Details for Patent: 6,403,649

Summary for Patent: 6,403,649

Title:	Non-acidic cyclopentane heptanoic acid,2-cycloalkyl or arylalkyl derivatives as therapeutic agents
Abstract:	The present invention provides cyclopentane heptanoic acid, 2-cycloalkyl or arylalkyl compounds, which may be substituted in the 1-position with amino, amido, ether or ester groups, e.g., a 1-OH cyclopentane heptanoic acid, 2-(cycloalkyl or arylalkyl) compound. The cyclopentane heptanoic acid, 2-(cycloalkyl or arylalkyl) compounds of the present invention are potent ocular hypotensives, and are particularly suitable for the management of glaucoma. Moreover, the cyclopentane heptanoic, 2-(cycloalkyl or arylalkyl) compounds of this invention are smooth muscle relaxants with broad application in systemic hypertensive and pulmonary diseases; smooth muscle relaxants with application in gastrointestinal disease, reproduction, fertility, incontinence, shock, etc.
Inventor(s):	David F. Woodward, Steven W. Andrews, Robert M. Burk, Michael E. Garst
Assignee:	Allergan Inc
Application Number:	US09/519,834
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 6,403,649
Patent Claim Types: see list of patent claims	Use;

US Drug Patent 6,403,649: Claim Scope, Bimatoprost Protection, Expiration, and Patent Landscape

US Patent 6,403,649 covers bimatoprost, the active pharmaceutical ingredient in Lumigan, through a compound claim and two ophthalmic method-of-use claims. The patent does not broadly claim every prostaglandin glaucoma therapy, every bimatoprost formulation, or every manufacturing process. Its central legal value was protection of the specific bimatoprost molecule and its use for ocular hypertension and glaucoma.

The patent was issued June 11, 2002. Its commercial relevance was tied to Allergan's Lumigan ophthalmic solution. The patent term has expired, and US generic manufacturers can market bimatoprost products subject to FDA approval and any separately applicable formulation or regulatory barriers. Bimatoprost is a small molecule, so biosimilar rules do not apply.

What drug does US Patent 6,403,649 cover?

US Patent 6,403,649 covers bimatoprost, also known as the free-acid amide prostaglandin analog used in Lumigan.

The compound in claim 1 corresponds to the following systematic description:

• Bimatoprost
• A prostamide analog of prostaglandin F2α
• An N-ethyl amide
• A cyclopentane prostaglandin structure
• Specific cis and trans stereochemistry
• A phenyl-substituted hydroxyalkenyl side chain
• Two cyclopentane hydroxyl groups

Bimatoprost is pharmacologically related to latanoprost, travoprost, and tafluprost but is structurally distinct. It is generally classified as a prostamide or prostaglandin analog and is used topically to reduce intraocular pressure.

The patent claims are directed to the compound and two therapeutic applications. They do not expressly claim the brand name Lumigan, the active ingredient concentration, a bottle, a preservative system, or a particular manufacturing method.

What does claim 1 of US 6,403,649 protect?

Claim 1 is a product claim covering the specifically identified bimatoprost molecule.

The claim is narrow in chemical identity but commercially important. A product claim generally provides stronger protection than a method claim because it can reach the compound itself, regardless of whether the accused product is sold for glaucoma, ocular hypertension, or another indication.

Claim 1 scope

Claim 1 requires the following characteristics:

Claim element	Scope
Chemical class	A substituted cyclopentane prostaglandin analog
Nitrogen functionality	N-ethyl heptenamide
Ring structure	Cyclopentane
Hydroxyl groups	Defined 3,5-dihydroxy substitution
Side chain	Hydroxy-substituted phenyl-containing trans-pentenyl group
Stereochemistry	Specific alpha, beta, cis, and trans configurations
Product type	The compound itself, rather than a composition or method

A generic bimatoprost product would have been exposed to literal infringement risk while the claim was enforceable because it contains the same active molecule. A formulation containing bimatoprost would also generally implicate the product claim if the claim covers the active compound as such.

What claim 1 does not cover

Claim 1 does not, on its face, cover:

• Latanoprost
• Travoprost
• Tafluprost
• Bimatoprost-free acid if chemically different from the claimed amide
• A different stereoisomer
• A prodrug with a materially different chemical structure
• A formulation that contains no bimatoprost
• A manufacturing process that produces a different compound
• All prostamides as a genus
• All drugs that lower intraocular pressure

A chemically modified derivative could avoid literal infringement, but doctrine-of-equivalents analysis would depend on the specific structural change, prosecution history, and prior art. The patent's detailed stereochemical definition would make substantial structural departures more defensible than minor, non-functional modifications.

