Scope of US Patent 6,458,836 (process for long-term glaucoma/ocular hypertension management with prostaglandin-related compounds that reduce iris pigmentation)
US Patent 6,458,836 claims a topical-ophthalmic, long-duration treatment regimen (at least once daily for at least six months) using a defined “prostaglandin related compound” structural class, where the claimed “improvement” is elimination or reduction of potential iris pigmentation caused by long-term prostaglandin-related ocular therapy. Dependent claims narrow to particular compound sub-classes (including specific named analogs) and to dosing cadence (twice daily), with additional patient demographic limitation (Caucasian) appearing in dependent claims.

What is US Patent 6,458,836 and what does it claim?

Quick answer (claim scope): The patent is directed to a process (method of treatment/prophylaxis) for ocular hypertension or glaucoma using topical ocular administration of a prostaglandin-related compound for ≥6 months, with an asserted improvement to eliminate or reduce iris pigmentation that can occur with long-term prostaglandin-related therapy.

Core independent claim construct (Claims 1, 13, 22)

Each of the independent claims follows the same architecture:

Indication: ocular hypertension or glaucoma.
Route: topical ocular administration to a human patient.
Dosing duration: at least once a day (or later dependent “twice daily” limits) for at least six months.
Agent: a therapeutically effective amount of a prostaglandin related compound defined by a broad formula scaffold (labeled (I), (III), (IV) in your claim recitations).
Claimed improvement: “eliminate or reduce potential pigmentation of the iris” from long-term application.

Claimed compound class is structural and very broad

The formula language (I)/(III)/(IV) is open-ended in several dimensions:

Core prostaglandin-like five-membered ring (may contain at least one double bond).
Variable heteroatom positions: W1/W2/W3 are carbon or oxygen.
Substituent variability: L, M, N are hydrogen, hydroxy, halogen, lower alkyl, lower alkoxy, hydroxy(lower)alkyl, or oxo, with at least one of L and M being not hydrogen.
Side-chain/alpha alcohol or acid functionality: A is CH2OH, COCH2OH, COOH, or functional derivative.
Linker B includes multiple unsaturation and chain-length options (single bond up to alkynyl and alkenyl motifs).
Omega-chain residues:
- R1 is a saturated/unsaturated lower to medium aliphatic bivalent residue, unsubstituted or substituted with varied groups (halogen, alkyl, hydroxy, oxo, aryl, heterocycle, etc.).
- Ra (and in claim 13, Z/Ra′) describes a “lower or medium” residue beyond a carbon number (notably beyond C15 in claim 13/16/18/19 dependent narrowing), with heavy flexibility including aryl/heterocycle/heterocyclic-oxy at the terminus.

The practical effect is that the claims target a family of prostaglandin-related analogs with specific functional chemistry (A and optional derivatives) and specific end-cap omega-chain features.

What parts of the claim are legally meaningful for infringement and validity?

Quick answer: The legal leverage sits in the (i) regimen duration, (ii) topical dosing frequency, (iii) “prostaglandin related compound” structural class, and (iv) the asserted iris pigmentation improvement. Dependent claims narrow those dimensions further using specific named compounds and specific chain-length/terminus features.

Regimen: “at least once a day for at least six months”

That time-and-frequency limitation is a core differentiator from many prostaglandin analog method patents that claim short-term reduction of IOP. Here, the claim is long-term/prophylactic management, explicitly tied to the pigmentation phenomenon.

Independent claims: once daily for ≥6 months.
Dependent claims: explicitly twice daily for ≥6 months (Claims 10, 20, 24).

Improvement: “eliminate or reduce potential pigmentation of the iris”

This is a treatment benefit embedded in the claim text. In practical patent-claim scope terms, it can be interpreted as requiring that the claimed prostaglandin-related compound, when used in the claimed regimen, yields that result.

Compound definition: formula scaffolds (I)/(III)/(IV) + functional derivatives

The structural formulas are broad but still impose a chemical genus. Dependent claims then select specific embodiments.

Which dependent claims narrow to specific drugs or sub-classes?

