United States Patent 10,695,308: Treprostinil Infusion Claims, Scope, Expiration Risk, and Patent Landscape

U.S. Patent No. 10,695,308 protects a treatment method for pulmonary hypertension using a sterile, blood-isotonic intravenous treprostinil solution at specified concentration and infusion-rate parameters. The patent does not broadly cover treprostinil as a molecule, all treprostinil formulations, oral treprostinil, or inhaled treprostinil. Its commercial relevance is concentrated in injectable treprostinil products, including Remodulin and potential generic equivalents.

The independent claim requires four material elements:

A human patient suffering from pulmonary hypertension.
An infusion solution containing 0.1% to 5% w/v treprostinil or an acceptable salt or ester.
Intravenous administration at 0.625 to 50 ng/kg/min.
A solution that is sterile and isotonic with blood.

Claim 2 adds an administration rate of 0.1 mL/min/kg. Claim 3 narrows the dosing rate to 10 to 15 ng/kg/min.

What does U.S. Patent 10,695,308 cover?

The patent covers a treatment method rather than a standalone drug composition. Infringement requires practice of the claimed treatment steps and conditions.

Claim element	Scope
Patient	Human patient
Disease	Pulmonary hypertension
Active ingredient	Treprostinil, or a pharmaceutically acceptable salt or ester
Concentration	0.1% to 5% w/v
Route	Intravenous infusion
Dose rate	0.625 to 50 ng/kg/min
Solution condition	Sterile and isotonic with blood
Claim 2 limitation	0.1 mL/min/kg administration rate
Claim 3 limitation	10 to 15 ng/kg/min dosing rate

The claim is narrower than a conventional formulation patent because it does not claim every injectable treprostinil product. It requires use in a particular clinical setting and at specified dosing parameters.

The claim is broader than a single labeled dose because claim 1 covers a continuous range from 0.625 to 50 ng/kg/min. A product or treatment protocol may fall within the claim even if its labeling emphasizes only a narrower dosing range.

How should the concentration range be interpreted?

The 0.1% to 5% w/v limitation corresponds to approximately 1 to 50 mg/mL:

Stated concentration	Approximate concentration
0.1% w/v	1 mg/mL
1% w/v	10 mg/mL
5% w/v	50 mg/mL

A formulation outside that concentration range should not literally satisfy claim 1. For example, a solution containing 0.05% w/v treprostinil would be below the claimed lower boundary, while a 6% w/v solution would exceed the upper boundary.

The active ingredient limitation includes treprostinil itself and specified salt or ester forms. Treprostinil sodium, the active form used in Remodulin, is the most commercially relevant example. The claim does not require a particular buffer, preservative, container, pump, excipient, pH, or device.

The absence of a specific excipient limitation gives the claim meaningful breadth across different injectable formulations, provided that the formulation remains sterile, isotonic with blood, and within the concentration range.

What does the intravenous dosing limitation require?

Claim 1 requires administration at 0.625 to 50 ng/kg/min. A treatment protocol below 0.625 ng/kg/min or above 50 ng/kg/min would fall outside the literal dosing range of claim 1, subject to possible doctrine-of-equivalents arguments.

Claim 3 is narrower and requires a rate from 10 to 15 ng/kg/min. Because that range is entirely within claim 1, claim 3 is a dependent fallback claim. It does not expand the patent. It provides an additional infringement theory for treatment protocols using the 10-to-15 ng/kg/min range.

The dosage limitation is measured in nanograms per kilogram per minute, while claim 2 uses a volumetric infusion rate. That distinction matters. A volumetric rate alone does not establish infringement unless the solution concentration and patient weight produce administration within the claimed nanogram-per-kilogram-per-minute range.

What is the significance of claim 2’s 0.1 mL/min/kg limitation?

Claim 2 requires administration at 0.1 mL/min/kg. Read literally, this is a high volumetric rate. At that rate, the delivered drug amount depends on concentration:

Concentration	Drug delivery at 0.1 mL/min/kg
1 mg/mL	100 mcg/kg/min
10 mg/mL	1,000 mcg/kg/min
50 mg/mL	5,000 mcg/kg/min

Those calculated amounts are materially higher than the 0.625-to-50 ng/kg/min range in claim 1. The apparent mismatch creates a claim-construction and technical-interpretation issue.

