PRESS RELEASE

SILVER SPRING, Md., July 11 /PRNewswire-FirstCall/ -- Lung Rx, Inc., a wholly-owned subsidiary of United Therapeutics Corporation (Nasdaq: UTHR), announced today that patient enrollment in its TRIUMPH (TReprostinil Sodium Inhalation Used in the Management of Pulmonary Arterial Hypertension) registration trial will close on July 13, 2007.

The company's enrollment target is for 200 patients to complete the 12- week study, net the number of patients who discontinue the study prior to completion. As of July 10, 2007, approximately 232 patients were enrolled in the TRIUMPH study and approximately 15 patients did not complete the 12-week study period.

"We are excited to achieve this important milestone," said Martine Rothblatt, Ph.D., Chairman and CEO of Lung Rx and United Therapeutics. "I am proud of the clinical development team, including all of the investigators who have participated in TRIUMPH. In particular, we owe a tremendous debt of gratitude to the Co-Chairmen of our Steering Committee, Dr. Lewis Rubin and Dr. Werner Seeger, and to our Vice-Chairman, Dr. Horst Olschewski, for shepherding TRIUMPH to this milestone."

TRIUMPH is a 12-week, multi-center, double-blind, randomized, placebo- controlled study of inhaled treprostinil in NYHA Class III and IV patients with severe PAH.

Lung Rx is a biotechnology company focused on unmet medical needs in pulmonary medicine and pulmonary delivery of innovative therapeutic products.

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.

SOURCE United Therapeutics Corporation