United Therapeutics Announces FDA Clearance to Proceed with Clinical Trial for Treprostinil-Iloprost SMI in Pulmonary Arterial Hypertension

The planned move into PAH patients in 2027 depends on a successful phase 1 study in healthy volunteers.

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If successful, Treprostinil-Iloprost SMI would be the first use-as-needed combination inhaled therapy to be developed for pulmonary arterial hypertension (PAH)

This investigational therapy combines two potent prostacyclin analogues, treprostinil and iloprost, and is delivered as an inhalation spray via a soft mist inhaler for pro re nata (PRN) use

SILVER SPRING, Md. & RESEARCH TRIANGLE PARK, N.C.--(BUSINESS WIRE)-- United Therapeutics Corporation (Nasdaq: UTHR), a public benefit corporation, today announced that the U.S. Food and Drug Administration (FDA) has granted clearance under the company’s Investigational New Drug application to proceed with a clinical trial of Treprostinil-Iloprost SMI.

The phase 1, open-label, single ascending dose study will evaluate the safety, tolerability, and pharmacokinetics of Treprostinil-Iloprost SMI in healthy volunteers. Assuming a successful outcome in the study, United Therapeutics anticipates commencing a subsequent phase 2 study in patients with PAH in 2027.

Treprostinil-Iloprost SMI combines two potent prostacyclin analogues, treprostinil and iloprost. The therapy is intended to be used as needed to provide episodic symptom relief for PAH patients, who may need a bridge between doses of their ongoing prostacyclin therapy due to acute symptom flare-ups.

"Many people living with PAH experience moments when their symptoms flare despite their maintenance medication, and today they have no therapy designed specifically for those moments. Treprostinil-Iloprost SMI is intended to explore whether an as-needed, combination prostacyclin therapy could help fill that gap. FDA clearance to begin clinical testing is an important first step, and we look forward to advancing this program,” said Ravi Patel, PharmD, Senior Vice President, Global Patient Safety and Strategic Clinical Development, United Therapeutics.

“As a company known for pioneering prostacyclin therapies, Treprostinil-Iloprost SMI represents another important advancement in United Therapeutics’ PAH treatment portfolio. It also reflects continued innovation from our product development platform and our culture of running down the corridors of indifference in pulmonary medicine,” said Martine Rothblatt, Ph.D., Chairperson and Chief Executive Officer of United Therapeutics.

Treprostinil-Iloprost SMI is an investigational-stage product, and is not yet approved in any jurisdiction for any indication.

About Pulmonary Arterial Hypertension

PAH is a life-threatening disease that affects the blood vessels in the lungs and is characterized by increased pressure in the pulmonary arteries, due to increased pulmonary vascular resistance in the small precapillary vessels (i.e., the small blood vessels leading from the heart to lungs). The elevated pressure in the pulmonary arteries strains the right side of the heart as it pumps blood to the lungs. This eventually leads to right heart failure and, ultimately, death. PAH is characterized by structural changes in blood vessel walls, aggregation of platelets, and alteration of smooth muscle cell proliferation. PAH affects about 500,000 individuals worldwide, with around 50,000 people affected in the United States. Increases in the number of people diagnosed with the disease have been observed, but due to the rarity of the disease and the complexity of diagnosing it, only a fraction of patients with PAH are treated.

About United Therapeutics

Founded by CEO Martine Rothblatt to discover a cure for her daughter's life-threatening rare disease, pulmonary arterial hypertension, United Therapeutics transforms the treatment of rare diseases and pioneers alternatives to expand the supply of transplantable organs. From our innovative therapies to our groundbreaking manufactured organs, we are bold and unconventional. We move quickly from scientific theory to practical technologies that can save lives. As a public benefit corporation, even our legal structure reflects our commitments. We serve patients, act with integrity, create long-term shareholder value, and operate with sustainable practices that protect the future we are working to build. Visit us at www.unither.com and follow us on LinkedIn, Facebook, and Instagram.

Forward-Looking Statements

Statements included in this press release that are not historical in nature are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include, among others, statements regarding: the timing and design of our planned studies of Treprostinil-Iloprost SMI, including our upcoming phase 1 study in healthy volunteers and our plan to commence a phase 2 study in PAH patients in 2027; the potential benefits of Treprostinil-Iloprost SMI for PAH patients; and our goals of expanding the supply of transplantable organs, developing practical technologies that can save lives, creating long-term shareholder value, and operating with sustainable practices. These forward-looking statements are subject to certain risks and uncertainties, such as those described in our periodic reports filed with the Securities and Exchange Commission, that could cause actual results to differ materially from anticipated results. Consequently, such forward-looking statements are qualified by the cautionary statements, cautionary language, and risk factors set forth in our periodic reports and documents filed with the Securities and Exchange Commission, including our most recent Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K. We claim the protection of the safe harbor contained in the Private Securities Litigation Reform Act of 1995 for forward-looking statements. We are providing this information as of October 28, 2026, and assume no obligation to update or revise the information contained in this press release whether as a result of new information, future events or any other reason.

View source version on businesswire.com: https://www.businesswire.com/news/home/20261028830210/en/

For Further Information Contact:
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Source: United Therapeutics Corporation

Key Terms

pharmacokinetics medical

Pharmacokinetics is the study of how a substance, such as a drug or chemical, moves through and is processed by the body over time. It tracks how it is absorbed, distributed, broken down, and eventually eliminated. For investors, understanding pharmacokinetics helps gauge the effectiveness, safety, and potential risks of new medications or treatments, which can influence a company’s success and valuation in the healthcare industry.

single ascending dose medical

A single ascending dose is a method used in testing new medicines where small amounts are given to participants, gradually increasing each time to find the safest and most effective dose. For investors, it provides important information about a drug’s safety and potential, helping gauge the progress and prospects of a pharmaceutical development.

open-label medical

Open-label describes a situation where everyone involved in a study or process knows the full details, such as who is receiving a treatment or intervention. For investors, understanding whether a project or product is open-label helps gauge the level of transparency and potential biases, influencing trust and decision-making. It’s like knowing whether a test or experiment is conducted openly or behind closed doors.

pro re nata medical

Latin for “as needed,” used to describe an action, payment, treatment, or decision that is not scheduled but is taken only when certain conditions arise. In medical contexts it describes treatments or doses given when symptoms or clinical criteria require them; in corporate, regulatory, or contract contexts it denotes measures (for example payments, authorizations, or interventions) that may be carried out at officers’ or trustees’ discretion whenever the triggering conditions in the governing document are met. It does not imply unlimited or arbitrary action—what counts as “needed” is determined by the clinical order, contract language, board resolution, or applicable rule that authorizes the pro re nata action.

prostacyclin analogues medical

Synthetic or semi‑synthetic medicines that mimic the action of the natural prostacyclin (PGI2) molecule: they bind prostacyclin (IP) receptors on blood vessel and platelet cells to dilate blood vessels and reduce platelet aggregation. They are used primarily to relieve high pressure in the lungs' arteries and other conditions caused by constricted blood vessels; different formulations are given by continuous infusion, injection, inhalation, or oral dosing because some agents have very short biological half‑lives while others are longer‑acting.

pah medical

Pulmonary arterial hypertension (PAH) is a chronic condition in which the small blood vessels that carry blood from the heart to the lungs become narrowed or stiff, raising pressure and forcing the heart to work harder—like trying to squeeze water through a narrowed garden hose. It matters to investors because drug development, clinical trial outcomes, regulatory approvals and pricing decisions for PAH therapies can create significant revenue opportunities or financial risks for biotech and pharmaceutical companies operating in this therapeutic area.