US Patent 9,199,908: Treprostinil Intravenous Treatment Claims, Expiration and Patent Landscape

US Patent 9,199,908 protects a method of treating pulmonary hypertension by intravenously administering treprostinil, its pharmaceutically acceptable salts or esters, in sterile water, isotonic saline, or 5% dextrose. The patent is assigned to United Therapeutics Corporation and was issued on December 1, 2015. Its principal commercial relevance is Remodulin, the branded treprostinil injection used to treat pulmonary arterial hypertension.

The patent does not broadly claim treprostinil as a molecule. It claims a clinical administration method. The highest-risk products are injectable treprostinil products labeled or promoted for intravenous use in pulmonary hypertension, particularly products using sterile water or saline and products containing treprostinil diethanolamine salt.

The patent’s nominal expiration is in 2028, subject to the controlling USPTO patent-term calculation and any applicable terminal disclaimer or adjustment. FDA regulatory exclusivity has expired; the remaining barrier is patent-based rather than new-drug exclusivity-based.

What does US Patent 9,199,908 cover?

The independent claim requires four principal elements:

Claim element	Scope
Patient	A human suffering from pulmonary hypertension
Treatment	Intravenous administration
Active ingredient	Treprostinil, or a pharmaceutically acceptable salt or ester
Diluent	Sterile water, isotonic aqueous saline solution, or 5% dextrose solution

Claim 1 uses “comprising,” which generally permits additional formulation components unless another claim limitation excludes them. The claim does not specify a particular concentration, infusion rate, dose, pH, container, pump, catheter, or treatment duration.

The claims therefore focus on the combination of:

The disease indication;
The intravenous route;
A treprostinil active form; and
One of three specified diluents.

A product could fall within the practical risk profile even if its trade name, concentration, pump, packaging, or manufacturing process differs from Remodulin.

What formulation types are protected?

The patent reaches several active-ingredient configurations:

Claims	Active form	Additional limitation
1, 7-11	Treprostinil or pharmaceutically acceptable salt	Claims 8-11 narrow the diluent and bioavailability
2-3	Treprostinil ester	Claim 3 defines a broad ester and prodrug genus
4	Treprostinil salt	No specific salt required
5-6	Polymorph of treprostinil salt	Claim 6 specifies a polymorph of treprostinil diethanolamine salt
8	Treprostinil or salt	Diluent consists of sterile water
9	Treprostinil or salt	Diluent consists of isotonic aqueous saline
10	Treprostinil or salt	Sterile-water IV administration approximates subcutaneous treprostinil-sodium bioavailability
11	Treprostinil or salt	Saline IV administration approximates subcutaneous treprostinil-sodium bioavailability

Claims 2 and 3 are dependent on the broad intravenous-treatment method in claim 1. Claims 4 through 6 create a separate salt and polymorph branch. Claims 7 through 11 narrow claim 1 by excluding esters and specifying particular diluents or bioavailability characteristics.

How broad is claim 1 of US 9,199,908?

Claim 1 is commercially broad but technically limited.

It is broad because it does not require:

A specific treprostinil concentration;
Treprostinil sodium;
A particular infusion pump;
A particular dose or infusion rate;
A particular duration of therapy;
A specific formulation pH;
A specific container or delivery set; or
A specific brand or manufacturing process.

It is limited because all of the following must be present:

Intravenous administration;
A human patient;
Pulmonary hypertension;
Treprostinil or a qualifying salt or ester; and
One of the specified diluents.

A subcutaneous, inhaled, oral, or transdermal treprostinil product does not satisfy the route limitation of claim 1. A product used for a non-pulmonary-hypertension indication would not satisfy the express disease limitation, although labeling, physician instructions, and actual use would affect induced-infringement analysis.

What do claims 2 through 6 add?

What is the scope of the ester claims?

Claim 2 covers the use of treprostinil in ester form. Claim 3 defines a Markush genus involving substituted or unsubstituted benzyl groups, glycolamide ester structures, phosphate groups, amino-acid or protein ester structures, enantiomers, salts, and polymorphs.

The proviso that all R1, R2, and R3 cannot be hydrogen is important. It excludes unmodified treprostinil from the specific compound genus in claim 3, although unmodified treprostinil remains covered by claim 1 where the other limitations are met.

The ester branch appears designed to capture prodrug or derivative approaches that preserve intravenous pulmonary-hypertension treatment while modifying solubility, stability, pharmacokinetics, or formulation properties.

What is the scope of the salt and polymorph claims?

