Triumph-1 Trial of Viveta in Pulmonary Arterial Hypertension Meets Primar...( Preliminary Analysis Demonstrates a 2...),Health

Preliminary Analysis Demonstrates a 20-Meter Improvement in Six-Minute Walk

Distance (p<0.0006) Conference Call to be Held at 9:00 a.m. Eastern Time on November 1, 2007

SILVER SPRING, Md., Nov. 1 /PRNewswire-FirstCall/ -- United Therapeutics Corporation (Nasdaq: UTHR) and its wholly-owned subsidiary, Lung Rx, Inc., announced today the completion of their TRIUMPH-1 Phase 3 trial of Viveta, an inhaled formulation of treprostinil, in pulmonary arterial hypertension (PAH). Preliminary analysis demonstrates that the trial has robustly met its primary endpoint.

The TRIUMPH-1 (TReprostinil Sodium Inhalation Used in the Management of Pulmonary Arterial Hypertension) trial was a randomized, double-blind, placebo-controlled trial of patients with severe PAH, a chronic, life- threatening illness. The study population consisted of 235 patients who were optimized on an approved oral therapy for PAH, either bosentan (Tracleer), an endothelin receptor antagonist, or sildenafil (Revatio), a phosphodiesterase-5 inhibitor. In addition to one of these oral therapies, patients were administered Viveta or placebo in four daily inhalation sessions with a maximum dose of 45 micrograms per session over the course of the 12-week trial. The majority (~98%) of patients were New York Heart Association (NYHA) Class III of varied etiologies, including idiopathic or familial PAH (~55%), collagen vascular disease associated PAH (~35%), and PAH associated with HIV, anorexigens or other associated conditions (~10%). Mean baseline walk distance was approximately 350 meters.

The primary efficacy endpoint of the trial was the change in six-minute walk (6MW) distance at 12 weeks measured at peak exposure, def
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