Breathing improved for some taking sildenafil marketed as Revatio, study finds
TUESDAY, May 18 (HealthDay News) -- People with a serious lung disease that causes progressive scarring of the lung tissue might get some relief from sildenafil, the drug used in Viagra, a new study finds.
The disease, called idiopathic pulmonary fibrosis, causes the lungs to become increasingly thick and stiff, reducing the ability to breathe. There's no known cause, and there's little in the way of treatment, researchers say. Most people with the disease live just three to five years after diagnosis.
"There are about 150,000 patients in the United States and about 5 million worldwide with the disease," said lead researcher, Dr. David A. Zisman, from the Sansum Clinic in Santa Barbara, Calif. He cited Jerry Lewis, Evel Knievel and Robert Goulet as celebrities who had the disease, which he said has "no proven therapy, except lung transplantation, and survival is quite limited."
His research team decided to try treatment with sildenafil because the disease usually causes constriction of the blood vessels in the lungs, and sildenafil expands these vessels, Zisman said.
They randomly assigned 180 men and women with advanced pulmonary fibrosis to take 20 milligrams of sildenafil (sold as Revatio) or a placebo for 12 weeks; Viagra is sold in dosages starting at 25 milligrams. They found little difference in the main point being assessed, with 10 percent of those taking sidenafil and 7 percent of the others recording a 20 percent or greater improvement in the distance they could walk in six minutes.
However, some people taking sildenafil were able to breathe more easily and did show an improvement in their quality of life, the researchers found.
A report on the study, which was funded in part by Pfizer, which markets Revatio, was published online May 18 in the New England Journal of Medicine to coincide with a presentation on the findings that is slated to be held at the American Thoracic Society annual meeting, in Denver.
"It seems like this approach is an interesting way to provide these patients with improvement in dyspnea [shortness of breath] and quality of life, which hasn't been seen in patients with advanced idiopathic pulmonary fibrosis," Zisman said.
However, he said, people with the disease should not rush out to try sildenafil. "These findings offer a ray of hope to treat these patients," Zisman said. "We just have to fine-tune it."
Mishka Michon, chief executive of the Coalition for Pulmonary Fibrosis, said that "although the sildenafil trial didn't meet its primary endpoint, we're encouraged by the fact that there was a demonstration of symptomatic relief for some patients."
Because there are no current therapies that offer people with this disease a better quality of life, he said, "this news is particularly meaningful for our patients who experience incredibly difficult and unrelenting symptoms."
Zisman theorized that testing sildenafil on people with earlier stages of the disease might improve results. Higher doses might also improve the response, he said.
"This opens many doors to try exploring different approaches to treat these patients," Zisman said.
In the long run, he said, the goal in treating the disease may be to turn it into a chronic but livable condition, Zisman said. Rather than concentrating on finding ways to stop its progression, targeting the blood vessels in the lungs could lead to many other possibilities for treatment, he noted.
"In the future, we are going to see our patients treated like patients with cancer -- that is, several drugs to target different mechanisms of the disease," Zisman said. "We are going to end up treating these patients with a number of agents that would not only make a difference in quality of life and dyspnea, but also in functional capacity and survival."
In another study being presented at the same meeting, Japanese researchers found that inhaled N-acetylcysteine (NAC) preserves lung function in some people with idiopathic pulmonary fibrosis, when compared with people given no treatment.
"This novel study provides encouraging evidence to pursue the potential of an efficacious treatment with NAC for patients with the early stage of idiopathic pulmonary fibrosis," lead researcher Dr. Sakae Homma, a professor of respiratory medicine at the Toho University School of Medicine in Tokyo, said in a news release from the American Thoracic Society.
The U.S. National Heart, Lung and Blood Institute has more on idiopathic pulmonary fibrosis.
SOURCES: David A. Zisman, M.D., Sansum Clinic, Santa Barbara, Calif.; Mishka Michon, chief executive, Coalition for Pulmonary Fibrosis, San Jose, Calif.; May 18, 2010, New England Journal of Medicine, online
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