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Patent landscape, scope, and claims: |
US Patent 4,844,902 (Drug): Scope, Claims, and US Patent Landscape
What does US 4,844,902 claim at the formulation level?
US 4,844,902 claims topically applicable antibacterial formulations that combine (i) an antibacterially active compound of a defined chemical formula at specific weight ranges, (ii) a corticosteroid at specific weight ranges, and (iii) a carrier. The claimed scope is broad on dosage form and materials, and it is anchored by a structured genus definition for the antibacterial actives and for the chemical substituent patterns.
Claim 1: Core combination claim (broadest independent)
Claim 1 is a composition claim that requires all of the following:
1) Antibacterially active compound
- Present at about 0.05 to 30% by weight of an antibacterially active compound of formula (defined as “formula ##STR6##”).
- The claim then defines multiple substitution variables that define a large chemical genus. Variables explicitly recited include:
- R1 (examples): methyl, ethyl, propyl, isopropyl, cyclopropyl, vinyl, 2-hydroxyethyl, 2-fluoroethyl, methoxy, amino, methylamino, dimethylamino, ethylamino, phenyl, 4-fluorophenyl, 2,4-difluorophenyl.
- R2: hydrogen, alkyl (1 to 4 C), or (5-methyl-2-oxo-1,3-dioxol-4-yl)-methyl.
- R3: methyl or a cyclic amino group of formula ##STR7## (further defined through R4-R8).
- R4: H, alkyl (1 to 4 C), 2-hydroxyethyl, allyl, propargyl, 2-oxopropyl, 3-oxobutyl, phenacyl, formyl, CFCl2-S-, CFCl2-SO2-, CH3O-CO-S-, benzyl, and another structural placeholder ##STR8##.
- R5: H or methyl.
- R6: H, alkyl (1 to 4 C), phenyl, or benzyloxymethyl.
- R7: H, amino, methylamino, ethylamino, aminomethyl, methylaminomethyl, ethylaminomethyl, dimethylaminomethyl, hydroxyl, hydroxymethyl.
- R8: H, methyl, ethyl, or chlorine.
- X: H, fluorine, chlorine, or nitro.
- A: N or C-R9.
- R9: H, halogen (fluorine or chlorine), methyl, nitro; or A, together with R1 can form a bridge with a further structure ##STR9##.
2) Corticosteroid
- Present at 0.01 to 10% by weight.
3) Carrier
- The claim is not limited by a carrier composition in Claim 1 beyond requiring “a carrier” for topical application.
Claim construction implication (practical): Claim 1 reads as a combination claim where the “infringement hinge” is whether the antibacterial component falls within the stated genus (substitution patterns and bridging possibilities), and whether the formulation contains 0.01-10% corticosteroid and 0.05-30% antibacterial active in a topical carrier.
Which additional claims narrow formulation and delivery form?
From Claim 2 onward, the patent layers specificity on:
- Which actives (specific antibacterial and corticosteroid lists)
- How the formulation is presented (solution/spray/gel/ointment/cream/etc.)
- Quantitative composition requirements (polymer, solvent, plasticizer ranges)
- Carrier chemistry (specific gel-forming agents and stabilizers)
- Particle size and solids content (for suspensions)
- Solvent lists (for solutions)
Claim 2: Antibacterial and corticosteroid selection lists (narrower but defined)
Claim 2 narrows Claim 1 by specifying:
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Antibacterially active selected from:
ciprofloxacin, norfloxacin, perfloxacin, amifloxacin, pirfloxacin, ofloxacin, enoxacin.
-
Corticosteroid selected from a long enumerated list including (as written in the claim):
beclomethasone dipropionate; clobetasol propionate; diflucortolone valerate; fluocinolone acetonide; betamethasone benzoate; betamethasone dipropionate; betamethasone valerate; desonide; desoxymethasone; diflorasone diacetate; diflucortolone valerate; fluclorolone acetonide; fluocinolone acetonide; fluocinonide; fluocortolone; fluprednidene (fluprednylidene) acetate; flurandrenolone; halcinonide; hydrocortisone butyrate; triamcinolone acetonide; clobetasone butyrate; flumethasone pivalate; fluocinolone acetonide; fluocortine butyl ester; fluocortolone; flurandrenalone; hydrocortisone (urea); dexamethasone; hydrocortisone (alcohol or acetate); methylprednisolone, among others in the claim text.
Claim 3: Dosage-form presentation (still broad)
Claim 3 specifies topical forms including:
- solution, spray, lotion, gel, ointment, cream, powder, dusting powder spray, paste, suspension, emulsion, foam.
