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At least 559 records · Page 31Linked to original sources
PubMed1990

Contraception with a vaginal ring releasing 3-keto desogestrel and ethinylestradiol.

Eleven healthy women used a contraceptive vaginal ring for three cycles. The rings released 15 micrograms of ethinylestradiol and 150 micrograms of 3-keto desogestrel per 24 hours. The rings were used for 21 days and then removed, rinsed in clean water and stored. After a 7-day ring-free period, the rings were reinserted. Totally, each ring was used for 3 cycles. The rings were well tolerated. The bleeding pattern was excellent. No woman showed any signs of ovulation when using the ring. Estradiol levels were suppressed, but showed an increase during the ring-free period as can be found during the pill-free period of an oral contraceptive regimen. When the ring was reinserted, the estradiol levels were rapidly suppressed again. SHBG capacity increased during use of the ring.

Adult↗
PubMed1994

Tissue and serum levels of steroid hormones and RU 486 after administration of mifepristone.

The present study was designed to examine the effect RU 486 administration on steroid hormone levels in serum and decidua. Sixty women at 6-7 weeks gestation were divided into three groups. The first group took a placebo 24 hours before interruption of pregnancy. The other two groups took 200 mg mifepristone 12 and 24 hours before the surgical procedure, respectively. The concentrations of steroids and mifepristone were measured by radioimmunoassay or high performance liquid chromatography. Mifepristone treatment increased the levels of estradiol, cortisol and testosterone in serum and decidual cytosol (p < 0.05 or p < 0.01). A minor elevation in progesterone level was observed but was not statistically significant. The tissue levels of progesterone, estradiol and testosterone were much higher than the serum levels, whereas RU 486 concentration in the tissue was only one-third of the serum level. In addition, the RU 486 level in decidual cytosol was of the same order as that of progesterone. This competitive concentration was not achieved in chorionic villi in our previous observation, explaining why mifepristone exerts its predominant effect on decidua rather than villi. It is concluded that RU 486 reached an effective inhibitory concentration in decidua and had significant effects on the endocrine milieu.

Abortion, Induced↗
PubMed1996

Effects of two antiprogestins on early pregnancy in the long-tailed macaque (Macaca fascicularis).

The abortifacient effects of mifepristone and HRP 2000 were compared in gravid long-tailed macaques. Thirty-six animals were studied with treatment administered either by the oral (0.5 or 5.0 mg/kg; N = 5 per antiprogestin per dose) or intramuscular (i.m.) routes (0.5 mg/kg; N = 5 per antiprogestin) on gestational days (GD) 23-26; six vehicle controls were included. Blood samples were collected for assay of progesterone (P4) and each of the antiprogestins (pre-treatment, daily GD 23-28, every other day GD 30-40), and animals were monitored sonographically throughout gestation. Results of these studies indicated high rates of abortion with i.m. administration (3/5 mifepristone, 4/5 HRP 2000) and 5.0 mg/kg oral route (4/5, 2/5, respectively), with less effects noted at oral doses of 0.5 mg/kg (2/5, 0/5, respectively). No early abortions were observed in the control groups. Following daily i.m. treatment, peak levels of 8-16 ng/ml mifepristone were detected whereas 6-10 ng/ ml of HRP 2000 were noted (GD 26-27). No serum levels of mifepristone were detected following either of the oral doses whereas serum levels of 2-6 ng/ml HRP 2000 were noted with high dose oral administratation. Results of these studies suggest: (1) both antiprogestins are roughly comparable in terminating early pregnancy although HRP 2000 may be more efficacious when administered i.m. whereas mifepristone may be more effective when administered orally; (2) similar levels of biological activity are seen with the i.m. and high dose oral dosing regimens, with little or no activity with the oral low dose; and (3) infants resulting from surviving pregnancies were not affected by early gestation exposure.

Abortifacient Agents, Steroidal↗
PubMed1996

Bioavailability of orally administered sex steroids used in oral contraception and hormone replacement therapy.

The concept of bioavailability is discussed with particular references to the sex steroids. Problems encountered in the measurement of bioavailability of these steroids and the various factors that may affect their bioavailability are briefly described. Information regarding the bioavailability of the estrogens and gestogens, some of which are prodrugs, used in oral contraception and hormone replacement therapy is summarized and the implications regarding the clinical use of these steroids are discussed.

