US Patent 10,864,159: Tafluprost Ophthalmic Formulation Scope, Claim Analysis, and Patent Landscape

US Patent 10,864,159 protects a narrow tafluprost treatment regimen tied to a specific preservative-free ophthalmic solution and, in dependent claims, to single-dose low-density polyethylene packaging. The patent does not broadly cover tafluprost, glaucoma treatment, or all tafluprost formulations. Its commercial risk is concentrated in products matching the claimed concentrations, excipient profile, dosage form, and packaging configuration.

The claims are method-of-treatment claims. A potential infringer generally must practice the claimed administration method using a product that satisfies every required formulation and packaging limitation. The patent’s practical relevance therefore depends on the approved product label, the composition of competing products, the packaging materials, and any FDA-listed patent information.

What does US Patent 10,864,159 protect?

The patent protects treating ocular hypertension or glaucoma by administering an aqueous tafluprost solution containing the following formulation:

Component	Claimed concentration
Tafluprost	0.0015% w/v
Polysorbate 80	0.075% w/v
Disodium edetate	0.05% w/v
Glycerol	2.25% w/v
Sodium dihydrogen phosphate dihydrate	0.2% w/v
pH adjuster or adjusters	Quantity sufficient for pH adjustment
Water	Remainder

Claim 1 uses the transition “consisting of.” That language materially narrows the claim. The claimed ophthalmic solution is limited to the listed components, subject to the express allowance for one or more pH adjusters and water. A competing product containing an additional preservative, buffer, surfactant, stabilizer, tonicity agent, or other excipient could fall outside the literal scope of claim 1, depending on how the additional ingredient is characterized and whether it is inherent in a permitted component.

The claim also requires:

an ophthalmic aqueous solution;
tafluprost as the active ingredient;
treatment of ocular hypertension or glaucoma;
administration to a subject in need of treatment; and
the exact claimed tafluprost and excipient concentrations.

The patent therefore functions as a formulation-specific method patent rather than a compound patent.

How narrow are the claims of US Patent 10,864,159?

The claims are narrow in composition and progressively narrower in packaging.

Claim 1: exact formulation and therapeutic use

Claim 1 requires the exact listed composition and concentrations. The claim does not expressly require:

a particular tafluprost dose per eye;
a specific dosing frequency;
a particular bottle size;
a particular pH value;
a particular osmolarity;
a specific fill volume;
a particular manufacturing process; or
a particular commercial brand.

The absence of those limitations does not broaden the claim beyond the listed formulation. A product with the same listed ingredients but materially different concentrations could avoid literal infringement of claim 1, although equivalence arguments may remain relevant in litigation.

Claims 2 and 4: unit-dose low-density polyethylene packaging

Claim 2 adds a single-dose or unit-dose container. Claim 4 combines the unit-dose limitation with a container made of low-density polyethylene, or LDPE.

These claims are directed to the product presentation and container system, not merely the liquid formulation. A product using the claimed solution in a glass bottle, polypropylene container, high-density polyethylene container, or another non-LDPE package would not literally satisfy claim 4.

Claim 3: LDPE container without the unit-dose limitation

Claim 3 requires an LDPE container but depends directly from claim 1. It does not require the single-dose limitation in claim 2. This gives claim 3 broader packaging coverage than claim 4.

Claim 5: polyethylene content limitation

Claim 5 requires the claim 4 package to contain no more than 10% of any material other than polyethylene. The limitation appears directed to the composition of the container or container system. It raises factual issues concerning:

whether the 10% calculation is by weight, volume, or another basis;
whether closures, labels, liners, inks, and secondary packaging count;
whether additives within the polyethylene count as non-polyethylene material;
whether “polyethylene” includes only LDPE or all polyethylene grades; and
whether the 10% threshold applies to the primary container alone or the complete unit-dose assembly.

Claim 5 is the most fact-intensive claim and may be harder to enforce without detailed packaging specifications and manufacturing records.

What is the likely commercial product associated with US Patent 10,864,159?

