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Comparison of pharmacodynamic properties of various estrogen formulations.

A group of 23 healthy postmenopausal women received one or more 2-week courses of daily administration of the following estrogen preparations: piperazine estrone sulfate (Ogen), 0.3, 0.625, 1.25, 2.5, and 5.0 mg; micronized estradiol (Estrace), 1, 2, and 10 mg; conjugated estrogens (Premarin), 0.3, 0.625, 1.25, and 2.5 mg; ethinyl estradiol (Estinyl), 10 and 20 micrograms; and diethylstilbestrol, 0.1 and 0.5 mg. Each dosage of each formulation was ingested by three women. In those women who received more than one dosage, each course was separated by a drug-free interval of at least 4 weeks. Pretreatment and posttreatment levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), corticosteroid-binding globulin-binding capacity, sex hormone-binding globulin-binding capacity, angiotensinogen, estrone, and estradiol were determined. The relative potency of these five estrogen formulations was determined by parallel line analysis for each of these responses, except LH. On a weight basis, piperazine estrone sulfate and micronized estradiol were equipotent for all responses. Conjugated estrogens suppressed FSH in a fashion equipotent to that of the other nonsynthetic estrogens; however, for all three hepatic parameters, the response was exaggerated twofold to threefold. The synthetic estrogens, diethylstilbestrol and ethinyl estradiol, were relatively more potent on a weight basis for every response and produced the most marked response (fourfold to eighteenfold in excess of their FSH suppression) for the hepatic parameters.

Angiotensinogen↗

Effect of dexamethasone treatment on sex steroid-binding protein, corticosteroid-binding globulin, and steroid hormones in cycling rhesus macaques.

We tested the hypothesis that dexamethasone lowers sex steroid-binding protein levels and observed the effect of dexamethasone on corticosteroid-binding globulin and specific steroid hormones in plasma. Four cycling rhesus macaques were studied during three consecutive menstrual cycles (first and third cycles served as controls). In the second cycle, each animal received 0.5 mg of dexamethasone intramuscularly at 8:00 AM and 8:00 PM daily for 21 consecutive days. Blood samples were taken at 1- to 3-day intervals during each cycle. Concentrations of sex steroid-binding protein, corticosteroid-binding globulin, cortisol, testosterone, progesterone, and estradiol were measured in plasma. The percentage and plasma concentration of free testosterone were also determined. Within 2 days of treatment, dexamethasone suppressed cortisol to 5% of baseline values, which returned in the third cycle. All cycles were ovulatory. Dexamethasone significantly lowered plasma levels of all the compounds except progesterone: sex steroid-binding protein, -30%; corticosteroid-binding globulin, -14%; testosterone, -36%; and estradiol, -45%. The percentage of free testosterone was significantly elevated, but free testosterone concentrations were unchanged. Although our data conclusively show that dexamethasone suppresses plasma sex steroid-binding protein levels in the rhesus macaque, it remains to be established whether this suppressive effect leads to an increase in the metabolic clearance rate of testosterone.

Animals↗

Comparison of hepatic impact of oral and vaginal administration of ethinyl estradiol.

The pronounced hepatic impact of oral ethinyl estradiol has been attributed by some to its so-called first-pass effect through the liver as only some 40% of ingested ethinyl estradiol reaches the systemic circulation. Others believe that ethinyl estradiol exerts its hepatic effects because of its chemical composition, specifically its 17 alpha-ethinyl group. In an attempt to resolve this controversy, a study was undertaken to determine whether vaginal administration of ethinyl estradiol can selectively reduce the hepatic effects of oral ethinyl estradiol. To compare the effects of oral and vaginal ethinyl estradiol, a group of postmenopausal subjects received either 5 micrograms of oral and 20 micrograms of vaginal ethinyl estradiol or 10 micrograms of oral and 50 micrograms of vaginal ethinyl estradiol in either sequence, respectively. Oral ethinyl estradiol was four to five times more potent than vaginal ethinyl estradiol. The potency ratios of the oral-vaginal ethinyl estradiol doses required to suppress follicle-stimulating hormone and luteinizing hormone were 4.4 and 3.2 and those to raise sex hormone-binding globulin binding capacity, corticosteroid-binding globulin binding capacity, and high-density lipoprotein cholesterol as well as lower low-density lipoprotein cholesterol were 3.5, 5.0, 4.2, and 4.2, respectively. These essentially equal oral-vaginal route potency ratios for both central nervous system and hepatic effects indicate that vaginal administration of ethinyl estradiol does not selectively reduce its hepatic impact in relation to its central nervous system effects. The pronounced hepatic effects of ethinyl estradiol are therefore attributed to its chemical composition.