Absorption↗
PubMed1978

Changes in peripheral hormone levels after therapeutic abortion.

Plasma levels of progesterone, 17 alpha-OH progesterone, hPL and beta-subunit hCG were measured in a group of women for 24 h after therapeutic abortion. Progesterone, hCG and hPL levels fell more rapidly than 17 alpha-OH progesterone levels. This might suggest that the main site of synthesis of 17 alpha-OH progesterone is probably in the corpus luteum of pregnancy or that the prolonged half-life of hCG maintains the corpus luteum to secrete longer. Human placental lactogen fell dramatically within 4 h but the hCG level was maintained. This difference probably reflects only the differences in half-lives of these hormones.

17-alpha-Hydroxyprogesterone↗
PubMed1977

Effect of indomethacin on estrogen-induced luteolysis in the ewe.

Three groups of 6 ewes were laparotomized on day 9 of an estrous cycle (estrus = day 0) and the corporà lutea (CL) were marked with India ink. Indwelling cannulae were inserted into the uterine horn adjacent to the CL in groups 2 and 3. Group 1 was injected intramuscularly (i.m.) with corn oil twice daily on day 9. Group 2 received 750 microng 17beta-estradiol (E2) i.m. twice daily on day 9 plus intrauterine injections of indomethacin (INDO) vehicle on days 9 through 13. Group 3 received in the same estrogen treatment plus the injection of 20 mg INDO twice daily on days 9 through 13. Jugular venous samples were taken once daily on days 9 through 14 for progesterone analysis. At re-laparotmy on day 14, the ovaries were examined for new ovulations, and the ovary bearing the marked CL was removed. Results showed that E2 induced premature luteal regression as indicated by decreased CL weights and plasma progesterone levels. INDO when given in conjunction with E2 effectively blocked the luteolytic action of E2. These results suggest that the luteolytic action of E2 is mediated via increased prostaglandin secretion and release from the uterus.

Animals↗
PubMed1992

The mechanism of RU486 antagonism is dependent on the conformation of the carboxy-terminal tail of the human progesterone receptor.

The human progesterone receptor form B (hPR-B) was expressed in Saccharomyces cerevisiae together with a specific reporter plasmid. To understand the mechanism underlying antagonist ligand activity, libraries of hormone binding domain (HBD)-mutated hPR-B molecules were prepared. A mutant receptor was identified that had lost the ability to bind either progesterone or R5020; it could still bind RU486 and, surprisingly, fully activated transcription in the presence of this "antagonist" and other antiprogestins. When this receptor mutant was assayed in mammalian cells, RU486 again demonstrated agonistic activity. Sequence analysis indicated that the mutant phenotype was due to truncation of the carboxy (C)-terminal 42 aa. We conclude that amino acids in the extreme C-terminal region are required for the receptor to bind progesterone, while antagonists bind to a site located more N-terminal of the HBD. Our results suggest that the extreme C-terminal region of the receptor contains an inhibitory function that silences receptor transactivation in the absence of agonist and in the presence of antagonist.

Amino Acid Sequence↗
PubMed1996

The novel progestin drospirenone and its natural counterpart progesterone: biochemical profile and antiandrogenic potential.

Drospirenone is a novel progestin under clinical development that is similar to the natural hormone progesterone, combining potent progestogenic with antimineralocorticoid and antiandrogenic activities. This specific pharmacological profile of drospirenone is defined by its pattern of binding affinities to a variety of steroid hormone receptors. In the present study the affinity of drospirenone to the progesterone receptor (PR), the androgen receptor (AR), the glucocorticoid receptor (GR), the mineralocorticoid receptor (MR), and the estrogen receptor (ER) was re-evaluated by steroid binding assays and compared to those obtained for the natural hormone progesterone. Drospirenone displayed high affinity to PR and MR and low binding to AR, similar to progesterone. Unlike progesterone, which showed considerable binding to GR, drospirenone exhibited only low binding to this receptor. Neither drospirenone nor progesterone did bind to the ER. In addition to receptor binding studies, transactivation assays were carried out to investigate the effects of drospirenone and progesterone on AR-, GR-, and MR-mediated induction of transcription. Both progestins showed no androgenic but antiandrogenic activity by inhibiting AR-mediated transcription in a dose-dependent manner. This observation could be confirmed by in vivo experiments carried out with orchiectomized male rats, where the antiandrogenic potency of drospirenone was found to be about five- to ten-fold higher than that of progesterone. In contrast to progesterone, drospirenone was devoid of glucocorticoid activity. Both progestins did not show any antiglucocorticoid action. Furthermore, drospirenone and progesterone both showed considerable antimineralocorticoid activity and weak mineralocorticoid activity.

