United States Patent 5,164,402 Scope and Claims: Compound, Salt, Prodrugs, Formulation, and Method-of-Use Coverage

US Patent 5,164,402 claims a defined class of antibacterial compounds structured around a substituted 1,8-naphthyridine core with a specific bicyclic azabicyclo substituent, plus permitted variations at multiple positions (R1, Y, W, A, and R2/R3/R6/R7/R9/R10/R25). The claim set covers (1) the core compounds and their pharmaceutically acceptable salts, (2) “prodrugs” of compounds with free amino groups, (3) specific exemplary compound identities and salt forms, (4) antibacterial compositions, and (5) methods of treating bacterial infections. The breadth is driven by a Markush framework across several substituent positions with constraints on the number of non-hydrogen substituents and an additional methyl “safeguard” condition.

High-level scope

Product claim coverage: broad Markush formula I compound class (plus acid addition salts) and explicit named exemplars.
Salts and hydrates: express coverage of multiple salt types (hydrochloride, methanesulfonate, p-toluenesulfonate) and hydrate form for at least one exemplar.
Prodrugs: covers prodrugs of the formula I compounds with free amino groups.
Use claims: antibacterial composition and method-of-treatment for bacterial infection.
Biologically functional scope: antibacterial; no restriction to specific pathogens in the provided claims text.

What is the scope of US 5,164,402 claim 1 (formula I): how broad is the Markush coverage?

Featured snippet answer: Claim 1 covers “a compound of the formula I” with structured substituent variability at R1, Y, W, A, and a further substituent set embedded in R2/R3/R6/R7/R9/R10/R25, plus pharmaceutically acceptable acid addition salts and prodrugs of formula I compounds with free amino groups.

Core structural limitations that define the class

Claim 1 requires a compound of formula I (with variables described in the claim). The class is anchored by:

A substituted bicyclic azabicyclo[3.1.0]hex-type group (implied by the named exemplars, e.g., “1-amino-3-azabicyclo[3.1.0]hex-3-yl” and “6-amino-3-azabicyclo[3.1.0]hex-3-yl”).
A substituted 1,8-naphthyridine-3-carboxylic acid motif (again fixed in the exemplars: “1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid” plus substitutions).
Substituent choices at:
- R1: hydrogen, pharmaceutically acceptable cation, or (C1–C6) alkyl
- Y: ethyl, vinyl, cyclopropyl, 2-fluoroethyl, p-fluorophenyl, or o,p-difluorophenyl
- W: hydrogen, fluoro, chloro, bromo, C1–C4 alkyl, C1–C4 alkoxy, amino or aminomethyl
- A: CH, CR, CCl, COCH3, C–CH3, C–CN or N
- R2 and its dependent substituent variables (R3, R6, R7, R9, R10, R25) each independently selected from H, CH3, CH2NH2, CH2NHCH3, or CH2NHC2H5, with additional numeric constraints (see below).
Salt limitation: “pharmaceutically acceptable acid addition salt thereof,” meaning only acid addition salts, not freebase equivalents.

How the “substituent-count” constraint narrows the Markush

The claim includes a constraint designed to limit the number of non-hydrogen substituents among the set {R3, R6, R7, R9, R10, R25}:

Not more than three of those substituents may be other than hydrogen.
If three of these substituents are not hydrogen, then at least one must be methyl.

Practical claim effect

The class includes many mono- and di-substituted variants at those positions.
Tri-substituted variants are allowed only if methyl appears at least once, which reduces the number of purely amino-alkyl (CH2NH2/CH2NHCH3/CH2NHC2H5) heavy combinations.

Prodrugs are explicitly claimed, but only for “free amino groups”

Claim 1 includes: “and prodrugs of those compounds of formula I having free amino groups.”

