United States Patent 5,688,819: Scope, Claims, Expiration and Bimatoprost Patent Landscape

U.S. Patent No. 5,688,819 is an expired Allergan patent directed principally to ophthalmic prostaglandin analogs for treating ocular hypertension and glaucoma. Its most commercially important subject matter is the prostaglandin-amide class that includes bimatoprost, the active ingredient in Lumigan. The patent also contains broader systemic-use claims covering cardiovascular, pulmonary-respiratory, gastrointestinal, reproductive, allergic and shock indications.

The patent is no longer an enforceable barrier to generic entry. Its principal U.S. term expired in December 2012, subject to the patent’s recorded term history. Current commercial protection for bimatoprost products therefore depends on later formulation, concentration, manufacturing, delivery and method-of-use patents rather than U.S. Patent 5,688,819.

What does U.S. Patent 5,688,819 protect?

The patent protects methods of administering selected prostaglandin derivatives, rather than a standalone composition claim to bimatoprost or a broad manufacturing process.

Its claims divide into two groups:

Claim group	Claims	Principal subject
Ophthalmic treatment	1-10	Treatment of ocular hypertension or glaucoma
Systemic treatment	11-20	Cardiovascular, pulmonary-respiratory, gastrointestinal, reproductive, allergic diseases and shock

The claims use Markush structures. They cover chemical families defined by:

A substituted cyclopentane prostaglandin core;
One or more hydroxyl, oxo or ester substituents;
A terminal alcohol, alkoxy or amide group;
Optional N-substitution, including methyl, ethyl, isopropyl and dimethyl groups;
Phenyl or substituted phenoxy side chains;
Chloro or trifluoromethyl substitution;
Cis or trans double-bond configurations;
Alpha and beta stereochemistry;
Pharmaceutically acceptable salts in the broader systemic claims.

The claims are therefore broader than a single commercial molecule but narrower than an unrestricted claim to all prostaglandin glaucoma treatments.

Which claims cover bimatoprost?

Bimatoprost is the clearest commercial compound falling within the claim set.

Bimatoprost is commonly identified chemically as:

(Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-[(E)-(3R)-3-hydroxy-5-phenylpent-1-enyl]cyclopentyl]-N-ethylhept-5-enamide.

The N-ethyl amide, prostaglandin F2-alpha-type cyclopentane ring and 5-phenyl-1-trans-pentenyl side chain correspond closely to the compound identified in claim 10 as a cyclopentane N-ethyl heptenamide derivative.

The relevant claim path is:

Claim 1 establishes an ophthalmic treatment genus for compounds of formula V.
Claims 5-9 narrow the structural configuration and functional groups.
Claim 10 identifies particular amide derivatives, including the N-ethyl compound corresponding to bimatoprost.
Claims 11-20 separately cover broader systemic-use structures and selected compounds.

Claim 10 is the most commercially relevant claim for bimatoprost because it moves from a broad chemical genus to a defined list of specific amide derivatives.

How broad is the ocular treatment coverage?

Claims 1 and 5 are the principal independent ocular claims.

Claim 1

Claim 1 covers applying to the eye an effective amount of a formula V compound for treating ocular hypertension or glaucoma. The claim permits:

An alcohol or amide at the terminal position;
Hydrogen or lower alkyl substitution;
Additional ester groups at the 9, 11 or 15 positions;
A carbonyl or reduced ketone functionality represented by Z;
Chlorine or trifluoromethyl substitution in the side chain.

Claim 1 is structurally broad but contains several limitations. It requires the specified prostaglandin framework, particular substitution patterns and the stated Y' and Z variables. It does not cover every prostaglandin analog used in ophthalmology.

Claim 5

Claim 5 is broader in some respects. It covers compounds having:

Variable cis or trans double bonds;
A broader R6 ester substituent;
Cycloalkyl, aryl or heteroaryl groups;
Multiple oxidation states at R1, R2 and R3;
Pharmaceutically acceptable salts.

