Sulprostone is a metabolism resistant synthetic analog of PGE2.{1993} It is a selective agonist for EP3 receptors with a Ki value of 0.35 nM at the human recombinant EP3-III receptor and an IC50 of 0.01 μM for the inhibition of PGE2 binding.{8322,3390} Sulprostone is a potent stimulator of uterine smooth muscle contractions with high abortifacient activity.{3335,2462}