Synthesis and Characterization of Two Impurities in Esomeprazole, an Antiulcerative Drug

Impurity control is a key factor for drug quality. Study for impurities is helpful to optimize the production process and improve the quality of drugs. Synthesis and characterization of two of impurities in esomeprazole, which used for treatment of acid-related diseases was described in this paper. The two impurities are known as 2-[(3,5-dimethyl-4-methoxy-2-pyridinyl) methylsulfinyl]-1H-benzimidazole (impurity 1) and (R)-5-methoxy-2-[(4-methoxy-3,5-dimethylpyridin-2-yl) methylsulfinyl]-1H-benzimidazole (esomeprazole impurity F), whose structures are characterized with MS, IR, H-1-NMR and elemental analyses, and the purities of the two impurities are above 99% by HPLC analysis. The two target compounds can be used as the reference substance of the impurities of esomeprazole.