- Idiopathic or familial pulmonary arterial hypertension (PAH)
- Mean PAP at least 25 mm Hg, PCWP
- For females of child-bearing potential negative pregnancy test at screening and use of
contraception during the study and 4 weeks after its completion
- Signed and dated informed consent
- Willingness to comply with the study plan and procedures
- pulmonary arterial hypertension (PAH)other than idiopathic or familial
- For females, pregnancy or lactation
- Use of specific PAH treatments, potent CYP3A4 inhibitors, protease inhibitors, alpha
blockers or arginine 30 days prior tio randomization and during the study
- Change of dose or class of standard background PAH therapy, i.e. oxygen, calcium
channel blockers, digoxin, diuretics 30 days prior tio randomization and during the
study
- Large shift in altitude (defined as >5000 feet or 1524 meters) during 90 days prior to
baseline visit and/or during the study visit
- Subjects with intracardiac shunts and/or serious heart, lung or other health
conditions
- HIV positive subjects
- Subjects participating in another clinical trial with an investigational drug or
device
- Subjects with degenerative retinal disorders, history of non-arteritic anterior
ischemic optic neuropathy or untreated proliferative diabetic retinopathy
- Allergies and previous intolerance of PDE5 inhibitors
- Alcohol or drug abuse
- Blood donation during the study, or 1 month before or after the study