Bioavailability of natural estrogens in young females with secondary amenorrhea

Pharmacokinetics and biotransformation of orally administered oestrone sulphate and oestradiol valerate in post-menopausal women

The pharmacokinetic properties and biotransformation of two orally active oestrogens, piperazine oestrone sulphate (PE1S, 2.5 mg/day) and oestradiol valerate (E2V, 2.0 mg/day), given alone or in combination with levonorgestrel (LNG, 250 micrograms/day) were compared in 8 post-menopausal women, using a randomized cross-over design. The end points measured in peripheral plasma included oestrone (E1), oestradiol (E2), oestriol (E3), oestrone sulphate (E1S), oestradiol sulphate (E2S) and oestriol sulphate (E3S). In addition, LNG and sex-hormone-binding globulin SHBG concentrations were also assessed. The plasma levels of E3 were invariably below the detection limit (220 pmol/l). The levels of all the other oestrogens analyzed were consistently higher and the area under the curve significantly greater (except in the case of E3S) following PE1S administration than those recorded after E2V ingestion. The terminal half-lives of the circulating oestrogens measured after PE1S administration did not differ from those found after E2V administration. After 21 days of PE1S administration (in combination with LNG for the last 10 days), the maximum levels of all the oestrogens (except those of E2) were significantly higher than those seen after the first dose. No such difference was observed after E2V administration. There was no difference between the effects of the two treatment regimens with regard to the E1/E2 ratios, but the E1/E1S ratios were significantly lower after PE1S treatment than after E2V administration. It is concluded that, compared with an equivalent dose of PE1S, daily repeated oral administration of E2V yields consistently lower peripheral plasma levels of E2 and its principal metabolites. However, in contrast to PE1S therapy, prolonged administration of E2V does not result in an accumulation of the circulating oestrogens measured.

Dose and time-course evaluation of a redox-based estradiol-chemical delivery system for the brain. I. Tissue distribution

Brain-enhanced delivery and sustained release of estradiol (E2) may be potentially useful in the treatments of vasomotor hot flushes and prostatic adenocarcinoma and for fertility regulation. Therefore, we have evaluated a redox-based estradiol-chemical delivery system (E2-CDS) for the brain. The mechanism of this drug delivery is based on an interconvertible dihydropyridine in equilibrium pyridinium salt redox reaction. In this study, we investigated the dose- and time-dependent effects of E2-CDS on the tissue distribution of E2-Q+ and E2, the inactive (intermediate) and active metabolites, respectively, of the E2-CDS. Ovariectomized rats received a single iv injection of E2-CDS at 0.01, 0.1, or 1.0 mg/kg or an E2 dose of 0.7 mg/kg or the drug's vehicle, 2-hydroxypropyl-beta-cyclodextrin (HPCD), on day 0. Tissue samples including brain and peripheral tissues were then analyzed for both E2-Q+ and E2 at 1, 7, 14, 21, or 28 days following the E2-CDS administration. Initially, both E2-Q+ and E2 were detected in all tissues analyzed. The dose-distribution and time-course study demonstrates that (1) at 24 hr (1 day) after administration of E2-CDS, all tissues showed a dose-proportional increase in concentrations of E2-Q+ and E2; (2) the enzymatic oxidation of E2-CDS to E2-Q+ was dose dependent over the 100-fold dose range examined; and (3) the disappearance of E2-Q+ as well as E2 was slow in whole brain and hypothalamus, with an apparent t1/2 = 8-9 days, while both of these metabolites were rapidly cleared from plasma, liver, fat, anterior pituitary, kidney, lung, heart, and uterus.(ABSTRACT TRUNCATED AT 250 WORDS)

Oestrogen replacement therapy: physiological considerations and new applications

The total impact of the menopause on the health of women and the ultimate benefit/risk ratio of oestrogen replacement therapy are yet to be defined completely. Until these are accomplished, broad general guidelines for the use of oestrogen replacement therapy in all patients cannot be given. Treatment should be individualized to the patient's specific needs. Use of appropriate dosages of oestrogen in combination with progestin administration should reduce risk and enhance benefits for those subjects requiring its use. The development of new non-oral methods of administration should also help.

The physiology of the perimenopausal years: a minireview

Selected studies on the physiology of the perimenopausal years and the subtle transitional changes that occur up to the postmenopause are reviewed. Extraovarian sources of estrogen, which must be considered when recommending dosage of replacement therapy, are described. The effects of hormonal therapy on endogenous hormones and the important roles of progesterone and prolactin are highlighted. The collected evidence suggests that (a) the vasomotor disturbance and depression experienced by estrogen-deficient women are not psychosomatic disorders, (b) osteoporosis is preventable if estrogen therapy is initiated soon after cessation of ovarian function, and (c) administraton of a weak estrogen combined with a progestogen can effectively prevent or treat the difficulties experienced during the female climacteric.