Esomeprazole is a proton pump inhibitor that is used to suppress the secretion of gastric acids. There are several different brand names for esomeprazole including Nexium, Essocam and Esmezol. The molecule is developed and marketed by AstraZeneca. Esomeprazole is the more active, S-isomer or S-enantiomer of the proton pump inhibitor omeprazole (the R-enantiomer).
In the United States, Canada, Australia and the United Kingdom, medication containing esomeprazole magnesium is available as delayed-release capsules or tablets at strengths of 20 mg or 40 mg. In the United states, delayed-release capsules containing 49.3 mg esomeprazole strontium are also available, as is injectable esomeprazole sodium for intravenous infusion.
The oral preparations are enteric coated, to prevent their breakdown by stomach acid. This is achieved using the multiple unit pellet system to make the capsules. This means that the capsule is made to contain tiny enteric-coated granules or pellets of the drug inside its outer casing. An enteric-coated capsule is made in such a way that it releases the drug only after it crosses the stomach and reaches the intestines. Water enters the capsule and the contents then swell, bursting open the shell and releasing the drug granules.
Usually, a single oral dose of 20 to 40 mg per day is recommended and can lead to a peak plasma or blood concentration of 0.5 to 1.0 mg/L within 1 to 4 hours of intake. After several days of use, this concentration can increase by half again. In some cases, intravenous administration may be required. A 30 minute intravenous infusion of a similar dose usually raises the peak blood concentration to around 1.0 to 3.0 mg/L.