Androstenes↗
PubMed1980

The menstrual cycle in women using an intrauterine device.

The duration and hormonal characteristics of the menstrual cycles of women using Copper T intrauterine devices (IUDs) were studied. Daily load samples were obtained during both the pre- and postovulatory phases of 30 IUD-associated cycles and the hormone values were compared with those of 15 normally menstruating women not using contraception. The ovulation rate and peak levels of 17 beta-estradiol and luteinizing hormone (LH) were not significantly different between the two groups. The average number of days from the 1st day of menstrual bleeding to the LH peak (the proliferative phase) was longer in the IUD users. The number of days from the LH peak to the onset of menstrual bleeding (the luteal phase) was shorter in the IUD users. Because of the compensating nature of these statistically significant differences, the total cycle length appeared to be unchanged. At the time of menstruation, the plasma levels of both progesterone and 17 beta-estradiol were significantly higher among IUD users. It is concluded that the presence of an IUD does not influence ovarian function, but that ovarian steroid production and endometrial events become asynchronous.

Adolescent↗
PubMed1983

Mode of action of dl-norgestrel and ethinylestradiol combination in postcoital contraception. III. Effect of preovulatory administration following the luteinizing hormone surge on ovarian steroidogenesis.

A combination of 1.0 mg dl-norgestrel and 0.1 mg ethinylestradiol was administered orally at 18 hours after the detection of luteinizing hormone rise and again at 30 hours in five healthy volunteers with normal menstrual cycles. The effects on ovarian function were studied by comparing the daily serum levels of progesterone (P), 17 alpha-hydroxyprogesterone, and estradiol (E2) measured in a control (placebo) cycle with those in two consecutive treatment cycles. Treatment did not alter the steroid levels in one subject. P was suppressed in one or both treatment cycles of four subjects. E2 was suppressed in both treatment cycles of one subject and produced widely fluctuating patterns in another. The hormonal patterns in the two consecutive treatment cycles of the same individual were similar in all but one instance, where only the P level in the second treatment cycle was diminished. These results showed that this treatment can elicit steroidogenic responses of varying degrees and duration. The contraceptive action may lie in the altered P and/or E2 level at certain points in the menstrual cycle.

17-alpha-Hydroxyprogesterone↗
PubMed1985

Ablation of folliculogenesis in women by a single dose of gonadotropin-releasing hormone agonist: significance of time in cycle.

Effects of single subcutaneous doses (1, 5, 20, and 100 micrograms) of nafarelin, a potent gonadotropin-releasing hormone agonist, on the physiologic events of the human menstrual cycle were studied in 28 normal women. Nafarelin entered the circulation rapidly after injection. Peak concentrations were observed within 1 hour, and the plasma half-life was 4 to 5 hours. Maximal concentrations of luteinizing hormone and follicle-stimulating hormone were reached 3 to 4 hours after nafarelin administration. The magnitude of the gonadotropin responses depended both on the phase of the menstrual cycle (smallest responses during the early follicular phase) and the dose of nafarelin. Nafarelin administration during the early follicular phase delayed ovulation by 4.6 +/- 1.7 (standard deviation) days and prolonged the duration of the menstrual cycle from a pretreatment length of 29.2 +/- 2.1 days to 33.4 +/- 4.0 days (P less than 0.001). When nafarelin was administered shortly before or after ovulation, cycle length was not altered consistently. Administration 5 to 10 days after ovulation resulted in a truncated luteal phase. These observations suggest that the hormonal events triggered by nafarelin during the early follicular phase temporarily arrest the process of selection of the dominant follicle. Repeated intermittent administration of nafarelin or other gonadotropin-releasing hormone agonists in the early follicular phase may prevent follicular maturation and ovulation and may be a practical approach to contraceptive development.

Adult↗