US Patent 8,252,307: Fluocinolone Acetonide Ocular Implant Claims, Patent Scope and Competitive Landscape

US Patent 8,252,307 covers sustained-release ocular implants containing fluocinolone acetonide (FA) as the sole active ingredient. Its central limitation is pharmacokinetic: the implant must maintain therapeutic vitreous exposure while keeping aqueous humor FA exposure below specified levels, including less than one-tenth of the vitreous concentration or below approximately 0.05 μg/mL.

The patent is directed primarily to intravitreal and posterior-segment implants using controlled or pseudo-zero-order release. It does not claim FA as a molecule. It claims a drug-device combination defined by implant location, active-agent composition, duration, release behavior, therapeutic effect, and reduced ocular or systemic steroid toxicity.

What does US Patent 8,252,307 cover?

The patent claims four overlapping subject-matter groups:

Claim group	Principal scope
Claims 1-11	FA implant dimensioned for the vitreous cavity
Claims 12-14	Steroid implant, including but not limited to FA, for the vitreous cavity or posterior segment
Claims 15-25	FA implant for the broader posterior segment
Dependent claims	FA concentration, release kinetics, duration, toxicity and selected indications

The independent claims are claims 1, 2, 3, 12, 13, 15, 16 and 17.

The patent does not require a particular polymer, reservoir, coating, geometry, drug load, applicator or implantation instrument in the asserted claims reproduced by the user. The claims instead define the implant largely through its performance after implantation.

What are the key limitations in the independent claims?

Claim 1: pharmacokinetic separation between vitreous and aqueous humor

Claim 1 requires:

A sustained-release device.
FA as the sole active agent.
Dimensioning for implantation in the vitreal cavity.
Release for at least four weeks.
An aqueous humor FA concentration below one-tenth of the vitreous FA concentration.

This is the narrowest core formulation of the patent's pharmacokinetic concept. A product that releases FA into the vitreous but produces a substantially lower aqueous humor concentration may fall within the literal language even if it uses a different implant architecture.

Claims 2 and 3: therapeutic effect and reduced intraocular pressure risk

Claims 2 and 3 add therapeutic and safety limitations. The device must release FA at a sustained therapeutic concentration effective against a long list of retinal and choroidal conditions. The release profile must also avoid an increase in intraocular pressure that could damage ocular tissue.

Claim 2 uses the absence of harmful intraocular-pressure elevation as the principal safety limitation. Claim 3 combines the safety requirement with the less-than-one-tenth aqueous-to-vitreous concentration ratio.

The disease list is extensive, but it does not mean that every listed disease independently creates a separate patent right. Each listed condition is a potential therapeutic application of the claimed device. The claim still requires the device and pharmacokinetic limitations.

Claims 12 and 13: broader steroid genus

Claims 12 and 13 cover a sustained-release device containing a steroid as the sole active agent. The device must be configured for implantation in the vitreous cavity or posterior segment and must release a therapeutically effective amount without ocular or systemic steroid-induced toxicity.

These claims are broader in chemical scope than the FA claims. They are not limited expressly to fluocinolone acetonide. Potentially relevant steroids could include corticosteroids used in ocular therapy, subject to claim construction and the patent's written description and enablement support.

Claims 15-25: posterior-segment expansion

Claims 15-25 substantially repeat claims 1-11 but replace the specific vitreous-cavity limitation with implantation in the posterior segment of the eye.

"Posterior segment" is broader than "vitreal cavity." Depending on claim construction, it may encompass delivery to or implantation in regions including the vitreous, retina, choroid or adjacent posterior ocular tissues. This creates a potentially wider infringement theory but also raises greater issues concerning written description, enablement and prior art.

How do the dependent claims narrow the patent scope?

Claims	Limitation	Commercial significance
4 and 18	Aqueous humor FA below approximately 0.05 μg/mL	Provides a quantitative concentration boundary
5 and 19	Pseudo-zero-order release	Targets controlled, substantially steady release
6 and 20	Release rate maintained over the stated time course	Reinforces duration requirement
7 and 21	At least 100 days	Extends the minimum four-week duration
8 and 22	No damaging intraocular-pressure increase	Adds safety limitation
9 and 23	Selected use in macular degeneration, uveitis or diabetic macular edema	Narrows therapeutic use
10 and 24	No ocular steroid-induced toxicity	Adds an express toxicity limitation
11 and 25	Selected therapeutic indications	Narrows the method of use

Claims 6 and 20 appear to add limited technical narrowing because they largely restate the requirement that the device have a release rate over the relevant period. Their practical value would depend on the construction of "configured to have a release rate" and whether the limitation is treated as structural, functional or merely intended use.

What formulations and delivery systems are protected?

