Vardenafil
Vardenafil is the sulfonamide resulting from formal condensation of the sulfo group of 4-ethoxy-3-(5-methyl-7-propylimidazo[5,1-f][1,2,4]triazin-4(1H)-one-2-yl)benzenesulfonic acid and the secondary amino group of 4-ethylpiperazine. It has a role as a vasodilator agent and an EC 3.1.4.* (phosphoric diester hydrolase) inhibitor. It is a N-alkylpiperazine, an imidazotriazine and a N-sulfonylpiperazine.