Claim effect

Prodrugs are not limited to a specific promoiety in the provided text. Instead, prodrugs are functionally linked to the presence of free amino groups in the underlying formula I compound.
This creates additional “coverage surface” against prodrug developers, because many amino-protected prodrug strategies could be argued to fall within “prodrugs” so long as they map to a formula I parent with free amino groups in the claimed structure.

Which specific compounds and salts are enumerated in claims 12–15 (narrow exemplars inside a broad genus)?

Featured snippet answer: Claims 12–15 list named exemplar structures (same core scaffold) and identify specific stereochemical azabicyclo configurations plus multiple salt forms including hydrochloride, methanesulfonic acid salt, p-toluenesulfonic acid salt, and a hydrate.

Explicit exemplar identities (as provided)

Claim 12 lists multiple named compound identities including:

“7-(1-amino-3-azabicyclo[3.1.0]hex-3-yl)-6-fluoro-1-(2,4-difluorophenyl)-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid”
Several “7-(...)-6-fluoro-1-(2,4-difluorophenyl)-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid” stereochemical variants with different azabicyclo substitution patterns.

Claim 13 further adds:

“7-([1α,5α,6α]-6-amino-3-azabicyclo[3.1.0]hex-3-yl)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid”
The 2,4-difluorophenyl substituted analogs and p-toluenesulfonic acid salt.

Claim 14 includes:

A specific stereochemical core plus the hydrate form.

Claim 15 includes:

The same stereochemical core plus hydrochloride salt and methanesulfonic acid salt.

Why these exemplars matter

Even though Claim 1 is a Markush genus, enumerated claims increase enforceability in practice:

They identify specific chemical structures that are easier to match to accused products and commercial candidates.
They strengthen novelty/enablement positions by showing the applicant contemplated concrete embodiments within the genus.

What do claims 2–5 narrow: how are R1, Y, W, and A constrained in dependent claims?

Featured snippet answer: Dependent claims select particular substituent sets (R1 = H; Y = cyclopropyl or o,p-difluorophenyl; W = H; A = CH or N; and W = H with A = N), narrowing the Markush scope to subsets.

R1 dependency (Claim 2)

Claim 2: “wherein R1 is hydrogen.”

This removes variants where R1 is a pharmaceutically acceptable cation or a (C1–C6) alkyl group (still within the genus of Claim 1).

Y dependency (Claim 3)

Claim 3: “wherein Y is cyclopropyl or o,p-difluorophenyl.”

This narrows the allowed Y substituent list to two options.

W and A dependencies (Claims 4–5)

Claim 4: “wherein W is hydrogen, and A is CH or N.”
Claim 5: “wherein W is hydrogen and A is N.”

These are meaningful narrowing steps because W is one of several positions allowed to vary across halogens, alkyl, alkoxy, and amino/aminomethyl; setting W = H removes those alternatives. Setting A further constrains the ring substituent/atom position variability.

How do claims 6–11 narrow the substituent-count rule at R3/R6/R7/R9/R10/R25?

Featured snippet answer: The dependent claims operationalize the core genus constraint by limiting the number and identity of substituents at the amino-alkyl/methyl-allowed positions, including restrictions on when CH2NH2, CH2NHCH3, CH2NHC2H5, and/or methyl appear.

Claim 6: one or two non-hydrogen substituents

“wherein one or two of R3, R6, R7, R9, R10 and R25 are other than hydrogen.”

This limits the class to mono- and di-substituted variants at those positions, excluding tri-substitution patterns.

Claim 7: one specific amino-alkyl substituent plus methyl elsewhere

“one of R3, R6, R7, R9, or R10 is CH2NH2 or CH2NHCH3”
and “another … may be methyl.”

This permits methyl co-substitution with a primary or N-methyl amino-methyl group at a selected position.

Claims 8–10: combination rules including amino vs methyl

Claim 8: “one of R6, R7, or R9 is NH2 or NHCH3” and “another … or one of R3, R10 or R25 may be methyl.”
Claim 9: “wherein R6, R7 or R9 is amino and one of … may be methyl.”
Claim 10: “wherein R7 is amino and one of … may be methyl.”

