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. Misoprostol has been used therapeutically for many years in humans for the treatment of gastric ulcer disease under the Searle tradename Cytotec. 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.