United States Patent 5,889,052: Scope, Claims, Expiration, and Travoprost Patent Landscape

U.S. Patent No. 5,889,052 protected topical ophthalmic treatment of glaucoma and ocular hypertension using stereochemically defined prostaglandin analogs, including compounds within the travoprost and fluprostenol family. Its broadest claims covered both treatment methods and ophthalmic compositions. The patent has expired, so it no longer creates an enforceable U.S. exclusivity barrier. Its commercial importance was greatest for Alcon’s travoprost products, including Travatan and Travatan Z.

What does U.S. Patent 5,889,052 protect?

The patent covers two principal subject-matter categories:

Methods of treating glaucoma or ocular hypertension by topical administration of a prostaglandin analog.
Topical ophthalmic compositions containing the analog in an ophthalmically acceptable carrier.

Claims 1 through 11 are method claims. Claims 12 through 22 are composition claims. The patent does not claim a single commercial product exclusively. It claims a chemical genus defined by structural variables, stereochemistry, substitution, dosage, and formulation concentration.

The patent’s central limitation is that the active compound must have the specified absolute stereochemical structure and be “substantially free” of its enantiomer. This limitation narrows the claims to the desired stereoisomer rather than a racemic mixture.

The patent identifies a broad class of prostaglandin analogs having:

A substituted cyclopentane ring;
Defined alpha- and omega-side-chain unsaturation;
A chlorine or trifluoromethyl substituent, represented by Z;
Optional ester, ether, alkyl, acyl, or salt substitutions;
Specified hydroxyl and carbonyl functionality;
A therapeutically effective ophthalmic dose or concentration.

The commercial relevance is highest for compounds containing the trifluoromethyl group, designated Z = CF3, and the structural configuration recited in claims 2 and 3.

How do the claims map to travoprost and related compounds?

Travoprost is an isopropyl ester prodrug of fluprostenol. Its chemical structure falls within the preferred embodiments of the patent, particularly the structural limitations in claims 2 and 3.

Patent claim	Principal limitation	Commercial relevance
Claim 1	Broad treatment method using stereochemically pure formula IV compounds	Genus-level protection for glaucoma and ocular hypertension treatment
Claim 2	Carbonyl-containing analog; CH2 ring heteroatom replacement; defined cis/trans side-chain geometry	Core preferred prostaglandin structure
Claim 3	Claim 2 structure with Z = CF3	Directly relevant to fluprostenol and travoprost-type compounds
Claims 4-8	Alternative oxygenated or reduced analogs, including 3-oxacloprostenol and dihydrocloprostenol pivaloate	Broader analog coverage beyond travoprost
Claims 9-11	Administration of approximately 0.01 to 1,000 micrograms per eye, with narrower preferred ranges	Dose-based method protection
Claim 12	Broad topical ophthalmic composition	Composition-level genus protection
Claims 13-14	Preferred carbonyl and CF3 analog	Core product-family coverage
Claims 15-19	Alternative reduced or oxygenated analogs and esters	Analog and prodrug coverage
Claims 20-22	Concentration of approximately 0.0003% to 0.3%, with narrower ranges	Formulation concentration protection

Travoprost ophthalmic solution is commonly supplied at 0.004% w/v. That concentration falls within the range recited by claims 20 through 22, particularly the 0.003% to 0.03% range in claim 22.

The claim language does not require the active ingredient to be named travoprost. A product may infringe a genus claim if its active compound satisfies every structural limitation, even if the compound has a different development code or nonproprietary name.

What are the key limitations in claim 1?

Claim 1 has five important legal limitations.

Topical administration to the affected eye

The method requires topical administration to the affected eye. Systemic administration, oral administration, or treatment of a non-ocular condition would not satisfy this limitation.

Treatment of glaucoma or ocular hypertension

The claimed therapeutic indication is limited to glaucoma and ocular hypertension. Use for unrelated retinal, inflammatory, or cosmetic indications would fall outside the express treatment purpose.

A therapeutically effective amount

The amount must be sufficient to treat the claimed condition. The dependent claims provide quantitative guidance, but claim 1 does not impose a fixed numerical dose.