The claim includes a proviso excluding certain compounds where Z is carbonyl and X is an alkoxy group. That proviso limits the reach of the broad Markush language and would be important in an infringement analysis.

Dependent claims 6-10

Claims 6 through 10 add stereochemical and structural restrictions. Claim 10 lists five specific amide compounds:

The unsubstituted heptenamide;
The N,N-dimethyl heptenamide;
The N-isopropyl heptenamide;
The N-ethyl heptenamide;
The N-methyl heptenamide.

This list substantially improves the claim’s ability to identify commercial compounds, but it also creates a narrower literal-infringement target than the genus claims.

Does the patent cover ophthalmic formulations?

Not directly in the way later formulation patents do.

Patent 5,688,819 covers the use of specified compounds in treating glaucoma. The supplied claims do not expressly recite:

A particular aqueous formulation;
A defined pH range;
A specific preservative;
Benzalkonium chloride;
A particular concentration;
A viscosity modifier;
A particle-size limitation;
A multidose container;
A preservative-free unit-dose package;
A particular dosing schedule.

An ophthalmic product could therefore fall within the patent based on its active ingredient and use without the patent claiming the formulation itself. The patent does not prevent a later patent from separately protecting a low-concentration bimatoprost formulation, a preservative system or a delivery device.

What are the method-of-use claims?

The ophthalmic method-of-use claims require treatment of:

Ocular hypertension; or
Glaucoma.

The claim language requires applying the compound to the eye in an amount sufficient to treat the condition. It does not specify:

Open-angle versus angle-closure glaucoma;
Reduction of intraocular pressure as a measured endpoint;
Once-daily or twice-daily dosing;
A particular patient population;
Monotherapy or combination therapy;
A particular ophthalmic dosage form.

That breadth benefits the patentee at the level of indication and administration route. It also creates potential validity and construction issues because “an amount sufficient to treat” is functional language and the claims do not define a precise dosage regimen.

The systemic claims in claim 11 and its dependents are materially different. They cover administering the compounds to humans for multiple disease categories, including cardiovascular and pulmonary-respiratory conditions. Those claims do not require ocular administration.

What is the patent’s expiration date?

U.S. Patent 5,688,819 expired in December 2012, based on the patent’s recorded term history and the applicable U.S. patent-term rules.

Event	Date or status
Patent issued	November 18, 1997
Patent type	Utility patent
Principal subject	Prostaglandin derivatives and therapeutic uses
U.S. status	Expired
Principal expiration	December 2012
Current enforceability	No enforceable exclusionary right from this patent

The patent’s expiration eliminated its ability to block manufacture, sale or ophthalmic use of bimatoprost products in the United States. Any later patent covering bimatoprost products must be analyzed independently for claim scope, expiration, terminal disclaimers, patent-term adjustment and Orange Book status.

What was the Orange Book status of U.S. Patent 5,688,819?

Patent 5,688,819 was associated with the Lumigan bimatoprost product and was listed in the FDA’s Orange Book patent framework for the reference product.

The patent’s listing was relevant to abbreviated new drug application litigation while the patent remained in force. After expiration, it ceased to provide a live patent basis for blocking an ANDA applicant.

The Orange Book distinction is important:

The Orange Book identifies patents submitted by an NDA holder for an approved drug product.
It does not establish that every claim in a listed patent covers every version of the product.
It does not extend an expired patent’s enforceability.
It does not automatically make later formulation or method patents coextensive with the original active-ingredient patent.

For present-day bimatoprost products, the material Orange Book questions concern later patents covering concentration, formulation, delivery and approved uses, not the expired 5,688,819 claims.

Were there Paragraph IV challenges?

Paragraph IV litigation involving generic bimatoprost products could have included challenges to listed Lumigan patents, including U.S. Patent 5,688,819 while it remained unexpired.

A Paragraph IV certification asserts that:

The listed patent is invalid;
The listed patent is unenforceable; or
The proposed generic product does not infringe the patent.