Below are the principal dependent claims as provided, mapped to what they narrow.

Dependent claims that name specific compounds (explicit embodiments)

Claim 4: “13,14-dihydro-15-keto-20 ethyl PGF2α isopropyl ester.”
Claim 5: “15-keto latanoprost.”
Claim 6: “15-keto-17-phenyl-18,19,20-trinor PGF2α N-ethylamide.”
Claim 7: “13,14,dihydro-15-keto 17-phenyl-18,1920-trinor PGF2α N-ethylamide.”
Claim 8: “15-keto-16-(3-trifluoromethyl phenoxy)-17,18,19,20-tetranor PGF2α isopropyl ester.”
Claim 9: “13,14-dihydro-15-keto-16-(3-trifluoromethyl phenoxy)-17,18,19,20-tetranor PGF2α isopropyl ester.”

These named compounds fall within the broader “prostaglandin related compound” structural genus of Claims 1/13/22.

Dependent claims that constrain delivery schedule

Claim 10: once daily claim basis, narrows to twice daily for ≥6 months.
Claim 20: for claim 13, narrows to twice daily for ≥6 months.
Claim 24: for claim 22, narrows to twice daily for ≥6 months.

Dependent claims that constrain patient population (demographic)

Claim 11: human patient is Caucasian.
Claim 21: patient is Caucasin (typo in recitation; treated as “Caucasian”).
Claim 25: patient is Caucasian.

These demographic limitations can affect the practical enforcement posture because infringement of a demographic-locked method claim typically requires evidence that the treated patient belongs to the limited population.

Dependent claims that constrain compound structural features: omega-chain length and terminus

Claim 12: compound contains a 15-keto substituent and an omega chain containing a phenyl ring.
Claim 16: compound used contains a straight chain beyond carbon atom number 15 of at least 6 carbon atoms.
Claim 17: compound used is a docosanoid.
Claim 18: omega chain beyond carbon atom number 15 of at least 3 carbon atoms substituted by cyclo(lower)alkyl / cyclo(lower)alkyloxy / aryl / aryloxy / heterocyclic / heterocyclic-oxy at the terminus.
Claim 19: terminus substituted by phenyl.

Dependent claims that define A as derivatives and further constrain amides

Claim 2: functional derivative of A is salts, ethers, esters, or amides.
Claim 3: amide of A: —CONR′R″ where each substituent can be hydrogen, lower alkyl, aryl, alkyl- or aryl-sulfonyl, lower alkenyl, lower alkynyl.

These are chemistry constraints but remain broad in terms of allowed substituents.

How broad is the patent’s chemical genus versus specific embodiments?

Quick answer: The independent claims describe a broad chemical genus using formula variables that allow multiple substitution patterns and side-chain options. The named compounds in dependent claims provide anchor points for interpretation and for infringement comparisons.

Genus breadth indicators in your recitation

W1/W2/W3 can be oxygen or carbon.
L/M/N allow varied functional groups (hydroxy, halogen, alkyl, alkoxy, oxo).
“At least one of L and M” is non-hydrogen: still allows many combinations.
B includes many unsaturation patterns.
Ra/Ra′/R1 allow substitution with aryl and heterocyclic groups.

Narrowing indicators

“Straight chain beyond carbon number 15” length constraints in Claims 16–18.
“Docosanoid” classification in Claim 17 (functionally narrowing, since docosanoids typically map to C22 docosa skeleton motifs).
“Phenyl ring at terminus” in Claims 12 and 19.

What does the patent likely cover in practice (product-level mapping)?

Quick answer: From the claim set you supplied, the patent is positioned to cover long-term topical therapy that uses modified prostaglandin (or prostaglandin-related) analogs designed to reduce iris pigmentation risk versus traditional prostaglandin analogs.

The explicit drug-like exemplars named in dependent claims align with analogs that share a prostaglandin motif but differ in:

ketone substitutions (“15-keto”),
“trinor/tetranor” truncations,
omega-chain terminus modifications (phenyl or phenoxy substituents),
and amide/ester choices for A derivatives.

