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Patent landscape, scope, and claims: |
United States Patent 6,797,732 (Entacapone + Levodopa/Carbidopa Stable Oral Solid Composition): Scope, Claim-by-Claim Coverage, and Patent Landscape
Executive summary: US Patent 6,797,732 claims a stable oral solid pharmaceutical composition containing entacapone + levodopa + carbidopa (or pharmaceutically acceptable salts/hydrates) with the critical limitation that the composition includes at least one pharmaceutically acceptable excipient other than microcrystalline cellulose. Dependent claims narrow the excipient system (no microcrystalline cellulose, tablet dosage form, no surface active agent, no silica, specific disintegrants, and specific sugar alcohol/hydrogenated vegetable oil excipients). In practice, the enforceable core is the combination of (i) the triple-actives and (ii) a non-MCC excipient architecture that supports stability in an oral solid format. A freedom-to-operate (FTO) design-around is feasible by changing excipient selection and/or dosage form, but the breadth of “stable” plus generic “pharmaceutically acceptable excipient” language creates litigation sensitivity around whether the formulation meets the stability and compositional thresholds.
What does US Patent 6,797,732 claim in entacapone/levodopa/carbidopa stable oral solids?
Short answer: It claims a tablet-form oral solid containing entacapone, levodopa, and carbidopa plus at least one excipient excluding microcrystalline cellulose (MCC), with stability as an express requirement.
Claim 1: independent claim scope (the “center of gravity”)
Claim 1 text (scope essentials):
- Stable oral solid composition
- Pharmacologically effective amounts of entacapone, levodopa, and carbidopa
- Active agents are either:
- the free forms, or
- pharmaceutically acceptable salts/hydrates
- Includes:
- at least one pharmaceutically acceptable excipient other than microcrystalline cellulose
Practical coverage implications
- Active combination lock: A product must include all three actives (entacapone + levodopa + carbidopa). Formulations with only two of the three do not fall within the claim.
- Oral solid lock: Coverage targets oral solid dosage forms (tablets implied by dependent claims but not limited to tablets in claim 1).
- Stability is an element: “Stable” is a substantive limitation. However, the claim does not specify the stability metric, storage conditions, or analytical thresholds. That ambiguity often becomes central in claim construction and infringement disputes (whether stability is inherent or must be proven for the accused product as formulated).
- Excipient architecture is the differentiator: The claim requires at least one excipient not MCC. It does not state that MCC is absent in claim 1; it only excludes a formulation where every excipient is MCC. Dependent claims 3 and 4 expressly exclude MCC.
Litigation posture
- If an accused product includes MCC among other excipients, claim 1 can still be implicated because claim 1 allows excipients other than MCC and requires only “at least one” such excipient.
- If an accused product uses only MCC as the excipient class (unlikely for practical tablets), it is designed to avoid claim 1 but could still be caught by dependent claims if other excipient elements exist.
Claim 2: tablet limitation
Claim 2 scope:
- Composition according to claim 1
- In the form of a tablet
This narrows to tablets. If a product is not a tablet (e.g., capsule, orally disintegrating film, multiparticulates in sachets), claim 2 does not apply, but claim 1 may still apply if the product remains an “oral solid.”
Claim 3 and 4: explicit “no microcrystalline cellulose”
Claim 3:
- Composition of claim 1
- Does not comprise microcrystalline cellulose
Claim 4:
- Composition of claim 2
- Does not comprise microcrystalline cellulose
Design-around relevance
- A formulation that includes MCC can still infringe claim 1 (if it has at least one excipient other than MCC), but it avoids claims 3 and 4.
- A formulation that avoids MCC entirely is at higher risk for claims 3/4 if it still satisfies the triple-actives + stability requirements.
Claim 5: excipient other than a surface active agent
Claim 5 scope:
- Composition according to claim 1
- Includes at least one excipient other than a surface active agent
This implies that surface-active agents may be present, but at least one non-surfactant excipient must exist. Since most tablet excipient blends include non-surfactant ingredients, this is typically a low barrier.
Design-around relevance
- Only a formulation using exclusively surface active agents as excipients (practically implausible) could attempt to avoid claim 5.
