Macitentan Use in an Idiopathic Pulmonary Fibrosis Clinical Study

Inclusion Criteria: 1. Signed informed consent. 2. Male or female patients of at least 18 years of age (females of child-bearing potential must use a reliable method of contraception). 3. IPF diagnosis within 3 years prior to randomization, proven according to the American Thoracic Society/European Respiratory Society consensus conference criteria, with surgical lung biopsy. Exclusion Criteria: 1. Interstitial lung disease due to conditions other than IPF. 2. Presence of extensive honeycombing on Baseline high-resolution computed tomography (HRCT) scan performed within 3 months prior to randomization. 3. Severe concomitant illness limiting life expectancy (\< 1 year). 4. Severe restrictive lung disease: forced vital capacity (FVC) \< 50% predicted, or FVC \< 1.2 liter. 5. Diffusing capacity of the lung for carbon monoxide (DLCO) \< 30% predicted. 6. Residual volume ≥ 120% predicted. 7. Obstructive lung disease: forced expiratory volume in 1 second (FEV1)/FVC) \< 0.70. 8. Documented sustained improvement of the patient's IPF condition up to 12 months prior to randomization with or without IPF-specific therapy. 9. Recent pulmonary or upper respiratory tract infection (up to 4 weeks prior to randomization). 10. Acute or chronic impairment (other than dyspnea) limiting the ability to comply with study requirements (e.g., pulmonary function tests). 11. Chronic heart failure with New York Heart Association class III/IV or known left ventricular ejection fraction \< 25%. 12. Moderate to severe hepatic impairment, i.e., Child-Pugh Class B or C. 13. Estimated creatinine clearance \< 30 mL/min. 14. Aspartate aminotransferase (AST) and/or alanine aminotransferase \> 1.5 x upper limit of normal. 15. Hemoglobin \< 75% of the lower limit of the normal range. 16. Systolic blood pressure \< 100 mmHg. 17. Pregnant or breast-feeding. 18. Current drug or alcohol dependence. 19. Chronic treatment with the following drugs (within 4 weeks of randomization): * Oral corticosteroids (\> 20 mg/day of prednisone or equivalent), * Immunosuppressive or cytotoxic drugs including cyclophosphamide and azathioprine, * Antifibrotic drugs including pirfenidone, D penicillamine, colchicine, tumor necrosis factor α blockers, imatinib and interferon γ, * Chronic use of N-acetylcysteine prescribed for IPF (\> 600 mg/day). * Oral anticoagulants prescribed for IPF. 20. Treatment with endothelin receptor antagonists within 4 weeks prior to randomization. 21. Systemic treatment within 4 weeks prior to randomization with cyclosporine A or tacrolimus, everolimus, sirolimus (calcineurin or mammalian target of rapamycin (mTOR) inhibitors). 22. Treatment with Cytochrome P450 3A inducers within 4 weeks prior to randomization. 23. Known hypersensitivity to drugs of the same class as the study drug, or any of their excipients. 24. Planned treatment, or treatment with another investigational drug within 4 weeks prior to randomization.