United States Patent 6,217,895: Claim Scope, Expiration, Litigation Risk, and Ocular Corticosteroid Patent Landscape

U.S. Patent No. 6,217,895 covers sustained-release corticosteroid delivery to the posterior segment of the eye, particularly intravitreal delivery designed to maintain a higher corticosteroid concentration in the vitreous than in the aqueous humor. The patent claims both treatment methods and implantable devices.

The patent issued on April 17, 2001, and its relevant 20-year patent term expired in 2018. The expiration eliminates current infringement risk from the issued claims, although the patent remains important for understanding the historical protection of fluocinolone and other intraocular corticosteroid implants.

What technology does U.S. Patent 6,217,895 protect?

The patent protects a pharmacokinetic and delivery concept rather than a single drug molecule. Its central requirement is localized corticosteroid delivery to the vitreous or posterior segment while maintaining a lower aqueous concentration.

The core technology has five components:

A corticosteroid.
An implantable sustained-release device.
Delivery to the vitreous or posterior eye.
A vitreous concentration that is higher than the aqueous concentration.
A therapeutic or controlled release profile.

The patent covers both method-of-treatment claims and apparatus or device claims.

Feature	Claim coverage
Posterior-segment treatment	Claims 1-15
Implantable sustained-release device	Claims 16-21
Intravitreous implantation	Claim 10
Corticosteroid selection	Claims 9 and 18
Aqueous concentration limits	Claims 2-4
Release duration	Claims 5-6
Therapeutic vitreous concentration	Claims 7-8
Pseudo-zero-order release	Claims 12 and 19
Release rate	Claims 13-14 and 20
Single-drug device	Claims 15 and 21
Ocular indications	Claim 11

The patent does not claim a corticosteroid compound in isolation. It also does not claim every ocular corticosteroid formulation. Infringement historically required the accused product or method to satisfy the delivery, concentration, release, and, where applicable, disease-treatment limitations.

How should independent claim 1 be interpreted?

Claim 1 is a method claim requiring administration of a corticosteroid to the posterior segment by implanting a sustained-release device that delivers corticosteroid to the vitreous.

Its principal limitation is:

The aqueous corticosteroid concentration must be less than the vitreous corticosteroid concentration during release.

This is a relative concentration limitation. It does not require a particular absolute vitreous concentration unless another dependent claim applies. A product could therefore fall within claim 1 if it produces a higher vitreous concentration than aqueous concentration, even if the precise concentrations differ from the numerical ranges in claims 2-4 and 8.

The claim also requires sustained release. A conventional intravitreal injection that produces rapid diffusion, without a sustained-release implant, would not satisfy the claim.

What does “posterior segment” mean?

The posterior segment generally includes the vitreous, retina, choroid, optic nerve, and related posterior ocular structures. Claim 1 expressly requires delivery to the vitreous. Claim 11 identifies three treatment categories:

Ocular neovascularization.
Ocular inflammation.
Retinal degeneration.

Claim 11 is dependent and narrows claim 1. A method directed to another posterior-segment condition would not satisfy claim 11, although it could still fall within claim 1 if all claim 1 requirements were met.

What corticosteroids are covered by the patent?

Claims 9 and 18 identify:

Triamcinolone.
Dexamethasone.
Fluocinolone.
Cortisone.
Prednisolone.
Flumetholone.
Derivatives of those corticosteroids.

The independent claims are broader than this list. Claim 1 does not expressly limit the corticosteroid to the listed compounds. A corticosteroid outside the dependent-claim list could potentially fall within claim 1 or claim 16 if the remaining limitations were satisfied.

The practical commercial importance is greatest for fluocinolone acetonide implants, including products historically associated with Retisert and later products such as Iluvien and Yutiq. Dexamethasone implants, including Ozurdex, are technically relevant but have different device structures, release profiles, indications, and product-specific patent estates.

What do the aqueous concentration claims require?

Claims 2-4 impose quantitative limits on aqueous corticosteroid concentration.

Claim	Stated limitation
Claim 2	About 0.002 to about 0.01 micrograms/mL
Claim 3	About 0.01 to about 0.05 micrograms/mL
Claim 4	Non-toxic and less than 0.05 micrograms/mL

Claim 3 depends on claim 2 as provided. That creates a drafting problem because claim 2 ends at approximately 0.01 micrograms/mL while claim 3 extends to approximately 0.05 micrograms/mL. Read literally as a dependent claim, claim 3 would require the overlap between the two ranges, centered around approximately 0.01 micrograms/mL. It would not independently claim the entire 0.01-to-0.05 range unless the dependency or claim text were corrected through an applicable prosecution-history or claim-construction analysis.