These dependent claims focus on where the amino (NH2/NHCH3) functionality is located within the set and whether methyl can co-occur.

Claim 11: R7 amino with all other R-set substituents as hydrogen

“A compound according to claim 11 wherein R7 is amino and R3, R6, R9, R10 or R25 are each hydrogen.” (As written, the numbering appears inconsistent in the user-provided text, but the substantive limitation is clear: a single amino substitution at R7 while the rest of the set positions are hydrogen.)

This defines a very narrow embodiment.

What is the peptide-bond scope in claims 16–21: does the patent cover conjugates to amino acids and polypeptides?

Featured snippet answer: Yes. Claims 16–21 extend Claim 1 to compounds where the amino group at R6, R7, or R9 is covalently bonded via a peptide bond to one or more amino acids (including two amino acids).

Claims 16–18: one to multiple amino acids

Claim 16: amino group covalently bonded through a peptide bond to one amino acid residue.
Claim 17: peptide bond to a polypeptide of two or more amino acids.
Claim 18: peptide bond to a polypeptide of two amino acids.

Claims 19–21: same concept but anchored at R7

Claim 19: peptide bond from the amino group of R7 to one amino acid residue.
Claim 20: peptide bond from R7 amino group to a polypeptide of two or more amino acids.
Claim 21: peptide bond from R7 amino group to a polypeptide of two amino acids.

Practical claim effect

These claims capture amino-acid/peptide-linked derivatives where an amino group is converted to an amide/peptide bond rather than a free amino. This can overlap with certain prodrug-conjugate approaches and targeting conjugates depending on structure.

What peptide-linked embodiments are explicitly named in claims 22–25 (L-Ala, L-Leu, L-Ala-L-Ala)?

Featured snippet answer: Claims 22–25 list explicit peptide-conjugate embodiments: L-Ala (one residue), L-Ala-L-Leu (two residues), and L-Ala-L-Ala (two residues), in hydrochloride salt and free-acid form (including methanesulfonate salt in at least one option).

Exemplars in the provided claims

Claim 22: “7-([...]-6-(L-Ala-amino)-3-azabicyclo[3.1.0]hex-3-yl-...)-6-fluoro-1-(2,4-difluorophenyl)-... carboxylic acid, hydrochloride salt.”
Claim 23: “7-([...]-6-(L-Ala-L-Leu-amino)-... carboxylic acid hydrochloride salt.”
Claim 24: “7-([...]-6-(L-Ala-L-Ala-amino)-... carboxylic acid, hydrochloride salt, or ... methanesulfonic acid salt.”
Claim 25: “7-([...]-6-(L-Ala-L-Ala-amino)-... carboxylic acid” (free acid form).

Claim interpretation

These are direct structure claims that reduce the burden of arguing coverage through Markush alone. They also expand the scope beyond generic “prodrugs” by expressly covering peptide-bonded amino replacements.

What do claim 26 and claim 27 cover: antibacterial compositions and methods of treatment?

Featured snippet answer: Claim 26 is an antibacterial composition claim with a compound of Claim 1 plus a pharmaceutically acceptable carrier. Claim 27 is a treatment method for bacterial infection using an antibacterially effective amount of a Claim 1 compound.

Claim 26: composition

“An antibacterial composition comprising an antibacterially effective amount of a compound according to claim 1 and a pharmaceutically acceptable carrier.”

No dosage form is limited in the claim language provided (it is a typical carrier-based composition claim).

Claim 27: method-of-treatment

“A method for the treatment of a bacterial infection … administering … an antibacterially effective amount of a compound according to claim 1.”

No limitation to route (oral, parenteral) or dosing regimen appears in the provided text.

What is the practical patent landscape around US 5,164,402: what likely surrounds this compound genus?