What do claims 2 and 3 protect?

Claims 2 and 3 are method-of-treatment claims.

Claim 2 covers applying an amount of the claimed compound to the eye to treat ocular hypertension. Claim 3 covers applying an amount of the compound to the eye to treat glaucoma.

Claim	Protected activity	Required disease or condition
2	Applying bimatoprost to the eye	Ocular hypertension
3	Applying bimatoprost to the eye	Glaucoma

Both claims require:

1. The claimed bimatoprost compound.
2. Application to the eye.
3. An amount sufficient to treat the relevant condition.

The claims do not specify a concentration, dosing frequency, vehicle, preservative, bottle, pH, or administration schedule. Their functional language establishes the therapeutic objective but does not create an unlimited claim to any use of bimatoprost.

Method-of-use infringement issues

A manufacturer could face induced-infringement exposure if its labeling instructs users to apply bimatoprost to treat glaucoma or ocular hypertension. A product approved and labeled for a non-claimed indication could present a different analysis, although the product claim historically provided the more direct barrier.

The claims are not limited to adults, a particular severity of disease, or a specific route within ophthalmic administration. They do require ocular application. Systemic administration would not ordinarily satisfy the express application-to-the-eye limitation.

When did US Patent 6,403,649 expire?

US Patent 6,403,649 was issued June 11, 2002. Its enforceable term has expired.

The effective expiration analysis must account for the patent's filing and priority history, any terminal disclaimer, and any patent-term adjustment or extension shown in the official USPTO record. For commercial purposes, the patent is no longer a current US exclusionary barrier to approved generic bimatoprost entry.

The key distinction is between:

• Patent expiration, which removes the patent right;
• FDA regulatory exclusivity, which can restrict approval timing independently;
• Other listed patents, which may have covered formulations or methods;
• Patent litigation settlements, which can delay launch before expiration but do not extend an expired patent.

What was the Orange Book status of bimatoprost and Lumigan?

Lumigan was approved by the FDA as an ophthalmic solution containing bimatoprost. FDA Orange Book listings historically identified patents associated with the reference product and its approved uses.

The principal patent landscape included patents directed to:

• The bimatoprost compound;
• Ophthalmic use in ocular hypertension and glaucoma;
• Ophthalmic formulations;
• Concentration, dosing, or delivery characteristics;
• Certain commercial presentations.

The Orange Book must be read product by product. A patent listed for a particular Lumigan strength or formulation does not automatically establish protection for every bimatoprost product.

FDA Orange Book-listed patents can affect an ANDA applicant through:

• Paragraph IV certification;
• A 30-month stay following qualifying litigation;
• A potential 180-day generic exclusivity period for the first eligible Paragraph IV applicant;
• Approval limitations tied to a listed method-of-use patent.

Because US Patent 6,403,649 has expired, it no longer provides a current Orange Book litigation basis. Any remaining assessment must focus on other listed patents, pediatric exclusivity, regulatory exclusivity, and product-specific labeling.

Which patents were important in the bimatoprost patent estate?

The commercial estate around Lumigan included more than one patent family. The following categories were material:

Patent category	Commercial purpose	Relevance to generic entry
Core compound patents	Protect bimatoprost as a chemical entity	Broadest historical barrier
Therapeutic-use patents	Cover ocular hypertension and glaucoma treatment	Relevant to labeled-use claims
Formulation patents	Protect aqueous ophthalmic compositions and excipient systems	May create narrower product barriers
Delivery patents	Cover dosage, bottle, or administration characteristics	Relevant only if the generic product practices the claims
Manufacturing patents	Protect synthesis, purification, or intermediates	Can affect process choice but generally does not block all products

US Patent 6,403,649 is the core compound and method patent identified by the supplied claims. Its claims should not be conflated with later formulation or delivery patents.

Formulation patent exposure

Formulation patents can be more difficult to assess than compound patents because infringement depends on the exact inactive ingredients, concentration, pH, preservative system, and manufacturing process.

A generic bimatoprost ophthalmic solution may avoid a formulation claim if it uses:

• A different preservative;
• A different buffer;
• A different surfactant;
• A different viscosity modifier;
• A different concentration;
• A different container or delivery system.

A formulation patent cannot extend the expired compound patent by itself. Its enforceability depends on claim construction, validity, statutory term, and whether the generic product practices every required limitation.

What Paragraph IV challenges affected bimatoprost?

Generic applicants seeking approval before expiration of listed Lumigan patents could submit Paragraph IV certifications asserting that listed patents were invalid, unenforceable, or not infringed.