The word “about” introduces ordinary analytical tolerance. It does not eliminate the need to establish that the accused product produces the claimed concentration during release.

Claim 4 adds two requirements: the aqueous concentration must be non-toxic and must remain below 0.05 micrograms/mL. “Non-toxic” is potentially fact-intensive and may depend on the relevant ocular tissue, exposure duration, corticosteroid, and scientific evidence available at the filing date.

What release duration and release-rate ranges are covered?

Claims 5 and 6 cover broad release durations:

Claim 5: approximately one month to approximately 20 years.
Claim 6: approximately six months to approximately five years.

Claims 13, 14, and 20 address release rates:

Claim 13: approximately 1 to 50 micrograms per day.
Claim 14: approximately 1 to 10 micrograms per day.
Claim 20: approximately 1 to 50 micrograms per day for the device claims.

The release-duration range is unusually broad. It captures many implant designs if the product maintains the required concentration relationship and sustained-release profile. The claim does not require a particular polymer, reservoir, membrane, geometry, drug load, or implantation procedure.

The rate limitations are also functional and quantitative. A product operating outside the claimed average rate may avoid those dependent claims but could remain exposed to claim 1 or claim 16 if the broader elements are met.

Does the patent require zero-order drug release?

No. Claims 12 and 19 require “pseudo zero order kinetics,” but claims 1 and 16 do not.

A device can therefore potentially fall within the independent claims without demonstrating pseudo-zero-order release. The independent claims focus on sustained release and the vitreous-to-aqueous concentration relationship. The pseudo-zero-order limitation is relevant only to the dependent claims.

“Pseudo zero order” ordinarily refers to a release profile that is sufficiently controlled and approximately constant over a defined period. It does not require mathematically perfect zero-order release.

What is the scope of the device claims 16-21?

Claim 16 is the principal device claim. It covers an implantable sustained-release device containing a corticosteroid and configured to deliver it to the vitreous while maintaining an aqueous concentration below the vitreous concentration.

The claim is broad because it does not specify:

A particular implant geometry.
A particular polymer or coating.
A specific corticosteroid.
A fixed drug dose.
A fixed release duration.
A specific implantation instrument.
A particular disease.

The functional concentration requirement remains central. A device containing a corticosteroid would not necessarily infringe merely because it is implantable or sustained release. The device must be configured to achieve the claimed distribution between the vitreous and aqueous compartments.

Claim 17, as supplied, repeats the operative limitation of claim 16 and adds no meaningful technical limitation. Its scope appears duplicative. The prosecution record would control whether the issued text contains a correction, amendment, or interpretation affecting its legal effect.

Claims 18-21 narrow claim 16 by adding the corticosteroid list, pseudo-zero-order release, release rate, and single-drug limitations.

What does the single-drug limitation require?

Claims 15 and 21 require a device that releases only one drug. A combination implant releasing a corticosteroid plus an anti-VEGF agent, antibiotic, immunosuppressant, or another active pharmaceutical ingredient would not meet that dependent limitation.

The single-drug limitation does not apply to claims 1 or 16. A multidrug implant could still be assessed against the independent claims.

What products are most closely related to the claimed technology?

The patent landscape is centered on sustained-release corticosteroid implants used in retinal disease, uveitis, diabetic macular edema, and other posterior-segment conditions.

Product	Active ingredient	Delivery format	FDA milestone	Relationship to Patent 6,217,895
Retisert	Fluocinolone acetonide, 0.59 mg	Non-biodegradable intravitreal implant	Approved 2005	Closely aligned with the claimed fluocinolone implant concept
Ozurdex	Dexamethasone, 0.7 mg	Biodegradable intravitreal implant	Approved 2009	Technically within the broader corticosteroid-implant field, with a separate product estate
Iluvien	Fluocinolone acetonide, 0.19 mg	Injectable non-biodegradable intravitreal implant	Approved 2014	Overlaps the claimed delivery concept but relies on separate product and formulation protection
Yutiq	Fluocinolone acetonide, 0.18 mg	Intravitreal implant	Approved 2018	Closely related fluocinolone implant technology with separate later patents
Xipere	Triamcinolone acetonide	Suprachoroidal suspension	Approved 2021	Corticosteroid posterior-segment delivery, but not the same sustained-release intravitreal implant structure

FDA product labeling identifies the relevant drug, delivery system, indication, dosing, and regulatory history. Product labels and the Orange Book must be reviewed separately from the patent specification because FDA approval does not determine claim scope. [FDA, 2005; FDA, 2009; FDA, 2014; FDA, 2018; FDA, 2021]

What was the Orange Book status of U.S. Patent 6,217,895?

