[Kinetics of transcutaneous penetration and fixation of 3-propoxy-17-methoxyestradiol and estradiol in various rat tissues].

The transcutaneous penetration of 3-propyl ether, 17-methyl ether oestradiol (POM) occurs by a diffusion phenomenon and does not seem to be modulated by a cutaneous receptor as it is the case for oestradiol. After transcutaneous administration of POM and oestradiol, a comparison of the kinetics of uptake on the uterus and of uterotrophic effects, as well as an analysis of radioactivity taken up by a partition method between petroleum ether and sodium hydroxide, indicates that cleavage of both ether groups of POM occurs leading to estradiol. It is likely that this de-etherification takes place in the liver after a period of quiescence. The lipophilic nature of POM allows an obvious uptake by the aorta and a very significant uptake by the adipose tissue. The etherification of the alcohol functions of oestradiol allows an adequate protection of the hormone against hepatic catabolism. This may explain, along with the release of metabolites taken up by the adipose tissue, that POM is bound to a greater extent than oestradiol by various tissues.