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Patent landscape, scope, and claims: |
United States Patent 5,565,473 (Scope, Claim Coverage, and Patent Estate Mapping)
US 5,565,473 is a broad small-molecule composition-and-method patent. Claim 1 covers a large genus of substituted thioether-containing heteroaryl/aryl ethenyl compounds with flexible substituent definitions, expressly limited by structural “provisos” (including sulfur/sulfonyl presence conditions) and broad salt coverage. Dependent claims carve out narrower embodiments (Formulas Ia/Ib/I’, and specific exemplified chemical entities including a cyclopropaneacetic acid core salt). The patent also covers (i) pharmaceutical compositions with the claimed compounds and (ii) methods tied to leukotrienes/SRS-A and asthma and ocular inflammatory indications.
H1: US Patent 5,565,473 Claim Scope for Leukotriene/SRS-A Inhibitors: Genus Formula Coverage, Dependent Formulas, and Pharmaceutical Use
What does claim 1 of US 5,565,473 cover: the full structural genus and built-in limiting provisos?
Instant answer: Claim 1 covers “a compound” within a multi-parameter formula where many substituent variables can vary across common medicinal chemistry ranges (halogens, CF3/CN/NO2/N3, multiple alkyl/aryl substituents, optional hydrogen bonding/heteroatoms, heteroaryl rings, and a variable side-chain linked via a thioether/methylene construct), plus pharmaceutically acceptable salts.
Claim 1: Coverage architecture
Claim 1 is drafted as a genus with:
- Core scaffold (the formula in the claim includes a W heteroatom and a linkage pattern to a “radical W–R9” moiety).
- Multiple variable substitution sets (R1, R2, R3, R4, R5, R6, R7, R8, R9, R11, R12, R13, R14, R16, R17, R18, R19, R21, R22, and ring count variables m, m’, n, n’, p, p’, r, r’, s).
- A “with the proviso” constraint that prevents the genus from being over-inclusive.
Key substituent variable definitions that drive real-world coverage
The breadth comes from how many substituents are allowed to vary:
- R1: H, halogen, CF3, CN, NO2, N3.
- R2: lower alkyl/alkenyl/alkynyl, CF3, fluorinated methyl (CH2F, CHF2), CH2CF3, substituted/unsubstituted phenyl, benzyl, 2-phenethyl, or two R2 groups that can cyclize to a carbocycle of up to 8 members.
- R3: H or R2.
- R4 and R5: expand allowed polar/functional groups (halogen, NO2, CN; OR3, SR3, NR3R3, NR3C(O)R7; and additional carbonyl/thiocarbonyl-like options via the defined patterns).
- R6: a flexible linker incorporating a thioether-like fragment and a repeating unit:
- “--(CH2)s--C(R7R7)--(CH2)s--R8” or “--CH2 C(O)NR12R12”
This language supports two mechanistic geometry families: (i) a carbon center with substituent radius and (ii) an amide-containing alternative.
- R8 and R9: “R8 is the radical W–R9”; and R9 is an alkyl group or an alkylcarbonyl group of an organic acyclic/monocyclic carboxylic acid (up to 20 carbons). This ties claim coverage to carboxylic acid-containing side chains and amphiphilic variants.
- Q1 (major functional handle): a wide set of substituents attached to the core, including carboxylic acid and acid bioisosteres:
- --C(O)OR3
- tetrazol-5-yl (1H/2H)
- --C(O)NHS(O)2R13
- --C(O)NR12R12 and several sulfonamide and sulfone-related options
- --NO2
- --NR21C(O)OR17, --C(NR12R12)=NR12, --C(R13)=NOH, etc.
- W: O, S, or NR3.
- X2 and X3: independently O, S, S(O), S(O)2, or CR3R16.
- Proviso about sulfur:
- when r = 1 and X2 is O/S/S(O)/S(O)2, the sum m+n+p is 1–10
- when r = 1 and X2 is CR3R16, m+n+p is 0–10
- when r = 0, m+n+p is 0–10
- and “at least one is S or SO2”
This “at least one S or SO2” requirement is a meaningful narrowing mechanism: it enforces a sulfur oxidation-state element in the defined heteroatom set.
