Sildenafil in Viagra may help children with Pulmonary Arterial Hypertension

27/06/05 Researchers found the active ingredient in Viagra, also known as sildenafil, helped children with pulmonary arterial hypertension (PAH) walk farther and breathe easier when taken over the course of a year. Viagra was first approved by the U.S. Food and Drug Administration in 1998. Over 130 clinical trials were used to test the drug's safety. Physicians all over the world have found that the drug sildenafil may help children suffering from pulmonary arterial hypertension. This research is reported in the June 14, 2005 issue of Circulation: Journal of the American Heart Association.

Currently, inhaled nitric oxide ( iNO ) is used to treat PAH patients by relaxing the arteries in the lungs. "In many respects, Viagra is superior, since it enhances overall cardiac performance more than iNO," said Dr. Evangelos Michelakis, professor of cardiology at the U of A., who led the research team along with Dr. Stephen Archer, director of the U of A Division of Cardiology in a news article published on the University of Alberta website. "These findings are particularly important because currently iNO can only be given in intensive care units and, furthermore, its price has recently increased dramatically."

Pulmonary arterial hypertension ( PAH ) is continuous high blood pressure in the pulmonary artery. The average blood pressure in a normal pulmonary artery is about 14 mmHg when the person is resting. In PAH, the average is usually greater than 25 mmHg.

The disease, which has no cure, causes continuous high blood pressure in the artery that carries blood from the heart to small vessels in the lungs. The vessels narrow, leaving less room for blood to flow. The heart can't keep up if the pressure gets too high, and excessively high pressure in the pulmonary artery can cause liquid to leak through the capillary walls and into the lungs. That causes symptoms including fatigue, dizziness, shortness of breath, and have frequent fainting spells, eventually heart failure and death. PAH can be inherited, or result from another chronic heart or lung disease. The exact cause of PAH is still a mystery, although it is often associated with such diseases as congenital heart disease, rheumatologic diseases or HIV infection. Currently, the disease is often fatal within months of diagnosis.

Viagra works by relaxing the smooth muscle that lines blood vessels, so it is able to treat PAH. PAH is a serious condition for which there are treatments but no cure, and treatment benefits many patients.