A NON-STEROIDAL ESTROGEN ANTAGONIST l-(p-2-DIETHYLAMINOETHOXYPHENYLH-PHENYL-2-p-METHOXYPHENYL ETHANOL

Abstract

MER-25, l-(p-2-Diethylaminoethoxyphenyl)-l-phenyl-2-p-methoxyphenyl ethanol, blocks the response of estrogen target organs to the stimulating action of estrogens. The estrogen antagonism activity of MER-25 has been demonstrated in intact and castrate rats, mice and monkeys and in chicks and rabbits. The estrogen target organs employed for the measurement of the estrogen antagonism activity of MER-25 were the uterus, vagina and pituitaries in the mammals, and the oviduct in chicks. An additional endpoint employed was the chick plasma phospholipids. This drug antagonizes the activity of both endogenous and exogenous estrogens and steroidal and non-steroidal estrogens. The pituitaries of rats administered MER-25 were smaller than those of control animals and it prevented estrogen and castration induced pituitary hypertrophy. Weak gonadotrophin inhibition was evident in the treated male rat and in parabiotic female rats. MER-25 interfered with normal pregnancy in the rat. Male offspring of animals administered the drug during lactation were fertile but the female offspring were infertile. Studies described show that MER-25 does not have estrogenic, androgenic, anti-androgenic, progestational, anti-progestational or gonadotrophin-like activities.