Metabolism of doubly labelled ethynylestradiol-3-cyclopentyl ether in women

Localization of Ethynyloestradiol in the Reproductive Tract of Women

“…Our finding that radioactivity in adipose tissue was in a freely extractable state agrees with the findings of Williams et al (1967) for the cyclopentyl ether of ethynyloestradiol, and of Pearlman, de Hertogh, Laumas & Pearlman (1969) and Demetriou, Crowley, Kushinsky, Donovan, Kotin & MacDonald (1964) for the naturally occurring oestrogens. Most of the radioactivity in the uterus and cervix was also freely extractable, but in plasma most of the radioactivity was in a con¬ jugated state.…”

“…Of the two subjects studied 48 h after injection, in one the concentration in the tissues had decreased compared with the 24-h values but in the second, amounts similar to the mean values for 24-h samples were present. These findings are at variance with those of Williams et al (1967) who could detect no radioactivity in the ovary, uterus, Fallopian tube or blood of a woman to whom the cyclopentyl ether of ethynyloestradiol labelled with both 14C and tritium had been administered 48 h previously. Insignificant amounts of radioactivity were detected in two samples of muscle obtained at 1 h and three samples obtained at 24 h ; however, only small samples of tissue (less than 0-5 g) were available for analysis.…”

“…A similar conclusion was reached by Twombly, Bassett, Meisel & Levitz (1967) who showed that oestradiol would localize initially in adipose tissue; the short half-life (10-5 h) suggested that adipose tissue did not act as a reservoir for oestradiol. They calculated that up to 89 % of the administered dose was present in the adipose tissue at 1 h, and 1 % was still present at 48 h. As in our study, Williams et al (1967) found small amounts of radioactivity in abdominal fat from two subjects given labelled ethynyl¬ oestradiol cyclopentyl ether 48 h previously.…”

“…Nilsen & Blahey (1967), no detailed study of the localization of synthetic oestrogens in the tissues of human beings has been reported. Since ethynyloestradiol is the most widely used of the synthetic oestrogens, being a component of most of the combined oral contraceptives, studies of this compound are important.…”

The effect of oral contraceptive steroids on bile secretion and bilirubin Tm in rats

“…All the compounds tested had a 17,/-OH. This group is not oxidized when there is a 17a-ethinyl group, and the latter has been shown to be very resistant to metabolism (Fotherby, Kamyab, Littleton & Klopper, 1966;Kamyab, Fotherby & Steele, 1969;Williams, Nilsen & Blahey, 1967). Our studies emphasize the importance of 17a-ethinyl substitution but leave open the question whether 3-hydroxyl, aromatic A ring and 17f/-OH are necessary for inhibition of bile secretion.…”