Claim 4 covers a pharmaceutically acceptable salt of treprostinil. Claim 5 narrows the salt to a polymorph. Claim 6 specifically identifies a polymorph of treprostinil diethanolamine salt.

These claims create potential formulation and solid-state barriers even where a competitor avoids treprostinil sodium. A generic developer using a different treprostinil salt may avoid claim 6 but remain exposed to claim 4 if the salt is pharmaceutically acceptable and the IV-treatment limitations are met.

The polymorph claims require careful solid-state characterization. X-ray powder diffraction, thermal analysis, microscopy, spectroscopy, and manufacturing records could become relevant in an infringement dispute.

When does US Patent 9,199,908 lose exclusivity?

The patent was issued on December 1, 2015. Public patent records identify United Therapeutics Corporation as the assignee and show a patent family directed to intravenous treprostinil treatment methods. The patent’s expected term extends into 2028, generally reported as January 2028 for the relevant family, subject to the official USPTO term calculation.

Event	Date or status
Underlying treprostinil discovery and composition patents	Older patents, many expired
US 9,199,908 issuance	December 1, 2015
FDA new-drug exclusivity for the original Remodulin approval	Expired
Reported US 9,199,908 patent term	Into January 2028
Post-expiration status	Claims generally cease to block conduct occurring after expiration

Patent expiration does not eliminate regulatory requirements. A generic applicant still must obtain FDA approval, demonstrate pharmaceutical equivalence and bioequivalence where applicable, and satisfy manufacturing and labeling requirements.

What is the Orange Book status of US Patent 9,199,908?

The Orange Book lists patent information submitted by sponsors for approved drug products. Remodulin is an FDA-approved treprostinil injection product indicated for pulmonary arterial hypertension. Its regulatory history includes intravenous and subcutaneous administration, with labeling that addresses preparation and administration of the injection product.[2]

The commercial question is whether US 9,199,908 is currently listed against the relevant Remodulin reference listed drug and whether the listing covers the dosage form or method of use at issue. An Orange Book listing would materially affect ANDA timing because an applicant could face a Paragraph IV certification and potential 30-month stay if the patent is listed and litigation is timely filed.

The patent itself is a method-of-treatment patent. It is not a composition-of-matter patent and does not by itself prevent FDA approval of every treprostinil product. Its practical effect depends on:

Whether it is listed against the relevant reference product;
Whether the applicant’s labeling includes the patented IV pulmonary-hypertension use;
Whether a section viii statement can remove the patented use;
Whether the applicant makes a Paragraph IV certification; and
Whether the patent remains unexpired when the generic launches.

FDA Orange Book listing and patent validity are separate issues. FDA does not determine whether the claims are valid or infringed.

How does the patent affect Paragraph IV challenges?

A generic applicant for an injectable treprostinil product generally has four relevant certification pathways:

Certification	Commercial effect
Paragraph I	No patent information has been submitted
Paragraph II	Listed patent has expired
Paragraph III	Applicant accepts delayed approval until patent expiration
Paragraph IV	Applicant alleges that the patent is invalid, unenforceable, or not infringed

For US 9,199,908, a Paragraph IV position could target several limitations:

The product is not administered intravenously;
The proposed label does not treat pulmonary hypertension;
The formulation does not use one of the claimed diluents;
The active ingredient is outside the claimed treprostinil, salt, or ester scope;
A claimed polymorph is absent;
The bioavailability limitation in claims 10 or 11 is not met;
The claims are invalid for anticipation or obviousness; or
The patent is unenforceable based on prosecution or conduct issues.

A section viii “skinny label” strategy may be more difficult if the reference product’s approved labeling centers on intravenous treatment of pulmonary arterial hypertension. Removing an indication from the label does not necessarily eliminate induced-infringement risk if the product is marketed, instructed, or designed for the patented use.

What patent litigation affects treprostinil injection products?

The claims supplied do not establish a litigation outcome, settlement, or final validity ruling. The principal litigation risk would arise if United Therapeutics asserts US 9,199,908 against an ANDA applicant or another sponsor of IV treprostinil.

A conventional Hatch-Waxman dispute could involve:

Paragraph IV notice;
A patent-infringement complaint under 35 U.S.C. § 271(e)(2);
A 30-month approval stay;
Claim-construction proceedings;
Invalidity defenses based on prior art;
Non-infringement defenses based on route, diluent, indication, or active form; and
A launch-at-risk decision before final judgment.

The patent’s method claims create a potentially narrower litigation target than a composition patent. A competitor could seek to avoid infringement through a different administration route, a different indication, a different diluent, or a non-covered active form. That design-around strategy becomes harder where the competitor’s product is intended as a direct substitute for Remodulin IV use.

