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At least 19 recordsLinked to original sources
PubMed1983

Structure of the isonicotinyl hydrazone of norethindrone.

The contraceptive steroid norethindrone reacts with isoniazid both in vivo and in vitro to give the corresponding hydrazone, which exists as syn and anti (with respect to C-4) isomers. These isomers rapidly interconvert, with the anti form predominating in solution. The identification of the isomers was based on an interpretation of 1H- and 13C-NMR spectroscopic data and corroborated by high-performance liquid chromatographic UV spectrophotometric evidence. 1H- and 13C-NMR spectroscopic data for other derivatives of norethindrone hydrazone are presented and interpreted.

Chemical Phenomena↗
PubMed1977

Radioimmunoassays of ethinyl-norgestrienone (R-2323) and medroxyprogesterone acetate (MPA) and their clinical applicability.

Radioimmunoassays for 2 synthetic progestins (Ethinyl-norgestrienone, R 2323 and medroxyprogesterone acetate, MPA) are demonstrated. 10 patients aged 31 to 72 years were treated with ethinyl-norgestrienone with different schedules and 3 men suffering from benign prostatic hypertrophy were treated with medroxygesterone acetate. Plasma levels of testosterone, LH, FSH were monitored before, during and after treatment.

Adult↗
PubMed1977

Serum levels of d-norgestrel, luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone in women during and following ingestion of combination oral contraceptives containing dl-norgestrel.

Three formulations of dl-norgestrel were administered daily to groups of three women for five consecutive days. The serum levels of d-norgestrel were related to the dosage of dl-norgestrel ingested. Peak concentrations in the circulation of synthetic gestagen were attained a half hour to three hours after oral administration, followed by a rapid and sharp decline in levels until the next dose. Three women received 500 micrograms of dl-norgestrel and 50 micrograms of ethinyl estradiol for 21 days followed by six to seven days of no medication for two consecutive cycles. The gonadotropins remained suppressed for four to six days when therapy was discontinued. The daily concentrations of estradiol varied from less than 5 to 81 pg. per milliliter, and there was no difference in estrogen values during the nontreatment and treatment days. Due to the long half life of norgestrel, the one-week pill-free interval is not long enough for the complete recovery of the reproductive axis from the inhibition of oral contraceptives.

Adult↗
PubMed1977

d-Norgestrel concentrations in maternal plasma, milk, and child plasma during administration of oral contraceptives to nursing women.

In order to correlate plasma and milk concentrations of d-norgestrel (d-Ng) in lactating women, three oral contraceptives, containing different amounts of this synthetic gestagen, were given to 15 fully lactating women, starting two months post partum. Plasma and milk samples were collected according to a special schedule. d-Ng concentrations in plasma and milk were measured by radioimmunoassay. When d-Ng was measured in milk, extraction was performed with petroleum ether and in the radioimmunoassay an internal standard was used. This method is evaluated in the present paper. The plasma: milk ratio of d-Ng was found to be about 100:15 and the amounts of d-Ng transferred with 600 ml. of milk per day were calculated to be 0.3 an 0.15 microgram with daily intakes of 250 and 150 microgram of d-Ng, respectively, corresponding to about 0.1 per cent of the given dose. When the women received 30 microgram of d-Ng daily, no d-Ng could be detected in the milk. In three of the breast-fed children the d-Ng concentration in plasma was measured. This concentration was found to be in the same range as would be expected after oral d-Ng medication to adults, allowing for body weight differences, indicating that d-Ng is metabolized and is not accumulated in the baby.

Contraceptives, Oral↗
PubMed1979

Pharmacokinetics of norethindrone acetate in women.

The plasma half-life, MCR and plasma metabolite levels at various time intervals have been studied in six women after an intravenous injection of 3H-norethindrone acetate. The disappearance curve due to norethindrone acetate showed an initial rapid disappearance of 3H with an average half-life of 7.5 minutes and a subsequent slow disapperance with a half-life of 51.5 hours. Norethindrone acetate was cleared from the plasma with an average MCR of 495 L/day. Norethindrone acetate is rapidly metabolised after an intravenous injection. Norethindrone, the main metabolite, disappears from the plasma with an average half-life of 34.8 hours. Norethindrone maintains a high level compared with norethindrone acetate at all time intervals up to 24 hours and an equilibrium is reached between the two at 24 to 48 hours.

Acetates↗
PubMed1979

New long-acting injectable microcapsule contraceptive system.

A new long-acting, injectable contraceptive which provides continuous controlled release of the steroid norethisterone (NET) for a precise period of 6 months following a single intramuscular injection is described. The prototype system consists of microcapsules made of the biodegradable polymer d, l-polylactic acid, in which micronized crystals of NET are homogeneously dispersed. NET is slowly released from the microcapsules following intramuscular injection at a rate of 0.90 microgram NET/day/mg of microcapsule by diffusion of the steroid from the polymer matrix. Three different doses of a standard preparation of microcapsules were tested in normally cycling female babbons (4 to 5 baboons/group). Following injection of either 300, 200, or 100 mg of microcapsules containing 75, 50, or 25 mg of NET, blood samples were collected at selected intervals and analyzed for NET, estrogen, and progesterone by radioimmunoassay. All three doses provided continuous NET release for 6 months following injection. The NET serum profiles for the different doses are parallel, and ovulation was inhibited in all baboons for 6 months following treatment.

Animals↗
PubMed1990

Pharmacokinetics of ethinyl estradiol and mestranol.

