claim 14: Composition with active agent = at least one of formula (I) and formula (II) plus acid quantity such that contact with water yields:

  • pH 2 to 6
  • and the composition is a paste comprising:
    • active particles of at least one of formula (I) and formula (II)
    • a wetting agent
    • a thickener
  • Scope anchor: paste-specific composition architecture.

• Claim 15: selects acid from the enumerated list.

Particle size and granule composition constraints (solid/granulated embodiments)

• Claim 16: For the claim 7 solid/granulated embodiment where active agent is formula (I):

  • active particles prior to granulating: particle size < 200 μm
  • mean particle size: > 10 μm.

• Claim 17: narrows mean particle size to 10 to 100 μm.

• Claim 18: For the claim 7 solid/granulated embodiment where active agent is formula (I):

  • granulated active solid particles comprise:
    • 2 to 99.97% by weight active compound
    • 0.03 to 10% by weight granulating agent.

• Claim 19: For the claim 7 solid/granulated embodiment where active agent is formula (I):

  • granulated particles have acid/active (by weight) ratio 0.01 to 0.5.

• Claim 20: For a claim 7 solid/granulated embodiment where active agent is formula (I) and specific particle size distribution metrics:

  • active particles < 200 μm
  • < 10% particles > 100 μm
  • < 50% particles > 50 μm
  • < 10% particles < 5 μm

Granulating agent identity

• Claim 8: granulating agent selected from:
  • polyvinylpyrrolidone (PVP), water, alcohol, sucrose, hydroxy cellulose, or mixtures.

Stabilized suspension claims (different drafting, still acid + pH range)

• Claim 21: A stabilized pharmaceutical suspension containing:
  • active agent = at least one of formula (I) and formula (II)
  • a liquid
  • pharmaceutically acceptable acid in an amount sufficient to provide stabilizing pH:
    • 2.0 to 6.0.
• Claim 22: Same, but liquid specified as water.
• Claim 23: Narrowed to active agent = compound of formula (II) with liquid and acid giving:
  • stabilizing pH 2.0 to 6.0.

Process claim tied to acid addition during granulation

• Claim 24: Process as in claim 7 where at least one pharmaceutically acceptable acid is added during the granulation process.
  • Scope anchor: temporal placement of acid during manufacturing.

Key claim architecture and “what changes infringement risk”

1) Two distinct acid definitions: identity vs. quantity/pH-on-contact

• Some claims require acid identity selection from the listed acids (e.g., claim 2; and dependent identity claims 3–4, 9, 15).
• Others require explicit acid amount/ratio and functional pH outcome on contact with water (claim 5; and claim 7, claim 10).
• The stabilized suspension set (claims 21–23) is drafted around stabilizing pH 2.0 to 6.0, without requiring the explicit acid-to-composition weight ratio found in claim 5 and without necessarily requiring a “contact with water” mechanism.

Business implication: a design-around can target either the acid identity constraint or the pH window/acid ratio constraint, depending on which claim family is most relevant.

2) Formulation platform: solid/granulated vs suspension vs paste

• Solid dosage form + granulation is a gating limitation in claim 7 (and dependent claims 8, 16–20, etc.).
• Suspension dosage form is a gating limitation in claim 10 (and dependent claims 11–13).
• Paste is a gating limitation in claim 14.

Business implication: if competitors use the same acid/pH strategy but change dosage form and eliminate granulated active particles prior to suspension, they risk avoiding the dependent scope tied to claim 7/10 manufacturing structure.

3) Pre-granulation particle size and post-granulation composition ranges narrow coverage

• Particle size constraints (claims 16–17 and 20) apply to the claim 7 solid/granulated embodiment with formula (I).
• Granule composition ranges (claim 18) and acid/active ratio (claim 19) also narrow coverage.

Business implication: if an alternative manufacturing process changes granule size distribution or active/granulating agent ratios outside these ranges, it may exit the dependent claim coverage, though independent claim coverage still depends on whether the base claim limitations remain satisfied.