The provided prompt includes claim text but not bibliographic data (assignee, priority date, publication date, related family members), and it does not provide any cited documents or Orange Book/FDA linkage. With only claim scope in hand, the landscape can be analyzed only at the claim-family level that is implied by the claim structure itself.

Claim-family breadth implied by the claim set

US 5,164,402 already reaches across multiple derivative classes:

salts (acid addition),
hydrates (explicit for an exemplar),
prodrugs (functional “free amino groups” trigger),
peptide conjugates (amino acid residues and dipeptides),
compositions and methods.

Landscape implication for freedom-to-operate (FTO)

Any competitor product that is:
- structurally within the formula I genus,
- uses an acid addition salt form,
- deploys a prodrug mapping to an amino-bearing formula I parent,
- or uses peptide-linked amino substitutes (at R6/R7/R9 positions), would likely face direct claim exposure.
If the competitor stays outside formula I by changing the scaffold, the main enforcement risk shifts to whether other patents in the same family cover alternative scaffolds, stereochemistry sets, or specific substituents.

Because no assignee or family member data is provided, no defensible list of additional US patents, jurisdictions, or litigated entities can be produced from the prompt alone.

When does this patent lose exclusivity in the US: what is the expiration driver for US 5,164,402?

No priority date, filing date, or patent term adjustment data is included in the prompt, so a specific expiration date cannot be computed from the provided information.

Key Takeaways

Claim 1 is a broad genus built on a substituted 1,8-naphthyridine-3-carboxylic acid scaffold with constrained variability at R1, Y, W, A, and the amino-alkyl/methyl substituent set at R3/R6/R7/R9/R10/R25.
The numeric substitution rule matters: no more than three non-hydrogen substituents among {R3, R6, R7, R9, R10, R25}, and if three are non-hydrogen, at least one must be methyl.
Dependent claims narrow the genus to subsets where R1=H, Y is limited, W=H, and A is limited to CH or N, with further narrowing on where amino and methyl substituents can appear.
Prodrugs and peptide conjugates are explicitly covered, with peptide-bonded amino acid and dipeptide embodiments named (L-Ala; L-Ala-L-Leu; L-Ala-L-Ala) including hydrochloride and methanesulfonate salts in the examples.
Enforcement hooks include named exemplars and multiple salt/hydrate forms, plus use claims for antibacterial compositions and bacterial infection treatment.

FAQs

1) Does US 5,164,402 claim include only freebase compounds or also acid addition salts?

It expressly includes pharmaceutically acceptable acid addition salts of formula I compounds and includes specific salt embodiments (hydrochloride, methanesulfonate, p-toluenesulfonate) and a hydrate for at least one exemplar.

2) Are prodrugs limited to a specific pro-moiety in claim 1?

No specific pro-moiety is stated in the provided claim text. Coverage is defined by the functional condition that the prodrugs are of formula I compounds that have free amino groups.

3) Can the patent reach peptide-linked derivatives where an amino group is converted to a peptide bond?

Yes. Claims 16–21 cover covalent peptide-bond linkage of amino groups (at R6/R7/R9, or specifically at R7) to one amino acid and polypeptides of two or more amino acids, including two amino acids.

4) What does the “not more than three” substituent constraint mean for design-around?

It restricts how many positions among R3/R6/R7/R9/R10/R25 can be non-hydrogen. Tri-substituted patterns require at least one methyl among those non-hydrogen substituents.

5) Does the patent restrict use to particular pathogens or routes of administration?

No. The provided method claim is broadly “for the treatment of a bacterial infection” with an “antibacterially effective amount,” without specifying pathogens or route.

References

US Patent 5,164,402. “(Claims provided in prompt text.)” United States Patent and Trademark Office.