Claim 4: Polymer/solvent composition window with “water-miscible solvent” rule
Claim 4 requires (by weight):
- 0.1 to 20% active compound of formula I
- 0.01 to 10% corticosteroid
- 1 to 40% water-soluble gel-forming or lacquer-forming polymer
- 40 to 98% organic water-miscible solvent that evaporates faster than water and in which the polymer does not dissolve
- 0.1 to 10% at least one additive chosen from: plasticizer, suspending auxiliary, antioxidant, spreading agent, dyestuff
Claim 5: Alternative composition window (different solvent/polymer balance)
Claim 5 requires (by weight):
- 0.1 to 5% active compound
- 0.02 to 5% corticosteroid
- 1 to 20% water-soluble gel/lacquer polymer
- 60 to 90% organic water-miscible solvent that evaporates faster than water and where polymer does not dissolve
- 0.1 to 10% additive category (same as Claim 4)
Claim 6-8: Spreading and gel carrier chemistry
- Claim 6: further containing a spreading agent.
- Claim 7: gel form; carrier’s gel-forming agent includes cellulose ether, polyacrylic acid, polymethacrylic acid, sodium alginate, propylene glycol alginate, sodium amylopectin semiglycolate, alginic acid, gum arabic, or guar gum.
- Claim 8: gel-forming system further includes a linear high molecular weight polysaccharide as stabilizing agent.
Claim 9: Suspension constraints (particle size and solids)
- Gel/solution not required; Claim 9 covers a suspension with:
- solid particles 0.1 to 100 μm
- solids content about 0.5 to 40% by weight
Claim 10-11: Emulsion and solution solvent list
- Claim 10: composition in the form of an emulsion.
- Claim 11: solution form where carrier includes at least one solvent selected from:
ethanol; isopropyl alcohol; propylene glycol; polyethylene glycol; glycerol; methylcellosolve; cellosolve; an ester; morpholine; dioxane; dimethylsulphoxide; water; cyclohexanone.
What is the claim “scope map” for infringement risk?
A product only needs to meet one claim’s full set of limitations to fall within that claim. Practically, the landscape divides into three infringement “buckets” aligned to the dependent claims.
Bucket A: Must-have genus active + corticosteroid + carrier (Claim 1)
- If your antibacterial active is a member of the genus defined by the nested R1-R9 and bridging allowances of formula ##STR6##, you are in Claim 1 territory.
- Then you must also formulate topically with 0.01-10% corticosteroid and about 0.05-30% antibacterial active.
Bucket B: Specific fluoroquinolone + listed corticosteroid (Claim 2)
- If the antibacterial is one of: ciprofloxacin, norfloxacin, perfloxacin, amifloxacin, pirfloxacin, ofloxacin, enoxacin, and the steroid is one listed in Claim 2, you fall into Claim 2 even if you use a wide variety of topical carriers, assuming topical applicability and Claim 1 carrier requirement are met.
Bucket C: Formulation architecture constraints (Claims 4-5, 7-9, 11)
These depend on product details:
- Polymer type and solvent behavior (Claims 4-5)
- Gel-former chemistry (Claim 7)
- Stabilizer (Claim 8)
- Particle size and solids (Claim 9)
- Emulsion format (Claim 10)
- Solution solvent selection (Claim 11)
How broad is the chemistry and how does it affect design-around?
Broad elements
1) Antibacterial genus
Claim 1’s formula-based genus is the broadest lever. It explicitly allows multiple substitution patterns across R1-R9, including halogenated and nitro substituents (X), and an additional bridging option “together with R1 can also form a bridge with the structure ##STR9##.”
2) Wide topical dosage forms
Claim 3 enumerates many common topical formats.
3) Carrier diversity
Claim 1 is “carrier” only; later claims define specific carrier types and subcomponents, but they do not eliminate the possibility of other carriers outside those dependent claims.
Narrow elements (where design-around tends to fail)
1) Corticosteroid window
Both Claim 1 and the formulation architecture claims require 0.01 to 10% corticosteroid.
2) Quantitative polymer/solvent constraints
Claims 4 and 5 define high solvent fractions (40-98% or 60-90%) plus evaporative behavior (“evaporates faster than water”) and polymer insolubility in that solvent. These are precise constraints that can be avoided only if the product stays outside the polymer-solvent design space.
3) Solution solvent list (Claim 11)
If a competitor uses a solution, Claim 11 is keyed to the named solvents. Avoiding those solvents can remove that dependent claim, though Claim 1 could still remain implicated.
