9-OXO-11ALPHA,16R-DIHYDROXY-17-CYCLOBUTYL-5Z,13E-DIEN-1-OIC ACID

Butaprost is a structural analog of prostaglandin E2 (PGE2) with good selectivity for the EP2 receptor subtype. Butaprost binds with about 1/10 the affinity of PGE2 to the recombinant murine EP2 receptor, and does not bind appreciably to any of the other murine EP receptors or DP, TP, FP, or IP receptors. CAY10408 is a free acid, 2-series analog of butaprost. It is the less active C-16 epimer compared to the 16(S) isomer, which has the same stereochemistry as butaprost. Butaprost has frequently been used to pharmacologically define the EP receptor expression profile of various human and animal tissues and cells. Since the majority of reports related to butaprost utilize the methyl ester derivative, it may be some time before the precise pharmacology of the free acid compounds, like CAY10408, is reported.