What this means for infringement analysis
Under standard claim interpretation, claim 1 is broad enough that a competitor cannot avoid it by using:
- most common halogens and CF3 substitutions at the variable positions;
- typical alkyl/aryl R2 variants;
- optional ring sizes in the allowed ranges;
- interchangeable salt forms.
Avoidance is more likely only through:
- failure to meet the structural linkages encoded by the formula (W–R9, Q1 placement, and the thioether/carbonyl alternatives reflected by R6);
- failure of the “at least one S or SO2” condition depending on how the competitor satisfies (or does not satisfy) the X2/X3/related S/SO2 requirement; and
- carving out by choosing different chemical families outside the defined “HET” diradical patterns and substituent connectivity.
Claim 1: Salt coverage
The claim expressly includes “pharmaceutically acceptable salts.” That expands practical coverage to:
- carboxylate salts,
- sulfonate salts,
- and other salt forms aligned with the functional groups defined in Q1 and related acid moieties.
Which dependent claims narrow the genus: what do claims 2–7 add beyond claim 1?
Instant answer: Claims 2–7 narrow claim 1 by restricting specific substituent ranges (R1, R2, R4/R5, m/p ranges, and Q1 subsets) and by introducing narrower structural “Formula Ia / Formula Ib / Formula I’” sub-genuses.
Claim 2: tightened substituent sets and smaller ranges
Claim 2 restricts:
- R1: H, halogen, CF3, or CN (cuts NO2 and N3 compared with claim 1).
- R2: largely C1–C4 alkyl plus limited fluorinated and CF3 variants; phenyl/benzyl/2-phenethyl carbocycle joining is removed relative to claim 1.
- R4: more specific: --OR3, --SR3, NR3R3, NHC(O)CH3, or R3.
- R5: H or halogen (very restrictive vs claim 1).
- m/p/n ranges: smaller numeric limits (m: 0–4; p: 0–4) for the combined counts.
- W: O, S, or NH (replacing NR3 from the broadest W options).
- X2 and X3: only O, S, or CR3R16 (removes some sulfur oxidation-state options other than S).
- proviso changed: “at least one is S” (drops the “SO2” explicitness in this dependent narrowing).
Net effect: claim 2 is a narrower embodiment within the claim 1 genus, more consistent with a class of analogs where one or more sulfur atoms appears but oxidation state flexibility is reduced.
Claims 3 and 4: embodiment targeting R22 and specific formula families
- Claim 3 narrows claim 1 so that the group “α to Q1” is lower alkyl, CF3, or substituted/unsubstituted phenyl. This targets steric/electronic features adjacent to the Q1 substituent.
- Claims 4–6 define Formula Ia and Formula Ib:
- Claim 4: Formula Ia includes Q1 restricted to carboxylic acid (C(O)OH), tetrazolyl, sulfonamide/sulfonyl-amide forms, and amide alternatives, and restricts m’ and p’ and m+p to small totals.
- Claim 5: adds that the carbon α to Q1 is lower alkyl-substituted.
- Claim 6: Formula Ib provides another restricted parameter set: R1 limited (H/halogen/CF3/CN), R22 restricted, Q1 restricted to a similar set, and m/p constraints.
Claim 7: Formula I’ with extensive enumerated substituent tables
Claim 7 is a distinct narrowing mode. It provides a large substitution table for “R1/Y/A/B” style assignments that correspond to concrete analog series. It spans:
- different R1 halogens and CF3/CN/NO2/N3 varieties,
- vinylic “CH═CH” vs C≡C cases,
- multiple sulfur linkers and chain lengths,
- multiple aryl substitution patterns (including chloro, bromo, nitro, methoxy, and fused ring patterns like quinoline noted in the specifically named compounds elsewhere in the document),
- and explicit stereochemical depictions in some entries.
This is the claim subset most likely to be used for pinpoint infringement once a specific marketed compound’s substituent identity is mapped onto the table.
Claim 17: another Formula I’ section with enumerated substituents (sub-genus compression)
Later, claim 17 includes “A compound of Formula I’” with a shorter enumerated list (including amino terminal variations like “CONH2” or dimethylamino substituted entries and other side-chain modifications). This reinforces that the patent’s enforceable value is split between:
- broad genus,
- intermediate constrained formula subsets, and
- an enumerated analog set for specific chemical families.