Claim 6: excipient other than silica
Claim 6 scope:
- Includes at least one excipient other than silica
Similar to claim 5, most formulations contain multiple excipient classes. Avoiding silica entirely or ensuring at least one non-silica excipient is common.
Claim 7–8: disintegrant limitation with specific species
Claim 7 scope:
- Composition according to claim 1
- Comprises a disintegrant as the excipient
Claim 8 scope (tightening):
- Disintegrant is sodium starch glycolate or croscarmellose sodium
Design-around relevance
- If the accused product uses a disintegrant other than these two (e.g., crospovidone, PVPP, pregelatinized starch not in the asserted categories), it may avoid claim 8 while still falling under claim 7 if any disintegrant exists (claim 7 is broader).
- If the accused product avoids adding a disintegrant (instead using alternate mechanisms like polymer swelling or manufacturing-driven disintegration), it may avoid both claim 7 and 8.
Claim 9: sugar alcohol excipient
Claim 9 scope:
- Includes a sugar alcohol as an excipient
Sugar alcohol candidates include sorbitol, mannitol, maltitol, xylitol (the claim does not specify which one). Many tablet formulations use mannitol or sorbitol.
Claim 10: hydrogenated vegetable oil excipient
Claim 10 scope:
- Includes hydrogenated vegetable oil as an excipient
This maps to a specific excipient class (e.g., hydrogenated castor oil is a common example). If a formulation uses alternative lubricants/binders without hydrogenated vegetable oil, it may avoid claim 10.
How broad is the claim set: product-structure vs excipient-by-excipient coverage?
Key breadth drivers
- Independent claim 1 is broad at the ingredient level (triple actives), and medium-to-broad at the excipient level (at least one excipient not MCC).
- The dependent claims narrow excipient content or the presence/absence of specific excipients (MCC exclusion, disintegrant identity, sugar alcohol, hydrogenated vegetable oil, silica/surfactant exclusions as “at least one other excipient” constraints).
Coverage matrix by limitation
| Claim |
Must contain actives (entacapone + levodopa + carbidopa) |
Must be oral solid |
Must be tablet |
MCC excluded |
Disintegrant specified |
Sugar alcohol included |
Hydrogenated vegetable oil included |
Other excipient carveouts |
| 1 |
Yes |
Yes |
No |
Not necessarily |
No |
No |
No |
At least one excipient other than MCC |
| 2 |
Yes |
Yes |
Yes |
Not necessarily |
No |
No |
No |
None beyond claim 1 |
| 3 |
Yes |
Yes |
No |
Yes |
No |
No |
No |
MCC absent |
| 4 |
Yes |
Yes |
Yes |
Yes |
No |
No |
No |
MCC absent + tablet |
| 5 |
Yes |
Yes |
No |
Not necessarily |
No |
No |
No |
At least one excipient other than surface active agent |
| 6 |
Yes |
Yes |
No |
Not necessarily |
No |
No |
No |
At least one excipient other than silica |
| 7 |
Yes |
Yes |
No |
Not necessarily |
Yes (any) |
No |
No |
Disintegrant present |
| 8 |
Yes |
Yes |
No |
Not necessarily |
Yes (Na starch glycolate or croscarmellose Na) |
No |
No |
Disintegrant identity limited |
| 9 |
Yes |
Yes |
No |
Not necessarily |
No |
Yes |
No |
Sugar alcohol present |
| 10 |
Yes |
Yes |
No |
Not necessarily |
No |
No |
Yes |
Hydrogenated vegetable oil present |
What patents protect entacapone + levodopa + carbidopa oral solid stability in the US around US 6,797,732?
Short answer: US 6,797,732 is a formulation/excipient-stability patent focused on triple-actives and a specific excipient exclusion strategy (non-MCC architecture; dependent exclusions for MCC, silica, and surface active agents; plus specific excipient selections like sodium starch glycolate/croscarmellose and hydrogenated vegetable oil).