Title:	Azabicyclo quinolone and naphthyridinone carboxylic acids
Abstract:	Quinolone carboxylic acids 7-substituted by azabicyclo groups have antibacterial activity.
Inventor(s):	Katherine E. Brighty
Assignee:	Pfizer Inc
Application Number:	US07/650,835
Patent Claim Types: see list of patent claims	Use; Composition;
Patent landscape, scope, and claims:	United States Patent 5,164,402 Scope and Claims: Compound, Salt, Prodrugs, Formulation, and Method-of-Use Coverage US Patent 5,164,402 claims a defined class of antibacterial compounds structured around a substituted 1,8-naphthyridine core with a specific bicyclic azabicyclo substituent, plus permitted variations at multiple positions (R1, Y, W, A, and R2/R3/R6/R7/R9/R10/R25). The claim set covers (1) the core compounds and their pharmaceutically acceptable salts, (2) “prodrugs” of compounds with free amino groups, (3) specific exemplary compound identities and salt forms, (4) antibacterial compositions, and (5) methods of treating bacterial infections. The breadth is driven by a Markush framework across several substituent positions with constraints on the number of non-hydrogen substituents and an additional methyl “safeguard” condition. High-level scope Product claim coverage: broad Markush formula I compound class (plus acid addition salts) and explicit named exemplars. Salts and hydrates: express coverage of multiple salt types (hydrochloride, methanesulfonate, p-toluenesulfonate) and hydrate form for at least one exemplar. Prodrugs: covers prodrugs of the formula I compounds with free amino groups. Use claims: antibacterial composition and method-of-treatment for bacterial infection. Biologically functional scope: antibacterial; no restriction to specific pathogens in the provided claims text. What is the scope of US 5,164,402 claim 1 (formula I): how broad is the Markush coverage? Featured snippet answer: Claim 1 covers “a compound of the formula I” with structured substituent variability at R1, Y, W, A, and a further substituent set embedded in R2/R3/R6/R7/R9/R10/R25, plus pharmaceutically acceptable acid addition salts and prodrugs of formula I compounds with free amino groups. Core structural limitations that define the class Claim 1 requires a compound of formula I (with variables described in the claim). The class is anchored by: A substituted bicyclic azabicyclo[3.1.0]hex-type group (implied by the named exemplars, e.g., “1-amino-3-azabicyclo[3.1.0]hex-3-yl” and “6-amino-3-azabicyclo[3.1.0]hex-3-yl”). A substituted 1,8-naphthyridine-3-carboxylic acid motif (again fixed in the exemplars: “1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid” plus substitutions). Substituent choices at: R1: hydrogen, pharmaceutically acceptable cation, or (C1–C6) alkyl Y: ethyl, vinyl, cyclopropyl, 2-fluoroethyl, p-fluorophenyl, or o,p-difluorophenyl W: hydrogen, fluoro, chloro, bromo, C1–C4 alkyl, C1–C4 alkoxy, amino or aminomethyl A: CH, CR, CCl, COCH3, C–CH3, C–CN or N R2 and its dependent substituent variables (R3, R6, R7, R9, R10, R25) each independently selected from H, CH3, CH2NH2, CH2NHCH3, or CH2NHC2H5, with additional numeric constraints (see below). Salt limitation: “pharmaceutically acceptable acid addition salt thereof,” meaning only acid addition salts, not freebase equivalents. How the “substituent-count” constraint narrows the Markush The claim includes a constraint designed to limit the number of non-hydrogen substituents among the set {R3, R6, R7, R9, R10, R25}: Not more than three of those substituents may be other than hydrogen. If three of these substituents are not hydrogen, then at least one must be methyl. Practical claim effect The class includes many mono- and di-substituted variants at those positions. Tri-substituted variants are allowed only if methyl appears at least once, which reduces the number of purely amino-alkyl (CH2NH2/CH2NHCH3/CH2NHC2H5) heavy combinations. Prodrugs are explicitly claimed, but only for “free amino groups” Claim 1 includes: “and prodrugs of those compounds of formula I having free amino groups.” Claim effect Prodrugs are not limited to a