Tadalafil EP Impurity A

Chemical Name: (6R,12aS)-6-(benzo[d][1,3]dioxol-5-yl)-2-methyl-2,3,6,7,12,12a-hexahydropyrazino[1',2':1,6]pyrido[3,4-b]indole-1,4-dione; cis-ent-Tadalafil; Tadalafil USP Impurity C;