Patent 6,217,895 was historically associated with the Retisert product and its sustained-release fluocinolone acetonide implant. The Orange Book is the relevant source for FDA-listed patents, use codes, and expiration information for approved small-molecule products. [FDA, 2024]

The listing did not mean that every corticosteroid implant infringed every claim. Orange Book listing is an FDA regulatory disclosure mechanism. It is not a judicial determination of validity, enforceability, or infringement.

Because the patent expired in 2018, it no longer provides an active Orange Book patent barrier against a current abbreviated new drug application. A new generic applicant would evaluate the patent as expired or otherwise non-blocking, subject to the specific Orange Book record and any separate unexpired patents listed against the relevant reference product.

When did U.S. Patent 6,217,895 lose exclusivity?

The patent’s 20-year term expired in 2018. The term was measured from the applicable nonprovisional filing date, subject to any patent-term adjustment or other statutory modification. The patent should therefore be treated as expired and unenforceable against conduct occurring after expiration.

The patent’s expiration does not terminate:

Separate patents covering later formulations.
Device-design patents.
Manufacturing patents.
Method-of-use patents.
Regulatory exclusivity.
Trade-secret rights.
Contractual restrictions.
Patents owned by competitors.

It also does not retroactively eliminate infringement exposure for conduct occurring during the enforceable term.

Were there Paragraph IV challenges involving this patent?

A Paragraph IV certification is relevant only while a listed patent remains unexpired and listed against an applicable reference product. After expiration, the patent cannot ordinarily function as a live patent obstacle to generic approval.

The major commercial risk during the patent term would have involved an ANDA applicant seeking approval for a fluocinolone implant or comparable corticosteroid implant. The applicant could have argued that:

The product did not produce the required aqueous-to-vitreous concentration relationship.
The implant was not a sustained-release device within the claim meaning.
The product did not satisfy the release-rate or duration limits.
The claims were invalid for anticipation or obviousness.
The claims lacked written description or enablement for the full breadth of the claimed corticosteroids, durations, and release profiles.

No current Paragraph IV exposure should be attributed to Patent 6,217,895 alone because the patent has expired. Current generic-entry risk depends on later patents associated with the specific reference product.

How strong was the patent estate?

The patent was commercially important during its term because the independent claims were broad and technology-focused. Its strength came from claiming the relationship between:

Intravitreal or posterior-segment delivery.
Sustained release.
Higher vitreous than aqueous exposure.
Therapeutic posterior-segment treatment.

Its principal vulnerabilities were claim breadth and functional language.

Strength	Risk
Broad corticosteroid coverage	Potential written-description and enablement challenges
Covers method and device categories	Functional concentration limitation may be difficult to prove
No required polymer or implant geometry	Prior-art risk from earlier ocular implants
Covers several release durations	Ambiguity in “about” ranges
Broad posterior-segment applications	Claim 3 dependency and claim 17 duplication
Potential relevance to multiple products	Product-specific engineering differences may avoid dependent claims

The broad independent claims could have created litigation leverage. The numerical and release-profile dependent claims offered narrower positions if the independent claims were invalidated or construed narrowly.

What manufacturing and intellectual-property barriers remain?

Patent 6,217,895 no longer creates an active manufacturing barrier. Current barriers may arise from other rights and from technical requirements, including:

Sterile manufacture of an implantable ophthalmic product.
Consistent drug loading.
Controlled long-term release.
Device insertion and placement.
Particle, polymer, and degradation control.
Stability over the labeled shelf life.
Extractables and leachables.
Clinical demonstration of ocular safety.
Product-specific FDA requirements.
Later patents covering formulation, applicator, implant geometry, or indications.

A manufacturer developing a new corticosteroid implant must conduct a current freedom-to-operate review. The expired patent should be treated as prior art and historical claim context, not as the principal current barrier.

How does Patent 6,217,895 compare with later ocular implant patents?

Patent 6,217,895 is broad and platform-oriented. Later patent families generally focus on narrower product attributes.

