LOS ANGELES -- There is more evidence that sildenafil (Viagra, Revatio) is beneficial to patients with idiopathic pulmonary fibrosis, researchers here reported.
LOS ANGELES, March 12 -- There is more evidence that sildenafil (Viagra, Revatio) is beneficial to patients with idiopathic pulmonary fibrosis, researchers here reported.
In a small pilot study, 57% of patients with idiopathic pulmonary fibrosis given sildenafil were able to increase the distance they could walk in six minutes, according to David Zisman, M.D., of the University of California at Los Angeles.
All 14 patients in the study also had documented pulmonary arterial hypertension and sildenafil has been shown to increase exercise capacity in patients with pulmonary arterial hypertension, Dr Zisman and colleagues said in the March issue of CHEST.
Idiopathic pulmonary fibrosis is the most common chronic diffuse lung disease, and data suggests that between 33% and 50% of patients also have pulmonary arterial hypertension, the researchers noted.
It has also been shown that sildenafil appears to produce "clinically significant" vasodilation in the lungs of patients with pulmonary fibrosis, but the long-term effect of the drug on exercise capacity hasn't been tested, Dr. Zisman and colleagues said.
Sildenafil, under the brand name Revatio, was approved by the FDA in 2005 to treat PAH patients who are in World Health Organization class I.
In this study, the 14 patients undertook a baseline six-minute walk test and were then treated with sildenafil at between 20 and 50 mg three times daily for three months.
At the end of treatment, they were asked to repeat the six-minute walk test. The study found:
The researchers divided the 14 patients into responders and non-responders, with responders those who had at least a 20% increase in distance walked in six minutes.
On that basis, 57% of the initial cohort responded to the therapy, Dr. Zisman and colleagues said.
On the basis of the results of this study, "we believe sildenafil is a promising therapy for patients with idiopathic pulmonary fibrosis and pulmonary arterial hypertension," the researchers concluded.
The findings are preliminary but "provide an intriguing suggestion that the modulation of pulmonary arterial pressure in idiopathic pulmonary fibrosis patients may provide a functional benefit," commented Charlene Fell, M.D., of the University of Calgary and Fernando Martinez, M.D., of the University of Michigan in an accompanying editorial.
However, they cautioned that the cohort was small, and three of 14 patients could not complete the primary endpoint. Moreover, the benefit for those patients who completed both - an average improvement of 49 meters - was well short of the 54 meters that's widely accepted as clinically significant, they said.
Nonetheless, they said, the researchers have provided data that will help design future placebo-controlled trials. They noted that two such studies are currently under way.