Absolute stereochemistry

The compound must have the absolute stereochemical structure shown in formula IV. A constitutional isomer, epimer, racemate, or opposite enantiomer may avoid the claim if it does not satisfy the stereochemical limitation.

Substantial absence of the enantiomer

The compound must be “substantially free” of the enantiomer. This is a purity limitation. The claim does not state a numerical enantiomeric purity threshold, leaving the phrase subject to specification disclosure, prosecution history, and claim construction.

What do claims 2 through 8 add?

Claims 2 and 3 define the most commercially significant preferred embodiment.

Claim 2 requires:

R2 and R3 together representing O;
X = CH2;
A cis double bond in the alpha chain;
A trans double bond in the omega chain;
R9 and R11 equal to hydrogen;
An alpha hydroxyl group at Y and beta hydrogen.

Claim 3 adds Z = CF3. This combination corresponds to the structural class associated with fluprostenol derivatives, including travoprost-type compounds.

Claims 4 through 8 extend protection to other structural families. They cover compounds with:

X = O or CH2;
Reduced or carbonyl-containing ring structures;
Free hydroxyl groups;
Alkyl, acyl, or salt substitutions at R1;
3-oxacloprostenol;
13,14-dihydrofluprostenol;
Dihydrocloprostenol pivaloate.

The dependent claims are narrower than claim 1 but are more useful for enforcement against a defined active pharmaceutical ingredient. A defendant may avoid an asserted dependent claim by changing the substituent, side-chain geometry, ring heteroatom, ester group, or stereochemical configuration while remaining within the general prostaglandin class.

What formulations are protected by Patent 5,889,052?

Claims 12 through 22 cover a topical ophthalmic composition containing:

The claimed prostaglandin analog;
An ophthalmically acceptable carrier;
A therapeutically effective amount of active ingredient.

The patent does not require a particular preservative, buffer, surfactant, tonicity agent, viscosity modifier, bottle, or dispensing system. Its composition claims are therefore broader than a conventional formulation patent directed to a specific preservative system or packaging configuration.

The concentration limitations are:

Claim	Concentration
Claim 20	0.0003% to 0.3%
Claim 21	Same range as claim 20 in the supplied text
Claim 22	0.003% to 0.03%

Claims 20 and 21 appear duplicative in the supplied text. The issued patent should be consulted for the authoritative claim set because OCR and database transcriptions can repeat or distort dependent-claim language.

The formulation claims could historically have reached a travoprost ophthalmic solution at 0.004% if the product also satisfied the structural, stereochemical, carrier, and therapeutic limitations.

When did U.S. Patent 5,889,052 expire?

The patent expired in the United States on or about June 1, 2016, based on the patent’s effective filing and priority history. Any applicable pediatric exclusivity would have extended the regulatory protection period by six months, but it would not revive the patent after statutory expiration for ordinary patent-enforcement purposes. The Orange Book historically listed the patent against travoprost products, including products associated with Alcon Laboratories. (U.S. Food and Drug Administration, 2024a; U.S. Patent No. 5,889,052, 1999)

Event	Date
Earliest relevant priority period	1990s
U.S. patent issued	March 30, 1999
Approximate U.S. patent expiration	June 1, 2016
Present status	Expired
Current blocking effect	None for new U.S. commercial entry

The patent’s expiration means that a current generic manufacturer does not need to design around its formula IV genus, dose range, or concentration range. Those claims remain relevant for historical litigation and freedom-to-operate analysis concerning conduct before expiration.

What was the FDA and Orange Book status?

Travoprost ophthalmic solution was approved by the FDA as Travatan under NDA 021994 in 2001. Travatan Z, a later formulation using the SofZia preservative system, was approved in 2006. The products were associated with Alcon Laboratories and later became part of Alcon’s ophthalmic franchise following corporate transactions involving Novartis. (U.S. Food and Drug Administration, 2024b)

The Orange Book listed multiple patents for travoprost products. Patent 5,889,052 was one part of a broader estate that included separate patents directed to:

Prostaglandin analog chemistry;
Ophthalmic treatment methods;
Preservative systems;
Formulation stability;
Specific ophthalmic compositions;
Product-specific or formulation-specific embodiments.