specific promoiety in the provided text. Instead, prodrugs are functionally linked to the presence of free amino groups in the underlying formula I compound. This creates additional “coverage surface” against prodrug developers, because many amino-protected prodrug strategies could be argued to fall within “prodrugs” so long as they map to a formula I parent with free amino groups in the claimed structure. Which specific compounds and salts are enumerated in claims 12–15 (narrow exemplars inside a broad genus)? Featured snippet answer: Claims 12–15 list named exemplar structures (same core scaffold) and identify specific stereochemical azabicyclo configurations plus multiple salt forms including hydrochloride, methanesulfonic acid salt, p-toluenesulfonic acid salt, and a hydrate. Explicit exemplar identities (as provided) Claim 12 lists multiple named compound identities including: “7-(1-amino-3-azabicyclo[3.1.0]hex-3-yl)-6-fluoro-1-(2,4-difluorophenyl)-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid” Several “7-(...)-6-fluoro-1-(2,4-difluorophenyl)-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid” stereochemical variants with different azabicyclo substitution patterns. Claim 13 further adds: “7-([1α,5α,6α]-6-amino-3-azabicyclo[3.1.0]hex-3-yl)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid” The 2,4-difluorophenyl substituted analogs and p-toluenesulfonic acid salt. Claim 14 includes: A specific stereochemical core plus the hydrate form. Claim 15 includes: The same stereochemical core plus hydrochloride salt and methanesulfonic acid salt. Why these exemplars matter Even though Claim 1 is a Markush genus, enumerated claims increase enforceability in practice: They identify specific chemical structures that are easier to match to accused products and commercial candidates. They strengthen novelty/enablement positions by showing the applicant contemplated concrete embodiments within the genus. What do claims 2–5 narrow: how are R1, Y, W, and A constrained in dependent claims? Featured snippet answer: Dependent claims select particular substituent sets (R1 = H; Y = cyclopropyl or o,p-difluorophenyl; W = H; A = CH or N; and W = H with A = N), narrowing the Markush scope to subsets. R1 dependency (Claim 2) Claim 2: “wherein R1 is hydrogen.” This removes variants where R1 is a pharmaceutically acceptable cation or a (C1–C6) alkyl group (still within the genus of Claim 1). Y dependency (Claim 3) Claim 3: “wherein Y is cyclopropyl or o,p-difluorophenyl.” This narrows the allowed Y substituent list to two options. W and A dependencies (Claims 4–5) Claim 4: “wherein W is hydrogen, and A is CH or N.” Claim 5: “wherein W is hydrogen and A is N.” These are meaningful narrowing steps because W is one of several positions allowed to vary across halogens, alkyl, alkoxy, and amino/aminomethyl; setting W = H removes those alternatives. Setting A further constrains the ring substituent/atom position variability. How do claims 6–11 narrow the substituent-count rule at R3/R6/R7/R9/R10/R25? Featured snippet answer: The dependent claims operationalize the core genus constraint by limiting the number and identity of substituents at the amino-alkyl/methyl-allowed positions, including restrictions on when CH2NH2, CH2NHCH3, CH2NHC2H5, and/or methyl appear. Claim 6: one or two non-hydrogen substituents “wherein one or two of R3, R6, R7, R9, R10 and R25 are other than hydrogen.” This limits the class to mono- and di-substituted variants at those positions, excluding tri-substitution patterns. Claim 7: one specific amino-alkyl substituent plus methyl elsewhere “one of R3, R6, R7, R9, or R10 is CH2NH2 or CH2NHCH3” and “another … may be methyl.” This permits methyl co-substitution with a primary or N-methyl amino-methyl group at a selected position. Claims 8–10: combination rules including amino vs methyl Claim 8: “one of R6, R7, or R9 is NH2 or NHCH3” and “another … or one of R3, R10 or R25 may be methyl.” Claim 9: “wherein R6, R7 or R9 is amino and one of … may be methyl.” Claim 10: “wherein R7 is amino and one of … may be methyl.” These dependent claims