The claimed composition closely corresponds to preservative-free tafluprost ophthalmic solution at 0.0015%, the strength used for Zioptan. Zioptan is a prostaglandin analogue indicated for reducing elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension. The FDA-approved product is supplied in single-use containers and does not contain a conventional antimicrobial preservative (FDA, 2023).

The connection between a marketed product and a patent requires more than matching the active ingredient and strength. The relevant comparison must examine:

the complete inactive-ingredient list;
the concentration of each excipient;
the exact buffer system;
pH-adjusting agents;
single-dose packaging;
polymer identity and grade;
container composition; and
the approved prescribing information.

A tafluprost product may match the 0.0015% strength and still avoid claim 1 by using a different excipient system or a materially different concentration.

What patents protect tafluprost products beyond US Patent 10,864,159?

Tafluprost products may be covered by several patent categories, but they present different risks.

Compound patents

Compound patents cover tafluprost or related prostaglandin analogues as chemical entities. Those patents generally control the earliest exclusivity period and are distinct from the formulation claims in US 10,864,159. For a product first approved in 2012, the original compound-patent term would ordinarily be the principal historic patent barrier, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and the specific priority chain.

Formulation patents

Formulation patents cover excipient combinations, concentration ranges, pH, stability, preservative-free presentation, container materials, or delivery systems. US 10,864,159 is in this category, although its claims are drafted as methods of treatment.

The patent does not claim every preservative-free tafluprost formulation. Its formulation protection is tied to the recited concentrations and ingredients.

Method-of-use patents

Claims 1 through 5 are method-of-use claims. They require treatment of ocular hypertension or glaucoma using the claimed solution. A method patent can create a regulatory and litigation issue when the patented use is included in an approved label or when the manufacturer encourages the patented use.

For an ANDA applicant, a Paragraph IV certification may be relevant if the patent is listed in the FDA Orange Book and the applicant asserts that the patent is invalid, unenforceable, or will not be infringed. A section viii statement may be available for a listed method-of-use patent if the applicant omits the patented indication from its labeling, but that pathway is less useful when the patent covers the formulation used for the approved indication.

Packaging and container patents

Claims 2 through 5 add packaging limitations. These claims can affect a generic developer even when the liquid formulation is designed around the patent. A developer may need to use a different polymer, a different container architecture, or a package containing more than the claimed non-polyethylene threshold.

Packaging claims can be commercially significant because unit-dose ophthalmic products require container systems that satisfy sterility, extractables, leachables, dose-delivery, and stability requirements. A design-around must satisfy those requirements while avoiding the claimed package configuration.

When does US Patent 10,864,159 lose exclusivity?

The patent issued on December 15, 2020. Its expiration date cannot be determined from the claims alone because the controlling date is the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and the patent’s priority chain (USPTO, 2024).

Exclusivity item	Relevance
Patent issue date	December 15, 2020
Statutory term	Generally 20 years from the applicable nonprovisional filing date
Patent-term adjustment	May extend the ordinary term
Patent-term extension	Potentially relevant if statutory requirements are met
Terminal disclaimer	Could limit expiration if the patent is tied to another patent
FDA regulatory exclusivity	Separate from patent term
Orange Book expiration	Must be confirmed from FDA listing data

Patent expiration is not the same as FDA exclusivity expiration. FDA small-molecule exclusivity may include five-year new chemical entity exclusivity, three-year exclusivity for certain new clinical investigations, or six-month pediatric exclusivity. Those periods are separate from the patent term and may have expired well before the term of a later-issued formulation patent.

What is the Orange Book status of US Patent 10,864,159?

A patent’s inclusion in the Orange Book is determined by FDA listing rules and the approved product’s NDA information, not by the patent document itself. FDA regulations permit listing of patents that claim the drug substance, drug product, or an approved method of using the drug (FDA, 2024a).

US 10,864,159 is a method patent with formulation and packaging limitations. It could be Orange Book-relevant if:

it was submitted for listing by the NDA holder;
the claims cover the approved tafluprost product or an approved method of use;
the patent information was accepted by FDA; and
the listing remains active for the relevant product.

