Abstract
Omeprazole is a proton pump inhibitor that inhibits secretion of gastric acid by irreversibly blocking the enzyme system of hydrogen/potassium adenosine triphosphatase, the “proton pump” of the gastric parietal cell. The drug is used in conditions, where the inhibition of gastric acid secretion may be beneficial, including aspiration syndromes, dyspepsia, gastro-oesophageal reflux disease, peptic ulcer disease, and the Zollinger–Ellison syndrome. Esomeprazole that is an isomer of Omeprazole is also used. The dose of Omeprazole may need to be reduced in patients with hepatic impairment. The chapter reviews the analytical methodologies that have been used for the determination of Omeprazole. The drug has been determined in formulation and in biological fluids by a variety of methods, such as spectrophotometry, HPLC with UV detection, and liquid chromatography coupled with tandem mass spectrometry. The overview includes most relevant analytical methodologies used for the determination of the drug since the origin. The ADME (absorption, distribution, metabolism, and elimination) is also discussed in this chapter.