United States Patent 8,252,839: Treprostinil Diethanolamine Salt Scope, Claims, Expiration, and Patent Landscape

U.S. Patent No. 8,252,839 protects pharmaceutical formulations containing treprostinil diethanolamine, including oral dosage forms and a specific polymorph of the (+)-treprostinil diethanolamine salt. The patent is directly relevant to Orenitram, United Therapeutics’ extended-release oral treprostinil product. Its strongest commercial coverage is the composition claim covering the diethanolamine salt itself when formulated with a pharmaceutical carrier. The patent is a small-molecule formulation patent, not a biologic patent, so biosimilar regulation is not relevant.

What does U.S. Patent 8,252,839 protect?

The patent claims a pharmaceutical formulation containing a therapeutically effective amount of treprostinil diethanolamine and a pharmaceutically acceptable carrier. Dependent claims extend coverage to specific formulation types, a P-glycoprotein inhibitor, the (+)-enantiomer, and a polymorph melting at approximately 107°C.

Claim	Principal limitation	Commercial significance
1	Formulation containing a therapeutically effective amount of treprostinil diethanolamine and a pharmaceutically acceptable carrier	Broadest composition claim
2	Claim 1 plus a P-glycoprotein inhibitor	Narrower formulation and absorption-enhancement coverage
3	Claim 1 in capsule, tablet, liquid, or suspension form	Covers multiple oral and liquid dosage formats
4	Claim 1 containing the diethanolamine salt of (+)-treprostinil	Stereochemically limited active ingredient
5	Claim 1 containing a polymorph of the (+)-treprostinil diethanolamine salt melting at 107°C	Narrow solid-state and polymorph claim

The patent issued on August 28, 2012, and is assigned to United Therapeutics Corporation. Its subject matter is associated with the conversion of treprostinil into a diethanolamine salt suitable for pharmaceutical development and oral administration (U.S. Patent No. 8,252,839, 2012).

How broad is claim 1 of Patent 8,252,839?

Claim 1 is materially broader than claims 2 through 5 because it does not require a particular dosage form, stereochemical designation, polymorph, release profile, or P-glycoprotein inhibitor.

The principal elements are:

A pharmaceutical formulation;
A therapeutically effective amount;
Treprostinil in the form of its diethanolamine salt; and
A pharmaceutically acceptable carrier.

The claim does not expressly require:

An extended-release matrix;
A particular tablet coating;
A particular dissolution profile;
A specified dose;
A specific route of administration;
A specified excipient;
A particular polymorph;
A P-glycoprotein inhibitor; or
A particular ratio of treprostinil to carrier.

That structure gives claim 1 potentially broad product coverage. A competing product could infringe even if it uses a different tablet technology, provided the finished pharmaceutical formulation contains the claimed diethanolamine salt and a pharmaceutically acceptable carrier.

The principal claim-construction issue is whether the accused product contains treprostinil diethanolamine as the active pharmaceutical ingredient in the claimed formulation. A product that uses a different treprostinil salt, such as treprostinil sodium, would not literally satisfy the diethanolamine-salt limitation. A product containing treprostinil diethanolamine but using a substantially different formulation could still fall within claim 1.

What do claims 2 through 5 add?

Claim 2: P-glycoprotein inhibitor

Claim 2 requires the formulation to include a P-glycoprotein inhibitor. The additional limitation narrows the claim substantially. A generic product would need to contain both treprostinil diethanolamine and a qualifying P-glycoprotein inhibitor to infringe literally.

This claim is commercially less central than claim 1 unless the branded or generic formulation uses an absorption-enhancing excipient or active inhibitor. The claim could become important if a manufacturer seeks to increase oral bioavailability by modulating intestinal drug transport.

Claim 3: Capsule, tablet, liquid, or suspension

Claim 3 expressly covers four dosage-form categories:

Capsules;
Tablets;
Liquids; and
Suspensions.

The claim does not require extended release. A tablet or capsule containing treprostinil diethanolamine may fall within the claim even if the release mechanism differs from the Orenitram formulation, assuming the product also satisfies claim 1.

The claim is therefore broader in dosage-form coverage than a claim limited to an extended-release tablet. Its vulnerability is that dosage-form claims can face prior-art challenges where the active salt and conventional pharmaceutical carrier were already known.

