United States Patent 8,124,799 (US8124799): Scope, Claim Coverage, and US Patent Landscape
US 8,124,799 is a chemical-structure patent framed around a Markush-style “compound of the formula” claim set. Based on the provided claim excerpts, the patent’s practical scope is driven by (i) the specific heteroatom substituent definition for Y, (ii) the two substituent handles R1 and R2 with broad enumerations, (iii) explicit support for stereochemical, tautomeric, and salt forms, and (iv) two alternative linkage states (C9–C11 single vs double bond) depending on dependent-claim selection.
This structure-forward drafting pattern typically produces broad protection on covered chemical entities, while leaving freedom for design-around through (a) removing the defined Y functionality or (b) changing the core scaffold or linkage state so it no longer satisfies the claim’s structural limitations.
What does US Patent 8,124,799 claim cover at a high level?
Answer: A broad Markush claim to compounds of a defined formula, where the claim coverage is determined by the allowed definitions of Y (hydroxy or amino-substituted form) and the allowed substituent patterns R1 and R2 (H/hydroxy or a wide list of organic radicals up to C12, including substituted variants), with coverage extended to salts, tautomers, and optical isomers. Dependent claims carve out bond state at C9–C11 (double or single) as additional structural constraints.
Core claim construction from the excerpts
From the text you provided, claim 1 is a “compound of formula” claim. The excerpted claim logic is:
- Y is hydroxy or NR1R2
- R1 and R2 are each independently selected from:
- hydrogen or hydroxy
- or a large set of organic groups, each with a carbon-count ceiling of C≤12, including:
- alkyl, alkenyl, alkynyl
- aryl, aralkyl
- heteroaryl, heteroaralkyl
- acyl
- alkoxy, alkenyloxy, alkynyloxy
- aryloxy, aralkoxy
- heteroaryloxy, heteroaralkoxy
- thioacyl
- alkylsulfonyl, alkenylsulfonyl, alkynylsulfonyl, arylsulfonyl, aralkylsulfonyl, heteroarylsulfonyl, heteroaralkylsulfonyl
- each group may be substituted, and the claim also covers pharmaceutically acceptable salts, tautomers, and optical isomers.
Claim 2 narrows claim 1 by constraining R1 and R2 to a subset that (from your excerpt) again includes H and a set of C≤12 radicals, with slightly different wording around “sulfonyl” (one occurrence drops the C≤12 constraint in your pasted text: “alkylsulphonyl” without the explicit carbon limit, suggesting either a transcription artifact or a deliberate claim wording difference).
Claims 3 and 4 are bond-state dependent:
- Claim 3: C9–C11 is a double bond
- Claim 4: C9–C11 is a single bond
Claim 5 and claim 6 are not included in full in your excerpt, other than “further defined as:” and “A compound of the formula:”, so their additional limitations cannot be reliably reconstructed.
How broad are the Markush substituents (R1/R2) in US 8,124,799?
Answer: The R1/R2 definition is broadly permissive and explicitly includes many functional families (alkyl through aralkyl, heteroaryl through heteroaralkyl, ethers, sulfonyl, thioacyl, and acyl), with a uniform upper carbon cap of C≤12 for most categories, plus substitution allowance for each group. That design increases the number of covered embodiments and makes it harder for a generic or competitor to avoid infringement while keeping the same core scaffold.
Practical scope implications
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Substituent-family breadth
- The inclusion of alkyl/alkenyl/alkynyl, aryl/aralkyl, and heteroaryl/heteroaralkyl sweeps across most common medicinal chemistry substituent classes.
- The inclusion of alkoxy/aryloxy/heteroaryloxy expands coverage to oxygenated substituents and prodrug-like fragments if they are present within the allowed group definitions.
- The inclusion of sulfonyl and thioacyl expands into heavier, polar, and electron-withdrawing substituent spaces commonly used for potency and PK tuning.
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Carbon-count ceiling (C≤12)
- C≤12 restricts the length/size of radicals for many listed groups.
- A competitor can potentially design around by using substituent groups that exceed C12 or fall outside the enumerated categories, but the “substituted version” language may still pull in many variations within the same category.
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H or hydroxy
- Allowing R1/R2 to be H or hydroxy means the patent covers both unsubstituted amino substituents and hydroxylated analogs at those positions.
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Y switch: hydroxy vs NR1R2
- This is a structural “fork” at Y: the claim covers either a hydroxyl-bearing functionality or an amino-differentiated functionality (Y = NR1R2). If a competitor’s structure uses a different heteroatom (e.g., halogen, carboxylate, ether substituent not matching the Y definition), it can fall outside the claim regardless of how R1/R2 are chosen.
Claim 2 narrowing effect
Claim 2 further defines R1/R2, tightening the set. From your text, claim 2 still looks broad, but it appears to be less expansive or more carefully bounded than claim 1, with one wording inconsistency for “alkylsulphonyl” lacking the C≤12 limit in your pasted excerpt. Even with that, claim 2 remains a Markush claim to a wide class of R1/R2 groups, so the narrowing is likely not a major carve-out.
What does “C9–C11 double bond vs single bond” do to infringement risk?
Answer: It creates two alternative dependent claim branches that each require a distinct scaffold connectivity state at the C9–C11 positions. If a product’s core chemistry does not match the selected bond state (double or single), it may avoid the narrower dependent claims, but it still could infringe the broader independent claim unless the independent claim already fixes the bond state.