Paragraph IV litigation in this area generally focused on:

• Whether bimatoprost claims were anticipated or obvious;
• Whether the claimed stereochemistry was adequately disclosed;
• Whether the compound had unexpected properties;
• Whether the generic product practiced formulation limitations;
• Whether proposed labeling induced infringement of method claims;
• Whether later-filed patents were valid and enforceable.

The exact litigation consequences depended on the patent and ANDA at issue. A Paragraph IV notice could trigger a 30-month stay if the patent owner filed suit within the statutory period. That stay would not revive or extend an expired patent.

Public FDA records show that generic bimatoprost ophthalmic products entered the US market after the principal Lumigan patent barriers expired or ceased to block approval. Current generic competition is therefore governed primarily by FDA approval, product quality, manufacturing capacity, and commercial contracting rather than by US Patent 6,403,649.

What is the biosimilar risk for bimatoprost?

There is no biosimilar pathway for bimatoprost.

Bimatoprost is a chemically synthesized small molecule. Generic applicants use the abbreviated new drug application pathway under section 505(j) of the Federal Food, Drug, and Cosmetic Act. The relevant competitive products are ANDA-approved generics, not biosimilars under the Public Health Service Act.

The principal regulatory issues are:

• Pharmaceutical equivalence;
• Bioequivalence or comparative performance;
• Sterility;
• Ophthalmic product quality;
• Container-closure integrity;
• Stability;
• Labeling;
• Manufacturing compliance.

How does bimatoprost compare with competing glaucoma drugs?

Drug	Brand	Drug class	Core patent position	Generic or follow-on status
Bimatoprost	Lumigan	Prostamide/prostaglandin analog	Core patents expired	Generic products available
Latanoprost	Xalatan	Prostaglandin F2α analog	Core patents expired	Generic products available
Travoprost	Travatan Z	Prostaglandin analog	Core patents expired or substantially eroded	Generic products available
Tafluprost	Zioptan	Prostaglandin analog	Later estate than older products	Generic and formulation-specific assessment required
Timolol	Timoptic	Beta blocker	Long-expired core protection	Generic products available
Brimonidine	Alphagan	Alpha-2 adrenergic agonist	Core patents expired	Generic products available
Netarsudil	Rhopressa	Rho kinase inhibitor	More recent patent estate	Higher current patent sensitivity
Rocklatan	Netarsudil/latanoprost	Combination product	Combination and formulation patents	Product-specific assessment required

Bimatoprost remains commercially differentiated by its efficacy profile, dosing familiarity, and use in ophthalmic products, but its US compound patent position no longer provides exclusivity.

How strong was the patent estate for bimatoprost?

The estate was historically strong because US Patent 6,403,649 combined:

• A product claim to the active molecule;
• A glaucoma method claim;
• An ocular-hypertension method claim.

The product claim was the most valuable element. It could reach the active ingredient directly and did not depend on proving a particular formulation or indication.

The estate was weaker in the following respects:

• The claims were limited to one defined compound rather than a broad chemical genus.
• Method claims required ocular application and specified treatment outcomes.
• Formulation protection depended on separate patents.
• Patent-term limits prevented indefinite exclusivity.
• Once the compound patent expired, generic applicants could use the same active ingredient.

Claim-strength assessment

Issue	Assessment
Literal coverage of bimatoprost	Strong
Coverage of other prostaglandin analogs	None or very limited
Coverage of bimatoprost formulations	Indirect through the compound claim; formulation-specific coverage requires separate claims
Coverage of glaucoma treatment	Direct through claim 3
Coverage of ocular hypertension treatment	Direct through claim 2
Coverage of manufacturing methods	Not provided by the supplied claims
Current blocking power	Expired
Biosimilar relevance	None

What generic entry risks exist after expiration?

After expiration, the main risks shift from patent exclusivity to execution and market structure.

Regulatory risks

Generic manufacturers must demonstrate a product that meets FDA requirements for ophthalmic solutions. Risks include failed sterility testing, stability deficiencies, container-closure problems, preservative performance issues, and manufacturing observations.

Commercial risks

Multiple generic entrants can compress pricing. Buyers may include pharmacy benefit managers, wholesalers, hospitals, retail pharmacies, and government programs. The commercial value of a bimatoprost launch depends on:

• Number of approved competitors;
• Supply reliability;
• Contracting access;
• Reimbursement;
• Product concentration and presentation;
• Ability to supply preservative-free or differentiated formulations;
• Manufacturing cost.

Residual patent risks

A new entrant must still review:

• Any unexpired formulation patent;
• Any unexpired delivery patent;
• Any patent listed for a specific strength or presentation;
• Any pending patent litigation;
• Any settlement restriction;
• Any separate patent covering a combination product.

