United States Patent 5,475,034: Scope, Claims, Expiration, and Nepafenac Patent Landscape

U.S. Patent No. 5,475,034 covers topical ophthalmic treatment using a defined class of 3-benzoylphenylacetic acid derivatives, including nepafenac, the active ingredient in Nevanac. The patent claims a method of use rather than the compound itself, a specific formulation, or a manufacturing process. Its nominal patent term has expired, eliminating current infringement risk based solely on this patent. Later patents may still affect particular nepafenac formulations, concentrations, dosing regimens, or combinations.

What does U.S. Patent 5,475,034 protect?

The patent protects topical administration to the eye of an ophthalmic composition containing an anti-inflammatory-effective amount of a specified 3-benzoylphenylacetic acid derivative for treating ophthalmic inflammation and ocular pain.

The principal claim elements are:

Element	Requirement
Disease or condition	Ophthalmic inflammatory disorder or ocular pain
Route	Topical administration to the eye
Product	Pharmaceutical composition
Active ingredient	Covered 3-benzoylphenylacetic acid derivative
Function	Anti-inflammatory treatment
Concentration	Claims 6 and 7 impose a concentration range
Dosage form	Not expressly limited to a particular vehicle, such as suspension or solution

Claim 1 is the broad independent claim. It requires the combination of:

A covered chemical structure;
Topical ocular administration;
An anti-inflammatory-effective amount; and
Treatment of ophthalmic inflammation or ocular pain.

The patent does not claim all uses of the covered molecules. It does not claim oral, injectable, dermatological, or systemic administration under the language supplied.

What chemical compounds fall within the claims?

The claims define a Markush genus based on a 3-benzoylphenylacetic acid derivative with variable substituents at several positions. The permitted substituents include hydrogen, alkyl groups, halogens, alkoxy groups, thioalkyl groups, trifluoromethyl, hydroxy, and nitro groups.

Claim 1 is broader than claim 2 because it allows:

A broader R group, including C1-C4 alkyl, trifluoromethyl, and thioalkyl;
Longer N-substituents, up to C10 alkyl;
Broader substitution patterns;
More substituents on the aromatic rings;
A wider range of halogenated and heteroatom-containing groups.

Claim 2 narrows the genus by limiting the relevant variables, including:

R to hydrogen or C1-C2 alkyl;
N-substituents to hydrogen or C1-C6 alkyl;
The number of substituents represented by m and m' to no more than two;
Certain substituent classes and alkyl-chain lengths.

Claims 3 through 5 identify progressively narrower lists of individual compounds.

Is nepafenac covered by U.S. Patent 5,475,034?

Yes. Nepafenac is 2-amino-3-benzoylbenzeneacetamide, also described as 2-amino-3-benzoylphenylacetamide. It corresponds to one of the compounds expressly recited in claim 5:

2-Amino-3-benzoyl-phenylacetamide

Nepafenac is also included in the broader compound lists in claims 3 and 4. The patent therefore provides both genus-level and species-level coverage for topical ophthalmic use of nepafenac.

The claim structure is commercially significant because an accused product containing nepafenac could fall within claim 5 without requiring a court to resolve every boundary of the broader Markush formula in claim 1.

How do the claims differ in breadth?

Claim	Subject matter	Relative scope
1	Topical ophthalmic treatment using the broad chemical genus	Broadest
2	Narrower chemical genus with tighter substituent limits	Narrower
3	Listed individual derivatives	Species-level
4	Subset of claim 3	Narrower species group
5	Three named compounds, including nepafenac	Narrowest compound group
6	Claim 1 treatment with approximately 0.001%-4.0% w/v active	Concentration-limited
7	Claim 6 treatment with approximately 0.01%-0.5% w/v active	Narrowest concentration claim

Claims 6 and 7 depend on claim 1, so they retain every limitation of claim 1 and add concentration requirements. They do not independently cover a formulation containing the active ingredient unless the formulation is used in the claimed topical ophthalmic treatment.

What formulations are protected by the patent?

The supplied claims do not require a particular formulation vehicle. They can potentially reach:

Ophthalmic solutions;
Ophthalmic suspensions;
Emulsions;
Gel formulations;
Preservative-containing formulations;
Preservative-free formulations; and
Other topical ocular pharmaceutical compositions.

The claims do not expressly require:

A specific pH;
A particular preservative;
A suspension particle size;
A particular viscosity;
A surfactant;
A penetration enhancer;
A particular dosing frequency;
A specific container or delivery device; or
A particular salt or crystalline form.

Claims 6 and 7 create concentration-based limitations, but they do not convert the patent into a complete formulation patent. A product outside the claimed concentration ranges could remain within claim 1 if it satisfies the chemical, topical, therapeutic, and amount limitations.

Does the patent claim nepafenac as a compound?

No. Based on the supplied claims, the patent does not contain a standalone composition-of-matter claim to nepafenac.

