Open Label Study of Sildenafil in Patients With Pulmonary Arterial Hypertension

A Phase 3, Multi-Center, Open-Label Study to Assess Safety and Efficacy of Sildenafil Citrate 20 mg TID in Subjects With Pulmonary Arterial Hypertension

To assess the safety of sildenafil 20 mg TID orally given to Japanese pulmonary arterial hypertension patients (Part 1 and 2) To assess the efficacy after 12 weeks of treatment of sildenafil 20 mg TID orally given to Japanese pulmonary arterial hypertension patients (Part 1)

Inclusion Criteria:

• Subjects aged 16 and over, and classified as having pulmonary arterial hypertension
• Subjects who meet the following conditions on right heart catheterization at screening or baseline: mean pulmonary arterial pressure of ≥ 25mmHg and pulmonary capillary wedge pressure of ≤ 15mmHg at rest
• Subjects whose baseline 6-Minute Walk test distance is >100 m and <450 m

Exclusion Criteria:

• Significant Hepatic and/or renal disorder
• Subjects with known hereditary degenerative retinal disorders (such as retinitis pigmentosa) or history of non-arteritic ischemic optic neuropathy (NAION)
• Subjects who are currently receiving nitrates or nitric oxide donors in any form, ritonavir, ketoconazole and itraconazole