Patent landscape (US 6,117,894 scope-based map)

This response can only be as complete as the information provided. The user supplied the claims text but not bibliographic metadata, filing date, assignee, related families, cited references, or prosecution history. Under the constraint that incomplete information prevents a complete and accurate landscape, the landscape section below is limited to claim-driven competitive positioning derived directly from the claim set.

1) Where competitors are most exposed (highest-risk implementation features)

The most “litigation-ready” features are those that sit in multiple claim layers:

1. Use of a pharmaceutically acceptable acid selected from the enumerated list with the specified actives (formula (I) and/or formula (II)).
2. pH control to 2–6 when contacted with water for compositions (claims 5, 7, 10, 14).
3. Granulated active particles in solid dosage form and, separately, in suspensions (claims 7 and 10).
4. Specific granulating agent options for solid/granulated embodiments (claim 8).
5. Stabilized suspension pH 2.0–6.0 for suspension embodiments (claims 21–23).

If a product uses the same acid and reaches the same pH window under the same reconstitution conditions, it most directly tracks the independent claim language.

2) Where design-arounds can credibly reduce claim overlap (feature toggles)

Claim drafting suggests the following “toggles”:

• Eliminate granulation step described as required in claim 7 and claim 10 (or change it so active particles are not “granulated in the presence of” the specified granulating agent).
• Avoid the specific “contact with water yields pH 2–6” condition by changing reconstitution chemistry or by using a formulation environment where the claimed pH outcome is not met under “contact with water.”
• Use an acid outside the enumerated list if a targeted claim relies on acid identity (claims 2, 3, 4, 9, 15).
• For dependent narrowings, shift away from:
  • acid/active weight ratio bounds (claims 5, 6, 19)
  • granulating agent concentration bounds (claim 18)
  • pre-granulation or distribution metrics (claims 16–17, 20)
  • suspension pH sub-ranges (claim 13).

3) Claim set segmentation for freedom-to-operate triage

A practical triage divides the claims into four non-overlapping technical buckets:

Key Takeaways

• US 6,117,894 protects acid-stabilized pharmaceutical compositions using actives defined by formula (I) and/or formula (II), with stabilization achieved either by listed acid identities or by meeting a pH 2–6 target under contact with water (and for suspensions via stabilizing pH 2.0–6.0).
• The claims impose formulation-specific limitations: solid dosage forms with granulated active particles (claims 7–8, 16–20), suspensions with granulated active particles (claims 10–13), and paste compositions with wetting agent and thickener (claims 14–15).
• Dependent claims narrow further using acid/active weight ratios, granulating agent type, granule composition, and particle size distribution metrics.
• Process coverage exists via acid addition during granulation (claim 24), increasing manufacturing-related exposure.

FAQs

1) What is the single most important formulation parameter across the claim set?

pH 2 to 6, achieved either upon contact with water (claims 5, 7, 10, 14) or as the stabilizing pH of the suspension (claims 21–23).

2) Do the claims require a specific acid identity in all cases?

No. Some claims require acid identity from an enumerated list (e.g., claim 2 and acid-specific dependents like claims 3–4, 9, 15). Other claims focus on achieving the pH/ratio requirements (notably claim 5 and the pH-on-contact claims).

3) Is granulation required for all dosage forms?

No. Granulation is explicitly required for solid dosage forms (claim 7) and for suspensions of solid particles (claim 10) via pre-suspension granulated active particles. The paste claim (claim 14) does not state granulation as the gating limitation.

4) What acid/active ratio ranges appear in the claims?

• 0.01 to 0.5 for acid weight ratio to pharmaceutical composition in claim 5
• 0.03 to 0.2 in claim 6
• 0.01 to 0.5 for acid/active weight ratio in claim 19

5) Does the patent cover manufacturing steps?

Yes. Claim 24 covers a process where at least one pharmaceutically acceptable acid is added during the granulation process described in claim 7.

References

[1] US Patent 6,117,894. Claims text provided in prompt (claims 1-24).