(S)-Duloxetine Succinamide,(S)-4-(methyl(3-(naphthalen-1-yloxy)-3-(thiophen-2-yl)propyl)amino)-4-oxobutanoic acid,An impurity of Duloxetine hydrochloride . It is formed by interaction of Duloxetine-HCl with enteric polymers. Impurity in commercial preparations of Duloxetine.,Duloxetine Impurity