A court would normally examine the issued patent, specification, prosecution history, and any certificate of correction to determine whether the unit is written as issued or contains an apparent drafting error. The claim cannot be analyzed solely by assuming that “0.1 mL/min/kg” means a different unit, such as mL/hr/kg. Until corrected or judicially construed, the language should be treated as written.

For freedom-to-operate purposes, claim 2 should be assessed separately from claim 1. A competitor should not assume that the internal dosing arithmetic invalidates the dependent claim. The issue could affect enforceability, construction, and infringement analysis, but it does not automatically remove claim 2 from the patent.

What products are most directly exposed?

The primary product category is continuous intravenous treprostinil therapy for pulmonary arterial hypertension.

Remodulin

Remodulin is United Therapeutics’ branded treprostinil injection product. Its FDA-approved labeling identifies intravenous and subcutaneous administration and provides titration instructions expressed in ng/kg/min. The product is therefore commercially aligned with the route and dosing subject matter of the patent.[2]

Exposure depends on whether the product or generic label and actual use satisfy all of the following:

Treprostinil concentration between 0.1% and 5% w/v.
Intravenous administration.
A pulmonary-hypertension indication.
A dose between 0.625 and 50 ng/kg/min.
Sterile and blood-isotonic infusion solution.

A product may be commercially related to Remodulin but still avoid literal infringement if it uses a concentration below 0.1%, a different route, or a dosing protocol outside the claimed range.

Generic treprostinil injection

Generic treprostinil injection products present the most direct patent risk because an ANDA applicant may seek approval for the same active ingredient, route, dosage form, and indication as the reference listed drug. A generic label that directs intravenous administration within the claimed range could create a method-of-use exposure even if the generic manufacturer does not manufacture the branded formulation.

The Hatch-Waxman analysis depends on the ANDA applicant’s Paragraph IV certification, the Orange Book listing, the use code, and whether the applicant’s proposed labeling includes the patented method.[3]

Tyvaso and Tyvaso DPI

Tyvaso and Tyvaso DPI are inhaled treprostinil products. They are not literally within claim 1 because the patent requires intravenous administration. Their formulations, delivery devices, and inhalation methods are subject to separate patent and regulatory analyses.

Orenitram

Orenitram is an oral extended-release treprostinil product. It does not satisfy the intravenous-route limitation and is outside the literal scope of claim 1. Its patent estate is directed principally to oral formulations, release characteristics, dosing, and treatment methods.

What formulations are protected by U.S. Patent 10,695,308?

The patent covers a relatively broad class of injectable formulations if they meet the specified concentration and physical conditions.

Potentially covered formulations include:

Treprostinil sodium solutions.
Other pharmaceutically acceptable treprostinil salts.
Treprostinil ester solutions where the ester falls within the claim.
Ready-to-use sterile infusion solutions.
Concentrated solutions diluted before administration, if the administered solution remains within the claimed range.
Formulations administered through an infusion pump or other intravenous delivery system.

The patent does not expressly require:

A specific pH.
A particular buffer.
A named excipient.
A particular vial, cartridge, syringe, or pump.
A specific infusion duration.
A specific catheter.
A particular manufacturing process.

That breadth increases formulation overlap risk. A design-around based only on changing an excipient or container would likely be weak if the resulting solution continues to satisfy the concentration, sterility, isotonicity, route, and dosing limitations.

How does the patent compare with other treprostinil patent categories?

Patent category	Typical protected subject matter	Relevance to U.S. 10,695,308
Compound patents	Treprostinil chemical structure or synthesis	Separate from the asserted treatment method
Injectable formulation patents	Concentration, stability, pH, excipients, containers	May overlap with the claimed infusion solution
Intravenous treatment patents	Dose, route, patient population, administration protocol	Closest category
Inhaled treprostinil patents	Nebulized or dry-powder delivery	Generally outside claim 1
Oral treprostinil patents	Extended release and oral dosing	Outside the intravenous limitation
Manufacturing patents	Synthesis, purification, salt formation	May create separate supply-chain barriers
Device patents	Pumps, cartridges, nebulizers, delivery systems	Relevant only if separately claimed

The key distinction is that U.S. 10,695,308 combines formulation parameters with a clinical-use limitation. A competing company could avoid the patent by changing any one of several variables, but each change may create regulatory, manufacturing, or clinical disadvantages.