What patent landscape findings can be made from the claim text alone?

No complete, accurate landscape can be produced from claim text alone. The provided material contains no bibliographic data (filing date, priority, assignee, continuations, prosecution history, cited art), no expiration term calculation inputs, and no Orange Book/FDA linkage identifiers.

Because of those missing elements, only claim-scope observations can be made. A full landscape (other patents in the family, competitor estates, litigation, or regulatory exclusivity status) would be speculative.

Claim-by-claim “scope map” (based on your recitation)

Independent claims

Claim	Treatment target	Dosing regimen	Agent limitation	Pigmentation improvement
1	ocular hypertension or glaucoma	topical ocular, ≥ once daily, ≥ 6 months	prostaglandin related compound with formula (I)	eliminate/reduce iris pigmentation
13	same	same	prostaglandin related compound with formula (III), includes Z/Ra′ structure	eliminate/reduce iris pigmentation
22	same	topical ocular, ≥ once daily, ≥ 6 months	prostaglandin related compound with formula (IV)	eliminate/reduce iris pigmentation

Key dependent narrowing claims (from your recitation)

Claim	Narrowing feature	What it does to scope
2	A derivative = salts/ethers/esters/amides	permits broader formulation forms for A
3	A amide substituent limits	constrains amide N-substituents
4–9	named compounds	locks onto specific exemplars inside genus
10, 20, 24	twice daily for ≥ 6 months	narrows dosing frequency
11, 21, 25	Caucasian patient	limits method reach by patient class
12	15-keto + omega chain phenyl	narrows omega-chain terminus
16–19	omega-chain length and terminus substitutions + “docosanoid”	narrows the chemical genus to longer-chain and aryl/heterocyclic end-caps

Key takeaways

US 6,458,836 is a long-term topical method-of-treatment patent for ocular hypertension/glaucoma, where the claimed agent class is selected to eliminate or reduce iris pigmentation after ≥6 months of daily dosing.
The infringement “center of gravity” is (i) regimen duration, (ii) once/twice-daily cadence, and (iii) whether the administered active is within the prostaglandin-related structural formulas (I)/(III)/(IV).
Dependent claims add enforceable narrowing using named analogs, omega-chain length/terminus features, and (in some claims) Caucasian patient status.

FAQs

1) Does US 6,458,836 cover only iris pigmentation reduction versus IOP lowering?
The independent claims require the iris pigmentation elimination/reduction improvement as part of the claimed process, tied to long-term (≥6 months) topical prostaglandin-related therapy.

2) What is the difference between the independent claim chemical definitions in formulas (I), (III), and (IV)?
They differ in the way the omega-chain and substituent variables are expressed (notably the inclusion of additional structural elements in (III) via Z/Ra′ and in (IV) via defined R′/R″ and other variable groupings), while keeping the same regimen and pigmentation improvement framework.

3) Can a generic product avoid infringement by changing ester/amide forms of A?
Claim 2/3 explicitly include A functional derivatives, including salts/ethers/esters/amides and a further-defined amide substitution formula in Claim 3, so avoiding infringement requires moving outside the claimed A derivative definition and/or outside the genus structural limits of the relevant formula.

4) Do twice-daily regimens expand or narrow the patent’s protection?
They narrow. Claims 10/20/24 are dependent and add a specific twice-daily dosing limitation on top of the independent regimen framework.

5) How critical is the “Caucasian” limitation in dependent claims?
It narrows the method claim coverage to that patient class where the dependent claim is asserted; enforcement on a demographic-limited method can hinge on proof of the patient population treated.

References

User-provided claim text for US Patent 6,458,836 (claims 1–25, as recited in the prompt).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	029818	⤷ Start Trial
Australia	2001241143	⤷ Start Trial
Australia	4114301	⤷ Start Trial
Brazil	0109192	⤷ Start Trial
Canada	2402597	⤷ Start Trial
China	100506232	⤷ Start Trial
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Details for Patent: 6,458,836

Summary for Patent: 6,458,836