What exact compounds are explicitly claimed: claims 18 and 19 and their salts
Instant answer: Claims 18 and 19 specifically identify a single named compound and its sodium salt: a thio-methyl cyclopropaneacetic acid derivative substituted with a quinoline-ethenyl-phenyl framework and a 2-hydroxy-2-propyl phenyl moiety.
Claim 18
“1-(((1(R)-(3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)-3-(2-(2-hydroxy-2-propyl)phenyl)propyl)thio)methyl) cyclopropaneacetic acid or a pharmaceutically acceptable salt thereof.”
Claim 19
“Sodium 1-(((1(R)-(3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)-3-(2-(2-hydroxy-2-propyl)phenyl)propyl)thio)methyl) cyclopropaneacetate.”
Claim 18’s significance
Even if the genus is challenged for some reason, claims 18/19 can remain valuable as specific embodiments with less claim-construction strain: they are tied to a precise chemical structure, including the “7-chloro-2-quinolinyl ethenyl” motif and “cyclopropaneacetic acid” acid headgroup.
What formulations are protected: does the patent claim compositions beyond APIs?
Instant answer: Yes. The patent claims pharmaceutical compositions comprising the claimed compounds plus a pharmaceutically acceptable carrier, plus combination regimens with a broad set of standard anti-inflammatory/anti-asthma drug classes.
Claim 8: basic composition
“A pharmaceutical composition comprising a therapeutically effective amount of a compound of claim 1 and a pharmaceutically acceptable carrier.”
Claim 9–11: combination compositions with second active ingredients
- Claim 9 expands to a second active ingredient selected from:
NSAIDs, peripheral analgesic agents, COX inhibitors, leukotriene antagonists, leukotriene bisynthesis inhibitors, H2 receptor antagonists, antihistaminics, prostaglandin antagonists, thromboxane antagonists, thromboxane synthetase inhibitors, ACE antagonists.
- Claim 10 limits second active ingredient to an NSAID.
- Claim 11 adds a weight ratio range of compound of claim 1 to the NSAID of about 1000:1 to 1:1000.
This is a meaningful claim category for product strategy: it targets not only monotherapy but also common combination use patterns.
What methods of use are protected: leukotriene/SRS-A and asthma/ocular inflammatory disease
Instant answer: The patent includes methods for preventing synthesis/action/release of SRS-A or leukotrienes, treating asthma, and treating inflammatory eye diseases (with human-specific dependent claims).
Claim 12–14: prevention and asthma
- Claim 12: “preventing the synthesis, the action, or the release of SRS-A or leukotrienes” via administering a claim 1 compound.
- Claim 13: mammal is man.
- Claim 14: treating asthma in a mammal via administering a therapeutically effective amount.
Claim 15–16: ocular inflammatory disease
- Claim 15: treating inflammatory diseases of the eye in a mammal.
- Claim 16: mammal is man.
Claim 21–23: methods tied to the specific cyclopropaneacetic acid compound (claim 18)
- Claim 21: preventing action of leukotrienes via claim 18 compound.
- Claim 22: treating asthma.
- Claim 23: treating inflammatory eye diseases.
Claim category implications
Even if a competitor designs around claim 1 structure, they may still face method claims if:
- their product still falls within the scope of claim 18 (specific structure) or other narrower formula claims (4–7, 17, etc.), and
- FDA-labeled or off-label practice matches the claimed method elements tied to leukotriene/SRS-A and asthma/ocular inflammation.
How strong is the patent estate for US 5,565,473: what can be inferred from claim drafting alone?
Instant answer: Strength is “structural” and “reach-to-markets” driven. Claim 1 is broad and salt-covering; the patent also has a specific named compound embodiment and includes use and combination claims.
Strength drivers in the claims themselves
- Genus breadth with many allowable substituents: increases probability of overlap with future analogs.
- Explicit sulfur and oxidation-state proviso: can strengthen novelty/defensibility by excluding some non-sulfur or non-sulfonyl embodiments.
- Explicit heteroaryl core choices (HET): benzene, pyridine, furan, thiophene diradical link.
