Details for Patent: 5,855,912

US Patent 5,855,912: What is the scope of the claims and how strong is the patent landscape?

US Patent 5,855,912 covers solid oral unit dosage pharmaceutical compositions that combine a “piperidinoalkanol” compound of a specific Markush formula with specific excipient systems and granulation/blending process steps. The dominant claim architecture is (1) compound-as-a-variable-in-a-Markush structure for X (0 to 5) plus optical isomers, (2) excipient ranges for croscarmellose sodium (CCS) and common tableting excipients, and (3) manufacturing process steps defining a wet granulation/drying/milling route, with optional magnesium stearate and optional compression into tablets.

The practical scope is broad on the drug identity (as permitted by the Markush formula and “individual optical isomers”), and narrower on the formulation and process because CCS and cellulose/lactose/starch/gelatin (and sometimes magnesium stearate) are required.

What compounds does the patent cover (Markush scope)?

Across claims, the active ingredient is described as a “piperidinoalkanol compound” (or a pharmaceutically acceptable salt), where the compound is defined by a Markush structure:

• Formula includes X ranging from about 0 to 5
• “individual optical isomers thereof” are included
• “pharmaceutically acceptable salts” are included

Claims repeatedly tie X to specific dependent claim embodiments:

• Claims 15 to 25 are dedicated to “wherein X is zero”, each depending on earlier composition claims.

So the patent scope is:

• Drug identity: broad within the allowed structural class and stereochemistry (optical isomers included).
• Drug variants outside X 0..5 (if any exist) are outside scope.
• Salt forms are explicitly covered.

What excipient system is required (formulation scope)?

Core excipient package

Many claims require the following excipients in combination with the piperidinoalkanol:

• croscarmellose sodium (CCS)
• microcrystalline cellulose (MCC)
• lactose
• pregelatinized starch
• gelatin
  …and, in some claim sets, magnesium stearate.

Excipient content as ranges (broad formulation options)

Claim 7 defines composition ranges as follows (by weight):

• CCS: about 1% to about 10%
• MCC: about 20% to about 85%
• lactose: about 20% to about 85%
• pregelatinized starch: about 1% to about 30%
• gelatin: about 1% to about 15%

Claim 9 adds magnesium stearate with ranges:

• CCS: about 1% to about 10%
• MCC: about 20% to about 85%
• lactose: about 20% to about 85%
• pregelatinized starch: about 1% to about 30%
• gelatin: about 1% to about 15%
• magnesium stearate: about 0.05% to about 3.0%

Claim 12 defines ranges without gelatin but with magnesium stearate:

• CCS: about 1% to about 10%
• MCC: about 20% to about 85%
• pregelatinized starch: about 5% to about 50%
• magnesium stearate: about 0.05% to about 3%

These claim sets create a formulation landscape where the “required excipient set” depends on which independent claim tier is asserted:

• Tier A (claim 7): requires CCS + MCC + lactose + pregelatinized starch + gelatin (no magnesium stearate).
• Tier B (claim 9): same as Tier A plus magnesium stearate.
• Tier C (claim 12): requires CCS + MCC + pregelatinized starch + magnesium stearate (and omits gelatin and lactose as separate required excipients in that claim text).

Excipient content as specific embodiments (narrower but easy-to-infringe points)

Multiple dependent claims lock in specific weight percentages. Representative examples:

Claim 2 (a direct formulation embodiment of claim 1):

• MCC 33.8%
• lactose 33.8%
• pregelatinized starch 9.6%
• gelatin 3.5%
• CCS 4.8%

Claim 3:

• MCC 33.7%
• lactose 33.7%
• pregelatinized starch 9.6%
• gelatin 3.5%
• CCS 4.8%

Claim 6 (includes magnesium stearate):

• MCC 33.7%
• lactose 33.7%
• pregelatinized starch 9.6%
• gelatin 3.5%
• CCS 4.8%
• magnesium stearate 0.5%

Claim 8:

• CCS 4.8%
• MCC 33.8%
• lactose 33.8%
• pregelatinized starch 9.6%
• gelatin 3.5%

Claim 10:

• CCS 4.8%
• MCC 33.7%
• lactose 33.7%
• pregelatinized starch 9.6%
• gelatin 3.5%
• magnesium stearate 0.5%

Claim 11:

• CCS 4.8%
• MCC 25.7%
• lactose 25.7%
• pregelatinized starch 9.6%
• gelatin 3.5%
• magnesium stearate 0.75%

Claim 13 (tier C embodiment):

• CCS 6%
• MCC 33.3%
• pregelatinized starch 30%
• magnesium stearate 0.75%

Claim 14 (mirrors claim 2, but framed as dependent on claim 4):

• MCC 33.8%
• lactose 33.8%
• pregelatinized starch 9.6%
• gelatin 3.5%
• CCS 4.8%
• magnesium stearate 0.5%

These “exact-percentage” dependents are critical for infringement analysis because they provide specific numerical targets within the broader ranges.

What process steps define infringement for the solid unit dosage form claims?

Claims 1 and 4 are process-driven in addition to composition, using wet granulation and subsequent milling.

Process steps in claim 1

Claim 1 requires:

1. Blending a compound of the formula (X 0..5, optical isomers) with MCC, lactose, pregelatinized starch
2. Adding a solution of gelatin in water with mixing
3. Drying and milling the mixture
4. Adding croscarmellose sodium with mixing

Process steps in claim 4

Claim 4 has the same pattern but adds magnesium stearate and changes order:

1. Blend compound with MCC, lactose, pregelatinized starch
2. Add gelatin-in-water solution with mixing
3. Dry and mill the granulated mixture
4. Add CCS with mixing
5. Add magnesium stearate with mixing

Manufacturing format

Claim 5 and dependent claims link to end-form:

• Claim 5: “final mixture is pressed into tablets” (dependent on claim 4).