What is the Orange Book status of U.S. Patent 10,695,308?

Orange Book relevance depends on whether the patent is listed against a particular treprostinil NDA and the use code assigned to the listing. Patent listing is product-specific. A patent number alone does not establish that every treprostinil product is subject to the patent.

For Remodulin, the relevant questions are:

Whether U.S. 10,695,308 is listed against the applicable NDA.
Whether the listing covers the intravenous method, the formulation, or both.
Whether the listing remains active.
Whether an approved generic applicant must certify against it.
Whether the listed use code corresponds to the indication and dosing language in the proposed label.

The FDA Orange Book identifies listed patents and exclusivity information, but it does not determine patent validity or infringement.[1] A listed patent can be challenged through Paragraph IV litigation, and an unlisted patent can still be relevant in commercial litigation under other legal theories.

When does the patent lose exclusivity?

The patent’s enforceable term is generally based on 20 years from the earliest effective nonprovisional U.S. filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, disclaimers, and other USPTO records.[4]

The June 30, 2020 grant date does not establish the expiration date. The controlling date must be taken from the patent’s continuity data and USPTO term information. Any Orange Book patent-term extension or pediatric extension would need to be evaluated separately from the ordinary patent term.

Regulatory exclusivity is also distinct from patent exclusivity:

Exclusivity type	Legal source	Effect
Patent term	Patent Act	May block making, using, selling, or importing covered subject matter
New-drug exclusivity	FDCA	Restricts certain FDA submissions
Pediatric exclusivity	FDCA § 505A	Adds six months to qualifying exclusivity or patent term
Orphan-drug exclusivity	FDCA § 527	Can restrict approval for the same disease or condition
Reference-product exclusivity	Hatch-Waxman or BPCIA pathway	Delays certain generic or biosimilar submissions

Treprostinil is a small molecule. Biosimilar exclusivity is therefore not the relevant pathway. Generic-drug exclusivity and Paragraph IV litigation are the principal regulatory mechanisms.

Which companies are most likely to challenge the patent?

The most likely challengers are manufacturers seeking approval for injectable treprostinil products, including companies that file ANDAs for the Remodulin reference product. The relevant challenger universe can include:

Generic injectable-drug manufacturers.
Contract manufacturers supplying a proposed generic.
Specialty pharmaceutical companies pursuing abbreviated approval.
Companies seeking a label that includes intravenous pulmonary-hypertension treatment.

A Paragraph IV challenge would typically allege one or more of the following:

Noninfringement because the proposed concentration is outside 0.1% to 5% w/v.
Noninfringement because the proposed label omits intravenous use.
Noninfringement because the labeled dose falls outside 0.625 to 50 ng/kg/min.
Invalidity for anticipation or obviousness.
Invalidity for indefiniteness, written description, or enablement.
A defect involving the claim 2 volumetric-rate limitation.
A regulatory argument that the patented method is carved out of the generic label.

The strength of a skinny-label strategy would depend heavily on the remaining label language. If the product is approved for intravenous pulmonary-hypertension treatment and the label necessarily recommends dosing within the claimed range, the method claim may remain difficult to avoid.

What patent litigation and settlement issues affect launch timing?

A Paragraph IV notice can trigger a 45-day period for the patent owner to file suit. A timely suit may impose a 30-month stay on FDA approval under Hatch-Waxman, subject to statutory exceptions and court actions.[3]

Potential launch outcomes include:

Scenario	Commercial result
No Paragraph IV challenge	Launch after patent and regulatory barriers clear
Paragraph IV suit with 30-month stay	FDA approval may be delayed while litigation proceeds
Early settlement	Launch date depends on the agreed entry date and restrictions
Judgment of invalidity or noninfringement	Earlier launch may follow, subject to other patents
At-risk launch	Generic enters before final patent resolution and assumes damages and injunction risk
Label carve-out	Approval may proceed for noninfringing uses, depending on the carved-out indication

A settlement concerning one Orange Book patent does not necessarily resolve other formulation, method-of-use, manufacturing, or device patents. The complete launch analysis requires the entire listed and unlisted estate.

How strong is the patent estate around injectable treprostinil?

