US Patent 4,963,590: Scope, Claims, Expiration, and COMT-Inhibitor Patent Landscape
US Patent 4,963,590 covers pharmaceutical compositions and treatment methods using nitrocatechol and cyanocatechol compounds that inhibit catechol-O-methyltransferase, or COMT. Its broadest claims are genus claims directed to substituted benzylidene compounds. The patent also claims two specifically identified compounds: 3-(3,4-dihydroxy-5-nitrobenzylidene)-2,4-pentanedione and N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide.
The patent issued on October 16, 1990. Its enforceable US term has expired. It does not create a current US blocking right for generic or follow-on development, although later patents covering particular COMT inhibitors, formulations, dosing regimens, manufacturing processes, or combinations may still be relevant.
What does US Patent 4,963,590 cover?
The patent covers two legal categories:
- Pharmaceutical compositions containing a COMT-inhibiting compound and a pharmaceutically acceptable carrier.
- Methods of inhibiting COMT by administering a claimed compound to a patient.
The central chemical structure is a substituted catechol attached to an activated olefinic or carbonyl-containing group. The claimed compounds contain:
- A 3,4-dihydroxyphenyl, or catechol, nucleus.
- A nitro or cyano substituent on the aromatic ring.
- An olefinic side chain represented by R3.
- Optional acyl protection of one or both catechol hydroxyl groups through R1 and R2.
- Cyano, acyl, ester, or carbamoyl substitution on the side chain.
The patent is directed to reversible COMT inhibition. COMT inhibition reduces methylation of catechol substrates, including levodopa-derived catechol compounds. In Parkinson's disease therapy, that mechanism can increase the fraction of levodopa available for conversion to dopamine when used with levodopa and a dopa-decarboxylase inhibitor.
How are the claims structured?
Claim architecture
| Claim |
Type |
Scope |
| 1 |
Composition |
Broad Markush genus of COMT-inhibiting compounds with a pharmaceutical carrier |
| 2 |
Composition |
Claim 1 limited to nitro substitution |
| 3 |
Composition |
Claim 1 limited to two acyl-substituted side-chain groups |
| 4 |
Composition |
Specific 3-(3,4-dihydroxy-5-nitrobenzylidene)-2,4-pentanedione compound |
| 5 |
Composition |
Claim 1 limited to cyano plus carbamoyl substitution |
| 6 |
Composition |
Claim 5 limited to methyl, ethyl, isopropyl, or hydroxypropyl carbamoyl substitution |
| 7 |
Composition |
Specific N,N-diethyl acrylamide compound |
| 8 |
Method |
Broad method genus corresponding to claim 1 |
| 9 |
Method |
Claim 8 limited to nitro substitution |
| 10 |
Method |
Claim 8 limited to two acyl-substituted side-chain groups |
| 11 |
Method |
Specific benzylidene-2,4-pentanedione compound |
| 12 |
Method |
Claim 8 limited to cyano plus carbamoyl substitution |
| 13 |
Method |
Claim 12 limited to specified carbamoyl substituents |
| 14 |
Method |
Specific N,N-diethyl acrylamide compound |
Claims 1 and 8 are the principal genus claims. Claims 4, 7, 11, and 14 are the principal species claims.
What chemical subject matter is covered by claim 1?
Claim 1 requires all of the following:
- A pharmaceutical composition.
- A compound present in an amount capable of inhibiting COMT.
- The claimed compound having formula I.
- R1 and R2 independently being hydrogen or an alkylcarbonyl group containing two to five carbon atoms.
- X being nitro or cyano.
- R3 being the specified substituted olefinic group.
- A pharmaceutically acceptable carrier.
The R1 and R2 limitations permit either free catechol hydroxyl groups or acylated hydroxyl groups. The acyl groups fall within the C2-C5 range, which includes acetyl and higher homologous acyl substituents.
The X limitation divides the genus into two important chemical families:
- Nitro-substituted catechols.
- Cyano-substituted catechols.
