<unk>  is a Phosphodiesterase 5 Inhibitor that is FDA approved for the treatment of pulmonary arterial hypertension.   Common adverse reactions include erythema，flushing, indigestion, headache, insomnia, visual disturbance, epistaxis, nasal congestion and rhinitis.
Sildenafil
Endralazine
Altretamine
Felodipine
Amlodipine Besylate
Alprostadil 
Silodosin
Buflomedil