US Patent 4,599,353 (United States Drug Patent): Scope, Claim Coverage, and U.S. Landscape
What does US 4,599,353 claim, in plain technical terms?
US Patent 4,599,353 claims topical ophthalmic methods and compositions that reduce intraocular pressure (IOP) in a primate (including humans) by periodically contacting the ocular surface with eicosanoids or derivatives, with an emphasis on PGF2α and lower-alkyl ester derivatives (C1 to C5), using dosing approaches designed to avoid an initial IOP increase.
The claims fall into three tight buckets:
- Method claims: topical application to reduce IOP without substantial initial increase and to maintain reduced IOP.
- Compound specificity: focuses on prostaglandins, particularly PGF2α and C1 to C5 alkyl esters.
- Formulation and dosing specificity: daily dosing; dose ranges; carrier options (including peanut oil and mineral oil); concentration by weight.
What is the core independent claim scope (Claim 1)?
Claim 1 is the main scope anchor:
- Subject: “a primate subject’s eye”
- Indication: “treating hypertension or glaucoma”
- Mechanism (functional): topical contact reduces IOP
- Safety/behavioral condition: “without any substantial initial increase” in said pressure
- Outcome durability: “maintain reduced intraocular pressure”
- Administration pattern: “periodically contacting the surface of the eye”
- Active class: “an eicosanoid or an eicosanoid derivative”
Claim 1 coverage map
| Dimension |
Claim 1 requirement |
Practical implication for infringement analysis |
| Route |
Topical contact of ocular surface |
Must be topical ocular (not systemic) |
| Target |
IOP reduction in primates |
Not limited to glaucoma drugs alone in text; includes “hypertension” |
| “No substantial initial increase” |
Functional limitation on IOP response curve |
Product must avoid early IOP rise meaningfully |
| Actives |
Eicosanoid / derivative |
Broad class, later claims narrow to prostaglandins / PGF2α esters |
| Timing |
“Periodically” |
Not limited to daily, though later dependent claims specify daily |
How do the dependent claims narrow the active ingredient?
From Claim 1, the patent narrows stepwise:
Prostaglandin restriction (Claim 3)
Claim 3: eicosanoid or derivative is a prostaglandin or prostaglandin derivative.
PGF2α restriction (Claims 5–10)
- Claim 5: prostaglandin derivative is PGF2α (or a derivative)
- Claim 6: PGF2α derivative is a C1 to C5 alkyl ester
- Claim 7: enumerated ester examples:
- PGF2α methyl ester
- PGF2α ethyl ester
- PGF2α isopropyl ester
- PGF2α isobutyl ester
- Claim 9: physiologically acceptable salt of PGF2α
- Claim 10: salt example: PGF2α tromethamine
Functional/chemical alternatives are built into the claim set
The patent creates two non-overlapping “chemical lanes” under PGF2α:
- Lane A (esters): C1–C5 lower alkyl ester derivatives (Claims 6–8)
- Lane B (salts): physiologically acceptable PGF2α salts (Claims 9–10)
If a product uses a PGF2α salt, it can land in the salt sub-scope. If it uses a lower alkyl ester, it lands in ester sub-scope. If it uses another PGF2α derivative outside these categories, it falls outside those dependent claim limitations.
What is the dosing and administration scope?
Frequency (Claim 2 and Claim 15)
- Claim 2: surface contacted daily
- Claim 15: daily contact with about 50 μl of a composition of Claim 14
The patent therefore has two frequency levels:
- “Periodically” (Claim 1) is broader.
- “Daily” is narrower (Claim 2, Claim 15).
Dose amount range (Claims 11–12)
- Claim 11: prostaglandin/prostaglandin derivative amount 0.01 μg to 1,000 μg
- Claim 12: narrower subrange 0.1 μg to 500 μg
These are dose-quantity limits for the active used in the method context (Claim 1 → 3 → 11 → 12 progression).
Composition unit volume (Claim 15)
- Claim 15: about 50 μl of a composition where the active is a “lower alkyl ester of PGF2α”
So the patent ties together:
- A specific daily administration regime
- A typical ocular dosing volume
- A specified active chemical subclass (Claim 14)
What compositions are claimed (Claims 13–19)?
The composition claims define topical ophthalmic formulations.
PGF2α methyl/ethyl/isopropyl/isobutyl ester composition (Claim 13)
- Active: PGF2α methyl ester or PGF2α ethyl ester or PGF2α isopropyl ester or PGF2α isobutyl ester
- Form: dissolved in an ophthalmically compatible carrier
- Indication: “topical treatment of glaucoma”
This claim is tighter than Claim 14 because it enumerates specific ester identities.