focus on where the amino (NH2/NHCH3) functionality is located within the set and whether methyl can co-occur. Claim 11: R7 amino with all other R-set substituents as hydrogen “A compound according to claim 11 wherein R7 is amino and R3, R6, R9, R10 or R25 are each hydrogen.” (As written, the numbering appears inconsistent in the user-provided text, but the substantive limitation is clear: a single amino substitution at R7 while the rest of the set positions are hydrogen.) This defines a very narrow embodiment. What is the peptide-bond scope in claims 16–21: does the patent cover conjugates to amino acids and polypeptides? Featured snippet answer: Yes. Claims 16–21 extend Claim 1 to compounds where the amino group at R6, R7, or R9 is covalently bonded via a peptide bond to one or more amino acids (including two amino acids). Claims 16–18: one to multiple amino acids Claim 16: amino group covalently bonded through a peptide bond to one amino acid residue. Claim 17: peptide bond to a polypeptide of two or more amino acids. Claim 18: peptide bond to a polypeptide of two amino acids. Claims 19–21: same concept but anchored at R7 Claim 19: peptide bond from the amino group of R7 to one amino acid residue. Claim 20: peptide bond from R7 amino group to a polypeptide of two or more amino acids. Claim 21: peptide bond from R7 amino group to a polypeptide of two amino acids. Practical claim effect These claims capture amino-acid/peptide-linked derivatives where an amino group is converted to an amide/peptide bond rather than a free amino. This can overlap with certain prodrug-conjugate approaches and targeting conjugates depending on structure. What peptide-linked embodiments are explicitly named in claims 22–25 (L-Ala, L-Leu, L-Ala-L-Ala)? Featured snippet answer: Claims 22–25 list explicit peptide-conjugate embodiments: L-Ala (one residue), L-Ala-L-Leu (two residues), and L-Ala-L-Ala (two residues), in hydrochloride salt and free-acid form (including methanesulfonate salt in at least one option). Exemplars in the provided claims Claim 22: “7-([...]-6-(L-Ala-amino)-3-azabicyclo[3.1.0]hex-3-yl-...)-6-fluoro-1-(2,4-difluorophenyl)-... carboxylic acid, hydrochloride salt.” Claim 23: “7-([...]-6-(L-Ala-L-Leu-amino)-... carboxylic acid hydrochloride salt.” Claim 24: “7-([...]-6-(L-Ala-L-Ala-amino)-... carboxylic acid, hydrochloride salt, or ... methanesulfonic acid salt.” Claim 25: “7-([...]-6-(L-Ala-L-Ala-amino)-... carboxylic acid” (free acid form). Claim interpretation These are direct structure claims that reduce the burden of arguing coverage through Markush alone. They also expand the scope beyond generic “prodrugs” by expressly covering peptide-bonded amino replacements. What do claim 26 and claim 27 cover: antibacterial compositions and methods of treatment? Featured snippet answer: Claim 26 is an antibacterial composition claim with a compound of Claim 1 plus a pharmaceutically acceptable carrier. Claim 27 is a treatment method for bacterial infection using an antibacterially effective amount of a Claim 1 compound. Claim 26: composition “An antibacterial composition comprising an antibacterially effective amount of a compound according to claim 1 and a pharmaceutically acceptable carrier.” No dosage form is limited in the claim language provided (it is a typical carrier-based composition claim). Claim 27: method-of-treatment “A method for the treatment of a bacterial infection … administering … an antibacterially effective amount of a compound according to claim 1.” No limitation to route (oral, parenteral) or dosing regimen appears in the provided text. What is the practical patent landscape around US 5,164,402: what likely surrounds this compound genus? The provided prompt includes claim text but not bibliographic data (assignee, priority date, publication date, related family members), and it does not provide any cited documents or Orange Book/FDA linkage. With only claim scope in hand, the landscape can be analyzed only at the claim-family level that is implied by the claim structure itself. Claim-family breadth implied by the claim set US 