Where this typically fits in a competitive estate
In US Parkinson’s drug combinations involving levodopa and carbidopa, the most common patent layers around combination products include:
- Composition of matter (rarely on the actives because entacapone and levodopa/carbidopa actives typically have their own earlier patents),
- Formulation patents (stability, excipients, manufacturing/process),
- Method-of-use patents (dose regimens, patient subsets),
- Crystalline form/polymorph patents (more common in APIs than fixed-dose combinations),
- Manufacturing/process patents (mixing/granulation steps, moisture control, scale-up),
- Device-related patents (less likely here given oral solid).
US 6,797,732 aligns most strongly with fixed-dose combination formulation IP.
How strong is the patent estate for US 6,797,732: what claim elements create infringement and validity pressure?
Infringement pressure points
- Triple-active requirement: Strongly narrows accused products. Many generic candidates may exist for the individual components or other combinations, but infringement depends on the same all-three active fixed-dose oral solid.
- Stability limitation: “Stable” is often litigated. If the accused formulation is shown to meet the patent’s stability rationale, that tends to help infringement arguments.
- Excipient boundary: The independent claim is triggered by inclusion of at least one excipient other than MCC. Since many tablet excipient blends include disintegrants, binders, lubricants, or coatings, the “other than MCC” requirement is frequently satisfied.
- Dependent claims add specific excipient selections: These are easier for an accused party to design around by selecting alternative excipients, unless the substitute excipient still maps into the “present” or “at least one excipient other than X” language.
Validity pressure points (claim construction and patentability)
- “Stable” indefiniteness risk can appear, but courts often interpret functional stability language as a claim scope interpretation rather than a strict indefiniteness bar if the spec provides guidance.
- Obviousness: Excipient substitutions and stability-improving formulation strategies are often argued as routine skill, especially if similar triple-actives formulations existed.
- Enablement: Depends on whether the specification provides detailed embodiments and whether the claim breadth covers formulations across excipient classes without sufficient disclosure.
(These are typical pressure points; a full strength assessment requires the patent’s specification and the prosecution history, not provided here.)
When does US 6,797,732 lose exclusivity for generics: patent term end vs regulatory exclusivity?
Short answer: Without the actual filing date, priority date, and any PTA/adjustments for US 6,797,732, a precise term-expiration calculation cannot be made from the claim text alone.
What matters for exclusivity analysis
- Patent term: 20 years from earliest effective nonprovisional filing date is the baseline, with potential Patent Term Adjustment (PTA) and any terminal disclaimer effects.
- Regulatory exclusivity: Fixed-dose combination products can have data exclusivity or market exclusivity depending on FDA approval pathway, supplement type, and whether it is a new molecular entity or new clinical investigation route. Those periods are independent of the patent and can delay generic entry even after patent expiration.
No FDA regulatory data are provided here; exclusivity timing must be derived from FDA records and the patent’s term specifics.
What Orange Book status issues exist for entacapone/levodopa/carbidopa combinations under US 6,797,732?
Short answer: Orange Book status is not determinable from the claim text provided. Determining listing status requires the FDA application’s Orange Book entry that corresponds to the drug product containing entacapone with levodopa/carbidopa in an oral solid.
What to look for in Orange Book (for this claim type)
- Patent listed for the specific dosage form (tablet vs other oral solid forms).
- Patents listed for method-of-use or formulation. This patent is formulation-driven; the listing would typically map to a particular NDA.
- Whether it lists for multiple strengths or a specific strength only.
- Any expiration date listed by FDA and whether it differs from calendar-based term due to adjustments.
Could a generic launch avoid infringement of US 6,797,732 using different excipients or dosage forms?
Short answer: Yes, design-around strategies often target the dependent claim boundaries first (MCC absence, disintegrant identity, sugar alcohol selection, hydrogenated vegetable oil inclusion), but claim 1 remains a general risk if the formulation is still a stable oral solid with the triple-actives and includes any excipient other than MCC.
Practical design-around routes (by claim element)
- Change disintegrant species
- Avoid sodium starch glycolate and croscarmellose sodium to target claim 8.
- Avoid adding a disintegrant as an excipient
- Target claim 7, though formulation feasibility depends on tablet disintegration mechanics.
- Avoid sugar alcohol
- Target claim 9 by selecting alternative excipients for tonicity and compression properties.
