They claim that the drug helps reverse loss of lung function in patients with pulmonary fibrosis by treating their pulmonary hypertension. The study included 14 patients with pulmonary fibrosis and pulmonary hypertension.

They completed a six-minute walking test to measure their lung function. They were then treated with 20-50mg daily sildenafil for three months.

Two of the patients discontinued treatment because they experienced diarrhoea and low BP.

At the end of the treatment period, eight of the patients had improved lung function as measured by the six-minute walking test.

The researchers conclude that sildenafil improves breathing in patients with pulmonary fibrosis by dilating blood vessels to allow more blood to flow to the lungs.

Chest 2007; 131: 897-903