Claim 4: (+)-treprostinil

Claim 4 narrows the active ingredient to the diethanolamine salt of (+)-treprostinil. This limitation is important because treprostinil has stereochemical attributes, and the claim excludes formulations that contain only a different stereoisomer or an unclaimed stereochemical mixture.

A product containing the same (+)-treprostinil diethanolamine salt would present a stronger literal-infringement risk than a product containing a different salt or stereochemical form.

Claim 5: 107°C polymorph

Claim 5 is the narrowest and most technically specific claim. It requires a polymorph of the (+)-treprostinil diethanolamine salt that melts at 107°C.

A polymorph claim generally raises several technical questions:

Whether the accused solid is the same crystalline form;
Whether the melting point is measured under comparable conditions;
Whether the 107°C value identifies a single polymorph or a range of forms;
Whether thermal decomposition affects the measured result;
Whether the patent adequately discloses and characterizes the claimed solid form; and
Whether the polymorph was anticipated or obvious over earlier salt and crystallization disclosures.

A generic manufacturer can attempt to avoid claim 5 by producing an amorphous form, a different polymorph, a hydrate or solvate, or a different salt. That strategy would not necessarily avoid claim 1, which is not expressly limited to the 107°C polymorph.

What is the relationship between Patent 8,252,839 and Orenitram?

Orenitram is an extended-release oral formulation of treprostinil diolamine, the United States product name for treprostinil diethanolamine. The FDA approved Orenitram on December 20, 2013, under NDA 203496 for pulmonary arterial hypertension (FDA, 2013).

The patent’s claim language maps most directly onto the active ingredient and dosage-form aspects of Orenitram:

Orenitram characteristic	Relevance to Patent 8,252,839
Treprostinil diolamine active ingredient	Directly relevant to claim 1
Oral tablet	Directly relevant to claim 3
(+)-treprostinil stereochemistry	Relevant to claim 4
Solid-state form of the active salt	Potentially relevant to claim 5
Extended-release delivery	Not expressly required by claims 1 or 3
Pulmonary arterial hypertension indication	Not required by the issued claims

The patent does not claim pulmonary arterial hypertension treatment as a method of use in the claims provided. It claims the formulation itself. That distinction matters because a generic applicant cannot avoid a composition claim merely by labeling the product for a different indication if the product still contains the claimed formulation.

When does U.S. Patent 8,252,839 lose exclusivity?

The patent’s nominal expiration is in December 2027 based on the patent-term calculation associated with its priority and filing history. The effective date must be determined from the USPTO patent-term data, including any patent-term adjustment and any applicable terminal disclaimer.

The patent does not provide exclusivity until 2027 by itself. Market entry depends on the full Orange Book patent listing, regulatory exclusivity, litigation outcomes, and any settlement restrictions.

Exclusivity category	Relevance
Patent term	Nominally extends into December 2027
New chemical entity exclusivity	Not the principal current barrier for Orenitram
Three-year clinical-investigation exclusivity	Applied after the 2013 approval period and is no longer the principal barrier
Pediatric exclusivity	Could add six months if granted and applicable
Orange Book-listed patents	Can delay approval or launch through ANDA litigation
Settlement restrictions	May establish an agreed generic launch date before patent expiration

The patent itself is not a guarantee of market exclusivity through its nominal expiration date. Orange Book listing and Paragraph IV litigation determine the practical timing of generic entry.

What is the Orange Book status of Patent 8,252,839?

Patent 8,252,839 has been associated with Orenitram’s FDA-listed patent estate. The key regulatory question is whether the patent remains listed for the relevant strength and dosage form at the time an ANDA is filed.

For an ANDA applicant, a listed patent may require one of four certifications:

Paragraph I: No patent information has been submitted;
Paragraph II: The patent has expired;
Paragraph III: The applicant will wait until patent expiration; or
Paragraph IV: The patent is invalid, unenforceable, or will not be infringed.

A Paragraph IV certification can trigger patent litigation if the NDA holder receives the statutory notice and files suit within the applicable period. A timely suit can impose a 30-month stay on ANDA approval under the Hatch-Waxman Act, subject to statutory exceptions and court action (21 U.S.C. § 355(j)(5)(B)(iii)).

