(Rac)-Acolbifene (EM-343; (Rac)-EM-652) is the racemic form of EM652 (estrogen receptor antagonist), has anti-estrogenic and estrogenic activities. (Rac)-Acolbifene (EM-343; (Rac)-EM-652) contains a piperidine ring, shows good pharmacological profile,relative binding affinity (RBA)=380^[1]. In Vitro: (Rac)-Acolbifene (EM-343; (Rac)-EM-652)  shows a inhibitory effect in T-47D cells with an IC₅₀ value of 0.110 nM^[1].
In Vivo: (Rac)-Acolbifene (orally adminstration; 7.5 nM, 75 nM; 9 days; once daily) shows a good pharmacological profile in ovariectomized mice, shows 63% and 84% antiuterotrophic inhibitions at the 7.5 and 75 nM doses, respectively (PK study, ovariectomized mice)^[1].