Patent focus	Typical claim subject
Early platform patents	Posterior-segment sustained corticosteroid delivery
Formulation patents	Drug concentration, excipients, polymers, stabilizers
Device patents	Reservoir architecture, membrane, shape, anchoring, insertion
Manufacturing patents	Drug loading, sterilization, assembly, release consistency
Method-of-use patents	Uveitis, diabetic macular edema, retinal vein occlusion
Later product patents	Specific fluocinolone or dexamethasone implant products

The resulting landscape is layered. Expiration of the early platform patent does not necessarily open the market to an identical product if later formulation or device claims remain active.

What generic launch scenarios exist?

The principal scenarios are:

A generic or follow-on fluocinolone implant launches after clearing later product-specific patents.
A manufacturer develops a different corticosteroid implant outside the scope of later formulation or device claims.
A product uses a different delivery route, such as suprachoroidal administration, and avoids intravitreal-implant claims.
A product uses a biodegradable matrix, reservoir, or release profile materially different from the reference product.
A manufacturer challenges remaining Orange Book patents through Paragraph IV certification and associated litigation.

Patent 6,217,895 itself does not support a current injunction or launch delay because its term has ended.

Is there biosimilar risk associated with this patent?

No. Biosimilar law applies to biological products. The corticosteroids addressed by Patent 6,217,895 are small-molecule drugs, and products such as fluocinolone acetonide and dexamethasone implants proceed through small-molecule FDA pathways rather than the biosimilar pathway.

The relevant competitive mechanisms are ANDAs, 505(b)(2) applications, new drug applications, and product-specific patent litigation.

Key Takeaways

Patent 6,217,895 covers sustained-release corticosteroid delivery to the vitreous or posterior segment.
The core limitation is a vitreous corticosteroid concentration higher than the aqueous concentration during release.
Claims cover both treatment methods and implantable devices.
The patent lists triamcinolone, dexamethasone, fluocinolone, cortisone, prednisolone, flumetholone, and derivatives, but the independent claims are broader.
Claims 2-4 impose aqueous concentration limits, while claims 5-6 address duration and claims 13-14 and 20 address release rate.
Claims 12 and 19 separately require pseudo-zero-order release.
Claim 17, as provided, duplicates claim 16.
Claim 3 appears internally constrained by its dependency on claim 2.
The patent expired in 2018 and is no longer an active infringement or Orange Book barrier.
Retisert is the product most closely associated with the patent’s historical commercial relevance.
Current freedom-to-operate risk must focus on later formulation, device, manufacturing, and method-of-use patents.
Biosimilar analysis is not applicable because the products are small-molecule corticosteroid products.

FAQs About U.S. Patent 6,217,895

Does Patent 6,217,895 cover Retisert?

It historically covered technology closely associated with Retisert’s sustained-release fluocinolone acetonide intravitreal implant. The patent expired in 2018.

Does Patent 6,217,895 cover Ozurdex?

The patent is broad enough to be technically relevant to sustained-release corticosteroid implants, but Ozurdex has a different biodegradable dexamethasone implant design and a separate patent and regulatory history.

Can a company currently sue over Patent 6,217,895?

No. An expired patent cannot support a new infringement action for post-expiration conduct.

Does an expired patent still matter for a generic launch?

Yes. It remains relevant as prior art, as a record of historical product protection, and as a guide to claim construction. It does not itself block FDA approval or commercial launch after expiration.

What is the most important limitation for infringement analysis?

The key limitation is the requirement that sustained release produce an aqueous corticosteroid concentration lower than the vitreous corticosteroid concentration during the release period.

References

U.S. Patent No. 6,217,895. (2001). Treatment of ocular conditions with sustained release corticosteroid implants. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2005). Retisert (fluocinolone acetonide intravitreal implant) prescribing information. FDA.
U.S. Food and Drug Administration. (2009). Ozurdex (dexamethasone intravitreal implant) prescribing information. FDA.
U.S. Food and Drug Administration. (2014). Iluvien (fluocinolone acetonide intravitreal implant) prescribing information. FDA.
U.S. Food and Drug Administration. (2018). Yutiq (fluocinolone acetonide intravitreal implant) prescribing information. FDA.
U.S. Food and Drug Administration. (2021). Xipere (triamcinolone acetonide injectable suspension) prescribing information. FDA.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.

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
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,217,895

Summary for Patent: 6,217,895