The R4 and R5 limitations cover multiple activated side-chain groups, including:
- Cyano groups.
- C2-C5 alkylcarbonyl groups.
- C2-C9 alkoxycarbonyl groups.
- Unsubstituted carbamoyl groups.
- Carbamoyl groups substituted with C1-C8 alkyl or hydroxyalkyl groups.
The claim therefore reaches beyond one marketed or development-stage molecule. It is a structure-based genus claim covering multiple substitution patterns around a nitrocatechol or cyanocatechol pharmacophore.
What compounds are specifically claimed?
3-(3,4-Dihydroxy-5-nitrobenzylidene)-2,4-pentanedione
Claims 4 and 11 specifically cover this compound in composition and method form.
The structure has:
- A 3,4-dihydroxy-5-nitrophenyl ring.
- A benzylidene linkage.
- A 2,4-pentanedione side chain.
- Two free catechol hydroxyl groups.
- A nitro group at the 5-position.
This compound is commonly associated with nitecapone, also known as OR-462, a COMT inhibitor investigated by Orion. The patent claims the molecule without limiting the claim to a particular dosage form, salt, tablet, capsule, route of administration, or Parkinson's disease indication.
N,N-Diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide
Claims 7 and 14 specifically cover this compound.
Its structure contains:
- A 3,4-dihydroxy-5-nitrophenyl group.
- A cyano-substituted acrylamide side chain.
- An N,N-diethyl carbamoyl group.
- Free catechol hydroxyl groups.
This compound is associated with the COMT inhibitor nebicapone, also known as BIA 3-202, which was developed by BIAL and later investigated with partners including Merck. The compound-specific claims are narrower than the genus claims but provide a clearer infringement analysis for the named molecule.
How broad are the composition claims?
Claim 1 is broad in chemical coverage but narrow in claim format because it requires a pharmaceutical composition containing the compound and a pharmaceutically acceptable carrier.
A drug substance sold as a neat active pharmaceutical ingredient would not, by itself, necessarily satisfy the composition claim unless the accused product is considered a pharmaceutical composition containing the required carrier. Commercial dosage forms such as tablets, capsules, oral suspensions, and injectable preparations would more naturally fall within the composition format if they contain a covered compound and excipient system.
The claim does not expressly require:
- A specific dosage.
- A particular route of administration.
- Treatment of Parkinson's disease.
- Concomitant levodopa use.
- A specific release profile.
- A specific salt or polymorph.
- A particular particle size.
- A specified pharmacokinetic profile.
Those omissions increase the potential breadth of the composition claims against products containing a covered chemical entity. They also leave room for later patents to claim formulation, dosing, delivery, salt, polymorph, or combination improvements.
How broad are the method claims?
Claim 8 covers administering a compound within the formula I genus to a patient in need of COMT inhibition. Claims 9, 10, 12, and 13 narrow the chemical structure. Claims 11 and 14 cover the two expressly identified compounds.
The method claims do not require a Parkinson's disease diagnosis. They refer generally to a patient in need of COMT inhibition. This language potentially reaches treatment of disorders or clinical situations in which COMT inhibition is therapeutically relevant, subject to ordinary claim-construction principles and the patent's specification.
The method claims also do not specify:
- Levodopa coadministration.
- Carbidopa or benserazide coadministration.
- A daily dose.
- Oral or parenteral administration.
- A treatment duration.
- A specific clinical endpoint.
A later patent could therefore claim a narrower clinical use, such as a defined dose range, a particular levodopa combination, or treatment of wearing-off fluctuations, without necessarily duplicating every limitation of claim 8.
What is the patent's US expiration status?
