Misoprostol is a widely sold analog of PGE1 which has potent but relatively non-selective agonist activity with respect to the prostanoid EP receptor subgroup.{8322} Misoprostol has been used therapeutically for many years in humans for the treatment of gastric ulcer disease under the Searle tradename Cytotec.{2958} 11β-Misoprostol is one of several impurities which are possible in the production of commercial lots of bulk misoprostol, and is somewhat difficult to distinguish from other impurities such as 8-iso misoprostol. The pharmacology and EP receptor binding affinity for 11β-misoprostol have not been published.