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At least 19 recordsLinked to original sources
PubMed1978

Determination of plasma concentrations of d-norgestrel during a one year follow-up in women with a d-norgestrel-releasing IUD.

Eight healthy women had a d-norgestrel-releasing intrauterine device inserted postmenstrually and maintained in the uterine cavity for a one year period. Plasma concentrations of d-norgestrel were measured by radioimmunoassay during the one year treatment period. d-Norgestrel could be detected in the plasma of all the subjects within a fairly narrow range during the whole period. The release rate of d-norgestrel was calculated from two IUDs removed after the treatment.

Adult↗
PubMed1976

Binding of norgestrel to human plasma proteins.

Binding of [14, 15-3H](+/-)-norgestrel to human plasma proteins has been investigated. Norgestrel showed greater affinity to plasma than to human serum albumin indicating specific norgestrel binding protein(s) in the plasma. alpha1-acid glycoprotein showed high affinity for norgestrel when compared with human serum albumin. The binding protein was eluted at pH 5.8 by step by step elution on a DEAE-cellulose column. Norgestrel binding to plasma proteins was not affected at 60 degrees C. The optimal binding occurred between pH 7 and 8. Ligand specificity of the binding protein revealed that progesterone was able to compete for the norgestrel binding sites, whereas corticosterone, testosterone, oestradiol, and norethindrone acetate did not show much competition. The molecular weight of the binding protein was found to be approximately 43 000. Sucrose density gradient analysis indicated that norgestrel bound to a macromolecular component of sedimentation coefficient 2.9 S. The association constant (Kass) and dissociation constant (Kdiss) of norgestrel-binding plasma protein was found to be 1.4-10(6) M-1 and 0.7-10(-6) M respectively. The number of binding sites was 0.5-10(-9) mol/mg protein. Norgestrel-binding protein in the plasma appeared to be a protein different from human serum albumin, corticosteroid-binding globulin and sex-steroid-binding protein. This binding protein showed some similarities to alpha1-acid glycoprotein.

Binding Sites↗
PubMed1976

Effects of norgestrel and metyrapone on pituitary-adrenal-ovarian function.

To assess the effects of d-norgestrel on pituitary-adrenal-ovarian function, basal levels and responses to metyrapone of urinary 17-ketogenic steroids (17-KGS) and 17-ketosteroids (17-KS), plasma cortisol (F), plasma delta4-androstenedione (A), plasma testosterone (T), plasma estrone (E1) and estradiol (E2), plasma and urinary LH and FSH were determined in 10 normal women before and while taking d-norgestrel 1 mg/day. Cortisol secretion rate (CSR) and binding capacities of cortisol binding globulin (CBG) and testosterone-estradiol binding globulin (TeBG) were also measured. Norgestrel did not significantly alter 17-KGS, 17-KS, F, LH, FSH, CSR, or the 17-KGS and 17-KS responses to metyrapone. Norgestrel reduced TeBG binding capacity but not CBG binding capacity. Norgestrel competitively inhibited the binding of dihydrotestosterone to TeBG under in vitro conditions. Levels of T, E2, and E1 were reduced by norgestrel. All measured hormone levels except FSH were increased following metyrapone prior to norgestrel administration. Norgestrel completely blocked the metyrapone-induced increases in LH and E2 and markedly reduced the E1 increase. Metyrapone reduced E2 during norgestrel treatment.

17-Hydroxycorticosteroids↗
PubMed1975

Metabolism of D- and L-norgestrel in humans.

Levels of DL-norgestrel, D-norgestrel, L-norgestrel and norethisterone were measured in blood by radioimmunoassay after oral administration of the progestin to 3 healthy male subjects and the half-lives calculated. Half-lives for D-norgestrel were much lower than those of L-norgestrel and similar to those of norethisterone. Measurement of norgestrel in blood can therefore be misleading unless the biologically active D-isomer is estimated. Since there was no difference in half-lives between norgestrel and norethisterone the greater potency of the former is probably due to it more strongly binding to target organ receptors.

Half-Life↗
PubMed1977

The detection and measurement of D-norgestrel in human milk using Sephadex LH 20 chromatography and radioimmunoassay.

An accurate sensitive method for the assay of D-norgestrel in human milk is described. The steroid is isolated from an ether extract of milk by Sephadex LH 20 chromatography in the system iso-octane-benzene-methanol (70:20:10 v/v). The radioimmunoassay utilises a specific antibody produced in rabbits against D-'norgestrel 3-(O-carboxymethyl) - oxime coupled to bovine serum albumin with D-norgestrel 3-(0-carboxymethyl) -oxime/ [125I]-iodohistamine conjugate as radioligand. Accuracy, sensitivity and blank value are satisfactory. Milk samples were obtained from three subjects treated with 30 microgram/day D-norgestrel, treatment commencing two weeks following parturition. Significant amounts of D-norgestrel were found, ranging between 92-135 pg/ml milk at the end of the first two-week treatment regimen. In two of three subjects, lower, but significant concentrations (53 pg and 35 pg/ml respectively) of steroid were found at the end of four weeks treatment. In the third subject, D-norgestrel could not be detected at this time. As a check on the specificity of the assay, three samples were submitted to additional chromatographic purification on alumina thin layer in the system benzene-cyclohexane-ethanol (70:27:3 v/v). Although this additional chromatographic step yielded somewhat lower values, agreement between the respective sets of results was good. The significance and implications of these findings are discussed.