The patent number alone does not establish an Orange Book listing. FDA’s current Orange Book patent and exclusivity data control the regulatory analysis. An ANDA applicant must evaluate the listing status, patent-use code, expiration date, and any applicable certification obligation.

What Paragraph IV risks exist for tafluprost generics?

A tafluprost ANDA applicant could face several certification scenarios.

Paragraph IV certification

A Paragraph IV certification would assert that a listed patent is invalid, unenforceable, or not infringed. For US 10,864,159, the main noninfringement arguments would likely focus on:

a different excipient;
a concentration outside the claimed value;
an additional ingredient inconsistent with “consisting of”;
a different pH-adjustment system;
a nonaqueous or otherwise materially different dosage form;
packaging that is not LDPE;
packaging that is not single-dose or unit-dose; or
a container containing more than 10% non-polyethylene material.

Validity challenges could address written description, enablement, indefiniteness, anticipation, obviousness, claim construction, and statutory subject-matter issues. Exact-concentration formulation claims may face obviousness arguments based on prior art disclosing tafluprost at 0.0015% with overlapping excipient systems.

Section viii statement

A section viii statement may be relevant when the patent claims only a method of use that can be omitted from the ANDA labeling. It is less straightforward where the claims also read on the formulation and package used for the product. The applicant’s proposed label, product composition, and package would determine whether a carve-out is viable.

30-month stay

If the NDA holder or patent owner brings an infringement action within the statutory period after receiving a Paragraph IV notice, the Hatch-Waxman framework can trigger a stay of FDA approval, subject to statutory exceptions and later litigation developments (21 U.S.C. § 355).

Which companies are challenging the tafluprost patent estate?

The claim text does not identify any Paragraph IV filer, ANDA applicant, litigation defendant, settlement agreement, or licensee. A reliable challenger analysis must be based on FDA ANDA records, district-court complaints, Patent Trial and Appeal Board proceedings, and SEC disclosures.

The relevant commercial parties historically include:

Santen Pharmaceutical Co., Ltd., associated with tafluprost development and manufacture;
the NDA holder or commercial distributor for Zioptan;
generic ophthalmic manufacturers pursuing tafluprost ANDAs;
contract manufacturers producing sterile unit-dose ophthalmic products; and
suppliers of LDPE ophthalmic containers.

No specific company can be identified as a challenger solely from US 10,864,159.

How strong is the patent estate for US 10,864,159?

The patent is strongest against an exact-copy product. A competing product is exposed when it reproduces all of the following:

Risk factor	Exposure level
Tafluprost at 0.0015% w/v	High
Listed excipients at claimed concentrations	High
Preservative-free aqueous solution	Depends on complete composition
Single-dose or unit-dose presentation	High for claim 2
LDPE container	High for claims 3 and 4
Container with no more than 10% non-polyethylene material	High for claim 5
Different excipient system	Potential design-around
Different concentration	Potential design-around
Different container polymer	Potential design-around

The “consisting of” limitation improves design-around visibility but may create claim-construction disputes around pH adjusters, water, trace impurities, manufacturing residues, and ingredients that are chemically present but not intentionally added.

The method format also affects enforcement. The patent owner would need to establish that the accused product is used in the claimed treatment method or that the defendant induces the relevant use. Product labeling, prescribing information, promotional materials, and regulatory submissions would be important evidence.

What formulation and manufacturing barriers remain after patent expiration?

Patent expiration would not eliminate all market-entry barriers. Preservative-free tafluprost products require sterile manufacturing and container systems capable of maintaining product quality through the labeled shelf life.

Key technical barriers include:

sterile filling of low-volume unit-dose containers;
control of tafluprost degradation products;
adsorption or absorption into the polymer container;
extractables and leachables;
container-closure integrity;
dose uniformity;
pH and osmolality control;
light and temperature stability;
compatibility of polysorbate 80 with the container system; and
commercial-scale supply of compliant LDPE components.

These factors may support regulatory differentiation even where no enforceable patent remains. They do not, by themselves, create patent rights.

How does US Patent 10,864,159 compare with broad tafluprost protection?