- Method claims tied to leukotrienes/SRS-A and asthma/ocular inflammation: increases leverage for regulatory and marketing-based arguments once product identity is mapped.
- Specific compound claims (18/19): creates a hard target even if genus interpretation narrows.
Weakness or vulnerability vectors that follow from claim structure
- Complex nested definitions can create claim-construction disputes, especially around:
- the scope of “at least one is S or SO2,”
- the connectivity of W–R9 and placement of Q1 and X2/X3,
- the interpretation of “diradical” HET and “Z1/Z2 independently --HET(--R3--R5)--” type constructs.
- Dependence on many variables can lead to enablement/definiteness challenges in some jurisdictions if a court finds the genus not sufficiently supported relative to breadth. (This is not a prediction of litigation outcome; it is a structural note on where courts commonly focus when claims are heavily parameterized.)
How would a competitor design around claim 1: which elements are most likely “avoidance levers”?
Instant answer: The highest-friction avoidance levers are the sulfur/SO2 proviso, the specific linkage pattern defining W–R9, and the Q1 functional substitution set combined with the core skeleton.
Primary design-around levers
- S proviso: ensure the competitor’s compound does not satisfy “at least one is S or SO2” in the relevant heteroatom positions that correspond to X2/X3 (and any implied “at least one” coverage).
- W–R9 radical: if W is constrained in the competitor’s core chemistry so that the “radical W–R9” linkage pattern is not met, claim 1 may be avoided even with similar substituent lists.
- Q1 set mismatch: if the competitor uses a functional group that is outside the explicit Q1 enumerations (and its defined analogities), it can reduce overlap.
- HET diradical restriction: changing the heteroaryl core away from the specified diradical set (benzene, pyridine, furan, thiophene) can reduce overlap.
Secondary levers
- R2 linkage/cyclization: claim 1 allows R2 combinations forming carbocycles up to 8 members; if the competitor uses different ring closure chemistry outside the described patterns, it can create mismatch.
- Count variables: m, m’, n, n’, p, p’, r, r’, s constrain the number of atoms/groups in specific positions. Competitors can avoid those by selecting substituent patterns that force sums outside the allowed ranges.
What is the likely regulatory and commercial relevance: how the claims map to FDA product risk
Instant answer: Claim structure is typical of a drug class core patent where:
- the API is the primary risk for Paragraph IV-style “carve-out” avoidance,
- the method claims add risk for label claims and litigation over medical practice tied to leukotrienes/SRS-A, and
- the composition claims add risk for combination products with NSAIDs or leukotriene-targeting drugs.
Composition + combination risk
If a marketed product is a single API, the main question is whether the API falls within claim 1 or claims 4–7/17.
If the marketed product is combined (e.g., with an NSAID), claim 9–11 can be a direct barrier even where the API alone might be argued.
Key Takeaways
- Claim 1 is a wide genus of substituted heteroaryl/aryl vinylic-thioether compounds with a defined carboxylic acid or acid bioisostere region (via Q1) and a sulfur-containing proviso requiring at least one S or SO2 across the relevant positions.
- Claims 4–7 and 17 carve out narrower structural sub-genuses using “Formula Ia,” “Formula Ib,” and “Formula I’,” including extensive enumerated substituent arrays.
- Claims 18 and 19 are “hard” targets that name a specific cyclopropaneacetic acid derivative and its sodium salt, strengthening enforcement beyond the genus.
- Use claims cover inhibition of SRS-A/leukotrienes and treatment of asthma and inflammatory eye diseases, with mammal “man” dependents.
- Composition claims cover monotherapy compositions and combination products with a broad basket of anti-inflammatory/anti-asthma classes, with an NSAID-specific embodiment and weight-ratio range.
FAQs
- How does the “at least one is S or SO2” proviso narrow claim 1 compared with a sulfur-free analog?
- Which dependent claims are most useful for pinning infringement to a specific marketed API: claims 4–7/17 or claims 18–19?
- What combination products are covered by the composition claims when the second active ingredient is an NSAID?
- How do the method claims constrain product labeling and litigation arguments around asthma and ocular inflammation?
- Which variable definitions (Q1, W, X2/X3) are the most common sources of claim-construction disputes in formula-based patents?
References
- US Patent 5,565,473 (claims provided in prompt).
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