 Esomeprazole magnesium is the latest proton pump inhibitor that has been developed. It is unique in that it is the S- isomer of omeprazole, and as such, has better bioavailability and elevated levels compared to the racemic omeprazole. Since the proton pump is the last step in acid production, blockade of this pump causes reduction in gastric acidity. This effect is dose related up to a dose of 20-40mg daily. Esomeprazole is currently clinically indicated for the treatment of erosive esophagitis and symptomatic gastroesophageal reflux disease. In addition, it is approved to treat Helicobacter pylori in patients with duodenal ulcer disease in conjunction with either amoxicillin or clarithromycin and amoxicillin. 