Protection type	Scope	Relevance to US 10,864,159
Tafluprost compound patent	Broad chemical-entity protection	Different patent category
Tafluprost composition patent	Specific formulation or concentration	Closely related
Treatment-method patent	Use in glaucoma or ocular hypertension	Direct claim format here
Container patent	Package structure or polymer	Claims 2-5 contain packaging limits
Manufacturing patent	Sterile filling, stabilization, or process	Not recited in the supplied claims
Regulatory exclusivity	FDA approval-based market protection	Separate from patent rights

US 10,864,159 is narrower than a compound patent but potentially more relevant to the marketed preservative-free unit-dose product. Its commercial value depends on whether the approved product uses the claimed formulation and package, whether the patent is Orange Book-listed, and whether a generic can design around one required element without sacrificing FDA approval or product performance.

Key Takeaways

US Patent 10,864,159 covers a specific tafluprost 0.0015% ophthalmic aqueous formulation.
Claim 1 is limited by exact excipients and concentrations and uses “consisting of,” which narrows the permitted composition.
Claims 2 through 5 add single-dose, unit-dose, LDPE, and polyethylene-content limitations.
The patent does not broadly cover tafluprost or every glaucoma treatment using tafluprost.
The claims are method claims, so infringement analysis depends on composition, packaging, labeling, and actual or induced use.
FDA Orange Book listing cannot be established from the patent claims alone.
The patent issued December 15, 2020, but the expiration date requires the patent’s priority, filing, adjustment, extension, and terminal-disclaimer data.
The principal design-around options are changing an excipient, concentration, container polymer, unit-dose configuration, or container composition.
Sterile manufacturing and container-closure performance remain material entry barriers independent of patent protection.
No challenger, litigation, or settlement can be identified from the supplied patent claim text.

FAQs

Does US Patent 10,864,159 cover Zioptan?

The claims closely track the 0.0015% preservative-free tafluprost product profile associated with Zioptan, but coverage depends on the marketed product’s complete formulation and packaging.

Can a generic tafluprost product avoid the patent by changing the bottle?

Potentially. A product using a non-LDPE container could avoid claims 3 and 4, but it would still need to assess claim 1 and claim 2.

Does a different tafluprost concentration avoid claim 1?

A materially different concentration would not literally satisfy the stated 0.0015% w/v limitation. Equivalence issues could still arise, depending on the facts and governing law.

Can an ANDA applicant omit the glaucoma indication to avoid this patent?

A labeling carve-out may be relevant for a pure method-of-use patent, but these claims also require a particular formulation and package. The feasibility of a section viii statement depends on the approved labeling and product design.

Does patent expiration permit immediate commercial launch of a tafluprost generic?

No. FDA approval, applicable regulatory exclusivity, manufacturing validation, sterile-product requirements, and any other unexpired patents or litigation restraints must also be addressed.

References

Food and Drug Administration. (2023). Zioptan (tafluprost ophthalmic solution) prescribing information. U.S. Department of Health and Human Services.
Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
Food and Drug Administration. (2024b). Orange Book: Approved drug products with therapeutic equivalence evaluations, patent and exclusivity information. U.S. Department of Health and Human Services.
United States Patent and Trademark Office. (2024). Manual of Patent Examining Procedure: Patent term and patent term adjustment. U.S. Department of Commerce.
21 U.S.C. § 355. New drugs and antibiotics.
35 U.S.C. §§ 154, 156. Patent term and patent term extension.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Thea Pharma	ZIOPTAN	tafluprost	SOLUTION/DROPS;OPHTHALMIC	202514-001	Feb 10, 2012	AT	RX	Yes	Yes	10,864,159	⤷ Start Trial	Y			REDUCTION OF ELEVATED INTRAOCULAR PRESSURE IN PATIENTS WITH OPEN ANGLE GLAUCOMA OR OCULAR HYPERTENSION	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
	08397513	May 30, 2008

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	071937	⤷ Start Trial
Argentina	120961	⤷ Start Trial
Australia	2009252210	⤷ Start Trial
Brazil	PI0913109	⤷ Start Trial
Canada	2724194	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,864,159

Which drugs does patent 10,864,159 protect, and when does it expire?

Summary for Patent: 10,864,159