Administration, Oral↗

Binding of oral contraceptive progestogens to serum proteins and cytoplasmic receptor.

Some progesterones widely used in oral contraceptives are characterized at the level of high-affinity receptor binding as well as binding to sex hormone-binding globulin and corticosteroid-binding globulin. With regard to binding to sex hormone-binding globulin, gestodene, levonorgestrel, and to a lesser extent 3-ketodesogestrel (which is only formed from the prodrug desogestrel in the body), show a behavior that is manifested in the relatively high affinity to sex hormone-binding globulin, whereas desogestrel and norgestimate do not display any measurable affinity for this specific steroid-binding serum protein. Furthermore, levonorgestrel and gestodene dissociate very much more slowly from the binding sites of sex hormone-binding globulin than 3-ketodesogestrel. A natural affinity of all these synthetic progestogens tested for corticosteroid-binding globulin could not be established. Gestodene, levonorgestrel, and 3-ketodesogestrel bind to the progesterone, glucocorticoid, and androgen receptor with high affinity, apart from slight differences, whereas estrogen receptor affinity could not be demonstrated in any of the progestogens investigated. In relation to aldosterone, the relative binding affinity values of gestodene, levonorgestrel, and the natural progestogen progesterone are relatively high, whereas 3-ketodesogestrel does not display any measurable affinity for this receptor species.

Animals↗

Protein binding of active ingredients and comparison of serum ethinyl estradiol, sex hormone-binding globulin, corticosteroid-binding globulin, and cortisol levels in women using a combination of gestodene/ethinyl estradiol (Femovan) or a combination of desogestrel/ethinyl estradiol (Marvelon) and single-dose ethinyl estradiol bioequivalence from both oral contraceptives.

Results from two clinical pharmacokinetic studies are given. The first study was an observational study in oral contraceptive users who took either a combination of gestodene and ethinyl estradiol (pill A, Femovan) or desogestrel and ethinyl estradiol (pill B, Marvelon). A total of 69 women (39 receiving pill A and 30 receiving pill B) were evaluated to determine serum ethinyl estradiol, sex hormone-binding globulin, corticosteroid-binding globulin, and cortisol levels. Samples were obtained on 1 day during the tenth to twenty-first days of pill intake. All women received the respective oral contraceptive for at least 3 months. The test power was such that an 80% difference of 1 standard deviation of each target variable would have been detected (alpha = 0.05; beta = 0.1). No statistically significant differences were found in sex hormone-binding globulin, corticosteroid-binding globulin, or cortisol serum levels between both groups. Time and height of maximum ethinyl estradiol levels were identical as was the area under the curves. Ex vivo protein-binding analysis of the progestins revealed a free portion of 0.6% for gestodene and 2.5% for 3-ketodesogestrel as the active metabolite of desogestrel. Sex hormone-binding globulin-bound portions were much higher for gestodene (75.3% +/- 9.1%) than for 3-ketodesogestrel (31.6% +/- 12%). The remaining fractions were bound to albumin. In a second study, ethinyl estradiol-bioequivalence from pills A and B was investigated in 18 women in a controlled, single-dose, randomized, crossover design. The area under the ethinyl estradiol serum levels were identical up to 4 hours after pill intake between both treatments. According to the relatively low variation in data in this group of women, a 10% difference in ethinyl estradiol-availability could have been detected. Both studies indicate that the pharmacokinetics of ethinyl estradiol were independent of the concomitantly administered progestin, that is, desogestel and gestodene.

Adult↗

Single and multiple administration of a new triphasic oral contraceptive to women: pharmacokinetics of ethinyl estradiol and free and total testosterone levels in serum.

Ethinyl estradiol is part of almost every combined oral contraceptive, and its pharmacokinetic characteristics have been thoroughly investigated in numerous studies. However, little is known about its pharmacokinetics during long-term administration, as compared with single-dose administration. In this study 10 women received a triphasic formulation that contained ethinyl estradiol together with the progestin gestodene over one treatment cycle. Mean area under the curve values of ethinyl estradiol were significantly higher on the last treatment day, as compared with the corresponding values obtained from the same women after single-dose administration. However, the observed increase in area under the curve was within the range of pharmacokinetic accumulation, to be expected on the basis of dosing interval and terminal half-life. Another point of interest was the effect of the triphasic preparation on testosterone concentrations in serum. Both total and free testosterone levels were suppressed by about 60% as compared with pretreatment values, and there was no correlation with corresponding sex hormone-binding globulin levels in the serum.

Adult↗