Background:

Sulprostone is a metabolism resistant synthetic analog of PGE2.[1] 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.[2],[3] Sulprostone is a potent stimulator of uterine smooth muscle contractions with high abortifacient activity.[4],[5]

Reference:
[1]. Schaaf, T.K., Bindra, J.S., Eggler, J.F., et al. N-(methanesulfonyl)-16-phenoxyprostaglandincarboxamides: Tissue-selective, uterine stimulants. Journal of Medicinal Chemistry 24, 1353-1359 (1981).
[2]. Abramovitz, M., Adam, M., Boie, Y., et al. The utilization of recombinant prostanoid receptors to determine the affinities and selectivities of prostaglandins and related analogs. Biochimica et Biophysica Acta 1483, 285-293 (2000).
[3]. Negishi, M., Harazono, A., Sugimoto, Y., et al. TEI-3356, a highly selective agonist for the prostaglandin EP3 receptor. Prostaglandins 48, 275-283 (1994).
[4]. Schillinger, E., Prior, G., Speckenbach, A., et al. Receptor binding in various tissues of PGE2, and sulprostone, a novel PGE2-derivative. Prostaglandins 18, 293-302 (1979).
[5]. Krishna, U., Gupta, A.N., Ma, H.K., et al. Randomized comparison of different prostaglandin analogues and laminaria tent for preoperative cervical dilation. Contraception 34, 237-251 (1986).