Chromatography, Gel↗
PubMed1978

Sustained intrauterine release of d-norgestrel.

Clinical experience with seventy-two first insertions of a d-norgestrel-releasing IUD is reported. Plasma d-norgestrel concentrations were measured in twelve subjects. No pregnancies occurred in the 522 woman-months of use (averaging 7.3 months/subject) that have been accumulated. Removals were performed in six subjects for medical reasons and in seven subjects for personal reasons. Plasma concentrations of d-norgestrel were highest during the first two weeks of use. A decline in the plasma concentration of d-norgestrel occurred and was only 0.05 ng/ml between 30 and 90 days after insertion.

Adult↗
PubMed1979

Some estrogenic effects of two oral contraceptives consisting of norgestrel and two different doses of ethynylestradiol.

Some biological and biochemical effects (i.e. KPI, cervical mucus, SHBG and ceruloplasmin) as well as serum ethynylestradiol and serum norgestrel, following the use of two oral contraceptives containing the same amount of norgestrel (dl-norgestrel 0.5 mg) and either 30 microgram or 50 microgram of ethynylestradiol were compared. There was no difference in the clinical features in either group of patients. There was a statistically significant difference in the levels of unconjugated ethynylestradiol but not in the other biochemical parameters studied. It is concluded that the absence of any such difference might be attributable to the strong antiestrogenic effects of dl-norgestrel.

Adolescent↗
PubMedDate not supplied

Excretion and stereoselective biotransformations of dl-, d- and l-norgestrel in women.

Excretion data and urinary metabolite patterns of di-, d-, and l-norgestrel were obtained from women who received a single, oral 1.5-mg dose of 14C-labeled racemic norgestrel (Ng) or one of its enantiomers. The average percentage of administered radioactivity +/- SD recovered in the urine after 7 days was 58.1 +/- 7.9% for dl-Ng, 44.8 +/- 8.9% for d-Ng, and 63.6 +/- 15.1% for l-Ng; in feces it was 23.4 +/- 7.7% (dl-Ng), 31.6 +/- 8.2% (d-Ng), and 24.8 +/- 10.7% (l-Ng). Different metabolite patterns were observed for each enantiomer in urine, and the pattern for the racemate appeared to be an approximate composite of the metabolite patterns of the two enantiomers. These differences in the metabolite pattern result from stereoselective transformations; notably 16 beta-hydroxylation of l-Ng and ring A reduction of d-Ng. Other stereoselective pathways noted were: 16 alpha- and 1 beta-hydroxylation as well as D-homoannulation of l-Ng and sulfate conjugation of l-16 beta-hydroxynorgestrel; 2 alpha-hydroxylation of d-Ng, formation of a labile neutral, polar compound which contained the norgestrel moiety in the d-form, and formation of a glucuronide of d-16 beta-hydroxynorgestre. The formation of phenolic derivatives occurred to a very minor degree from transformations of the biologically inactive l-enantiomer. With d-norgestrel, this formation occurred to an even lesser extent, if at all.

Adult↗
PubMed1978

Endometrial morphology of women using a d-norgestrel-releasing intrauterine device.

Endometrial biopsies were obtained from 12 volunteers treated with d-norgestrel-releasing intrauterine devices (IUDs) with two different release rate. Four subjects scheduled for hysterectomy had d-norgestrel-releasing IUDs inserted approximately 1 month prior to surgery. The effect of d-norgestrel on the endometrium and fallopian tubes of the removed uteri was examined. A uniform suppression of the endometrium with glandular atrophy and decidualization of the stroma was found in all of the endometrial specimens. Moreover, changes similar to those observed during the luteal phase and early pregnancy could be seen in the tubal epithelium.

Adult↗
PubMed1977

Changes in serum lipids during treatment with norgestrel, oestradiol-valerate and cycloprogynon.

The serum concentrations of triglycerides, cholesterol, and free glycerol were determined in 23 climacteric women, before and after the administration of three different steroid drugs. Each drug was given within a period of 12 weeks (3 cycles). Period I: Norgestrel, 0.5 mg daily from the 12th to 21st day of each cycle. Period II: Oestradiol-valerate (Progynon) 2 mg daily from the 2nd to 21st day of each cycle. Period III: Oestradiol-valerate 2 mg from the 1st to 11th day followed by oestradiol-valerate 2 mg+0.5 mg dl-norgestresl from day 12 to 21 of each cycle (Cycloprogynon). A significant decrease in triglycerides was observed following the administration of norgestrel and Cycloprogynon, whereas oestradiol-valerate had no effect on the triglyceride levels. On the other hand, oestradiol-valerate, following a period of norgestrel, produced an increase in serum cholesterol levels.

