The FDA has approved Letairis (ambrisentan) for the treatment of pulmonary arterial hypertension, a rare, life-threatening condition characterized by continuous high blood pressure within the arteries of the lungs. “Letairis represents a valuable addition to the treatment alternatives for this orphan disease,” said John Jenkins, M.D., director of FDA’s Office of New Drugs. “Letairis is similar to an existing drug, but offers the potential for fewer drug interactions.” In pulmonary arterial hypertension, the small arteries in the lungs become narrowed or blocked, and the heart must work harder to pump the blood through them. Over time, the overworked heart muscle may become weak and lose its ability to pump enough blood through the lungs. Symptoms include shortness of breath, fatigue, chest pain, dizzy spells and fainting. About 100,000 people in the United States have pulmonary arterial hypertension. Letairis, a new drug not previously approved in the United States, was granted a priority review by FDA. A priority review designation is intended for those products that address unmet medical needs. For priority drug applications, FDA sets a target date of six months after the date of receipt for the agency to complete all aspects of a review and to take action. The safety and effectiveness of Letairis were demonstrated in two international clinical trials involving 393 patients. Letairis significantly improved physical activity capacity compared with a placebo, as shown by a six-minute walk, a standard test. Letairis also delayed the worsening of the pulmonary hypertension. Letairis will be available in five-milligram and 10-milligram once-daily tablets. Letairis was granted orphan drug status by FDA because it treats a rare disease and meets other criteria. Orphan designation qualifies the drug’s sponsor for a tax credit and marketing incentives. Letairis is manufactured by Gilead Sciences, Inc., Foster City, Calif. Gilead acquired the U.S. rights to ambrisentan when it acquired Myogen, Inc. in 2006. GlaxoSmithKline holds rights to ambrisentan outside of the United States.
