PRESS RELEASE

SILVER SPRING, Md., Feb. 26 /PRNewswire-FirstCall/ -- United Therapeutics Corporation (Nasdaq: UTHR) today announced new guidance from pulmonary arterial hypertension opinion leaders relating to intravenous therapies. The new guidance was issued by the Scientific Leadership Committee (SLC) of the Pulmonary Hypertension Association in response to the release of a slide presentation prepared by CDC researchers entitled "Bloodstream infections among patients treated with intravenous epoprostenol and intravenous treprostinil for pulmonary arterial hypertension, United States 2004 - 2006". The slides accompanied a presentation to the SLC on February 23, 2007, and may be published as a report in the CDC's Morbidity and Mortality Weekly Report. The new guidance from pulmonary hypertension opinion leaders is for physicians to be mindful of the range of possible gram negative and gram positive infectious organisms in patients with long-term central catheters and initiate appropriately broad spectrum antibiotics in patients with suspected bloodstream infections until culture results and antibiotic sensitivity are known.

"We welcome the new guidance from pulmonary hypertension opinion leaders," said Martine Rothblatt, Ph.D., United Therapeutics' Chairman and Chief Executive Officer. "We believe that if a patient is predisposed to sepsis, then subcutaneous Remodulin, which has never been associated with septicemia, is the safest catheter-based treatment option; other patients have a very small chance of developing sepsis. For a disease in which mean survival is counted in single digit years, everyone wants to go the extra mile to provide patients needing prostacyclin therapy with the most options -- this is why we developed the micro-pump, ice-free and rapid-switch characteristics of intravenous Remodulin."

                   Scientific Leadership Committee Guidance

The Pulmonary Hypertension Association Scientific Leadership Committee (SLC) is composed of more than 20 leaders in the field of pulmonary hypertension. The members of the SLC are clinicians, research scientists, and nurses who come from medical centers recognized for performing outstanding research and providing excellent care for patients with pulmonary hypertension. The mission of the SLC is to provide medical and scientific leadership and guidance for the mission of the Pulmonary Hypertension Association by proactively facilitating the development of new knowledge about pulmonary hypertension, actively disseminating knowledge about pulmonary hypertension to medical and public audiences, and advocating and raising awareness about pulmonary hypertension.

Following the CDC researcher's presentation, the SLC posted the following guidance statement on the Pulmonary Hypertension Association website, http://www.phassociation.org:

"The SLC notes the observation that patients on long-term intravenous therapy are susceptible to bloodstream infections caused by a broad range of organisms. The Centers for Disease Control and Prevention (CDC) report suggests a hypothesis that different patient profiles may be subject to higher risk of various types of infections. The SLC considers the CDC document to be a hypothesis generating report which does not permit definitive or specific conclusions at this time. Therefore, the SLC supports the following:

      1. Further appropriately designed studies are required to determine the
         validity of the hypothesis raised by the current document.
      2. Pending rigorous studies, physicians should be mindful of the range
         of possible gram negative and gram positive infectious organisms in
         patients with long-term central catheters and initiate appropriately
         broad spectrum antibiotics in patients with suspected bloodstream
         infections until culture results and antibiotic sensitivity are
         known.
      3. Choice of specific parenteral prostacyclin agents, as well as all
         pulmonary vascular targeted therapy should continue to be based on a
         global assessment of efficacy, risk, expense and feasibility of each
         agent in each individual patient's clinical context."

                        United Therapeutics' Response

"We will work closely with the Pulmonary Hypertension Association and prescribers to improve patient care. We are confident that central line filters and heightened emphasis on sterility best practices will go a long way to address the issues raised in the CDC presentation," said Roger Jeffs, Ph.D., United Therapeutics' President and Chief Operating Officer. "As with any therapy for a life-threatening condition, prescribers will balance the risk/benefit profile of IV Remodulin against their patients' needs in light of the experiences they have had with the drug."