- Avoid hydrogenated vegetable oil
- Target claim 10 by selecting a different lubricant/binder system.
- Include microcrystalline cellulose (MCC)
- To avoid claims 3 and 4, include MCC in the tablet. But that may still leave exposure under claim 1 unless the formulation can be engineered so it does not include “at least one excipient other than MCC” (highly impractical).
Dosage form strategy
- If a product is not a tablet, it can target the dependent tablet claims (2 and 4) while still facing claim 1 if it remains an oral solid.
What Paragraph IV challenge profile fits US 6,797,732?
Short answer: A Paragraph IV certification against a formulation patent like US 6,797,732 would most often hinge on either:
- non-infringement based on excipient composition (MCC presence, disintegrant species, absence of sugar alcohol or hydrogenated vegetable oil),
- or invalidity based on anticipation/obviousness over prior fixed-dose combination formulations.
The strongest non-infringement cases for this claim family generally come from:
- including MCC to avoid the “does not comprise MCC” limitations, and/or
- using disintegrant systems not covered by claim 8 and potentially avoiding “disintegrant” entirely.
A full Paragraph IV profile requires known FDA ANDA defendants, lawsuit dockets, and settlement details, which are not included in the prompt.
What specific excipient changes would most reduce infringement risk vs US 6,797,732?
Short answer: The highest-yield excipient changes are those that control the presence/absence of MCC, the disintegrant identity, and the inclusion of sugar alcohol and hydrogenated vegetable oil.
Candidate “risk reducers” mapped to dependent claims
- Add MCC → reduces risk for claims 3 and 4.
- Use disintegrant other than sodium starch glycolate/croscarmellose sodium → reduces risk for claim 8.
- Avoid including any disintegrant (formulation redesign) → reduces risk for claim 7.
- No sugar alcohol → reduces risk for claim 9.
- No hydrogenated vegetable oil → reduces risk for claim 10.
Claim 1 still remains a baseline risk as long as the product is a stable oral solid with the triple actives and has at least one excipient other than MCC (which is typical).
Key Takeaways
- US 6,797,732 is an oral solid fixed-dose formulation patent covering entacapone + levodopa + carbidopa plus stability, with the excipient axis anchored on “at least one excipient other than microcrystalline cellulose.”
- Dependent claims create targeted barriers: no MCC, tablet form, excipient exclusion constraints (surface active agent, silica), and specific formulation elements (sodium starch glycolate/croscarmellose sodium, sugar alcohol, hydrogenated vegetable oil).
- For generic or reformulation strategies, the most effective non-infringement levers are MCC inclusion (to escape MCC-absent dependent claims), disintegrant substitution (to escape claim 8), and removal of sugar alcohol and hydrogenated vegetable oil (to escape claims 9 and 10).
- Claim 1’s “stable” requirement and the broad “pharmaceutically acceptable excipient other than MCC” language keep the independent-claim risk materially relevant even when dependent-claim-specific excipient choices are altered.
- Patent-term and Orange Book exclusivity dates cannot be derived from the claim text alone.
FAQs
-
Does US 6,797,732 cover capsules or only tablets?
Claim 2 is tablet-specific, but claim 1 covers an “oral solid composition” generally; product form matters for dependent claims.
-
If my formulation includes microcrystalline cellulose, do I avoid infringement?
You may avoid claims 3 and 4 (MCC absent), but claim 1 can still be implicated if the product has the triple actives, is stable, and includes at least one excipient other than MCC.
-
Which excipient choice most directly impacts infringement under claim 8?
The disintegrant identity. Claim 8 is limited to sodium starch glycolate or croscarmellose sodium.
-
Is “stability” defined in the claims of US 6,797,732?
No. The claims include “stable” as an element but do not specify a stability metric in the claim language provided.
-
Can a generic avoid this patent by using only two of the three actives?
No. The independent claim requires pharmacologically effective amounts of entacapone, levodopa, and carbidopa together.
References
- US Patent 6,797,732, “Stable oral solid composition comprising entacapone, levodopa, and carbidopa.” (Claims provided in prompt).
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