United States Patent 5,112,861 (Parkinson’s): Claim Scope, Treatment Coverage, and Landscape Map
US Drug Patent 5,112,861 is directed to methods of treating Parkinson’s disease by giving (i) a catechol-O-methyltransferase (COMT) inhibiting amount of a specified set of chemical compounds and (ii) a sufficient amount of levodopa. Dependent claims add peripheral decarboxylase inhibition (carbidopa or benzerazide), which targets early dopamine formation outside the brain.
What is the core independent-claim structure (method + levodopa + COMT inhibitor)?
The patent has three independent method claims: claims 1, 9, and 13. They share a single therapeutic architecture:
- Identify a Parkinson’s patient in need of treatment
- Administer a COMT-inhibiting amount of a specified compound (generic formula in claim 1; two narrower single-compound selections in claims 9 and 13)
- Administer levodopa at a “sufficient amount” to treat Parkinson’s disease
Claim 1: Broad formula-based coverage (COMT inhibitor class + levodopa)
Claim 1 recites a method using a compound having formula I with structural variables:
The dependent claims (2-5) tightly narrow this same formula framework around nitro vs cyano and around R4/R5 substitution choices.
Claim 9: Fixed COMT inhibitor identity + levodopa
Claim 9 specifies:
- COMT inhibitor: 3-(3,4-dihydroxy-5-nitrobenzylidene)-2,4-pentanedione
- Plus levodopa sufficient to treat Parkinson’s disease
Claim 13: Another fixed COMT inhibitor identity + levodopa
Claim 13 specifies:
- COMT inhibitor: N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide
- Plus levodopa sufficient to treat Parkinson’s disease
What does the claim add when you apply the dependent constraints (nitro, R-group narrowing, decarboxylase inhibitors)?
Nitro-focused narrowing (claim 2)
This fixes the formula-level selection to nitro rather than cyano for that variable.
R4 and R5 substitution constraints (claims 3-5)
- Claim 3: “R4 and R5 are both alkylcarbonyl of 2 to 3 carbon atoms.”
- Claim 4: “R4 represents cyano and R5 represents carbamoyl …”
- Claim 5: “R5 is carbamoyl substituted with methyl, ethyl, isopropyl or hydroxypropyl.”
These dependent claims do not change the therapeutic mechanism (still COMT inhibition + levodopa), but they enforce specific substitution patterns that narrow the covered chemical variants.
Peripheral decarboxylase inhibitor additions (claims 6-8, 10-12, 14-16)
The dependent claims add a second pharmacologic axis that is standard in levodopa therapy: blocking peripheral decarboxylation so that more levodopa reaches the brain.
- Claim 6: method of claim 1 further comprises a peripheral decarboxylase inhibitor
- Claim 7: peripheral decarboxylase inhibitor is carbidopa
- Claim 8: peripheral decarboxylase inhibitor is benzerazide
Corresponding dependent chains exist for claims 9 and 13:
- Claims 10-12: add peripheral decarboxylase inhibitor to claim 9; specify carbidopa (claim 11) or benzerazide (claim 12)
- Claims 14-16: add peripheral decarboxylase inhibitor to claim 13; specify carbidopa (claim 15) or benzerazide (claim 16)
Which chemical substitutions define the COMT inhibitor boundary?
For infringement and freedom-to-operate, the relevant boundary is not “any COMT inhibitor.” The claims require COMT-inhibiting amounts of compounds that fall within the claim’s structural definitions.
Key “hard” structural requirements (claim 1)
The formula I structure is constrained by:
- presence of a variable X = nitro or cyano
- presence of R3 fragment that includes:
- R4 = cyano or alkylcarbonyl (2-5 carbons)
- R5 = cyano and/or carbamoyl where:
- carbamoyl can be unsubstituted or substituted with:
- alkyl (C1-C8) or hydroxyalkyl (C1-C8)
Key “soft” dosing requirement
Even within the structural boundary, the claim uses functional language:
- “a catechol-O-methyl-transferase inhibiting amount”
- “a sufficient amount of levodopa”
- for dependent claims: a “sufficient amount” of peripheral decarboxylase inhibitor
In practice, the dosing language can read broadly to many schedules and formulations, but it still anchors infringement to the specific compound identity/structure.
What is the effective treatment scope?
Across claims, the medical intent and target are the same:
- Indication: Parkinson’s disease
- Patient type: “a patient in need of such treatment”
- Combination: COMT inhibitor + levodopa
- Optional extension: add peripheral decarboxylase inhibitor (carbidopa or benzerazide)
This produces a treatment “coverage lattice”:
Coverage matrix (what the claims require)
| Claim group |
COMT inhibitor requirement |
Levodopa requirement |
Peripheral decarboxylase inhibitor requirement |
| Claim 1 |
Compound formula I (R1/R2/X/R3-R4-R5 variables) |
Required |
Not required (optional via dependent claims) |
| Claim 9 |
Exact compound: 3-(3,4-dihydroxy-5-nitrobenzylidene)-2,4-pentanedione |
Required |
Not required (optional via dependent claims) |
| Claim 13 |
Exact compound: N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide |
Required |
Not required (optional via dependent claims) |
| Claims 6-8, 10-12, 14-16 |
Same as respective independent claim |
Required |
Required in those dependent claims, with carbidopa or benzerazide |
How narrow are claims 9 and 13 compared to claim 1?
Claims 9 and 13 are narrower on the chemical axis:
- Claim 9 locks COMT inhibitor to a single structure: a benzylidene-2,4-pentanedione with 3,4-dihydroxy-5-nitro substitution.
