Esomeprazole

Esomeprazole is a medication that reduces stomach acid. It belongs to the group of drugs called proton pump inhibitors. It is used to treat gastroesophageal reflux disease, peptic ulcer disease, and Zollinger-Ellison syndrome. It is taken by mouth or as an injection into a vein.

Pharmacodynamics

Esomeprazole exerts its effect by preventing the final step of gastric acid production. In doing so, it covalently binds to the enzyme H+/ K+-ATPase on the surface of the gastric islet cells. This effect results in inhibition of gastric acid secretion, regardless of the stimulus. Because the binding of esomeprazole to the enzyme is irreversible and new enzyme must be expressed to resume acid production, the duration of the antisecretory effect of esomeprazole lasts longer than 24 hours.

Pharmacokinetics

A single oral dose of 20 to 40 mg generally results in maximum plasma concentration within 1 to 4 hours. The drug is rapidly eliminated from the body, largely by urinary excretion of pharmacologically inactive metabolites such as 5-hydroxymethylesomeprazole and 5-carboxyesomeprazole. The plasma half-life is approximately 1-1.5 hours.

Drug Interactions

Esomeprazole is a competitive inhibitor of the enzyme CYP2C19 and may therefore interact with drugs that are metabolised by this enzyme, these include diazepam and warfarin. The concentrations of these drugs may increase when used concomitantly with esomeprazole.

Furthermore, clopidogrel is a so-called prodrug whose conversion to its active form is partly dependent on CYP2C19. Inhibition of CYP2C19 blocks the activation of clopidogrel and thus reduces its effect.

Side effects

Common side effects are headache, diarrhea, nausea, bloating, decreased appetite, constipation, dry mouth, and abdominal pain.

More serious side effects include severe allergic reactions, chest pain, dark urine, fast heartbeat, fever, paresthesias, persistent sore throat, severe stomach pain, unusual bruising or bleeding, unusual tiredness, and yellowing of the eyes or skin.