FDA approves an orphan disease drug

WASHINGTON, June 18 (UPI) -- The U.S. Food and Drug Administration has approved Letairis (ambrisentan) for the treatment of pulmonary arterial hypertension.

"Letairis represents a valuable addition to the treatment alternatives for this orphan disease," said Dr. John Jenkins, director of the FDA's Office of New Drugs. An orphan disease is one with an extremely low rate of occurrence.

"Letairis," added Jenkins, "is similar to an existing drug, but offers the potential for fewer drug interactions."

In pulmonary arterial hypertension, small arteries in the lungs become narrowed or blocked, making the heart work harder to pump blood. Over time, the overworked heart muscle may become weak and lose its ability to pump enough blood through the lungs.

Letairis, a new drug not previously approved in the United States, was granted a priority review by the FDA, which subsequently found the safety and effectiveness of Letairis were demonstrated in two international clinical trials involving 393 patients.

Letairis, manufactured by Gilead Sciences Inc. of Foster City, Calif., will be available in five-milligram and 10-milligram once-daily tablets. Gilead acquired the U.S. rights to ambrisentan when it acquired Myogen Inc. last year. GlaxoSmithKline holds rights to ambrisentan outside the United States.