esomeprazole and its Impurities
The (S)-(−)-enantiomer of omeprazole, it is a proton pump inhibitor, which is used to reduce the stomach acid. It treats gastroesophegeal reflux and peptic ulcers. It is an OTC drug in many countries. Reference standards of Esomeprazole API, and its pharmacopeial, non pharmacopeial impurities, and stable isotopes are listed below.

![1-(6-Methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethy PA 05 18550](https://www.pharmaffiliates.com/pimages/PA0518550.jpg)
1-(6-Methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethyl-4-oxo-1,4-dihydropyridine-2-carboxylic acid Hydrochloride
1-(6-Methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethyl-4-oxo-1,4-dihydropyridine-2-carboxylic acid Hydrochloride
Catalogue No.:PA 05 18550
CAS :
2172852-91-2
Molecular Formula : C16H16ClN3O4
Molecular Weight : 349.77


2-(Mercaptomethyl)-4-methoxy-1-(5-methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethylpyridin-1-ium Chloride
2-(Mercaptomethyl)-4-methoxy-1-(5-methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethylpyridin-1-ium Chloride
Catalogue No.:PA 05 18600
CAS :
NA
Molecular Formula : C17H20ClN3O2S
Molecular Weight : 365.88

![12-Mercapto-8-methoxy-1,3-dimethylbenzo[4',5']imid PA 05 18610](https://www.pharmaffiliates.com/pimages/PA0518610.jpg)
12-Mercapto-8-methoxy-1,3-dimethylbenzo[4',5']imidazo[2',1':2,3]imidazo[1,5-a]pyridin-2-ol
12-Mercapto-8-methoxy-1,3-dimethylbenzo[4',5']imidazo[2',1':2,3]imidazo[1,5-a]pyridin-2-ol
Catalogue No.:PA 05 18610
CAS :
2748245-58-9
Molecular Formula : C16H15N3O2S
Molecular Weight : 313.38

![Lithium 1-(6-methoxy-1H-benzo[d]imidazol-2-yl)-3,5 PA 05 18630](https://www.pharmaffiliates.com/pimages/PA0518630.jpg)
Lithium 1-(6-methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethyl-4-oxo-1,4-dihydropyridine-2-carboxylate
Lithium 1-(6-methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethyl-4-oxo-1,4-dihydropyridine-2-carboxylate
Catalogue No.:PA 05 18630
CAS :
NA
Molecular Formula : C16H14LiN3O4
Molecular Weight : 319.25


Magnesium (R)-5-methoxy-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)benzo[d]imidazol-1-ide
Magnesium (R)-5-methoxy-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)benzo[d]imidazol-1-ide
Catalogue No.:PA 32 02510
CAS :
NA
Molecular Formula : C34H36MgN6O6S2
Molecular Weight : 713.12


5-Methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)thio)-1H-benzo[d]imidazole
5-Methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)thio)-1H-benzo[d]imidazole
Catalogue No.:PA 05 0171002
CAS :
1346600-29-0
Molecular Formula : C26H30N4O3S
Molecular Weight : 478.61


6-methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)-1H-benzo[d]imidazole
6-methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)-1H-benzo[d]imidazole
Catalogue No.:PA 05 0171008
CAS :
2101206-66-8
Molecular Formula : C26H30N4O4S
Molecular Weight : 494.61


5-Methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfonyl)-1H-benzo[d]imidazole
5-Methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfonyl)-1H-benzo[d]imidazole
Catalogue No.:PA 05 0171009
CAS :
1346599-74-3
Molecular Formula : C26H30N4O5S
Molecular Weight : 510.61


6-Methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfonyl)-1H-benzo[d]imidazole
6-Methoxy-1-((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfonyl)-1H-benzo[d]imidazole
Catalogue No.:PA 05 0171010
CAS :
2101206-41-9
Molecular Formula : C26H30N4O5S
Molecular Weight : 510.61

![(S)-(4-Methoxy-6-(((6-(methoxymethyl)-1H-benzo[d]i PA 05 0171011](https://www.pharmaffiliates.com/pimages/PA050171011.jpg)
(S)-(4-Methoxy-6-(((6-(methoxymethyl)-1H-benzo[d]imidazol-2-yl)sulfinyl)methyl)-5-methylpyridin-3-yl)methanol
(S)-(4-Methoxy-6-(((6-(methoxymethyl)-1H-benzo[d]imidazol-2-yl)sulfinyl)methyl)-5-methylpyridin-3-yl)methanol
Catalogue No.:PA 05 0171011
CAS :
19648-27-7
Molecular Formula : C18H21N3O4S
Molecular Weight : 375.44


(S)-6-Methoxy-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)-1-methyl-1H-benzo[d]imidazole
(S)-6-Methoxy-2-(((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)sulfinyl)-1-methyl-1H-benzo[d]imidazole
Catalogue No.:PA 05 0171020
CAS :
1346240-11-6
Molecular Formula : C18H21N3O3S
Molecular Weight : 359.44

![(1-(5-Methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimeth PA 05 0171032](https://www.pharmaffiliates.com/pimages/PA050171032.jpg)
(1-(5-Methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethyl-4-oxo-1,4-dihydropyridin-2-yl)methanesulfinic Acid
(1-(5-Methoxy-1H-benzo[d]imidazol-2-yl)-3,5-dimethyl-4-oxo-1,4-dihydropyridin-2-yl)methanesulfinic Acid
Catalogue No.:PA 05 0171032
CAS :
NA
Molecular Formula : C16H17N3O4S
Molecular Weight : 347.39