The regulatory exposure is highest where an ANDA product uses the same treprostinil diethanolamine active ingredient and a tablet or capsule dosage form. A formulation designed around a different salt may avoid literal infringement of Patent 8,252,839 but could encounter separate patents covering treprostinil formulations, processes, release profiles, or methods of use.

What generic entry risks exist for Orenitram?

The principal generic-entry scenarios are:

Same-salt tablet

A generic treprostinil diolamine tablet would face the highest risk under claims 1 and 3. If it also uses the claimed (+)-form or 107°C polymorph, claims 4 and 5 could provide additional infringement theories.

Same salt with a different extended-release technology

Changing the release mechanism may not avoid claim 1 because claim 1 does not require a particular release profile. A different matrix, coating, excipient system, or dissolution curve could still fall within the broad formulation claim.

Different treprostinil salt

A product using treprostinil sodium or another salt may avoid literal infringement of claim 1. The alternative product would require separate analysis under the doctrine of equivalents and against other patents in the treprostinil portfolio.

Amorphous or alternative polymorph

An alternative solid form may avoid claim 5, but it would not necessarily avoid claim 1 or claim 3. The manufacturer would need to establish that the product does not contain the claimed diethanolamine salt in the claimed formulation.

Liquid or suspension

A liquid or suspension can fall within claim 3 even though it does not resemble Orenitram’s marketed tablet. The claim expressly covers both forms.

How strong is the patent estate for treprostinil diethanolamine?

Patent 8,252,839 has a mixed strength profile.

Strengths

Claim 1 covers the active salt in a pharmaceutical formulation without requiring a specific release technology.
Claim 3 covers several dosage forms.
Claims 4 and 5 provide stereochemical and solid-state fallback positions.
The claim set is product-focused, which can simplify infringement analysis against a finished drug product.
The claims correspond closely to the active ingredient used in Orenitram.

Vulnerabilities

Claim 1 may face anticipation or obviousness arguments if treprostinil diethanolamine, conventional carriers, and pharmaceutical dosage forms were disclosed in earlier references.
The “therapeutically effective amount” limitation may be challenged as functional language that does not materially narrow ordinary pharmaceutical formulations.
Claim 3 may be vulnerable if the listed dosage forms were conventional for the active salt.
Claim 5 depends on reliable polymorph identification and reproducible melting-point analysis.
The patent does not require the extended-release performance that differentiates Orenitram commercially.
A design-around using a different treprostinil salt could reduce exposure to this patent.

The practical strength of claim 1 depends heavily on the validity of the salt disclosure, the scope of the specification, and the prior art available before the relevant priority date. The practical strength of claim 5 depends on the quality of the crystalline-form disclosure and analytical evidence.

What other patents are likely to matter?

A complete freedom-to-operate analysis for oral treprostinil requires review of patent families covering:

Treprostinil salts;
Extended-release tablets;
Controlled-release matrices;
Tablet coatings;
Dissolution profiles;
Crystalline and amorphous forms;
Manufacturing and crystallization processes;
Oral dosing regimens;
Pulmonary hypertension treatment methods; and
Combination treatment with other pulmonary arterial hypertension drugs.

Patent 8,252,839 should therefore be treated as one layer of the Orenitram estate. It does not, based on the claims provided, cover every formulation or every method of administering treprostinil.

What litigation and settlement issues affect generic entry?

The principal litigation trigger is a Paragraph IV certification directed to Patent 8,252,839 or other Orange Book-listed Orenitram patents. The relevant issues would include:

Whether the proposed ANDA product contains treprostinil diethanolamine;
Whether the product uses the claimed polymorph;
Whether a different formulation still satisfies claim 1;
Whether the patent is invalid for anticipation or obviousness;
Whether the asserted claims are enabled and adequately described;
Whether the claims are enforceable;
Whether the NDA holder filed suit within the statutory period; and
Whether a settlement permits a licensed launch before patent expiration.

Settlement agreements can set a confidential or publicly disclosed launch date, provide a license, impose supply restrictions, or allocate limited generic-entry rights. A settlement does not establish that the patent is valid or infringed.

