Esomeprazole magnesium trihydrate [bis(5- methoxy-2-[(S)-[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl] sulfinyl]-1H-benzimidazole-1yl) magnesium trihydrate] (ESO) is a well-known gastric proton-pump inhibitor (PPI) used in treatment of gastric-acid related diseases. AstraZeneca’s Nexium brand of ESO was approved for marketing in 2000. Compared to the corresponding racemic drug omeprazole (OME), the (S)-enantiomer has more favorable metabolic properties leading to a more pronounced effect on gastrointestinal disorders such as gastric and duodenal ulcers [1].

Application

Esomeprazole is used to treat certain stomach and esophagus problems (such as acid reflux, ulcers) [2]. It inhibits gastric acid secretion and relieves heartburn. Further, it is cost effective in treatment of gastric esophageal reflux diseases. It is S-isomer of omeprazole and the first single optical isomer proton pump inhibitor. It provides better acid control than current racemic proton pump inhibitors and has a favorable pharmacokinetic profile relative to omeprazole [3]. 

Mechanism of Action

Esomeprazole belongs to a class of drugs known as proton pump inhibitors (PPIs)，and exerts its stomach acid-suppressing effects by preventing the final step in gastric acid production by covalently binding to sulfhydryl groups of cysteines found on the (H+, K+)-ATPase enzyme at the secretory surface of gastric parietal cells. This effect leads to inhibition of both basal and stimulated gastric acid secretion, irrespective of the stimulus. As the binding of esomeprazole to the (H+, K+)-ATPase enzyme is irreversible and new enzyme needs to be expressed in order to resume acid secretion, esomeprazole's duration of antisecretory effect persists longer than 24 hours [4].

Interactions

Esomeprazole is metabolised by cytochrome P450 2C19 and 3A4 so there is a potential for interactions. Known interacting drugs include diazepam, cisapride, clarithromycin, citalopram, imipramine and phenytoin. Severe liver disease reduces the clearance of esomeprazole [5].  Esomeprazole is very similar to omeprazole. Do not use any medications containing omeprazole while using esomeprazole [6]. 

Adverse Effects

Due to their good safety profile and as several PPIs are available over the counter without a prescription, their current use in North America is widespread. Long term use of PPIs such as esomeprazole has been associated with possible adverse effects, however, including increased susceptibility to bacterial infections (including gastrointestinal C. difficile), reduced absorption of micronutrients such as iron and B12, and an increased risk of developing hypomagnesemia and hypocalcemia which may contribute to osteoporosis and bone fractures later in life [7].

References

[1] "A comparative study of the novel spectrophotometric methods versus conventional ones for the simultaneous determination of Esomeprazole magnesium trihydrate and Naproxen in their binary mixture." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 151(2015):538-546.
[2] https://www.webmd.com/drugs/2/drug-20537-4143/esomeprazole-magnesium-oral/esomeprazole-delayed-release-capsule-oral/details
[3] Rao, N. Rama, M. E. Gupta, and P. Vineela. "FORMULATION OF ENTERIC TABLETS OF ESOMEPRAZOLE MAGNESIUM TRIHYDRATE USING A SYRINGE IN COATING PROCESS." Indo American Journal of Pharmaceutical Research 4.9(2014):3754-3762.
[4] Kale-Pradhan, Pramodini B , H. K. Landry , and W. T. Sypula . "Esomeprazole for Acid Peptic Disorders." The Annals of Pharmacotherapy 36(2002):655-663.
[5] https://www.nps.org.au/australian-prescriber/articles/esomeprazole-magnesium-trihydrate