Pharmacokinetally, a 50 micrograms oral dose of mestranol (which itself is inactive) is bioequivalent to a 35 micrograms dose of ethinyl estradiol. Physiologically, mestranol ranges from 50% to 100% of the activity of ethinyl estradiol, depending on the endpoint chosen. Compounds such as these, which are metabolized with a first-pass effect and are enterohepatically recirculated, demonstrate large interindividual and intraindividual variability in their pharmacokinetics. Thus a given dose of ethinyl estradiol in one person may produce an effect equivalent to a substantially larger (or smaller) dose in another person. This wide variability confounds efforts to establish tight dose-response relationships, a point rarely considered in clinical or epidemiologic studies of these compounds. The circulating levels of ethinyl estradiol sulfates may be higher than those of free ethinyl estradiol itself. It has been thought that these sulfates represent a "reservoir" of ethinyl estradiol. Our studies show that this idea is untenable because the half-life of the sulfates is not long enough for such an effect. Differences in the pharmacokinetics of ethinyl estradiol and mestranol have been observed in studies of various populations. The reality of these group differences is affirmed by analyses of urinary metabolite patterns.

Biological Availability↗
PubMed1990

Pharmacokinetics of the contraceptive steroids levonorgestrel and gestodene after single and multiple oral administration to women.

Little is known about the pharmacokinetics of the two progestins levonorgestrel and gestodene during long-term administration compared with single-dose pharmacokinetics. The predictive value of single-dose administration for the pharmacokinetic behavior of a progestin during long-term treatment was investigated for two triphasic oral contraceptives. One contained levonorgestrel and the other gestodene, each in combination with ethinyl estradiol. In eight Japanese women who received the levonorgestrel-containing formulation over a treatment cycle, steady-state trough levels of levonorgestrel were higher than those obtained by computer simulation based on single-dose administration. An analogous observation was made in a group of 10 white women who received the gestodene-containing formulation. A close correlation between gestodene and sex hormone-binding globulin concentrations was demonstrated for eight subjects; the other two patients already had initially high sex hormone-binding globulin levels. Ethinyl estradiol-induced production of sex hormone-binding globulin seems to be a major factor that contributes to the accumulation of the two progestins in the plasma. Computer simulation, based on single-dose pharmacokinetics, allows an estimation of this contribution.

Adult↗
PubMed1990

Gastrointestinal metabolism of contraceptive steroids.

A number of oral contraceptive steroids undergo first-pass metabolism in the gastrointestinal mucosa. Ethinyl estradiol (mean systemic bioavailability 40% to 50%) is extensively metabolized, principally to a sulfate conjugate. In vivo studies that use portal vein catheterization and the administration of radiolabeled ethinyl estradiol have shown that the fraction of steroid metabolized in the gut wall is 0.44. In vitro studies with jejunal biopsy samples or larger pieces of jejunum or terminal ileum mounted in Ussing chambers have indicated that more than 30% of added ethinyl estradiol is sulfated. The progestogen desogestrel is a prodrug that is converted to the active metabolite 3-ketodesogestrel. Substantial first-pass metabolism of desogestrel occurs in the gut mucosa, with evidence from Ussing chamber studies for the formation of the active metabolite. Another progestogen, norgestimate, is also metabolized by the gut wall in vitro of which the principal metabolite is the deacetylated product, norgestrel oxime. It seems very likely that this will also occur in vivo. Drug interactions occurring in the gut wall have been reported with ascorbic acid (vitamin C) and paracetamol.

Aged↗
PubMed1991

The effect of tetracycline on levels of oral contraceptives.

Despite the widespread use of tetracycline for treatment of dermatologic disorders and sexually transmitted diseases, the pharmacodynamics of oral contraceptive use in the presence of tetracycline has not been studied. Seven normal women ingested an oral contraceptive containing ethinyl estradiol 35 micrograms and norethindrone 1 mg in the follicular phase of the menstrual cycle. On day 0 baseline ethinyl estradiol and norethindrone levels were obtained at 0, 1/2, 3/4, 1, 2, 4, 12, and 24 hours after oral contraceptive administration. On day 1 tetracycline 500 mg was given orally every 6 hours while the oral contraceptive was continued. Tetracycline, ethinyl estradiol, and norethindrone levels were determined at the same time intervals as on day 0. Oral contraceptive and tetracycline were continued for up to 10 days, and additional concentrations of ethinyl estradiol, norethindrone, and tetracycline were determined between days 5 and 10. Four additional normal women ingested tetracycline for 5 to 10 days. Tetracycline levels were determined at the time intervals noted above on day 1 and days 5 to 10. No significant decrease in plasma ethinyl estradiol or norethindrone concentration was seen with either short-term (24 hours) or long-term (5 to 10 days) ingestion of tetracycline. Similarly, levels of tetracycline do not significantly decrease with ingestion of a low-dose oral contraceptive.

Adolescent↗
PubMed1980

Specific quantitation of plasma medroxyprogesterone acetate by gas chromatography/mass spectrometry.

Investigation of various derivatives (O-methyloxime, trifluoroenol acetate and t-butyldimethylsilyl enol ether) coupled with the efficient preparation of a trideuterated analogue of medroxyprogesterone acetate, has allowed the development of a rapid and accurate assay for its quantitation in plasma by isotope dilution gas chromatography/mass spectrometry. High oral doses (2.8 g weekly) of medroxyprogesterone acetate are shown to lead consistently to plasma levels of less than 16 ng.ml-1.

Cholesterol↗