The distinction matters:

Claim type	Present in U.S. 5,475,034?
Nepafenac compound per se	No
Composition containing nepafenac	Not as a standalone composition claim based on supplied claims
Topical ophthalmic method using nepafenac	Yes
Treatment of ocular inflammation using nepafenac	Yes
Treatment of ocular pain using nepafenac	Yes
Specific ophthalmic vehicle	No express limitation
Manufacturing process	No
Particular dosing schedule	No express limitation

A method patent can be infringed by practicing the claimed method even when the active ingredient itself is no longer protected by a composition-of-matter patent. That distinction is important during the patent term.

When did U.S. Patent 5,475,034 expire?

U.S. Patent 5,475,034 issued on December 12, 1995. Because it was filed during the pre-Uruguay Round Agreements Act transition period, its baseline term was generally 17 years from issuance rather than 20 years from the earliest effective nonprovisional filing date. The resulting nominal expiration date was December 12, 2012, subject to any recorded patent-term adjustment or extension.

The patent is now expired. Its claims cannot support a current infringement action for post-expiration activity. Expiration also means that a new generic manufacturer does not need to establish that its product avoids this patent, although other unexpired patents may remain relevant.

Event	Date
Patent issued	December 12, 1995
Nominal expiration	December 12, 2012
Current status	Expired
Current enforceability	None for new post-expiration conduct

The controlling status should be confirmed against the USPTO patent record and the FDA Orange Book entry applicable to the relevant drug product. The USPTO identifies patent term and legal status; the Orange Book identifies patents submitted by the NDA holder for approved drug products. [USPTO, n.d.; FDA, 2024a]

What was the FDA and Orange Book significance?

Nepafenac was approved by the FDA as Nevanac ophthalmic suspension for topical ophthalmic use. The product was originally marketed by Alcon Laboratories, Inc. The approved product was used for treatment of pain and inflammation associated with cataract surgery. [FDA, 2005]

U.S. Patent 5,475,034 was associated with the Nevanac patent estate and covered the therapeutic use of nepafenac in ophthalmic treatment. Its expiration removed the patent-based barrier supplied by that patent, but did not necessarily eliminate every later patent issue involving:

Nepafenac concentration;
Ophthalmic suspension technology;
Particle-size control;
Dosing schedules;
Postoperative treatment;
Additional approved indications;
Preservative systems;
Delivery devices; or
Manufacturing and crystallization methods.

Orange Book listing does not itself establish validity or enforceability. It identifies patents submitted by an NDA holder under the Hatch-Waxman framework. FDA patent listing practice also distinguishes patents covering active ingredients, drug products, and methods of use. [FDA, 2024b]

What Paragraph IV risk existed for generic nepafenac?

A generic applicant seeking approval before expiration of a listed method-of-use patent could submit a Paragraph IV certification asserting that the patent was invalid, unenforceable, or would not be infringed. For U.S. Patent 5,475,034, the practical Paragraph IV window ended when the patent expired in 2012.

A generic applicant could also use a section viii statement to carve out a patented indication if the approved generic label did not include the protected method. That strategy would be relevant only where the patent covered a method not required for the remaining nonpatented uses.

Because U.S. 5,475,034 is expired, it no longer creates a current Paragraph IV obstacle. Any present Hatch-Waxman challenge would focus on later-listed patents, not this patent.

Which companies challenged or competed with Nevanac?

The historical competitive field included:

Alcon, the original Nevanac sponsor;
Generic manufacturers filing abbreviated new drug applications for nepafenac ophthalmic products;
Manufacturers of competing ophthalmic NSAIDs, particularly ketorolac and bromfenac products;
Other postoperative anti-inflammatory products used after cataract surgery.

Nepafenac competes primarily with topical ophthalmic NSAIDs rather than with biologics. The relevant alternatives include ketorolac tromethamine ophthalmic products, bromfenac ophthalmic products, and steroid/NSAID treatment strategies.

No biosimilar pathway applies to nepafenac. Nepafenac is a chemically synthesized small molecule regulated through the ANDA pathway, not a biologic regulated under the Public Health Service Act biosimilar framework.

How does the patent estate compare with competing ophthalmic NSAIDs?

Product	Active ingredient	Regulatory pathway	Main patent risk category
Nevanac	Nepafenac	NDA	Method of use, formulation, concentration, dosing
Acular and generics	Ketorolac tromethamine	NDA/ANDA	Formulation, dosing, use patents
Bromday, Prolensa and generics	Bromfenac	NDA/ANDA	Formulation and dosing patents
Pred Forte and generics	Prednisolone acetate	NDA/ANDA	Formulation, suspension, use patents

U.S. 5,475,034 was comparatively broad in therapeutic concept but narrow in legal category because it is a method patent. Its strongest historical position came from the express recitation of nepafenac in claim 5 and the broad concentration coverage in claims 6 and 7.

