In vitro evaluation of estrogenic, estrogen antagonistic and progestagenic effects of a steroidal drug (Org OD-14) and its metabolites on human endometrium.

The human endometrial model for in vitro evaluation of estrogenic, estrogen antagonistic, and progestagenic effects of endogenous steroids, natural products or synthetic drugs was applied to the study of Org OD-14, an analog of norethynodrel developed by Organon International, Oss, The Netherlands, and some of its metabolites. Estrogen antagonistic actions of Org OD-14 and its 4-ene isomer were evident from their ability to suppress the enhancement of PGF2 alpha output elicited by estradiol on fragments of secretory endometrium and to decrease the rate of output of the prostaglandin by proliferative tissue, already stimulated by endogenous estrogens. These inhibitory effects were similar to those obtained with progesterone and do not appear to involve competition for the estrogen receptor since the antiestrogen 4-hydroxyamoxifen was not active in parallel incubations of proliferative endometrium. The progestagenic effects of Org OD-14 and its 4-ene isomer were also evident from their capability to enhance estradiol 17 beta-dehydrogenase activity and glycogen accumulation in specimens of proliferative endometrium. Estrogenic effects of the 3 alpha- and 3 beta-hydroxy metabolites of Org OD-14 were demonstrated by their stimulatory actions on PGF2 alpha output during incubations of secretory endometrium. The estrogenic and progestagenic actions of these compounds are in general agreement with their relative affinity for binding to the estradiol and progesterone receptors, although their actions may be influenced by intracellular metabolism in the endometrial tissue. For instance, the similarity in progestagenic activity of Org OD-14 and the 4-ene isomer, contrasting with their different affinities for the progesterone receptor, may result from in situ isomerization of Org OD-14 to the 4-ene metabolite.