Generic lower-alkyl ester composition (Claim 14)
- Active: “a lower alkyl ester of PGF2α”
- Structure constraint: implied by later dependent claims (Claim 16 says C1–C5)
- Dissolved in an ophthalmically compatible carrier
Dose-volume and administration linking (Claim 15)
Claim 15 ties Claim 14 to a daily method:
- Daily contact
- About 50 μl applied
Ester chain-length (Claim 16)
- Lower alkyl ester is C1 to C5
Carrier exemplars (Claims 17–18)
- Carrier examples:
- sterile anhydrous peanut oil
- sterile mineral oil
This creates a narrow but explicit infringement anchor: products using those carriers can be more straightforward to map. The patent text still keeps Claim 14 broader with “ophthalmically compatible carrier,” but the dependent claims lock in specific carrier options.
Concentration by weight (Claim 19)
- Effective amount: 0.01% to 1.0% by weight
This is a formulation concentration limiter within the composition claim lineage.
Claim-by-claim scope matrix (coverage and limiting conditions)
| Claim |
Category |
Key scope elements |
Built-in limitations that narrow or control infringement |
| 1 |
Method |
Periodic topical ocular contact; eicosanoid/derivative; reduce IOP; no substantial initial IOP increase; maintain reduced IOP; primate; treat hypertension or glaucoma |
Functional “no substantial initial increase” and “maintain reduced IOP”; primate; topical |
| 2 |
Dependent method |
Daily contact |
Frequency limited to daily |
| 3 |
Dependent method |
Active is prostaglandin/prostaglandin derivative |
Narrows from any eicosanoid to prostaglandin class |
| 4 |
Dependent method |
Prostanglandin is PGE2 or derivative |
Specific to PGE2 line (not PGF2α) |
| 5 |
Dependent method |
Prostaglandin is PGF2α or derivative |
Locks to PGF2α line |
| 6 |
Dependent method |
PGF2α derivative is C1–C5 alkyl ester |
Restricts to lower-alkyl esters |
| 7 |
Dependent method |
Specific esters: methyl/ethyl/isopropyl/isobutyl |
Enumeration narrows to 4 ester identities |
| 8 |
Dependent method |
Derivative is lipid soluble |
Additional functional/chemical property limiter |
| 9 |
Dependent method |
Derivative is physiologically acceptable PGF2α salt |
Alternative chemical form lane vs esters |
| 10 |
Dependent method |
Salt is PGF2α tromethamine |
Enumeration narrows to one salt |
| 11 |
Dependent method |
Dose range 0.01 μg to 1,000 μg |
Active quantity range |
| 12 |
Dependent method |
Dose range 0.1 μg to 500 μg |
Narrower quantity range |
| 13 |
Composition |
PGF2α methyl/ethyl/isopropyl/isobutyl esters in ophthalmically compatible carrier |
Enumerated actives + glaucoma-only |
| 14 |
Composition |
Lower alkyl ester of PGF2α in ophthalmically compatible carrier |
Keeps actives generic; carrier compatible |
| 15 |
Method |
Daily contact; about 50 μl of Claim 14 composition |
Volume and frequency fixed; method ties to composition |
| 16 |
Dependent composition |
Lower alkyl ester is C1–C5 |
Restates ester chain length limitation |
| 17 |
Dependent composition |
Carrier: sterile anhydrous peanut oil |
Specific carrier |
| 18 |
Dependent composition |
Carrier: sterile mineral oil |
Specific carrier |
| 19 |
Dependent composition |
Effective amount 0.01% to 1.0% w/w |
Concentration range |
What is the practical patent “shape” of this family?
Even without file-history details, the claim architecture indicates a classic early ophthalmic PGF2α-derivative strategy:
- A broad functional method claim (Claim 1) tied to a specific therapeutic effect profile (IOP reduction without early IOP spike).
- Narrower dependent method claims that pin down:
- prostaglandin class
- PGF2α focus
- derivative chemical form (lower alkyl esters and/or salts)
- dose ranges and frequency
- A matching composition claim set that covers:
- specific lower alkyl ester identities (Claim 13)
- generic C1–C5 ester formulations (Claim 14 + Claim 16)
- selected oil carriers (Claim 17–18)
- concentration range (Claim 19)
- A method that operationalizes the composition (Claim 15: 50 μl daily).
This combination tends to give the patent enforceable coverage across:
- product formulations that use the enumerated actives and carriers, and
- method-of-use for the dosing paradigm that avoids the early IOP increase.
How does this impact the U.S. patent landscape (freedom-to-operate lens)?
