Omeprazole characterized

Lasker JM, Wester MR, Aramsombatdee E, et al. Characterization of CYP2C19 and CYP2C9 from human liver respective roles in microsomal tolbutamide, S-meph-enytoin, and omeprazole hydroxylations. Arch Biochem Biophys 1998 353(1) 16-28. 

Omeprazole belongs to a new class of antisecretory compounds, the snbstitnted benzimidazoles, that do not exhibit anticholinergic or H2-histamine-antagonistic properties bnt suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory snrface of the gastric parietal cell. Because this enzyme system is the acid (proton) pump within the gastric mucosa, omeprazole has been characterized as a gastric acid pump inhibitor it blocks the final step of acid prodnction. This effect is dose-related, and inhibits both basal and stimnlated acid secretion irrespective of the stimnlns. 

When different configurations of the same molecule crystallize in separate crystalline forms, they are termed as configurational polymorphs. As a caveat, since configurational isomers can be considered to be separate chemical entities, these solids may not be strictly classified as polymorphs. Yet another classification of polymorphs that is closely related to confignrational polymorphism is tautomeric polymorphism which occurs when different tautomers of a compound exist in different polymorphs. There are cases where confignrational isomers or tautomers can interconvert in solution, and the fact that their relative population and stability depends on factors such as temperature, solvent, pH, and so on makes them appear as different crystalline polymorphs. In contrast to other, previously described classes of polymorphs, tautomeric polymorphs are rare. An early report of tautomeric polymorphism by Desiraju is the compound 2-amino-3-hydroxy-6-phenylazopyridine, which exists as hydroxyazo and quinonehydrazone crystals of different colors. Polymorphs of the antiulcer drug omeprazole (Figure 6) also represent tautomeric polymorphs that were characterized by SC-XRD. ... 

Proton pump inhibitors (PPIs) such as omeprazole, lanzoprazole and pan-toprazole are chemically characterized as substituted benzimidazoles. They are chemically relatively stable at neutral pH tia = 24 h), whereas at acidic pH they are labile and at pH 1 the half-life is 2 min. 

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