Patent 5,889,052 should not be treated as the entire Travatan or Travatan Z estate. Its broad method and composition claims overlapped commercially with travoprost, but later patents may have controlled the practical launch date for a generic product.

Which patents were most relevant to travoprost?

The principal U.S. patents historically associated with travoprost products included the following.

Patent	General subject matter	Historical commercial relevance
U.S. 5,631,287	Prostaglandin analog chemistry and ophthalmic use	Early travoprost-related protection
U.S. 5,889,052	Ophthalmic treatment methods and compositions using formula IV analogs	Broad method and composition coverage
U.S. 6,011,062	Ophthalmic prostaglandin compositions and related formulations	Product and formulation protection
U.S. 6,235,781	Later travoprost formulation or product protection	Relevant to later commercial formulation coverage

The exact scope and expiration of each patent depended on prosecution history, terminal disclaimers, patent-term adjustments, patent-term extensions, and Orange Book listing history. Patent 5,889,052 itself is expired and cannot independently block a current generic launch.

What Paragraph IV challenges affected travoprost?

Generic travoprost applicants could challenge listed patents through Paragraph IV certifications under the Hatch-Waxman Act. A Paragraph IV certification asserts that a listed patent is invalid, unenforceable, or will not be infringed by the proposed generic product.

Historical disputes involving travoprost products focused on the broader Orange Book estate rather than only Patent 5,889,052. The commercial incentive for litigation was strongest before 2016, when the principal chemical, method, and formulation patents were still active.

A Paragraph IV challenge to Patent 5,889,052 would have had several potential arguments:

The proposed product does not contain a compound within formula IV;
The product uses the wrong absolute stereochemistry;
The product is not substantially free of the enantiomer;
The claimed ophthalmic indication is absent from the label;
The formulation does not satisfy the claimed carrier or concentration limitations;
The patent claims are invalid for anticipation or obviousness;
The claims are indefinite because of terms such as “substantially free” or “therapeutically effective amount.”

After expiration, the practical significance of a Paragraph IV challenge to this patent ended. Current entry depends primarily on remaining unexpired patents, regulatory requirements, manufacturing capability, and product-specific approval status.

Is biosimilar risk relevant to this patent?

No. Travoprost is a small-molecule prostaglandin analog, not a biologic. The relevant competitive pathway is an abbreviated new drug application, not a biosimilar application under the Public Health Service Act.

The principal competitive risks are:

Generic travoprost ophthalmic solution;
Authorized generic or authorized alternative products;
Formulation substitution between preserved and preservative-free products;
Private-label ophthalmic products;
New glaucoma therapies with longer dosing intervals or different mechanisms.

How strong was the patent estate?

Patent 5,889,052 was commercially strong during its term because it combined broad genus claims with claims directed to the preferred fluprostenol-type structure, ophthalmic composition, dose, and concentration. Its principal strengths were:

Coverage of both treatment and composition claims;
Inclusion of travoprost-relevant CF3 analogs;
Coverage of ophthalmic doses used in practice;
Coverage of a concentration range encompassing 0.004% travoprost;
Stereochemical protection against use of the desired enantiomer as a racemate or opposite stereoisomer.

Its weaknesses included:

Broad structural language vulnerable to prior-art and obviousness challenges;
Dependence on precise stereochemical and substitution mappings;
Potential claim-construction disputes over “substantially free” of the enantiomer;
Lack of a patent-specific preservative or delivery-system limitation;
Expiration, which removed all forward-looking enforcement value.

The estate as a whole was stronger than Patent 5,889,052 standing alone because later formulation and product patents could delay generic entry after the earliest chemical claims expired.

What generic launch risks exist today?

The patent-related risk from Patent 5,889,052 is zero for new U.S. activity because the patent has expired. Current risk analysis for travoprost should focus on:

Any later-expiring formulation patents.
Orange Book listings for the specific reference drug and dosage form.
Product labeling and potential method-of-use carve-outs.
FDA requirements for ophthalmic sterility, container closure, impurities, and stability.
Manufacturing controls for prostaglandin analogs and stereochemical purity.
Commercial substitution against Travatan, Travatan Z, and other prostaglandin analogs.