Enforcement pressure points
-
PGF2α lower alkyl ester topical formulations
Claims 13 and 14 + 15 + 16 are the most direct coverage for modern competitor compounds if any use these specific ester forms and concentrations/carriers.
-
Carrier choice matters only where dependent claims are invoked
Claim 14 is broader (“ophthalmically compatible carrier”), but the dependent carrier claims are explicit:
- sterile anhydrous peanut oil (Claim 17)
- sterile mineral oil (Claim 18)
-
IOP response curve becomes a legal hook
The method claim’s “without any substantial initial increase” is an outcome limitation. In enforcement, this can shift the evidentiary battle toward pharmacodynamic profiling and clinical/animal IOP time-course.
What is likely outside scope
Based strictly on the provided claim text:
- Actives that are not eicosanoids/prostaglandins are outside Claim 3 and dependent chain.
- PGF2α derivatives that are not C1–C5 alkyl esters are outside Claims 6–8 and 13, and also outside the operational daily 50 μl method tied to those esters (Claim 15).
- Formulations not within 0.01% to 1.0% w/w are outside Claim 19 (though not necessarily outside Claim 14 unless the asserted claim is dependent).
Scope summary by competitor archetype (claim-mapping logic)
| Competitor archetype |
Potential claim alignment |
Key reason |
| Topical glaucoma drop using PGF2α methyl/ethyl/isopropyl/isobutyl ester in compatible carrier |
High alignment |
Hits Claim 13; composition breadth extends through Claim 14/15 path depending on exact use/dose |
| Topical glaucoma drop using generic lower alkyl ester (C1–C5) of PGF2α in compatible carrier |
High alignment |
Hits Claim 14 and Claim 16; operational method exposure if dosing is daily with ~50 μl (Claim 15) and if method is asserted (Claim 1–2 plus 3–6 chain) |
| PGF2α tromethamine salt formulation |
Medium alignment |
Hits Claim 9–10 sub-scope and the relevant method/composition if such salt is used and the asserted dependent claim chain is met |
| Prostaglandin analogs that are not PGF2α and not prostaglandin derivatives within Claim 3-4 (e.g., unrelated prostaglandin receptor ligands) |
Low alignment |
Claim chain requires prostaglandin and then specific PGF2α or PGE2 depending on which dependent claim is asserted |
| Formulations with carriers outside the listed oils |
Variable |
Claim 14 does not limit carrier to peanut/mineral oil; dependent claims 17–18 limit only if those are asserted |
| Products that show a meaningful early IOP rise after initiation |
Reduced alignment |
Method claim 1 requires “without any substantial initial increase” |
Key Takeaways
- Independent method claim (Claim 1) is built around a topical ocular dosing paradigm for primates that reduces IOP for glaucoma/hypertension while avoiding an initial IOP spike and maintaining reduced pressure.
- The patent’s enforceable chemical focus concentrates on PGF2α derivatives, especially C1 to C5 lower alkyl esters (methyl/ethyl/isopropyl/isobutyl) and, separately, PGF2α salts (including tromethamine).
- Composition claims (13–19) expand coverage to formulations with those PGF2α ester identities or the general lower-alkyl ester class, with dependent limits on C1–C5, carrier options (peanut oil, mineral oil), and concentration (0.01% to 1.0% w/w).
- Method operationalization (Claim 15) sets a practical dosing template: daily topical use with about 50 μl of the claimed composition.
FAQs
1) Does Claim 1 require a specific amount of drug?
No. Claim 1 requires “an amount … effective” to reduce IOP without substantial initial increase and to maintain reduction. Specific numeric dosing appears in dependent Claims 11–12.
2) Are PGF2α esters limited to only the four enumerated types?
Dependent Claim 7 enumerates methyl, ethyl, isopropyl, and isobutyl. Broader coverage exists in Claim 6 (C1–C5 alkyl esters) and Claim 16 (C1–C5 in composition), but the exact alignment depends on which dependent claim is asserted.
3) Can a product use a different carrier and still infringe?
If the asserted claims are Claim 14 (generic “ophthalmically compatible carrier”), yes in principle. If the asserted claims are dependent 17 or 18, then carrier must match sterile anhydrous peanut oil or sterile mineral oil.
4) What makes the method claim distinctive versus standard IOP-lowering claims?
The method claim includes a functional time-course limitation: topical contact reduces IOP “without any substantial initial increase” and maintains reduced IOP.
5) What dosing regimen is explicitly claimed?
The most concrete regimen is daily dosing with about 50 μl of a composition of Claim 14 (Claim 15). Numeric dose ranges for the active appear in Claims 11–12.
References
[1] United States Patent 4,599,353 (claims provided in prompt).
