Orally active pure antiestrogen

ICI 164,384 and fulvestrant (ICI 182,780) (Fig. 13) represent the first generation of pure anti-estrogens with ER destabilising activity [146]. These compounds are 7-a-substituted analogues of 17/f-estradiol. SAR studies identified fulvestrant (ICI 182,780), a compoimd with significantly increased antiestrogenic potency. As fulvestrant has a very low bioavailabiUty when administered orally it has to be applied by intramuscular injection [146]. 

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