No loss of estrogenic or anti‐estrogenic activity after demethylation of droloxifene (3‐OH‐Tamoxifen)

Abstract

The binding affinity of 3-OH-Tamoxifen (Droloxifene or DROL) and N-demethyl-droloxifene (ND-DROL) to the cystosolic estrogen receptor of rabbit uteri was 10 times higher than that of Tamoxifen. Both compounds exhibited similar stimulation (estrogenic effect) and inhibition (anti-estrogenic effect) of uterine growth of immature female rats. 3H-Uridine incorporation into the RNA of MCF-7 and ZR-75 cells as a measure of anti-estrogenic activity was equally inhibited by concentrations of 0.05-1.0 mumol/l of both compounds. Thus, the pharmacological properties of DROL were not changed by N-demethylation.