- Claim 13 locks COMT inhibitor to a single structure: an acrylamide with:
- N,N-diethyl
- 2-cyano
- aromatic ring with 3,4-dihydroxy-5-nitro
By contrast, claim 1 creates a broader perimeter through a general formula with multiple variable substitution options.
What are the key infringement-relevant “combination” elements?
For method claims of this format, all required steps must be practiced:
- Administration of the claimed COMT inhibitor in a quantity that inhibits COMT
- Administration of levodopa sufficient to treat Parkinson’s
- For dependent claims: administration of a peripheral decarboxylase inhibitor (carbidopa or benzerazide)
So infringement risk is driven by:
- whether the COMT inhibitor used falls within the formula I definitions (claim 1) or matches the exact structures (claims 9 and 13), and
- whether the clinician/product uses it in a levodopa treatment regimen.
How do these claims map to the broader Parkinson’s combo strategy used in practice?
The claims align to two established pillars:
- COMT inhibition to reduce peripheral breakdown of levodopa
- Peripheral decarboxylase inhibition to reduce early conversion of levodopa to dopamine outside the brain
Within this patent, the novelty is framed as the specific COMT inhibitor structures used in combination with levodopa, with optional addition of carbidopa/benzerazide.
What does the patent landscape likely look like around US 5,112,861 (strategic positioning)?
The relevant landscape elements for business decisions are:
- Prior art: earlier disclosures of COMT inhibition in levodopa-treated Parkinson’s
- Adjacent chemical space: COMT inhibitor analogs structurally close to the formula I population
- Formulation/brand: method-of-treatment claims like this typically leave room for label and formulation carve-outs, but still constrain product combinations.
Because the user supplied only the claim text and not the patent’s bibliographic data (filing date, assignee, specification details) or prosecution history, an “exhaustive” citation-level landscape cannot be produced without adding non-claim-specific assertions. The actionable conclusions below therefore focus on claim-driven landscape boundaries rather than asserting unknown filing dates or citing non-provided documents.
Landscape boundaries imposed by claim drafting
- A product using levodopa + a non-covered COMT inhibitor does not meet the COMT inhibitor element.
- A product using one of the covered COMT inhibitors but without levodopa also does not meet the method-of-treatment combination element.
- Even with the correct COMT inhibitor identity, the dependent claims further narrow if the therapy includes carbidopa or benzerazide.
Scope risks and design-around levers
Primary scope risks
- Any development program using levodopa co-therapy with a compound matching claim 1’s formula I is exposed.
- Any program using the exact compounds named in claims 9 or 13 is exposed even if the program does not aim at the broader formula scope.
Design-around levers (claim-structure-based)
- Chemical structure: shift outside the formula I variable set (R1/R2/X/R3 with R4/R5 rules) and avoid literal match to claims 9 and 13.
- Combination choice: avoid administering the covered COMT inhibitor with levodopa (though this is clinically uncommon for COMT inhibitors intended for levodopa potentiation).
- Peripheral decarboxylase inhibitor: this affects dependent claims only. The independent claims (1/9/13) can still be implicated if levodopa + the covered COMT inhibitor are used without carbidopa/benzerazide. Still, carbidopa/benzerazide inclusion can heighten multi-claim exposure.
What is not covered (negative scope signals embedded in the claims)?
- The claims do not cover:
- treatment without levodopa
- COMT inhibition alone not tied to Parkinson’s levodopa therapy
- peripheral decarboxylase inhibitor alone without the COMT inhibitor element (in these dependent claims)
Operating summary for investors and R&D leaders
US 5,112,861 is not a broad “COMT inhibitor for Parkinson’s” patent. It is a method-of-treatment patent that requires:
- COMT-inhibiting amounts of a specific chemical class (formula I) or two specific compounds
- administered together with levodopa
- with optional dependent claim coverage adding carbidopa or benzerazide.
That structure makes the patent’s enforceability and value highly sensitive to chemical identity and combination use.
Key Takeaways
- The independent claims (1, 9, 13) require COMT inhibitor + levodopa for Parkinson’s disease, with claim 1 covering a formula I chemical class and claims 9/13 covering two exact structures.
- Dependent claims (2-5) narrow the formula by fixing X (nitro) and substitution patterns on R4/R5.
- Dependent claims (6-8, 10-12, 14-16) add peripheral decarboxylase inhibitors, specifically carbidopa or benzerazide, but those are additive requirements to dependent coverage, not substitutes for the levodopa + COMT inhibitor core.
- Scope is determined primarily by whether the COMT inhibitor matches the formula/structures, and secondarily by whether it is administered in a levodopa regimen.
FAQs
1) Does US 5,112,861 cover Parkinson’s treatment with levodopa alone?
No. The claims require a COMT-inhibiting amount of the specified compound(s) in addition to levodopa.
2) Are carbidopa or benzerazide required for all claim coverage?
No. They are required only for the dependent claims that explicitly add a peripheral decarboxylase inhibitor.
3) What is the broadest chemical coverage in the patent?
Claim 1 via formula I with variable R1/R2, X, and R3-substituent constraints for R4 and R5.
4) How much narrower are claims 9 and 13?
They are narrower because each specifies a single exact COMT inhibitor structure rather than the broader formula I population.
5) What is the key infringement hook for method-of-treatment claims?
Administering the claimed COMT inhibitor in a COMT-inhibiting amount and administering levodopa to a Parkinson’s patient (with dependent claims adding carbidopa/benzerazide).
References
[1] US Patent 5,112,861. Claims 1-16 (method for treatment of Parkinson’s disease using COMT-inhibiting compounds and levodopa; dependent claims include peripheral decarboxylase inhibitors such as carbidopa and benzerazide).
