4'-substituted analogues of the antiestrogen idoxifene have been prepa
red. All the compounds were assayed for antagonism of calmodulin depen
dent c-AMP phosphodiesterase and for binding to rat uterine estrogen r
eceptor. The 4'-amino compound was the most potent antiestrogen (RBA =
47) whilst retaining a similar calmodulin antagonism to idoxifene.