Adult↗
PubMed1976

GPC diesterase activity in human endometrial secretion. (Its variations under the action of estrogens, clomiphene citrate, D-norgestrel (post-coital and low dose) and intrauterine device (IUD).)

Diesterase activity was studied in human uterine secretions of normal women and in those under treatment for sterility or contraception. Endometrial secretions were obtained from 78 patients and the material divided into four groups: normal women, under different estrogens; with D-Norgestrel treatment (daily and post-coital) and patients with IUD Lippes D. The mean concentration of free choline delivered by the GPC diesterase in the normal group was 777 +/- 128 mug/ml (SD 286). Under hormonal treatment an increase of diesterase activity was observed. D-Norgestrel post-coital produced a fall of the enzymatic activity between 180 to 420 minutes. The uninterrupted use of D-Norgestrel (30 gammas daily) produced a loss of diesterase activity in 80% of cases studied. The use of IUD (Lippes D) did not modify the enzymatic activity in this group.

Clomiphene↗
PubMed1979

The biological activities of norgestrel and its enantiomers.

The dextrorotatory enantiomer of norgestrel has now been tested by oral and parenteral routes in a broad range of biological assays and its inactivity has been confirmed. The active enantiomer has been further compared with the racemate in a similarly broad range of tests, largely by the oral route. Levonorgestrel was twice as potent as the racemate in experiments in which norgestrel was effective. These data reinforce earlier findings that levonorgestrel is responsible for all the biological activity found in norgestrel.

Administration, Oral↗
PubMed1979

[Quantifiable morphokinesis of parts of the hypothalamo-adenohypophyseal-gonadal axis of hormonally desexed boars. 4. Studies on boars that have undergone combined treatment with the steroid test substance 547 and norgestrel].

Steroid test substance 547 and Norgestrel were used in a combination treatment of parts of the hypothalamo-adenohypophyseo-gonadal axis of boars. The quantifiable parameters of the morphokinetic effect thus produced (cell nucleus volumes of Nucleus praeopticus medialis hypothalami and its neurons as well as those of Leydig's cells testicle weight, length and diameter of tube, percentage of Leydig's cells, testicle weight, length and diameter of tube, percentage of Leydig's cells) did not differ significantly from the findings obtained from boars treated with Norgestrel only (cf. Dorst and co-workder, 1978). The same combination treatment, however, differed from exclusive Norgestrel treatment by causing the occurrence of socalled castration cells, which led to the assumption of an anti-androgenic effect of such combination treatment.

Androstenes↗
PubMed1978

[In-vitro studies on the effect of D-norgestrel and norethisterone acetate on the formation of sex steroids in the human ovary].

In vitro incubations with slices of four normal human ovaries and 4-(14)C-pregnenolone as precursor were carried out to study the possibility of a direct influence of D-norgestrel and norethisterone acetate on the metabolism of pregnenolone. In agreement with our previous studies the in vitro-synthesis of progesterone, 17 alpha-hydroxyprogesterone, estrone and estradiol represents the characteristic profile of steroids of the ovaries from the corpus luteum phase. The in vitro-synthesis of 17 alpha-hydroxypregnenolone, DHA, androstenediol (basic metabolites) and androstenedione represents the characteristic profile of steroids of the ovaries from the follicle phase. The addition of D-norgestrel and norethisterone acetate to the incubation medium influences these steroid profiles in the same way. The metabolites of these characteristic profiles were inhibited by the progestogens, whereas the basic metabolites increased. In previous studies the same influence was found by addition of chlormadinone acetate. The influence of these progestagens on the two different profiles of steroids indicate that D-norgestrel and norethisterone acetate exert an inhibitory effect on the 3 beta-hydroxysteroiddehydrogenase-delta 5-4-isomerase system and the aromatase system of the human ovary. These results suggest that these progestogens act directly upon ovarian function, an action which may be assumed to be operative in their contraceptive effect.

17-alpha-Hydroxypregnenolone↗
PubMed1979

Mode of action of DL-norgestrel and ethinylestradiol combination in postcoital contraception.

Possible mechanisms of action of a combination of ethinylestradiol (EE) and dl-norgestrel as a postcoital contraceptive agent were studied in 12 healthy female volunteers. An oral dose of 0.1 mg of EE and 1.0 mg of dl-norgestrel was given at the predicted time of ovulation and again 12 hours later. Serum luteinizing hormone, prolactin, progesterone, 17 alpha-hydroxyprogesterone, and estradiol were measured by specific radioimmunoassays in blood samples obtained daily from the 8th day of the menstrual cycle to the 1st day of menses. Hormone profiles suggested that the medication elicited a range of individual variations in pituitary and/or ovarian responses. Histologic examination of the endometrium consistently showed significant alteration in endometrial development with a dissociation in maturation of glandular and stomal components. This postcoital contraceptive acts either by (1) suppressing ovulation or (2) disrupting luteal function by acting directly on the corpus luteum or by interfering with appropriate endometrial responses to ovarian steroids.

Contraceptives, Postcoital↗