Esomeprazole is a proton pump inhibitor (PPI), a drug that is used to reduce acid secretion in the stomach. 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 PPI omeprazole (the R-isomer), which is marketed as Losec or Prilosec.
Studies in laboratory rats have shown that the R-isomer is more potent, while the S-isomer is more potent in humans and, in dogs, the two enantiomers are equally effective.
AstraZeneca claims esomeprazole is superior to the R-isomer in terms of controlling stomach acid.
However, many esteemed researchers such as Dr Otis Brawley, chief medical officer of the American Cancer Society, are of the opinion that the superior efficacy of esomeprazole can be attributed to the low therapeutic dose it is prescribed at, as opposed to any inherent superiority of the substance. Furthermore, studies have shown less variability in the efficacy of esomperazole versus omeprazole.
Two randomized, double blind studies of patients with gastroesophageal reflux disorder (GERD) have also shown that, at 4 and 8 weeks of treatment, the endoscopic appearance was healthy in a significantly greater proportion of patients receiving daily esomeprazole 40 mg than those receiving daily omeprazole 20 mg. Furthermore, 68.3% of those on esomeprazole experienced relief from symptoms such as heart burn compared to 58.1% in the omeprazole group.