U.S. 10,695,308 is strongest against a product that reproduces the claimed injectable use case:

Sterile isotonic treprostinil solution.
Concentration of at least 0.1% w/v.
Intravenous administration.
Pulmonary-hypertension treatment.
Dose within 0.625 to 50 ng/kg/min.

Its principal weaknesses are claim dependence on multiple measurable parameters and the possibility of designing around the concentration, route, or dosing range. The patent also appears less capable of blocking:

Inhaled treprostinil.
Oral treprostinil.
Low-concentration injectable formulations below 0.1% w/v.
Non-pulmonary-hypertension uses.
Treatment protocols outside the specified dose range.
Products that do not direct intravenous administration in their approved labeling.

The patent’s commercial value is therefore linked to the injectable pulmonary arterial hypertension market, not the entire treprostinil franchise.

What generic entry risks exist?

Generic entry risk is highest when the proposed product matches both the reference product and the claim limitations. The risk increases if:

The generic formulation is at least 1 mg/mL.
The label includes intravenous infusion.
The label covers pulmonary hypertension.
The label provides dosing within the claimed range.
FDA or patent records identify the patent with a relevant use code.
The generic manufacturer cannot credibly carve out the claimed method.

Risk decreases if the proposed generic uses a concentration below 1 mg/mL, removes intravenous instructions, or limits labeling to uses outside the claim. Those strategies may create clinical or commercial disadvantages and may not avoid other patents.

Key Takeaways

U.S. Patent 10,695,308 is a method-of-treatment patent focused on intravenous treprostinil for pulmonary hypertension.
Claim 1 requires a sterile, blood-isotonic solution containing 0.1% to 5% w/v treprostinil and intravenous administration at 0.625 to 50 ng/kg/min.
Claim 3 narrows the dose to 10 to 15 ng/kg/min and is the more targeted claim for common maintenance-dose protocols.
Claim 2 contains a volumetric-rate limitation that creates a significant claim-construction and dosing-arithmetic issue.
Remodulin and generic intravenous treprostinil products face the most direct exposure.
Tyvaso, Tyvaso DPI, and Orenitram are generally outside the literal scope because they use inhaled or oral administration.
The patent does not by itself block all treprostinil products or all treprostinil formulations.
Generic launch risk depends on Orange Book listing, use-code language, Paragraph IV certifications, label design, and other patents in the injectable treprostinil estate.
Treprostinil is a small molecule, so biosimilar analysis is not applicable.
Patent expiration must be determined from the patent’s earliest effective filing date and USPTO term adjustments, not from the 2020 grant date.

FAQs About U.S. Patent 10,695,308

Does U.S. Patent 10,695,308 cover Remodulin itself?

No. It covers a method of treating pulmonary hypertension using specified intravenous treprostinil infusion parameters. The patent is not a broad compound claim to treprostinil.

Can a generic treprostinil product avoid the patent by changing its concentration?

Potentially. A concentration below 0.1% w/v or above 5% w/v would not literally meet the concentration limitation in claim 1, although other patents and regulatory requirements would remain relevant.

Does the patent cover subcutaneous treprostinil administration?

Not literally under claim 1. The claim expressly requires intravenous administration.

Are inhaled treprostinil products subject to this patent?

They generally fall outside claim 1 because inhaled products do not satisfy the intravenous-route limitation. Separate inhalation formulation, device, and method patents may apply.

Is claim 2 commercially important despite its unusual units?

Yes. Claim 2 remains a separate dependent claim. Its 0.1 mL/min/kg language should be analyzed as issued and against the specification and prosecution history rather than disregarded based solely on dosing arithmetic.

References

U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
U.S. Food and Drug Administration. (2023). Remodulin (treprostinil sodium) injection prescribing information. United Therapeutics Corporation.
U.S. Food and Drug Administration. (n.d.). Hatch-Waxman letters. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/hatch-waxman-letters
United States Patent and Trademark Office. (n.d.). Patent term adjustment and patent term extension. https://www.uspto.gov/patents/laws/patent-term-adjustment-patent-term-extension and U.S. Patent No. 10,695,308.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	E473736	⤷ Start Trial
Canada	2549724	⤷ Start Trial
China	101647792	⤷ Start Trial
China	1917866	⤷ Start Trial
Germany	602004028155	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,695,308

Summary for Patent: 10,695,308