Infringement map for bond-state limitations
- If independent claim 1 leaves C9–C11 bond state implicit or variable, then a competitor would still be exposed under claim 1 even if it avoids claim 3 or claim 4.
- If independent claim 1 already fixes or strongly implies one bond state, then:
- a product matching the other bond state would avoid that dependent branch and may avoid the independent claim as well depending on how the formula is defined in the claim drawing/text.
Your excerpt does not specify whether the independent formula fixes C9–C11. Only claims 3 and 4 explicitly state the bond state. The safest read of the excerpt is that claims 3 and 4 are additional narrowing options relative to claim 2, which likely means the bond state is not fixed until the dependent claim. That is typical: independent claims contain the scaffold, dependent claims specify particular linkage states.
What is the enforceable scope: compounds, salts, tautomers, and optical isomers?
Answer: Coverage extends beyond a single “free base” structure to pharmaceutically acceptable salts, tautomers, and optical isomers. This increases capture of typical formulation and API choices.
Salt/tautomer/isomer coverage consequences
- A competitor cannot generally avoid infringement by switching to a pharmaceutically acceptable salt if the free base falls within the claim.
- Tautomer coverage matters when the compound has prototropic sites (e.g., heteroatoms that can switch proton locations).
- Optical isomer coverage means stereochemical variants can still be captured unless they are excluded by the specific formula representation in the independent claim (your excerpt explicitly includes optical isomers, so exclusion via stereochemistry alone is unlikely).
What is the US patent landscape around US 8,124,799 (related patents, claim coverage overlap, design-around routes)?
Answer: Insufficient information is provided to identify the patent’s family members, related continuations, continuation-in-part filings, terminal disclaimers, or the assignee-specific cluster of related compounds.
Because no additional identifiers are provided (assignee, title, filing date, publication number, priority data, or claim set beyond 1–6 fragments), a complete and accurate landscape cannot be produced.
How many claims are likely tied to the independent Markush formula (and where are the likely narrow points)?
Answer: From the excerpts, at least claims 1–4 are tied to the formula scaffold with definitional narrowing through (i) R1/R2 choices (claim 2) and (ii) the C9–C11 bond state (claims 3 and 4). Claims 5 and 6 likely add additional constraints, but the provided text does not specify them.
Likely narrowing hotspots in chemical Markush patents
Even without claim 5–6 text, chemical Markush families typically narrow through one or more of the following:
- a specific substitution pattern on the substituents (e.g., particular substituted heterocycles)
- a specific substituent identity chosen from the broad R1/R2 sets
- explicit core ring substitution or positioning
- a specific bond state or valence pattern
- a specific tautomer or stereochemical subset (though your excerpt already includes optical isomers broadly)
How strong is US 8,124,799 for litigation and generic or follow-on compound challenges?
Answer: Based on the claim style shown, the patent’s strength for covering a competitor’s compound is driven by how tightly the competitor can be kept outside the Y and R1/R2 definitions and whether the scaffold match is exact.
Strength factors from the excerpt
- Broad Markush definitions generally support broad literal infringement coverage.
- Explicit coverage of salts, tautomers, and optical isomers supports broader capture of typical commercial forms.
- Dependent claims specifying bond state can help structure the infringement narrative and can provide alternative claim theories if the independent claim leaves certain connectivity aspects variable.
Common vulnerability points (cannot be adjudicated from excerpt)
- If the independent “formula” language is interpreted narrowly by the claim construction of the depicted substituent positions, apparent breadth can compress in practice.
- If the “substituted version” language is not tied to clear substitution rules, some embodiments can be argued outside the scope.
- Markush claims can face validity challenges, but those require full specification and claim charts not provided here.
Patent expiration, exclusivity, and FDA status for products tied to US 8,124,799
Answer: Cannot be provided because the drug identity (active ingredient and product) is not stated, and no FDA regulatory data (Orange Book listing, reference product, application number, or approval date) is included.
Key takeaways
- US 8,124,799 is a Markush “compound of formula” patent whose coverage is primarily controlled by Y (hydroxy vs NR1R2) and broad, substituted R1/R2 definitions.
- The patent explicitly covers pharmaceutically acceptable salts, tautomers, and optical isomers, which reduces common design-around strategies.
- Dependent claims 3 and 4 carve out C9–C11 double vs single bond, creating scaffold-structure alternatives but likely not eliminating exposure under broader independent claims depending on how the base formula fixes bonding.
- A complete US patent landscape (family members, related patents, Orange Book connections, litigation, and expiration timelines) cannot be produced from the excerpted claim fragments alone.
FAQs
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Does US 8,124,799 cover salt forms and different isomers?
Yes. The provided claim language includes pharmaceutically acceptable salts, tautomers, and optical isomers.
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Can a competitor avoid infringement by using a different stereochemistry only?
Not if the stereochemical variant is still an “optical isomer” of a covered compound; the claim explicitly includes optical isomers.
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What is the key structural trigger in the claims you provided?
The definitions of Y and the allowed substituent families R1/R2 on the Y = NR1R2 form, plus whether the compound matches the C9–C11 bond state required by dependent claims.
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Do the bond-state dependent claims protect both single and double bonds?
Claims 3 and 4 each recite one bond state (double vs single), but whether the independent claim already fixes this cannot be concluded from the excerpt.
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What patent estate breadth exists beyond claim 1–4?
Not determinable here because claim 5 and claim 6 content is not provided, and no bibliographic/family data is included to map the surrounding portfolio.
References (APA)
- United States Patent and Trademark Office. (n.d.). US Patent 8,124,799 (claims excerpt provided).
