Endometrial effect of transdermal estradiol and progestin ST-1435 in postmenopausal women

Abstract

To study the endometrial effect of the transdermal synthetic progestin ST-1435. Prospective. City Maternity Hospital, Helsinki, Finland. Eleven postmenopausal women used transdermal estradiol (E2) patches for 6 weeks immediately before a vaginal operation for prolapse. For the last 10 days, 1 mg of ST-1435 transdermally in a gel was combined to the treatment. Blood samples were taken to follow serum concentrations of E2, follicle-stimulating hormone, and ST-1435. Endometrial samples for histologic examination were collected during the operation to evaluate the effect of the progestin. Transdermal absorption of ST-1435 resulted in reasonably constant serum concentrations of ST-1435 in each subject. A progestin effect on the endometrium was seen in 9 of 10 samples obtained. One sample did not show any progestin effect in spite of adequate ST-1435 levels, but this patient's E2 concentrations were low. When the estrogen stimulation was adequate, the transdermal ST-1435 induced a progestin effect on the endometrium, i.e., it had an end-organ effect.