The claims protect the performance of an implant rather than a specific formulation. The claim text does not require:

A particular polymer;
A particular coating;
A reservoir or matrix configuration;
A specific FA loading;
A specific implant size;
A particular insertion device;
A particular manufacturing process;
A particular release-rate value in micrograms per day.

The commercial products most closely associated with this technology use nonbiodegradable, controlled-release ocular implant platforms. Retisert contains FA and is used for chronic noninfectious posterior uveitis. Iluvien is a low-dose FA intravitreal implant approved for diabetic macular edema in specified patient populations. FDA product labeling identifies the active ingredient, route and release duration, but labeling alone does not establish infringement of every claim in US 8,252,307. [1, 2]

A competing product could attempt design-around through a different active agent, combination therapy, nonimplant delivery system, shorter duration, materially different aqueous exposure, or a release profile that does not satisfy the claimed ratio or toxicity limitations. A design-around based only on a different polymer may be weak if the product still meets every functional limitation.

What is the relationship to Retisert and Iluvien?

Retisert

Retisert is a surgically implanted FA device for chronic noninfectious posterior uveitis affecting the posterior segment of the eye. It releases FA over an extended period. The product is commercially relevant to claims 12, 13 and 15-25, although product-specific infringement depends on the exact claim construction and the patent's enforceability at the relevant time. [1]

Iluvien

Iluvien is an injectable intravitreal FA implant designed for prolonged low-dose release. The product received FDA approval for diabetic macular edema in 2014. Its commercial profile most closely matches the patent's emphasis on low aqueous humor exposure, sustained vitreous concentration, reduced steroid toxicity and long-duration release. [2]

Attribute	Retisert	Iluvien
Active agent	Fluocinolone acetonide	Fluocinolone acetonide
Delivery	Surgically implanted	Intravitreal injectable implant
Primary FDA use	Chronic noninfectious posterior uveitis	Diabetic macular edema
Claim relevance	Posterior-segment and steroid-device claims	Intravitreal FA, duration and concentration claims
Key commercial issue	Surgical implantation and steroid adverse effects	Long-duration release and intraocular-pressure risk

When does US Patent 8,252,307 lose exclusivity?

The patent's ordinary term is governed by the earliest effective US nonprovisional filing date, not necessarily the earliest provisional or foreign priority date. Patent term adjustment, patent term extension and terminal disclaimers can change the effective expiration date. The grant record and USPTO Patent Center file history control the final calculation. [3]

Because the supplied material contains claims but not the complete prosecution record, a definitive enforceable expiration date cannot be established from the claim text alone.

The patent's commercial relevance also depends on whether it was listed in the FDA Orange Book for a particular approved product and whether a qualifying patent term extension applied. FDA Orange Book listing does not itself establish validity, enforceability or infringement. [4]

What is the Orange Book status of US 8,252,307?

Orange Book status is product-specific. A patent may be listed for one approved drug and not for another, even if both products use FA or a related delivery platform. The relevant questions are:

Whether the patent is listed against Retisert, Iluvien or another approved product.
Whether it is listed for composition, formulation, method of use or drug-device claims.
Whether the listed claims correspond to the approved labeling.
Whether any listing has been withdrawn, delisted or superseded.
Whether the patent's expiration date has passed.

The FDA Orange Book should be reviewed by product and active ingredient rather than by patent number alone. [4]

How strong is the patent estate?

The patent has meaningful breadth but several litigation pressure points.

Strengths

Claims cover both vitreous-cavity and broader posterior-segment implantation.
FA is claimed as the sole active agent, matching commercial FA implant products.
Functional limitations address clinically relevant pharmacokinetics.
The claims include long-duration release, low aqueous exposure and reduced steroid toxicity.
Claims 12 and 13 extend beyond FA to a steroid genus.
The therapeutic indication list creates multiple potential method-of-use positions.

Weaknesses

Several independent claims rely heavily on functional results rather than structural limitations.
"Therapeutically effective," "pseudo zero order," "does not produce toxicity" and "does not cause an increase in intraocular pressure" can create claim-construction disputes.
The aqueous-to-vitreous concentration ratio may require validated sampling methods and defined measurement conditions.
The claims do not specify a single release rate, making infringement dependent on pharmacokinetic evidence.
The broad steroid claims may face written-description and enablement challenges if the specification does not support the full genus.
The long list of diseases does not cure a lack of technical support for each claimed therapeutic application.
Prior-art references involving FA implants, intravitreal corticosteroids and sustained-release ocular devices could support novelty or obviousness challenges.

What Paragraph IV challenges and generic entry risks exist?