Manufacturing remains a technical barrier even without active composition claims. Travoprost requires control of stereochemistry, side-chain geometry, impurity profile, ester hydrolysis, oxidation, and low-dose uniformity. Those factors can increase development cost without creating patent exclusivity.

How does Patent 5,889,052 compare with competing glaucoma-drug patents?

Product	Active ingredient	Drug class	Patent position today
Travatan / Travatan Z	Travoprost	Prostaglandin analog	Original key patents, including 5,889,052, expired
Xalatan	Latanoprost	Prostaglandin analog	Core U.S. exclusivity expired
Lumigan	Bimatoprost	Prostamide	Core patents expired or no longer generally blocking
Vyzulta	Latanoprostene bunod	Nitric oxide-donating prostaglandin	Later-generation patent estate
Rocklatan	Netarsudil/latanoprost	Rho kinase inhibitor plus prostaglandin	Combination and formulation patents may remain relevant depending on product

Travoprost competes primarily with latanoprost and bimatoprost. The commercial distinction is driven more by price, formulary status, tolerability, preservative system, dosing convenience, and physician preference than by Patent 5,889,052.

Key Takeaways

U.S. Patent 5,889,052 covers stereochemically defined prostaglandin analogs for topical treatment of glaucoma and ocular hypertension.
Its claims include both treatment methods and topical ophthalmic compositions.
Claims 2 and 3 are the most relevant to travoprost-type CF3 prostaglandin analogs.
Claims 9 through 11 cover ophthalmic dose ranges; claims 20 through 22 cover concentration ranges that encompass 0.004% travoprost.
The patent expired around June 1, 2016.
It no longer blocks generic travoprost development or launch.
Historical Paragraph IV disputes would have involved the full Orange Book estate, not necessarily this patent alone.
Travoprost is a small molecule, so biosimilar provisions do not apply.
Current competitive analysis should focus on later formulation patents, FDA approval requirements, manufacturing controls, and commercial positioning.

FAQs

What drug is most directly associated with U.S. Patent 5,889,052?

Travoprost is the principal commercial drug associated with the patent, although the claims cover a broader family of prostaglandin analogs.

Does Patent 5,889,052 cover the 0.004% travoprost formulation?

The concentration falls within the patent’s composition ranges, including the narrower 0.003% to 0.03% range. The patent is expired, however, so that coverage no longer creates a current U.S. patent barrier.

Can a generic manufacturer still be sued under Patent 5,889,052?

No, not for new conduct after expiration. Historical conduct before expiration could raise different issues, including damages, but the expired patent cannot support a current infringement injunction.

Does the patent cover racemic travoprost?

The claims require the specified absolute stereochemical structure and substantial freedom from the enantiomer. A racemic product would face a substantial non-infringement argument, subject to claim construction and the actual stereochemical composition.

Are preservative-free travoprost products covered by this patent?

The patent’s composition claims require an ophthalmically acceptable carrier but do not mandate a particular preservative. A preservative-free product could fall within the claims if it met the structural, stereochemical, therapeutic, and concentration limitations. The patent’s expiration eliminates current blocking effect.

References

U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
U.S. Food and Drug Administration. (2024b). Drugs@FDA: Travatan and Travatan Z approval histories. U.S. Department of Health and Human Services.
U.S. Patent No. 5,889,052. (1999). Ophthalmic use of prostaglandin analogs. United States Patent and Trademark Office.
U.S. Patent and Trademark Office. (2024). Patent Center and Patent Examination Data System records for U.S. Patent No. 5,889,052. U.S. Department of Commerce.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1514548	⤷ Start Trial	C300671	Netherlands	⤷ Start Trial
European Patent Office	1514548	⤷ Start Trial	PA2014029	Lithuania	⤷ Start Trial
European Patent Office	1514548	⤷ Start Trial	CA 2014 00038	Denmark	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,889,052

Summary for Patent: 5,889,052