Abstract. Sex hormone binding globulin (SHBG) levels were studied for possible effects of oestradiol-17β on SHBG. No change in SHBG plasma was recorded during normal menstrual cycles or during treatment with oestradiol-17β to menopausal women. However, gonadotrophin treatment to amenorrhoeic women to induce ovulation resulted in high oestradiol concentrations and a pronounced increase in SHBG was found during the luteal phase of these cycles. A marked increase of SHBG was also recorded in a woman with pronounced fluctuations of oestradiol during treatment with levonorgestrel sc implants for contraception. In conclusion, effects on SHBG were only found when extraordinarily high levels of plasma oestradiol were recorded.

No abstract

This study was done to evaluate the absorption of a single oral dose of 12 mg oestriol (Triovex@, Leo AB, Sweden) and to confirm the hypothesis that the enterohepatic recirculation can prolong the plasma oestriol elevation obtained.Twelve menopausal women, six of whom had been cholecystectomized earlier, were given 12 mg oestriol orally. Fatty meals were given immediately after drug administration and then a t four hourly intervals. Fat was given to induce the bileflow and provide oestriol to the intestine for deconjugation and enterohepatic recycling. One of the non-cholecystectomized women also remained fasting for 24 hours after oestriol administration.Plasma concentrations of unconjugated oestriol were measured by a specific RIA-method.In all women the plasma oestriol levels were considerably elevated for 24 hours. In the non-cholecystectomized women the plasma oestriol levels fluctuated in relation to meals whereas in the cholecystectomized women the fluctuations were not as pronounced, indicating that the release of biliary oestriol metabolites is the source of intestinal degradation and reabsorption to the systemic circulation. Fasting also gave increased and stable plasma oestriol levels.After a high oral dosage of oestriol , the enterohepatic recycling renders oestriol an enhanced potency since the plasma oestriol elevation time is prolonged.

Summary Peripheral plasma from five postmenopausal women was analyzed for oestrone and oestradiol during 48 hours after administration of 1‐25 mg Premarin (conjugated equine oestrogen) orally and vaginally. Oestrone and oestradiol were separated on columns of Sephadex LH 20 before radioimmunoassay. Administration of 1.25 mg of Premarin produced a marked increase in plasma oestrone levels and 24 hours after treatment the oestrone levels were still above follicular phase levels. The plasma pattern of oestradiol was similar but the elevation was less pronounced. The biological activity of Premarin as indicated by depressed gonadotrophin levels was similar with the intravaginal and oral routes of administration.

Estriol is a weak estrogen with a claimed specific action on the epithelium in cervix uteri and vagina and with no or limited ability to induce endometrial proliferation. In a previous pharmacokinetic study we have shown elevated estriol levels for only 2-3 hours after oral administration of the drug. The present study was performed to test if estriol, when given orally in daily divided doses to postmenopausal women, has any effect on the endometrium. Twenty postmenopausal women who had no vaginal bleeding in response to lynestrenol (Orgametil 5 mgX2XV) were treated with 6 mg estriol a day (Ovesterin 2 mgX3), divided into three doses, for 2 up to 3.5 months. When lynestrenol (5 mgX2XV) was given following the estriol treatment periods, 12 women out of 20 experienced a vaginal bleeding and one reported spotting. Endometrial biopsies in ten of these women who had a bleeding were examined histologically. The endometrium was atrophic in four women, proliferative in two, slightly hyperplastic in one and showed signs of weak hormonal activity in one. Two women had secretory endometrium. It is concluded that estriol, administered in a way that gives prolonged elevation of the blood levels, is able to produce the same effect on the endometrium as other estrogens.