How strong are the claims?

Strengths

The claims have several features that historically supported enforcement:

Claim 5 expressly identifies nepafenac;
The method requires topical ocular administration, which corresponds to the commercial route;
The claims cover treatment of both ophthalmic inflammation and ocular pain;
Claims 6 and 7 cover commercially relevant concentration ranges;
The patent does not depend on a narrow vehicle or device limitation.

Vulnerabilities

The principal vulnerabilities include:

The broad genus in claim 1 may face written-description and enablement scrutiny;
The phrase "anti-inflammatory-effective amount" is functional and may create proof issues;
The treatment indication is broad relative to a specific clinical indication;
Claim 6 uses "3-benzoylphenylacetic acid" in a manner that may create a terminology issue because the claimed active is a derivative;
The supplied text contains typographical inconsistencies, including "benzoly" and a duplicated compound in claim 4;
The patent is expired, making validity disputes commercially moot for present conduct.

The claim 5 species recitation would generally be less vulnerable to genus-boundary disputes than claim 1, assuming the claim text and specification consistently identify the compound.

What manufacturing and intellectual-property barriers remain?

The expired patent does not block manufacturing nepafenac or selling a generic nepafenac product. Residual barriers may arise from separate rights covering:

Particle engineering;
Stable ophthalmic suspensions;
Crystalline or polymorphic forms;
Impurity control;
Manufacturing intermediates;
Sterility and aseptic processing;
Container-closure systems;
Preservative-free delivery;
Dosing regimens; and
Specific postoperative indications.

These rights must be analyzed separately by jurisdiction and product presentation. A freedom-to-operate analysis for a current generic should not stop with U.S. Patent 5,475,034.

What litigation or settlement risk remains?

U.S. Patent 5,475,034 itself presents no current litigation risk because it has expired. Historical ANDA litigation involving nepafenac products may have involved this patent or later patents in the Nevanac estate, but an expired patent cannot support an injunction against current future sales.

Settlement agreements may still affect launch timing, authorized-generic arrangements, or commercial supply, but those terms are contract-specific and do not revive the expired patent. Any current launch analysis should focus on unexpired patents listed for the relevant nepafenac NDA and on applicable state, federal, and regulatory exclusivities.

Key Takeaways

U.S. Patent 5,475,034 is a method-of-treatment patent for topical ophthalmic use of 3-benzoylphenylacetic acid derivatives.
Nepafenac is expressly covered by claim 5 as 2-amino-3-benzoylphenylacetamide.
The patent does not claim nepafenac as a compound per se based on the supplied claims.
Claims 6 and 7 add concentration ranges of approximately 0.001%-4.0% and 0.01%-0.5% w/v, respectively.
The nominal expiration date was December 12, 2012.
The patent is expired and creates no current infringement barrier.
Nepafenac is a small molecule, so biosimilar analysis is inapplicable.
Current generic-entry risk depends on later formulation, dosing, manufacturing, and method-of-use patents, not U.S. 5,475,034 alone.
The strongest historical claim was claim 5 because it specifically recited nepafenac.
The broadest claim, claim 1, is more exposed to written-description, enablement, construction, and proof disputes.

FAQs

Is nepafenac still patented in the United States?

The original method patent discussed here is expired. Later patents may have covered specific formulations, dosing methods, or manufacturing technologies.

Can a generic company sell nepafenac after expiration of U.S. 5,475,034?

Yes, expiration removes the barrier created by this patent. The generic must still satisfy FDA approval requirements and avoid any other unexpired applicable patents.

Does U.S. 5,475,034 cover Nevanac suspension specifically?

The supplied claims do not require a suspension. They cover topical ophthalmic administration of a qualifying derivative in a pharmaceutical composition.

Is claim 7 limited to nepafenac?

No. Claim 7 depends on claim 6, which depends on claim 1. It covers the claimed chemical genus when used topically within the stated concentration range, not only nepafenac.

Does the patent cover bromfenac or ketorolac?

No, not based on the supplied claim structures. Bromfenac and ketorolac are different active ingredients and require separate patent analysis.

References

U.S. Patent and Trademark Office. (1995). U.S. Patent No. 5,475,034: Ophthalmic compositions and methods of treatment.
U.S. Food and Drug Administration. (2005). Nevanac (nepafenac ophthalmic suspension) prescribing information.
U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations.
U.S. Food and Drug Administration. (2024b). Approved drug product and patent listing requirements under the Hatch-Waxman Act.
U.S. Food and Drug Administration. (2024c). Orange Book: Approved drug products with therapeutic equivalence evaluations.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0716600	⤷ Start Trial	C00716600/01	Switzerland	⤷ Start Trial
Austria	215366	⤷ Start Trial
Australia	2818495	⤷ Start Trial
Australia	689277	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,475,034

Summary for Patent: 5,475,034