Oral replacement with estradiol-cyclooctyl acetate: a new estradiol analogue. Effects on serum lipids, proteins, gonadotrophins, estrogens and uterine endometrial morphology.

Estradiol-cyclooctyl acetate (E2CoA) dissolved in arachis oil was given orally at a dose of 0.5 mg/day for 21 days to 11 oophorectomized women. The study was performed in two steps. In the first step the effects of E2CoA, administered after an overnight fast, on plasma estrone, estradiol, FSH, LH, prolactin as well as on serum proteins, fatty acids, oral glucose tolerance test and on the cervical and endometrial morphology were compared to the effects of daily oral intake of 25 micrograms ethinyl estradiol (EE) in a cross-over study. In the second step the effects of E2CoA in nonfasting conditions on plasma estrone, estradiol, FSH and LH were studied. E2CoA alleviated climacteric estrogen-deficiency symptoms in all women. It showed an estrogenic effect on cervical and endometrial morphology and depressed FSH, though more weakly than EE. No side effects were seen. The unchanged metabolic parameters after 21 days of E2CoA treatment may support the assumption of a weak estrogenic effect, but the relatively slow resorption and relatively low estradiol/estrone ratio found in this study do not confirm the hypothesis that the drug is resorbed by the chylomicrones. Further investigation on the resorption of E2CoA in nonfasting women is, however, needed.