Because patent 5,688,819 expired in 2012, a present-day ANDA applicant would not need to make a Paragraph IV challenge to this patent as an active barrier. The patent’s historical litigation relevance does not create current exclusivity.

For current products, Paragraph IV exposure is determined by the live Orange Book listings for the relevant reference product and strength. A generic applicant may still need to address later patents even though the original bimatoprost method patent has expired.

What later patents matter for bimatoprost?

The commercial patent estate for bimatoprost has historically included several layers:

Patent layer	Typical protection	Relevance
Active compound	Bimatoprost chemical structure	Largely expired
Ophthalmic use	Glaucoma and ocular hypertension treatment	Patent 5,688,819, expired
Formulation	Concentration, pH, excipients and preservative system	May have delayed generic entry
Product strength	Bimatoprost 0.01% versus 0.03%	May be covered by separate patents or regulatory records
Delivery	Containers, drops and administration systems	Potential secondary protection
Manufacturing	Synthesis, purification and crystallization	May create process or supply-chain barriers
Combination therapy	Use with timolol or other glaucoma agents	Separate method claims

The important commercial distinction is between Lumigan 0.03% and Lumigan 0.01%. A generic applicant can face different patent and regulatory issues for each strength. Approval of one strength does not automatically establish freedom to market another strength.

How strong were the claims from a validity perspective?

The patent had meaningful historical scope but several potential attack points.

Written description and enablement

The claims cover large chemical genera and multiple therapeutic indications. A challenger could argue that the specification did not adequately describe or enable the full breadth of the Markush classes, particularly across:

Multiple side-chain substituents;
Different ester groups;
Various stereoisomers;
Broad systemic indications;
Numerous salts and oxidation states.

The strength of such an argument would depend on the examples and biological data in the specification.

Claim construction

Terms requiring construction include:

“Lower alkyl”;
“Amido radicals”;
“Amount sufficient to treat”;
“Applying to the eye”;
“Pharmaceutically acceptable salt”;
The structural meaning of the formula variables;
The scope of the cis and trans configurations.

Structural interpretation would likely dominate a literal-infringement dispute.

Anticipation and obviousness

The relevant prior art would include earlier prostaglandin analog patents, glaucoma-treatment publications and compound-specific disclosures. The most significant prior-art issue would be whether the specific N-ethyl amide compound and its ophthalmic use were disclosed before the applicable priority date.

A broad genus claim is more exposed to prior-art overlap than a claim directed to a single stereochemically defined compound. Conversely, a specifically listed compound may have stronger anticipation resistance if the prior art disclosed only related prostaglandins.

Double patenting and patent-term issues

Because prostaglandin analog portfolios often contain continuations and continuation-in-part applications, terminal disclaimers, priority claims and overlapping claims must be checked in the complete family. The enforceability period may differ among related patents even when the claims cover the same commercial product.

What manufacturing and IP barriers remain after expiration?

The expiration of patent 5,688,819 removed the principal composition-use barrier for the claimed compounds. It did not eliminate all commercial barriers.

A generic or follow-on manufacturer still must address:

API synthesis and impurity control;
Stereochemical purity;
Stability of the prostaglandin analog;
Oxidation and hydrolysis risks;
Sterility assurance;
Container-closure compatibility;
Drop-size consistency;
Preservative tolerability;
FDA bioequivalence requirements for ophthalmic products;
Live Orange Book patents on the reference product;
Supply-chain patents or contractual restrictions.

These are regulatory and operational barriers, not continuing rights under Patent 5,688,819.

How does this patent compare with competing glaucoma patents?

Product or class	Principal active ingredient	Patent strategy
Lumigan	Bimatoprost	Compound, ophthalmic-use and later formulation protection
Xalatan	Latanoprost	Separate prostaglandin analog patent family
Travatan	Travoprost	Separate ester prodrug and ophthalmic-use patents
Zioptan	Tafluprost	Separate prostaglandin analog and preservative-free formulation estate
Rescula	Unoprostone	Distinct prostaglandin-related compound and use claims

Patent 5,688,819 is not a platform patent covering all prostaglandin glaucoma products. Latanoprost, travoprost, tafluprost and unoprostone require separate freedom-to-operate analyses because their structures and patent families differ.

