 It is said to have minimal antigonadotropic effect and to not suppress ovulation, which has precluded its use in hormonal contraception.Based on "in vitro" research, ethisterone and norethisterone are about equipotent in their values for activation of the androgen receptor (AR), whereas, conversely, norethisterone shows markedly increased potency relative to ethisterone in terms of its EC50 for the progesterone receptor.As such, there is a considerable separation in the ratios of androgenic and progestogenic activity for ethisterone and norethisterone.