Rosaprostol is an antiulcer drug. This compound acts on the mucosal barrier in the stomach, preventing a drop in pH. More specifically, rosaprostol exhibits gastric antisecretory activity and cytoprotective action. Importantly, it does not have the undesired side effects (such as diarrhea and uterine stimulation) of other prostanoids. Rosaprostol was found to antagonize gastric acid output induced by NSAID administration and to prevent and treat the digestive disorders that resulted from taking NSAIDs. Furthermore, symptoms in patients with gastritis disappeared after administration of rosaprostol, and the drug was well-tolerated. Positive effects of rosaprostol were also reported in patients with duodenal ulcer. Several stereoisomers of rosaprostol have been synthesized.