Chemical Name: Esomeprazole USP Related Compound A ; Esomeprazole EP Impurity D = Omeprazole EP Impurity D = Esomeprazole USP RC A ; Omeprazole Sulfone ; 5-methoxy-2-[(4-methoxy-3,5-dimethylpyridin-2-yl)methanesulfonyl]-1H-benzimidazole (omeprazole sulfone),