Efficacy and Safety of Nintedanib Co-administered With Sildenafil in Idiopathic Pulmonary Fibrosis Patients With Advanced Lung Function Impairment

Inclusion criteria: * Written informed consent consistent with International Conference on Harmonization-Good Clinical Practice and local laws, signed prior to any study procedures being performed (including any required washout); * Male or female patients aged \>= 40 years at visit 1; * A clinical diagnosis of IPF within the last 6 years before visit 1, based upon the American Thoracic Society/European Respiratory Society/Japanese Respiratory Society/Latin American thoracic Association 2011 guideline \[P11-07084\]; * Combination of high-resolution computed tomography (HRCT) pattern, and if available, surgical lung biopsy pattern consistent with a diagnosis of IPF as assessed by the investigator based on a HRCT scan performed within 18 months of visit 1; * Carbon Monoxide Diffusion Capacity (corrected for Hb) less or equal to 35% predicted of normal at visit 1. Exclusion criteria: * Previous enrolment in this trial; * Alanine Transaminase, Aspartate Transaminase \> 1.5 fold upper limit of normal (ULN) at visit 1; * Total bilirubin \> 1.5 fold ULN at visit 1; * Relevant airways obstruction (i.e. pre-bronchodilator Forced Expiratory Volume in 1 second/Forced Vital Capacity \<0.7 at visit 1) * History of myocardial infarction within 6 months of visit 1 or unstable angina within 1 month of visit 1 * Bleeding Risk: * Known genetic predisposition to bleeding; * Patients who require fibrinolysis, full-dose therapeutic anticoagulation (e.g. vitamin K antagonists, direct thrombin inhibitors, heparin, hirudin, etc.) or high dose antiplatelet therapy; * History of haemorrhagic central nervous system (CNS) event within 12 months prior to visit 1; * History of haemoptysis or haematuria, active gastro-intestinal bleeding or ulcers and/or major injury or surgery within 3 months prior to visit 1; * International normalised ratio (INR) \> 2 at visit 1; * Prothrombin time (PT) and activated partial thromboplastin time (aPTT) \> 150% of institutional ULN at visit 1; * Planned major surgery during the trial participation, including lung transplantation, major abdominal or major intestinal surgery; * History of thrombotic event (including stroke and transient ischemic attack) within 12 months of visit 1; * Creatinine clearance \< 30 mL/min calculated by Cockcroft-Gault formula at visit 1; * Presence of aortic stenosis (AS) per investigator judgement at visit 1; * Severe chronic heart failure: defined by left ventricular ejection fraction (EF) \< 25% per investigator judgement at visit 1; * Presence of idiopathic hypertrophic subaortic stenosis (IHSS) per investigator judgement at visit 1; * Second-degree or third-degree atrioventricular (AV) block on electrocardiogram (ECG) per investigator judgement at visit 1; * Hypotension (systolic blood pressure \[SBP\] \< 100 mm Hg or diastolic blood pressure \[DBP\] \< 50 mm Hg) (symptomatic orthostatic hypotension) at visit 1; * Uncontrolled systemic hypertension (SBP \> 180 mmHg; or DBP \> 100 mmHg) at visit 1; * Known penile deformities or conditions (e.g., sickle cell anemia, multiple myeloma, leukemia) that may predispose to priapism; * Retinitis pigmentosa; * History of vision loss; * History of nonarteritic ischemic optic neuropathy; * Veno-occlusive disease; * History of acute IPF exacerbation or respiratory infection within 8 weeks of visit 2. * Treatment with nitrates, n-acetylcysteine, pirfenidone, azathioprine, cyclophosphamide, cyclosporine, prednisone \>15 mg daily or \>30 mg every 2 days OR equivalent dose of other oral corticosteroids as well as any investigational drug within 4 weeks of visit 2; * Treatment with prostaglandins (e.g., epoprostenol, treprostinil), endothelin-1 antagonists (e.g., bosentan, sitaxsentan, ambrisentan), phosphodiesterase inhibitors (e.g., sildenafil, tadalafil, vardenafil) or a stimulator of guanylatcyclase (e.g.,riociguat) within 4 weeks of visit 2; * Treatment with potent cytochrome CYP3A4 inhibitors such as ketoconazole, itraconazole and ritonavir within 4 weeks of visit 2; * Supplementation with L-arginine and concurrent use of grapefruit juice or St John's wort within 4 weeks of visit 2; * Treatment with the reduced dose of nintedanib (100 mg bid) within 4 weeks of visit 2; 27. Permanent discontinuation of nintedanib in the past due to adverse events considered drug-related; * Known hypersensitivity or intolerance to nintedanib, sildenafil, galactose, peanut or soya or any other components of the study medication; * A disease or condition which in the opinion of the investigator may interfere with testing procedures or put the patient at risk when participating in this trial; * Alcohol or drug abuse which in the opinion of the treating physician would interfere with treatment; * Further exclusion criteria apply.