Those risks are distinct from US Patent 6,403,649.

What licensing deals and settlement agreements mattered?

Allergan was the commercial sponsor associated with Lumigan and the bimatoprost product franchise. Licensing and settlement arrangements involving generic applicants may have affected launch timing before patent expiry, but a settlement cannot extend the statutory term of an expired patent.

The commercial analysis should distinguish between:

• A patent assignment or license, which changes ownership or freedom to operate;
• A Paragraph IV settlement, which may establish an agreed generic launch date;
• A supply or authorized-generic agreement, which can alter market entry economics;
• A regulatory settlement, which may affect labeling or approval timing.

No settlement agreement can create post-expiration exclusivity under US Patent 6,403,649.

What is the geographic coverage of US Patent 6,403,649?

The patent covers the United States only. It does not establish protection in Canada, Europe, Japan, China, or other jurisdictions.

International protection must be assessed through corresponding national patents and regional filings. Differences may arise in:

• Patent grant dates;
• Claim scope;
• Patent-term adjustment;
• Supplementary protection certificates;
• Pediatric extensions;
• Litigation outcomes;
• Generic approval timing.

A US freedom-to-operate conclusion cannot be applied to foreign markets without reviewing the relevant national patent families.

What manufacturing and intellectual-property barriers remain?

The compound patent's expiration removes the principal product barrier, but manufacturing remains technically demanding. Bimatoprost production requires control of:

• Stereochemical purity;
• Double-bond geometry;
• Hydroxyl-group configuration;
• Impurity profile;
• Residual solvents;
• Ophthalmic sterility;
• Stability in the finished solution.

A process patent could create a barrier if a proposed manufacturer uses the patented route. A different synthetic route may reduce that risk. Process claims must be analyzed separately from the supplied product and method claims.

Key Takeaways

• US Patent 6,403,649 covers bimatoprost, the active ingredient in Lumigan.
• Claim 1 is a compound claim with defined chemical structure and stereochemistry.
• Claim 2 covers ocular application of bimatoprost to treat ocular hypertension.
• Claim 3 covers ocular application of bimatoprost to treat glaucoma.
• The patent does not broadly cover all prostaglandin analogs, all glaucoma drugs, or all bimatoprost manufacturing methods.
• The patent has expired and no longer blocks US generic entry.
• Bimatoprost is a small molecule, so biosimilar rules do not apply.
• Historical Orange Book and Paragraph IV issues involved the broader Lumigan estate, including formulation and delivery patents.
• Current risks are product-specific and may involve formulation patents, regulatory approval, supply, and commercial contracting.
• Foreign freedom to operate requires separate analysis of corresponding national patent rights.

FAQs

Does US Patent 6,403,649 cover Lumigan by brand name?

No. It covers the bimatoprost compound and specified therapeutic uses. Lumigan is the branded ophthalmic product that contains bimatoprost.

Can a generic manufacturer use the same bimatoprost molecule after patent expiration?

Yes, subject to FDA approval and compliance with any separately enforceable patents covering the proposed formulation, delivery system, or manufacturing process.

Does the patent cover latanoprost or travoprost?

No. Those are chemically distinct prostaglandin analogs and are not covered by the supplied claims to bimatoprost.

Can a different bimatoprost concentration avoid the patent?

Changing concentration would not ordinarily avoid a compound claim covering bimatoprost itself. It could matter for a separate formulation claim that requires a specific concentration.

Does patent expiration eliminate FDA approval requirements?

No. Expiration removes the patent barrier but does not eliminate ANDA requirements for pharmaceutical equivalence, bioequivalence, sterility, stability, labeling, and manufacturing quality.

References

1. United States Patent and Trademark Office. (2002). US Patent No. 6,403,649: [Bimatoprost compound and ophthalmic methods of use]. U.S. Department of Commerce.

2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

3. U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/

4. U.S. Food and Drug Administration. (2018). Abbreviated new drug application regulations and guidance for industry. https://www.fda.gov/drugs

5. U.S. Food and Drug Administration. (n.d.). Biosimilar and interchangeable products. https://www.fda.gov/drugs/biosimilars.

Drugs Protected by US Patent 6,403,649

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

International Family Members for US Patent 6,403,649

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0660716		CA 2002 00020	Denmark
European Patent Office	0660716		SPC/GB02/035	United Kingdom
European Patent Office	0660716		90957	Luxembourg
European Patent Office	0660716		SPC023/2002	Ireland
European Patent Office	0660716		C300099	Netherlands
European Patent Office	0660716		02C0033	France
Austria	209494