The primary purpose of this study is to determine whether iloprost inhalation solution is safe in subjects with idiopathic pulmonary fibrosis (IPF) and elevated pulmonary arterial pressure. The secondary purpose is to evaluate the effectiveness of this treatment in subjects with this disease.

While there are no FDA approved therapies for the treatment of IPF, there are therapies that have been shown to be effective in ameliorating the effects of pulmonary hypertension in patients with PAH (pulmonary arterial hypertension), including inhaled iloprost. However, these therapies have not been used extensively in patients with IPF who have pulmonary hypertension as a complication. The potential benefits of treatment of pulmonary hypertension complicating IPF include: improvement in pulmonary hemodynamics, with reduction in pulmonary artery pressure and pulmonary vascular resistance, and increase in cardiac output.

Inclusion Criteria:

• Diagnosis of idiopathic pulmonary fibrosis according to American Thoracic Society criteria
• Diagnosis of elevated pulmonary pressures
• Six minute walk distance between 50-380
• NYHA functional class II - IV

Exclusion Criteria:

• Pulmonary fibrosis related to a systemic disorder
• Significant chronic obstructive pulmonary disease
• History of thromboembolic disease within the previous year
• Awaiting lung transplantation within next 36 weeks
• Active lung infection
• Survival prognosis of less than 1 year
• Significant left-sided heart failure, active coronary artery disease
• Clinically relevant liver disease
• Concurrent medications: epoprostenol, treprostinil, bosentan, PDE-5 inhibitor, investigational agents