Which earlier patents cover treprostinil?

The relevant US estate includes older composition, method, formulation, and administration patents. The following patents are frequently associated with the Remodulin and treprostinil portfolio:

Patent	General subject matter	Commercial significance
US 5,153,222	Treprostinil and related prostacyclin analog compounds	Core compound protection; expired
US 6,765,117	Treprostinil treatment methods	Earlier method protection; expiration predates or approaches the later family
US 7,999,007	Treprostinil pulmonary-hypertension treatment methods	Method and administration protection
US 8,318,802	Intravenous treprostinil treatment and formulation subject matter	Closely related family protection
US 9,199,908	IV treprostinil treatment using specified diluents and active forms	Later continuation or related method protection

The exact scope and term of each family member depend on priority claims, continuations, terminal disclaimers, patent-term adjustment, and prosecution history. A patent-family review should not treat all listed patents as interchangeable. Some claims may cover the active compound, while others cover administration, formulations, salts, polymorphs, or particular indications.

How strong is the patent estate for intravenous treprostinil?

The estate has moderate commercial strength and narrower technical breadth than a live composition patent.

Strengths

It targets the clinically important IV pulmonary-hypertension use.
It covers treprostinil and pharmaceutically acceptable salts or esters.
It identifies common diluents used in injectable products.
It includes a salt and polymorph branch.
It does not depend on a particular dose, concentration, pump, or container.
It can potentially reach a generic product’s labeled use and commercial instructions.

Weaknesses

The claim requires intravenous administration.
The claim requires pulmonary hypertension treatment.
The diluent list is closed at the claim level.
Treprostinil composition patents are older and do not provide the same remaining term.
A competitor may design around the route, indication, diluent, or active form.
Claims 10 and 11 use the functional phrase “approximating” bioavailability, which may create claim-construction and proof issues.
Method patents are generally more dependent on labeling and actual-use evidence than composition patents.

The strongest commercial claims are likely claims 1, 4, 7, 8, and 9. Claims 10 and 11 add a pharmacokinetic limitation that may be harder to prove but may also narrow the prior-art field. Claim 6 could be valuable against a competitor using the specified diethanolamine polymorph, provided the polymorph can be analytically identified in the accused product.

What generic entry risks exist for Remodulin?

Scenario 1: Paragraph III delay

A generic applicant accepts the patent and delays approval or launch until expiration. This produces the lowest litigation risk but postpones competition.

Scenario 2: Paragraph IV challenge

The applicant alleges invalidity or non-infringement. United Therapeutics may file suit, triggering a statutory approval stay if the listing and filing requirements are satisfied. Approval could be delayed until settlement, judgment, or expiration.

Scenario 3: Skinny-label launch

The applicant removes the patented pulmonary-hypertension IV use if FDA permits the carve-out. This strategy is less effective where the approved product’s principal commercial use is the patented treatment or where promotional conduct supports induced infringement.

Scenario 4: Formulation design-around

The applicant uses a different diluent, route, or active form. This may avoid some claims but can reduce substitutability and create separate regulatory or clinical-development burdens.

Scenario 5: Launch after patent expiration

The applicant launches after the relevant patent term ends. The principal remaining barriers are FDA approval, manufacturing capacity, supply reliability, and physician or hospital switching costs.

Does treprostinil have biosimilar risk?

No. Treprostinil is a chemically synthesized small molecule, not a biological product. Biosimilar regulation under the Public Health Service Act does not apply. Competitive products would generally use the ANDA pathway for a pharmaceutically equivalent generic or another applicable small-molecule pathway.

The principal regulatory competition is therefore generic injectable treprostinil, not biosimilar treprostinil.

What licensing deals affect the patent landscape?

United Therapeutics commercializes Remodulin and has held the principal US commercial position for treprostinil products. Historical development and commercialization arrangements involving treprostinil rights are relevant to ownership and chain-of-title analysis, but the claims at issue are assigned to United Therapeutics in the US patent record.

A licensing review should distinguish:

Ownership of US 9,199,908;
Rights to the treprostinil molecule;
Rights to Remodulin marketing and distribution;
Rights to inhaled treprostinil products such as Tyvaso;
Manufacturing licenses; and
Settlement or supply agreements with generic applicants.

A license to treprostinil technology does not necessarily grant freedom to operate under every later method, formulation, salt, or polymorph patent.

How does US 9,199,908 compare with other treprostinil patent categories?

