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Recommended Reading from the University of Pennsylvania Pulmonary and Critical Care Fellows: Robert Kotloff, M.D., Program Director.

Preclinical research and small case series have suggested that sildenafil may be a safe treatment for idiopathic pulmonary fibrosis (IPF). The IPF Clinical Research Network performed a randomized, double-blind, placebo-controlled study of sildenafil for idiopathic pulmonary fibrosis. Participants (n 5 180) were included if they had advanced disease, defined as diffusing capacity for carbon monoxide (DLCO) of less than 35% of predicted. Exclusion criteria included 6-minute walk distance less than 164 feet, resting oxygen saturation less than 92% on high-flow oxygen, and significant cardiac disease. The study consisted of a 12-week double-blind period followed by a 12-week open-label study. After the initial 12 weeks, there was no difference in the primary endpoint, defined as an increase in 6-minute walk distance of more than 20%, between the study and placebo groups. Sildenafil treatment was associated with statistically significant improvements in DLCO, oxygenation, degree of dyspnea, and quality of life. Serious adverse events were common (z 15%) but equally balanced across groups. Overall, this is a negative study. Although secondary endpoint findings do suggest that sildenafil is safe in patients with severe IPF and may favorably influence physiologic variables and symptoms, more evidence is needed before clinical practice is changed. A significant limitation is the lack of hemodynamic measurements. Future trials should address subsets of patients with IPF, such as those with less advanced IPF or those with significant pulmonary hypertension.