US Patent 4,963,590 is expired.
| Event |
Date or status |
| US patent issued |
October 16, 1990 |
| Patent term framework |
Pre-1995 US patent term, generally 17 years from issuance |
| Nominal term endpoint |
October 16, 2007 |
| Current enforceability |
Expired |
| Current Paragraph IV relevance |
None for this patent itself |
| Current Orange Book blocking effect |
None identified for this expired patent |
The patent was issued before the Uruguay Round Agreements Act changed the US patent term from 17 years from grant to 20 years from the earliest effective nonprovisional filing date. Accordingly, the principal term calculation is based on issuance rather than the modern filing-date rule, subject to any terminal disclaimer, patent-term adjustment, or statutory term effects recorded in the official file. The patent is now well beyond any ordinary enforceable term. [1]
What is the Orange Book status of US Patent 4,963,590?
US Patent 4,963,590 is not a current Orange Book barrier.
The FDA Orange Book lists patents and exclusivity information for approved drug products. A patent must generally be submitted by an NDA holder and meet applicable listing requirements to appear in the relevant product record. The patent at issue predates the commercial US approvals of the principal COMT drugs and is not a current patent protecting entacapone, tolcapone, or opicapone products in the Orange Book. [2]
The patent also does not appear to have been the operative Orange Book patent for:
- Comtan or generic entacapone.
- Tasmar or generic tolcapone.
- Ongentys or generic opicapone.
Those products are associated with later compound, formulation, method-of-use, or manufacturing patents.
Did this patent generate Paragraph IV litigation?
The expired status of US Patent 4,963,590 eliminates present-day Paragraph IV risk based on this patent.
A Paragraph IV certification applies when an ANDA applicant challenges a listed patent for an approved reference drug. Because this patent is expired and is not the operative Orange Book patent for the major approved COMT products, an ANDA applicant would not ordinarily face a current Paragraph IV challenge directed to this patent.
Potential historical disputes involving COMT inhibitors would more likely have concerned later patents covering:
- The active ingredient used in an approved product.
- A specific formulation.
- A method of treating motor fluctuations.
- A combination with levodopa and carbidopa.
- A polymorph or crystalline form.
- A manufacturing process.
How does this patent compare with later COMT-inhibitor patents?
| COMT inhibitor |
Representative product |
Commercial status |
Relation to US 4,963,590 |
| Nitecapone |
Investigational |
No major FDA-approved US product |
Directly associated with the patent's specific nitro-diketone species |
| Nebicapone |
Investigational |
No FDA-approved US product |
Directly associated with the patent's N,N-diethyl acrylamide species |
| Tolcapone |
Tasmar |
FDA-approved |
Different later COMT-inhibitor compound and patent estate |
| Entacapone |
Comtan, Stalevo |
FDA-approved |
Different later compound and patent estate |
| Opicapone |
Ongentys |
FDA-approved |
Later-generation COMT inhibitor with separate patent estate |
US 4,963,590 is chemically important because it claims the nitrocatechol COMT-inhibitor platform that preceded the later commercial products. It should not be treated as the core composition patent for entacapone, tolcapone, or opicapone. Chemical similarity alone does not establish claim overlap. Each later molecule must be mapped against the exact Markush limitations, including the aromatic substituent, side-chain functionality, and R1/R2 groups.
What formulation patents are covered?
US 4,963,590 does not claim a particular formulation technology. It requires a pharmaceutical composition containing a covered compound and a pharmaceutically acceptable carrier, but it does not specify:
- Immediate-release or extended-release delivery.
- Enteric coating.
- A particular tablet matrix.
- A specified excipient ratio.
- A solid dispersion.
- Nanoparticle delivery.
- A transdermal system.
- A liquid formulation.
- A defined dissolution profile.
The carrier language is a conventional composition limitation. It supports pharmaceutical composition claims but does not create a detailed formulation platform. Later formulation patents could claim a dosage form with narrower technical features even if the active ingredient fell within the old patent's chemical genus.
What manufacturing and intellectual-property barriers remain?
The expired patent does not block manufacture of the claimed compounds in the United States. Commercial development may still face non-patent barriers, including:
- Process reproducibility for substituted catechol compounds.
- Control of oxidation and impurity formation.