Which companies challenged or commercialized the covered products?

Allergan was the principal innovator associated with bimatoprost and Lumigan. Generic competition later came from companies developing ANDA products after expiration or resolution of later patent barriers.

The relevant competitive groups include:

Allergan and successor commercial owners of Lumigan;
Generic ophthalmic manufacturers;
Contract API suppliers;
Companies developing preservative-free or lower-concentration bimatoprost formulations;
Manufacturers of competing prostaglandin analogs.

The expired status of Patent 5,688,819 means that current competition is primarily determined by later patents, FDA approval requirements, formulation capability and commercial access to sterile ophthalmic manufacturing.

Key takeaways

U.S. Patent 5,688,819 is an expired method-of-treatment patent.
Claims 1-10 focus on ocular hypertension and glaucoma.
Claim 10 specifically identifies amide prostaglandin derivatives, including the N-ethyl compound corresponding to bimatoprost.
Claims 11-20 cover broader systemic therapeutic uses.
The patent does not directly claim a complete ophthalmic formulation, concentration or container system.
The principal U.S. patent term expired in December 2012.
The patent no longer creates a current Paragraph IV or launch barrier.
Current bimatoprost freedom-to-operate analysis must focus on later formulation, strength, delivery, manufacturing and combination-use patents.
The patent does not cover competing prostaglandin analogs such as latanoprost, travoprost or tafluprost merely because they are used for glaucoma.
Historical Orange Book listing and Paragraph IV litigation do not revive the expired patent.

FAQs

Does U.S. Patent 5,688,819 cover Lumigan?

Yes. Its ocular claims cover prostaglandin-amide compounds corresponding to bimatoprost and their use for ocular hypertension or glaucoma. The patent is expired.

Is bimatoprost still patent protected in the United States?

The original compound and method claims associated with Patent 5,688,819 are no longer enforceable. Later formulation, concentration, delivery or use patents may have had separate expiration dates and must be reviewed independently.

Can a generic manufacturer use the bimatoprost molecule after Patent 5,688,819 expired?

Yes, subject to FDA approval, applicable live patents, product-specific regulatory requirements and compliance with manufacturing and quality standards.

Does Patent 5,688,819 cover bimatoprost 0.01% and 0.03% equally?

The patent claims the compound and ophthalmic use, not a stated commercial concentration. Both strengths may fall within the expired method claims, but later concentration or formulation patents can differ between the products.

Does the patent cover all prostaglandin glaucoma drugs?

No. Its claims are limited to specified prostaglandin structures and substituent patterns. Latanoprost, travoprost, tafluprost and other agents require separate patent analyses.

References

Allergan, Inc. (1997). Prostaglandin derivatives for the treatment of glaucoma, U.S. Patent No. 5,688,819. U.S. Patent and Trademark Office.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. (2024). Approved drug products and patent and exclusivity information. Center for Drug Evaluation and Research.
U.S. Patent and Trademark Office. (2024). Patent term calculator and patent term adjustment information. U.S. Department of Commerce.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0660716	⤷ Start Trial	CA 2002 00020	Denmark	⤷ Start Trial
European Patent Office	0660716	⤷ Start Trial	SPC/GB02/035	United Kingdom	⤷ Start Trial
European Patent Office	0660716	⤷ Start Trial	90957	Luxembourg	⤷ Start Trial
European Patent Office	0660716	⤷ Start Trial	SPC023/2002	Ireland	⤷ Start Trial
European Patent Office	0660716	⤷ Start Trial	C300099	Netherlands	⤷ Start Trial
European Patent Office	0660716	⤷ Start Trial	02C0033	France	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,688,819

Summary for Patent: 5,688,819