No biosimilar pathway applies because treprostinil is a chemically synthesized small molecule. Generic competition would proceed through the ANDA pathway rather than a 351(k) biosimilar application.

How does Patent 8,252,839 compare with a typical formulation patent?

Patent 8,252,839 is broader than a conventional release-profile patent because claim 1 does not require a particular pharmacokinetic or dissolution result. It is narrower than a pure active-ingredient patent because it requires a pharmaceutical formulation containing a specific salt.

Patent type	Typical limitation	Comparison with 8,252,839
Active-ingredient patent	Chemical compound itself	8,252,839 is narrower
Salt patent	Specific salt form	8,252,839 combines salt and formulation coverage
Polymorph patent	Specific crystalline form	Claim 5 has this character
Formulation patent	Active plus excipients or dosage form	Claims 1 and 3 fit this category
Release-profile patent	Dissolution or pharmacokinetic limits	Not expressly required by the supplied claims
Method-of-use patent	Treating a disease or patient group	Not covered by the supplied claims

What is the revenue exposure from generic entry?

Orenitram revenue is exposed to generic entry because the product is administered chronically, has an oral dosage form, and competes in a high-cost pulmonary arterial hypertension market. The commercial impact would depend on:

The number of approved generic applicants;
The launch date permitted by patent litigation or settlement;
Generic pricing discounts;
Pharmacy substitution;
Patient conversion rates;
Payer restrictions;
Availability of other treprostinil products; and
The proportion of United Therapeutics revenue generated by Orenitram.

A first generic entrant would generally have the greatest pricing advantage. Subsequent entrants could accelerate erosion. Patent 8,252,839 is commercially important because a same-salt oral tablet may encounter direct composition and dosage-form claims even if it uses different extended-release technology.

Key Takeaways

Patent 8,252,839 covers pharmaceutical formulations containing treprostinil diethanolamine.
Claim 1 is the principal commercial claim and does not require extended release.
Claim 3 covers capsules, tablets, liquids, and suspensions.
Claim 4 targets the (+)-treprostinil diethanolamine salt.
Claim 5 targets a specific polymorph melting at approximately 107°C.
The patent is directly relevant to Orenitram, an FDA-approved oral treprostinil product.
A different release mechanism may not avoid claim 1.
A different treprostinil salt presents a stronger design-around path.
Generic entry would proceed through the ANDA and Paragraph IV framework.
The patent’s nominal term extends into December 2027, subject to the official USPTO term calculation.
No biosimilar pathway applies.
The full freedom-to-operate analysis requires review of related salt, formulation, polymorph, manufacturing, and method-of-use patents.

Frequently Asked Questions

Does Patent 8,252,839 cover treprostinil sodium?

No. The supplied claims require treprostinil diethanolamine. Treprostinil sodium would not literally satisfy the claimed diethanolamine-salt limitation, although other patents or an equivalents theory could remain relevant.

Does a different Orenitram tablet coating avoid Patent 8,252,839?

Not necessarily. The supplied claims do not require a specific coating. A different coating may still leave the product within claim 1 if it contains treprostinil diethanolamine and a pharmaceutically acceptable carrier.

Is the 107°C polymorph required for infringement of claim 1?

No. Claim 1 does not require the 107°C polymorph. That limitation appears only in claim 5.

Can a liquid treprostinil diethanolamine product infringe?

Yes. Claim 3 expressly includes liquid and suspension dosage forms, provided the product also satisfies the limitations inherited from claim 1.

Is Patent 8,252,839 a method-of-use patent?

No. The supplied claims are formulation claims. They do not require treatment of pulmonary arterial hypertension or any other disease indication.

References

Food and Drug Administration. (2013). Orenitram (treprostinil) extended-release tablets: Approval letter and prescribing information. U.S. Department of Health and Human Services.
Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
United States Patent No. 8,252,839. (2012). Treprostinil diethanolamine salt. United States Patent and Trademark Office.
United States Code, 21 U.S.C. § 355. New drug application and abbreviated new drug application provisions.
United States Patent and Trademark Office. (2024). Patent term adjustment and patent term information. U.S. Department of Commerce.

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Details for Patent: 8,252,839

Summary for Patent: 8,252,839