Esomeprazole (Nexium) - Uses, Method of Action, Dosage and side effects

Esomeprazole is a proton pump inhibitor developed and marketed by AstraZeneca which is used in the treatment of dyspepsia, peptic ulcer disease (PUD), gastroesophageal reflux disease (GORD/GERD) and Zollinger-Ellison syndrome. It is available under brand names Sompraz, Zoleri, Nexium, Lucen, Esopral; Axagon in Italy, Nexiam in Belgium and South Africa. Generic Nexium in Tablet form is also now available.

Method Of Action

Esomeprazole is a proton pump inhibitor which reduces gastric acid secretion through inhibition of H+/K+-ATPase in gastric parietal cells. By inhibiting the functioning of this enzyme, the drug prevents formation of gastric acid.
Single 20-40 mg oral doses generally give rise to peak plasma esomeprazole concentrations of 0.5-1.0 mg/L within 1-4 hours, but after several days of once-daily administration these levels may increase by about 50%. The drug is rapidly cleared from the body.

Esomeprazole Dosage

Esomeprazole is available as delayed-release capsules in the United States. In Australia and Canada as well as several other countries it is available as delayed release tablets in containing esomeprazole magnesium in strengths of 20 mg and 40 mg. It is also available as esomeprazole sodium for intravenous injection/infusion.
Oral esomeprazole preparations are enteric-coated, due to the rapid degradation of the drug in the acidic conditions of the stomach.The multiple-unit pellet system is used to formulate capsules for achieving this.

Side Effects Of Esomeprazole

Common side effects include headache, diarrhea, nausea, gas, decreased appetite, constipation, dry mouth, and abdominal pain. More severe side effects are severe allergic reactions, chest pain, dark urine, fast heartbeat, fever, persistent sore throat, severe stomach pain, unusual bruising or bleeding, unusual tiredness, and yellowing of the eyes or skin.
Proton pump inhibitors may be associated with a greater risk of hip fractures, clostridium difficile-associated diarrhea. Patients are frequently administered the drugs in intensive care as a protective measure against ulcers, but this use is also associated with a 30% increase in occurrence of pneumonia.

Interactions with Other Drugs

Esomeprazole is a competitive inhibitor of the enzymes CYP2C19 and CYP2C9, and may therefore interact with drugs that depend on them for metabolism, such as diazepam and warfarin; the concentrations of these drugs may increase if they are used concomitantly with esomeprazole. Conversely, Clopidogrel (Plavix) is an inactive prodrug that partially depends on CYP2C19 for conversion to its active form; inhibition of CYP2C19 blocks the activation of clopidogrel, thus reducing its effects.
Drugs that depend on stomach pH for absorption may interact with omeprazole; drugs that depend on an acidic environment (such as ketoconazole or atazanavir) will be poorly absorbed, whereas drugs that are broken down in acidic environments (such as erythromycin) will be absorbed to a greater extent than normal.

Further Information

Manufacturers pamphlet: Astra Zeneca's Nexium Information

Considerable portions of the text here is from http://en.wikipedia.org/wiki/Esomeprazole and is reproduced here under the Creative Commons Attribution-ShareAlike License