Clinical utility and safety of omeprazole.

Omeprazole inhibits H+,K+-ATPase, the enzyme responsible for the exchange of H+ and K+ in the final step in the acid secretory process within the parietal cell. It has been shown to produce a marked and long-lasting inhibition of acid secretion with a decrease in 24-hour intragastric acidity after repeated daily dosing. Omeprazole has been shown to give significantly higher healing rates than ranitidine or cimetidine in patients with duodenal ulcer and gastric ulcer. Similarly, a more pronounced effect on ulcer symptoms has been observed. In patients with reflux esophagitis, omeprazole has been shown to decrease the time with an acid milieu in the esophagus. Omeprazole has consistently given about twice as high healing rates and faster decrease in symptoms than with ranitidine. In patients with Zollinger-Ellison syndrome, omeprazole has been found to have a rapid and long-lasting effect on acid secretion and acid-induced symptoms.