Patent category	Typical protected subject	Relevance to US 9,199,908
Composition patents	Treprostinil molecule and chemical analogs	Broader chemical protection but largely expired
IV method patents	Administering treprostinil intravenously for pulmonary hypertension	Directly overlaps with US 9,199,908
Formulation patents	Concentration, excipients, stability, packaging	May create separate product-specific barriers
Salt and polymorph patents	Treprostinil sodium, diethanolamine salts, crystal forms	Important for solid-state and injectable formulation design
Inhalation patents	Aerosolized treprostinil and inhalation devices	Generally outside the IV route limitation
Manufacturing patents	Synthesis, purification, crystallization, sterilization	Can restrict supply without directly blocking use

The patent is most important for Remodulin-type IV treatment. It is less relevant to Tyvaso inhalation products, oral treprostinil products, or non-pulmonary-hypertension uses unless separate claims or patents cover those products.

What are the key geographic and manufacturing barriers?

US 9,199,908 has territorial effect only in the United States. It does not directly block IV treprostinil manufacture, sale, or use in Europe, Canada, Japan, or other jurisdictions. Equivalent foreign family members must be analyzed separately for filing, grant, claim scope, opposition, lapse, and expiration.

Manufacturing barriers may remain after patent expiration because injectable treprostinil requires:

Sterile manufacturing;
Validated aseptic processing;
Control of impurities and degradation products;
Consistent salt or polymorph characteristics;
Container-closure integrity;
Stability data;
Reliable supply of active pharmaceutical ingredient; and
FDA-compliant quality systems.

These barriers do not extend the patent term, but they can delay generic commercialization and limit the number of credible entrants.

Key Takeaways

US 9,199,908 is a method-of-treatment patent, not a basic treprostinil composition patent.
Its core claim requires IV administration to a human with pulmonary hypertension.
The formulation must contain treprostinil or a qualifying salt or ester and sterile water, isotonic saline, or 5% dextrose.
Claims 4 through 6 create additional salt and polymorph protection, including treprostinil diethanolamine polymorphs.
The patent was issued on December 1, 2015, and its reported US term extends into January 2028.
FDA exclusivity is not the principal barrier; patent status and ANDA certification strategy are.
Treprostinil has generic, not biosimilar, competition.
The most important generic defenses are non-infringement based on route, indication, diluent, active form, or polymorph, plus invalidity challenges.
IV products directly substitutable for Remodulin face greater exposure than inhaled, oral, or subcutaneous products.
Patent expiration will not eliminate sterile-manufacturing, FDA approval, supply-chain, or market-entry barriers.

FAQs

Can a generic treprostinil product avoid US 9,199,908 by using treprostinil sodium?

Not necessarily. Treprostinil sodium is a pharmaceutically acceptable salt and may fall within claims 1, 4, 7, 8, or 9 when the product is administered intravenously for pulmonary hypertension with a claimed diluent.

Does a subcutaneous treprostinil product infringe US 9,199,908?

A purely subcutaneous method does not satisfy the express intravenous-administration limitation. Separate patents or other infringement theories could still apply.

Does the patent cover treprostinil inhalation products?

The supplied claims do not cover inhalation because they require intravenous administration. Inhaled treprostinil products must be evaluated against separate formulation, device, method, and use patents.

Can a competitor avoid claim 6 by using treprostinil sodium instead of treprostinil diethanolamine?

Potentially, but claim 4 is not limited to diethanolamine. A sodium-salt product may avoid claim 6 while remaining exposed to broader salt or method claims.

Does FDA approval of a generic treprostinil injection establish that US 9,199,908 is invalid?

No. FDA approval and patent validity are separate. Approval may proceed subject to patent certifications, litigation, a settlement, a delayed launch, or expiration of the listed patent.

References

United States Patent and Trademark Office. (2015). US Patent No. 9,199,908, Methods of treating pulmonary hypertension.
U.S. Food and Drug Administration. (2023). Remodulin (treprostinil sodium) injection: Prescribing information. United Therapeutics Corporation.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
United States Patent and Trademark Office. (1992). US Patent No. 5,153,222, Benzindene prostaglandins.
United States Patent and Trademark Office. (2004). US Patent No. 6,765,117, Methods of treating pulmonary hypertension.
United States Patent and Trademark Office. (2011). US Patent No. 7,999,007, Methods of treating pulmonary hypertension.
United States Patent and Trademark Office. (2012). US Patent No. 8,318,802, Methods of treating pulmonary hypertension.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	2526534	⤷ Start Trial
Canada	2736406	⤷ Start Trial
Canada	2851309	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,199,908

Summary for Patent: 9,199,908