What is the patent landscape impact in the US based on this claim set?
The information provided is limited to the claims text of US 4,844,902. A complete US landscape normally requires family member identification, priority dates, expiration status, prosecution history, and citation mapping across citing/cited documents. That information is not present here.
What can be stated from the claim text itself is the likely landscape posture:
- The patent is not limited to a single dosage form and is not limited to a single antibacterial/corticosteroid pairing.
- It is structurally capable of covering multiple fluoroquinolone actives and multiple corticosteroids via dependent claims (Claim 2 list).
- It also covers common topical vehicle architectures (gel, suspension, emulsion, solution), and it defines specific gel-former chemistries and solvent ecosystems.
In business terms, US 4,844,902 functions as a combination barrier around:
- topical co-formulations of a defined fluoroquinolone-like antibacterial genus with corticosteroids in defined ranges, and
- at least some vehicle systems that match polymer plus fast-evaporating water-miscible solvent constraints.
Where are the most actionable “scope boundaries” for product strategy?
High-probability boundaries to test in freedom-to-operate
- Corticosteroid dose: must remain outside 0.01-10% if avoiding Claim 1 and its dependent formulations.
- Antibacterial dose: must remain outside 0.05-30% for Claim 1, outside dependent claim ranges like 0.1-5% or 0.1-20% for Claims 4-5 if you are in those architecture windows.
- Active identity vs genus: if your antibacterial is one of the enumerated fluoroquinolones in Claim 2, Claim 2 is directly implicated if corticosteroid is also enumerated and the rest of Claim 1 elements are met.
- Vehicle system selection:
- Gel-former selection: avoid listed cellulose ether/polyacrylic/polymethacrylic/sodium alginate derivatives, etc., if you want to exit Claim 7-8.
- Suspension particle size and solids: if you are a suspension, particle size and solids must be outside 0.1-100 μm and 0.5-40%.
- Solution solvents: avoid the specific solvent list in Claim 11 if your product is a solution.
- Polymer/solvent constraints: avoid the polymer-plus-fast-evaporating-water-miscible-solvent with polymer insolubility criteria in Claims 4-5.
Key Takeaways
- US 4,844,902 Claim 1 is a broad topical combination claim: about 0.05 to 30% antibacterial of formula ##STR6## + 0.01 to 10% corticosteroid + a carrier.
- Claim 2 locks in a direct product-relevance subset: ciprofloxacin, norfloxacin, perfloxacin, amifloxacin, pirfloxacin, ofloxacin, enoxacin paired with a long enumerated corticosteroid list.
- Claims 4-5 add stringent formulation architecture constraints via polymer fraction, high fast-evaporating water-miscible solvent fraction, polymer insolubility, and additive ranges.
- Claims 7-9 and 11 narrow scope by carrier chemistry (gel formers), stabilizers, suspension particle size/solids, and solution solvent selection.
- The claim set is structured for wide topical dosage-form coverage, so product format alone (gel vs cream vs solution vs suspension vs emulsion) does not eliminate risk unless the formulation also exits the relevant dependent-claim limitations.
FAQs
1) Does Claim 1 require a specific corticosteroid structure?
Yes. Claim 1 requires a corticosteroid present at 0.01 to 10% by weight, but it does not limit corticosteroid identity in Claim 1; the identity constraints appear in Claim 2.
2) Is the antibiotic scope in Claim 1 limited to a single compound?
No. Claim 1 defines a formula-based genus with multiple substitution variables (R1-R9, X, A), and dependent Claim 2 lists specific fluoroquinolones.
3) If I make a gel, is the patent necessarily implicated by the gel-forming claims?
Not necessarily. Claim 7-8 impose specific gel-forming agents and stabilizing polysaccharides, but a gel product can still be implicated under Claim 1 if it meets the combination requirements.
4) Do Claims 4 and 5 require a particular solvent behavior?
Yes. They require an organic water-miscible solvent that evaporates faster than water and in which the polymer does not dissolve, with specific fraction ranges.
5) What is the fastest route to reducing infringement exposure in this claim set?
To reduce exposure, the most direct approach is to control the corticosteroid percentage relative to 0.01-10%, and to ensure the antibacterial active and/or vehicle architecture remain outside the defined claim ranges or lists in the relevant dependent claims.
References
[1] US Patent 4,844,902, “Topically applicable antibacterial formulations comprising a corticosteroid.” Claims 1-11 (as provided).
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