WEDNESDAY, Nov. 16, 2005 (HealthDay News) -- Sildenafil, better known as Viagra, is an effective treatment for the deadly lung condition called pulmonary arterial hypertension, according to a new international study.
This is not exactly breaking news, since the U. S. Food and Drug Administration approved the drug's use for that condition in June. But the report by researchers ranging from the United States to France to Germany to Italy puts a seal on that decision.
Sildenafil, marketed by Pfizer for this purpose as Revatio, is only the second oral medication approved for the disease, said Dr. Nazzareno Galie, an associate professor of cardiology at the University of Bologna. The first was bosentan, he noted.
"It is common practice now to start with one of the two oral medications, adding the second in case of unsatisfactory results," Galie said. "In the absence of head-to-head comparisons, it is not possible scientifically to define the first-line among bosentan and sildenafil, and sildenafil is cheaper."
The new findings appear in the Nov. 17 issue of the New England Journal of Medicine.
As its name implies, pulmonary arterial hypertension consists of unusually high pressure in the blood vessels of the lungs, particularly the pulmonary artery. It can result from chronic disease of the heart or lungs, or it can be inherited.
Children with the condition usually die within a year without treatment.
"At the European Society of Cardiology meeting in Stockholm this year I presented the survival data of the sildenafil-treated cohort as compared to the [U.S.] National Institutes of Health registry collected in the '80s," Galie said. "In this historical comparison, the survival of sildenafil-treated patients has improved by 30 percent."
Sildenafil acts by relaxing the smooth muscle of blood vessels, causing them to expand so blood flows more freely. Other drugs used to treat pulmonary hypertension act through nitric oxide, which widens blood vessels. Sildenafil acts in a different way, by altering the activity of an enzyme called phosphodiesterase.
The new study included 278 people diagnosed with the condition. Participants were given either sildenafil or a placebo, an inactive substance, three times a day, as the researchers measured the distance they could walk in six minutes. Those who completed the first 12 weeks of treatment could enter a longer-term study.
"Among the 222 patients completing one year of treatment with sildenafil, the improvement from baseline at one year in the distance walked was 51 minutes," the researchers reported.
One reason for the good result was that the trial included only people with milder forms of the condition, the researchers said. But patients who got sildenafil also appeared to be hospitalized less frequently that those who did not receive the drug.
Only minor side effects, such as stomach upset and diarrhea, were reported among those receiving sildenafil, the scientists said.
Dr. Jeffrey Fineman, professor of pediatrics and head of the Cardiovascular Research Institute at the University of California, San Francisco, said sildenafil is certainly not the final answer to the problem of pulmonary arterial hypertension, but it "will be one of the things you will start with or add."
But, he continued, "It will be a long time before we see if this has a dramatic effect on mortality. When we combine it with other agents, perhaps it will make a difference."
More information
For more on pulmonary hypertension, visit the National Heart, Lung, and Blood Institute.