5,164,402 already reaches across multiple derivative classes: salts (acid addition), hydrates (explicit for an exemplar), prodrugs (functional “free amino groups” trigger), peptide conjugates (amino acid residues and dipeptides), compositions and methods. Landscape implication for freedom-to-operate (FTO) Any competitor product that is: structurally within the formula I genus, uses an acid addition salt form, deploys a prodrug mapping to an amino-bearing formula I parent, or uses peptide-linked amino substitutes (at R6/R7/R9 positions), would likely face direct claim exposure. If the competitor stays outside formula I by changing the scaffold, the main enforcement risk shifts to whether other patents in the same family cover alternative scaffolds, stereochemistry sets, or specific substituents. Because no assignee or family member data is provided, no defensible list of additional US patents, jurisdictions, or litigated entities can be produced from the prompt alone. When does this patent lose exclusivity in the US: what is the expiration driver for US 5,164,402? No priority date, filing date, or patent term adjustment data is included in the prompt, so a specific expiration date cannot be computed from the provided information. Key Takeaways Claim 1 is a broad genus built on a substituted 1,8-naphthyridine-3-carboxylic acid scaffold with constrained variability at R1, Y, W, A, and the amino-alkyl/methyl substituent set at R3/R6/R7/R9/R10/R25. The numeric substitution rule matters: no more than three non-hydrogen substituents among {R3, R6, R7, R9, R10, R25}, and if three are non-hydrogen, at least one must be methyl. Dependent claims narrow the genus to subsets where R1=H, Y is limited, W=H, and A is limited to CH or N, with further narrowing on where amino and methyl substituents can appear. Prodrugs and peptide conjugates are explicitly covered, with peptide-bonded amino acid and dipeptide embodiments named (L-Ala; L-Ala-L-Leu; L-Ala-L-Ala) including hydrochloride and methanesulfonate salts in the examples. Enforcement hooks include named exemplars and multiple salt/hydrate forms, plus use claims for antibacterial compositions and bacterial infection treatment. FAQs 1) Does US 5,164,402 claim include only freebase compounds or also acid addition salts? It expressly includes pharmaceutically acceptable acid addition salts of formula I compounds and includes specific salt embodiments (hydrochloride, methanesulfonate, p-toluenesulfonate) and a hydrate for at least one exemplar. 2) Are prodrugs limited to a specific pro-moiety in claim 1? No specific pro-moiety is stated in the provided claim text. Coverage is defined by the functional condition that the prodrugs are of formula I compounds that have free amino groups. 3) Can the patent reach peptide-linked derivatives where an amino group is converted to a peptide bond? Yes. Claims 16–21 cover covalent peptide-bond linkage of amino groups (at R6/R7/R9, or specifically at R7) to one amino acid and polypeptides of two or more amino acids, including two amino acids. 4) What does the “not more than three” substituent constraint mean for design-around? It restricts how many positions among R3/R6/R7/R9/R10/R25 can be non-hydrogen. Tri-substituted patterns require at least one methyl among those non-hydrogen substituents. 5) Does the patent restrict use to particular pathogens or routes of administration? No. The provided method claim is broadly “for the treatment of a bacterial infection” with an “antibacterially effective amount,” without specifying pathogens or route. References US Patent 5,164,402. “(Claims provided in prompt text.)” United States Patent and Trademark Office. More… ↓ ⤷ Start Trial

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0413455	⤷ Start Trial	SPC/GB98/045	United Kingdom	⤷ Start Trial
European Patent Office	0413455	⤷ Start Trial	SPC/GB98/046	United Kingdom	⤷ Start Trial
European Patent Office	0413455	⤷ Start Trial	98C0039	Belgium	⤷ Start Trial
European Patent Office	0413455	⤷ Start Trial	98C0040	Belgium	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 5,164,402