Vardenafil EP Impurity A Catalogue F34150 CAS 2169247-39-4 M.W 460.55 M.F C21H28N6O4S Specifications FAQs 2-(2-Ethoxy-5-((4-ethylpiperazin-1-yl)sulfonyl)phenyl)-5,7-dimethylimidazo[5,1-f][1,2,4]triazin-4(3H)-one