United Therapeutics plans to take the following actions in response to the Scientific Leadership Committee guidance:

    -- United Therapeutics will commence a multi-center, multi-national,
       multi-year and multi-agent prospective study to scientifically test the
       hypothesis of whether there are differences in the risk of sepsis and
       sepsis sub-types among parenterally-delivered prostacyclin mimetics and
       analogs.  The company anticipates this study to enroll several hundred
       patients and is expected to commence later this year.  "We are excited
       about taking the lead in testing some of the hypotheses suggested by
       the CDC's observations," said David Zaccardelli, PharmD, United
       Therapeutics' Senior Vice President for Pharmaceutical Development. "No
       doubt there is much new information to be learned from prospective
       study of a large number of patients receiving chronic intravenous
       therapy for pulmonary hypertension."
    -- United Therapeutics also plans to coordinate a working group with the
       Pulmonary Hypertension Association and physicians and nurses, along
       with its network of specialty distributors and home health care
       providers, to develop unified best practice recommendations related to
       the chronic administration of IV prostanoids via central venous
       catheters.
    -- United Therapeutics will revise Remodulin package labeling to more
       fully describe the known infection risk and appropriate technique that
       should be practiced when preparing and administering intravenous
       treprostinil.

                               Conference Call

United Therapeutics will host a teleconference on February 26, 2007, at 9:00 a.m. Eastern Time to discuss the SLC guidance. The teleconference is accessible by dialing 800-603-1777, with international callers dialing +1-706- 679-8129. A rebroadcast of the teleconference will be available for one week following the teleconference by dialing 800-642-1687, with international

callers dialing +1-706-645-9291, and using the conference call identification number 9283612.

                               About Remodulin

Remodulin(R) is indicated as a continuous subcutaneous infusion or IV infusion (for those not able to tolerate a subcutaneous infusion) for the treatment of PAH in patients with NYHA Class II-IV symptoms to diminish symptoms associated with exercise.

Remodulin is indicated to diminish the rate of clinical deterioration in patients requiring transition from Flolan(R); the risks and benefits of each drug should be carefully considered prior to transition.

Important Safety Information:

Remodulin is contraindicated in patients with hypersensitivity to Remodulin, its ingredients, or similar drugs. Remodulin is a potent vasodilator. It lowers blood pressure, which may be further lowered by other drugs that also reduce blood pressure. Remodulin inhibits platelet aggregation and therefore, may increase the risk of bleeding, particularly in patients on anticoagulants. Abrupt withdrawal or sudden large reductions in dosage of Remodulin may result in worsening of PAH symptoms and should be avoided. Caution should be used in patients with hepatic or renal problems. The most common side effects of Remodulin included those related to the method of infusion. For subcutaneous infusion, infusion site pain and infusion site reaction (redness and swelling) occurred in the majority of patients. These symptoms were often severe and could lead to treatment with narcotics or discontinuation of Remodulin. For IV infusion, line infections, sepsis, arm swelling, tingling sensations, bruising, and pain were most common. General side effects (>5% more than placebo) were diarrhea, jaw pain, vasodilation, and edema.

                          About United Therapeutics

United Therapeutics is a biotechnology company focused on the development and commercialization of unique products for patients with chronic and life- threatening cardiovascular, cancer and infectious diseases.

                          Forward-Looking Statements

In addition to historical information, this press release contains forward-looking statements about the publication of a report in the CDC's Morbidity and Mortality Weekly Report, United Therapeutics' plans to commence a study of sepsis in parenterally-delivered prostanoids, and the design of such study and its enrollment commencement date, United Therapeutics' plans to coordinate a working group to develop unified best practice recommendations for IV prostanoids, its plans to revise Remodulin package labeling, and expectations with respect to the impact of central line filters and best practices on the issues raised in the presentation that are based on United Therapeutics' current beliefs and expectations as to future outcomes. These expectations are subject to risks and uncertainties such as those described in United Therapeutics' periodic reports filed with the Securities and Exchange Commission which may 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 United Therapeutics' periodic reports and documents filed with the Securities and Exchange Commission, including the company's most recent Form 10-K and Form 10-Q. United Therapeutics is providing this information as of February 26, 2007 and undertakes no obligation to publicly update or revise the information contained in this press release whether as a result of new information, future events or any other reason.

SOURCE United Therapeutics Corporation