A generic or follow-on applicant seeking approval for an FA implant could challenge listed patents under Hatch-Waxman through a Paragraph IV certification. The likely invalidity theories would include:

Anticipation by earlier sustained-release FA ocular implants;
Obviousness based on known FA, intravitreal delivery and controlled-release technologies;
Lack of written description for the broad posterior-segment and steroid-genus claims;
Lack of enablement for every claimed disease, steroid and toxicity profile;
Indefiniteness of pharmacokinetic and toxicity limitations;
Noninfringement based on aqueous humor concentration, duration or release kinetics.

The strongest infringement risk would involve an FA implant that:

Uses FA as its only active agent;
Is implanted intravitreally or in the posterior segment;
Releases for at least 100 days;
Produces sustained vitreous exposure;
Produces aqueous humor FA below one-tenth of vitreous levels; and
Is approved for diabetic macular edema, posterior uveitis or a related retinal condition.

A product with a materially different aqueous-to-vitreous exposure ratio could avoid claims 1, 3, 15 and 17, but claims 2, 8, 12, 13 and related dependent claims may require separate analysis.

Which companies are relevant to the competitive landscape?

The principal commercial entities associated with this class include:

Alimera Sciences, associated with Iluvien;
pSivida, associated with the Durasert controlled-release platform and historical development of FA ocular implants;
Bausch + Lomb, associated with Retisert commercialization;
Generic and specialty pharmaceutical companies evaluating intravitreal corticosteroid implants and alternative long-acting delivery systems.

The main competitive substitutes are not limited to FA implants. They include dexamethasone intravitreal implants, steroid injections, anti-VEGF therapies, corticosteroid suspensions and emerging sustained-release retinal delivery systems.

What litigation and settlement issues matter?

Patent disputes involving an FA implant would likely center on:

Whether the approved product meets the aqueous humor concentration limitation;
Whether the product's release profile is pseudo-zero-order;
Whether the product produces the claimed therapeutic effect;
Whether elevated intraocular pressure or steroid toxicity defeats the claim;
Whether the asserted claims are valid after considering earlier ocular implants;
Whether a generic settlement permits a licensed or deferred launch date.

A settlement could include a license, an authorized-generic arrangement, a delayed entry date, manufacturing restrictions or a covenant not to sue. No settlement term should be inferred from the existence of an Orange Book listing or a Paragraph IV certification alone.

Key Takeaways

US 8,252,307 is a drug-device patent focused on sustained-release FA implants for the vitreous and posterior segment.
Its central technical concept is sustained vitreous exposure with comparatively low aqueous humor FA exposure.
Claims 12 and 13 are broader because they cover a steroid, not only FA.
Claims 4, 7, 18 and 21 provide the most concrete numerical narrowing through concentration and duration limitations.
Iluvien is the commercial product most closely aligned with the patent's low-dose, long-duration intravitreal FA concept.
Retisert is relevant to the broader posterior-segment and steroid-device claim categories.
Infringement analysis requires product-specific pharmacokinetic data, not only the active ingredient and route.
Validity risk is concentrated in functional claim language, broad steroid coverage, enablement, written description and obviousness.
Orange Book listing, patent expiration and Paragraph IV exposure must be assessed by approved product and current FDA records.

FAQs

Does US 8,252,307 claim fluocinolone acetonide itself?

No. The patent claims sustained-release ocular devices containing FA. It does not claim the FA molecule as a composition of matter.

Can an FA implant infringe if it uses a different polymer?

Yes. A different polymer does not avoid infringement if the implant still satisfies the claimed active-agent, implantation, duration, concentration and therapeutic limitations.

Does a four-week release period satisfy the patent?

Potentially. Claims 1-3 and 15-17 require at least four weeks. Claims 7 and 21 impose the narrower requirement of at least 100 days.

Are the listed diseases separate patents?

No. They are alternative therapeutic uses within the claims. The device must still satisfy the applicable structural and functional limitations.

Can a nonimplant FA injection fall within these claims?

Generally, the claims require a sustained-release device dimensioned for implantation in the vitreous cavity or posterior segment. A conventional bolus injection would not ordinarily satisfy those device and implantation limitations.

References

U.S. Food and Drug Administration. (2005). Retisert fluocinolone acetonide intravitreal implant prescribing information.
U.S. Food and Drug Administration. (2014). Iluvien fluocinolone acetonide intravitreal implant prescribing information.
United States Patent and Trademark Office. (2012). U.S. Patent No. 8,252,307, Methods and devices for treating ocular conditions.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2005200243	⤷ Start Trial
Australia	4174800	⤷ Start Trial
Australia	777727	⤷ Start Trial
Brazil	0010869	⤷ Start Trial
Canada	2367092	⤷ Start Trial
European Patent Office	1162978	⤷ Start Trial
Japan	2002539263	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,252,307

Summary for Patent: 8,252,307