Claim 1 and 4 therefore create two layers of potential enforcement:

• Formulation layer (required excipients)
• Process layer (how gelatin is introduced, and when CCS and magnesium stearate are added, plus drying/milling)

How do the claim set’s independent anchors work (scope hierarchy)?

Independent anchors

• Claim 1: Process + excipient set (MCC/lactose/pregelatinized starch + gelatin-in-water addition + drying/milling + CCS addition) and includes the Markush compound.
• Claim 4: Same process theme with magnesium stearate addition and “granulated mixture” drying/milling.
• Claim 7: Composition definition with ranges and requires gelatin (no magnesium stearate required).
• Claim 9: Composition definition with ranges including magnesium stearate.
• Claim 12: Composition definition with ranges and includes magnesium stearate but omits gelatin and lactose as required excipients in the claim text.

Dependent chain to X = 0

Claims 15 to 25 specialize the compound definition to X=0 by explicitly depending on each earlier composition claim. This is a built-in design-around reducer because it creates a parallel infringement path even if the accused product targets a specific member of the Markush set.

Claim-by-claim scope map (practical infringement checklist)

What is the design space the claims implicitly leave open (non-infringement levers)?

Because the claim text locks in a specific excipient set and/or process steps, the main legal “escape hatches” are structural:

1. Remove one required excipient from the asserted claim tier.

   • For claims 1 and 7/9: gelatin and CCS and either lactose (claims 7/9) and/or pregelatinized starch are required by the claim text.
   • Claim 12 omits lactose and gelatin as required excipients (in its own structure), which means a product can still be evaluated under a different tier.

2. Alter magnesium stearate presence to avoid tiers that require it.

   • Claims 1/2/3/7 do not require magnesium stearate.
   • Claims 4/5/6 and claims 9/10/11 and claim 12/13 require it (with specific range language in the independent claims).

3. Change manufacturing steps only matters for the process-linked claims (1 and 4) but not for pure composition claims (7, 9, 12).

   • A product with same composition can still fall under independent composition claims even if made differently.

4. Change X outside 0..5 avoids the Markush scope across all claims where X is defined as 0..5.

Patent landscape: How does US 5,855,912 typically position against generics and follow-on formulation patents?

On a practical enforcement plane, US 5,855,912 is a formulation-and-process patent anchored on a specific class of actives (piperidinoalkanol with X 0..5) and a tablet-ready excipient package centered on CCS and a cellulose/lactose/starch matrix plus gelatin (in most tiers).

That positioning creates a landscape with three typical battleground types:

• Direct ANDA-style infringement: accused products matching excipient ranges and drug structure within X 0..5, including salt forms, can read onto claims 7 and 9 (composition range claims) without needing to match the process.
• Process-copy risk: even if a generic changes manufacturing steps, claims 1 and 4 can still matter if the excipient set and process steps are met. But litigation typically focuses first on composition overlap because it is easier to prove at the product level.
• Design-around formulation attempts: challengers often attempt to remove or reduce inclusion of required excipients (especially gelatin or CCS) or change Mg stearate inclusion to shift between claim tiers (7 vs 9 vs 12).

In-landscape implications of specific excipient targets

The exact embodiments (claims 2/3/6/8/10/11/13/14) form “pressure points” for both infringement and validity attacks. If a competitor’s approved product or development prototype uses those exact or near-exact percentages, the patent’s dependent claims can become high-probability assertion targets.

Key Takeaways

• US 5,855,912 protects solid oral unit dosage compositions containing a piperidinoalkanol defined by a Markush X=0..5 plus optical isomers and salts, combined with a tablet excipient system centered on MCC + lactose + pregelatinized starch, plus gelatin and CCS, with optional inclusion of magnesium stearate depending on claim tier.
• The independent claim set spans process-linked claims (1, 4) and composition-only claims (7, 9, 12). This matters because composition-only claims are not avoided by changing manufacturing route.
• The strongest “numerical” scope resides in dependents with exact weights (notably MCC 33.7-33.8%, lactose 33.7-33.8%, pregelatinized starch 9.6%, gelatin 3.5%, CCS 4.8%, plus Mg stearate 0.5% or 0.75%), and the separate tier CCS 6%, MCC 33.3%, starch 30%, Mg stearate 0.75%.
• The patent includes a dedicated X=0 claim series (15-25) that locks in one specific Markush member as a separate infringement path.
• The practical landscape risk for challengers is highest when an accused product matches both the active-class definition (X 0..5) and the excipient tier (gelatin/CCS presence and Mg stearate inclusion).

FAQs

1. Does US 5,855,912 require a specific tableting method?
   No for most claims; only claim 5 explicitly states the mixture is pressed into tablets (dependent on claim 4).

2. Can a product infringe without copying the manufacturing process?
   Yes. Claims 7, 9, and 12 are composition claims with excipient ranges and do not require the wet granulation steps.

3. Is gelatin required?
   Yes for claims 1, 2, 3, 7, 8, 9, 10, 11, 14. Claim 12 is a different formulation tier and does not require gelatin as written.

4. Is magnesium stearate required in all embodiments?
   No. It is not required for claim 7 (and its dependents), but it is required in claim 4/5/6 and claim 9/10/11, and in claim 12/13.

5. What is the active-ingredient scope limit?
   The piperidinoalkanol is defined with X ranging from about 0 to 5 plus individual optical isomers, and the patent also has explicit X=0 dependents.

References

[1] US Patent 5,855,912, “Pharmaceutical composition in solid unit dosage form,” claims 1-25.