- Stability of catechol-containing drug substances.
- Control of regioisomers and geometric isomers.
- Pharmaceutical acceptable salt or solid-form selection.
- Toxicology and clinical-development requirements.
- Freedom-to-operate issues under later process or formulation patents.
- Regulatory requirements for a new active ingredient.
Catechol compounds can present oxidation and stability challenges because the catechol ring is chemically prone to oxidation under some conditions. Those technical issues are separate from the expired composition and method claims.
What is the commercial and competitive significance?
The patent's commercial value was concentrated in its ability to claim early COMT-inhibitor chemistry before the later commercial products reached the US market. Its current direct revenue exposure is zero because the patent is expired and the specifically associated compounds did not become major FDA-approved US products.
The commercial COMT market is instead associated with:
- Entacapone, marketed as Comtan and used in Stalevo combinations.
- Tolcapone, marketed as Tasmar, with significant liver-safety monitoring considerations.
- Opicapone, marketed as Ongentys, a once-daily COMT inhibitor.
The main current patent risks for these products arise from their own product-specific patent and regulatory records, not from US 4,963,590. [2-5]
How strong is the patent estate for US 4,963,590 today?
| Factor |
Assessment |
| Chemical breadth |
Strong at issuance; covers a defined but substantial Markush genus |
| Species coverage |
Clear for nitecapone- and nebicapone-associated structures |
| Composition coverage |
Broad carrier-based pharmaceutical composition claims |
| Method coverage |
Broad COMT-inhibition treatment claims |
| Formulation coverage |
Limited; no detailed delivery-system limitations |
| Current enforceability |
None; patent expired |
| Current Orange Book impact |
None identified |
| Current generic launch risk |
No risk from this patent |
| Historical platform value |
Material for early COMT-inhibitor chemistry |
| Current licensing value |
Limited unless tied to know-how, data, or later unexpired rights |
Key Takeaways
- US Patent 4,963,590 covers COMT-inhibiting nitrocatechol and cyanocatechol compounds.
- Claims 1 and 8 are the broad genus claims for compositions and treatment methods.
- Claims 4 and 11 specifically cover 3-(3,4-dihydroxy-5-nitrobenzylidene)-2,4-pentanedione.
- Claims 7 and 14 specifically cover N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide.
- The patent issued on October 16, 1990 and is expired.
- It is not a current Orange Book or Paragraph IV barrier.
- The patent does not provide the operative patent protection for entacapone, tolcapone, or opicapone.
- Current freedom-to-operate analysis must focus on later compound, formulation, method-of-use, solid-form, and manufacturing patents.
FAQs
Is US Patent 4,963,590 still enforceable?
No. The patent expired after its statutory term and does not create a current US infringement right.
Does US Patent 4,963,590 cover entacapone?
Not on the information provided by the asserted claims. Entacapone has a different side-chain structure and is protected, if at all, by separate later patent families.
Does the patent cover nitecapone?
The patent expressly covers the nitecapone-associated compound 3-(3,4-dihydroxy-5-nitrobenzylidene)-2,4-pentanedione in composition claim 4 and method claim 11.
Does the patent cover nebicapone?
The patent expressly covers the nebicapone-associated compound N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide in composition claim 7 and method claim 14.
Can a company rely on the expired patent for FDA approval?
No. Patent expiration removes this patent as a US exclusivity barrier, but FDA approval would still require satisfaction of the applicable regulatory pathway, including quality, nonclinical, clinical, manufacturing, and labeling requirements.
References
-
United States Patent and Trademark Office. (1990). Catechol-O-methyl-transferase inhibitors, U.S. Patent No. 4,963,590.
-
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
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U.S. Food and Drug Administration. (2009). Tasmar prescribing information: Tolcapone tablets.
-
U.S. Food and Drug Administration. (2010). Comtan prescribing information: Entacapone tablets.
-
U.S. Food and Drug Administration. (2020). Ongentys prescribing information: Opicapone capsules.
