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At least 19 recordsLinked to original sources
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↗
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↗
PubMed2000

Impact of subdermal norgestrel on hepatic acyl-coenzyme A:cholesterol- acyltransferase (ACAT) activity: possible antiatherogenic effect.

The impact of subdermally placed ethinyl estradiol, norgestrel, and the combination of the two on cholesterol metabolism as measured by hepatic acyl:cholesterol-acyltransferase (ACAT) activity was examined in the rat model. A total of 48 rats were assigned to one of 6 groups, receiving either 0.1 mg or 1.0 mg of ethinyl estradiol daily, 1.0 or 10 mg of norgestrel daily, and combinations of either 0.1 mg ethinyl estradiol/1.0 mg norgestrel or 1.0 mg ethinyl estradiol/10 mg norgestrel daily. All drugs were administered through subdermally placed time release capsules. The administration of norgestrel only in either 1.0 mg or 10 mg resulted in significantly lower rates of ACAT activity (0.77 +/- 0.566 and 0.91 +/- 0.239 pmol/mg/min, respectively). The combination of 1.0 ethinyl estradiol and 10 mg norgestrel resulted in a significant increase in ACAT activity to 2.17 +/- 0.873. This combination also resulted in significantly greater weight loss at the conclusion of treatment [247.83 +/- 6.2 g (pre) vs. 205.50 +/- 10.6 (post)]. There were no other differences in ACAT activity between groups and no other differences in weight, both between groups and pre- and post-treatment within groups. In summary, subdermally placed norgestrel resulted in a significant lowering of ACAT activity not seen with either administration of ethinyl estradiol alone or the combination of ethinyl estradiol and norgestrel in doses ranging from 0.1 to 1.0 mg of ethinyl estradiol and 1.0 to 10.0 mg of norgestrel. Significantly increased ACAT activity for the combination of 1.0 ethinyl estradiol and 10 mg norgestrel over either ethinyl estradiol or norgestrel alone or a lower dose combination suggests a dose-related threshold and drug-drug interaction for this effect. These results suggest that subdermally placed norgestrel may result in significantly lower ACAT activity and may have a potential role as an antiatherogenic treatment.

Administration, Cutaneous↗
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↗
PubMed1976

Disappearance of (14,15-3H)d,1-norgestrel from plasma and its distribution in the reproductive tract of women.

After an iv injection of [14,15-3H]d,1-norgestrel into 7 women, its disappearance from the plasma and its distribution in the reproductive organs has been investigated. It was found that initially norgestrel disappeared rapidly from the plasma with a half-life of 38.8 min followed by a slower disappearance with a half-life of 45.18 h. The disappearance curve has been analysed on the basis of a biexponential curve representing a two compartmental model. The low metabolic clearance rate of 458.5 1/24 h indicated a more prolonged persistance of norgestrel in the body. Uptake of norgestrel and its metabolites was very high in the endometrium, myometrium, cervix. Fallopian tube, ovary and body fat. Compared to the myometrium, more norgestrel as such was concentrated in the endometrium at 30 min and 12 h after injection of [14,15-3H]d,1-norgestrel. The myometrium on the other hand contained higher amounts of norgestrel at 5 min. The significance and the possible role of localization of norgestrel at multiple sites in the reproductive tract and its contraceptive action are discussed.

Adipose Tissue↗
PubMed1989

Effect of norgestrel on development of mouse pre-embryos.

The effect of synthetic progestins found in oral contraceptives has potential implications for developing embryos in women who receive oral contraceptives during early pregnancy. We assessed the effect of the progestin norgestrel on the developing pre-embryo. B3C6F1 mice were given 5 IU PMSG followed by 5 IU hCG 48h later. Studies were performed on pre-embryos recovered and pooled at both 24h (Group A) and 48h (Group B) post hCG. At each time period, they were randomly assigned to control or norgestrel (4.0 ng/ml) treatment. In a third study, pre-embryos collected 24h post hCG were cultured in the absence or presence of 8.0, 80.0, or 800 ng/ml norgestrel. Cultures were performed in Ham's F-10 media with 10% fetal calf serum at 37 degrees C in an atmosphere of 5% CO2, 5% O2 and 90% N2 with 15-30 embryos per 1 ml of culture fluid. At 24h, 48h and 72h post recovery, cultures were viewed, the appearance of embryos noted, and number of blastomeres recorded. Compared to control groups, analysis demonstrated no significant difference in the rate of development of control and norgestrel pre-embryos in any group at any time period (24h, 48h, or 72h post recovery). We conclude that norgestrel at the dose tested has no acute adverse morphological effects on development of mouse pre-embryos. This observation has potential clinical implications with regard to inadvertent use of norgestrel-containing oral contraceptives during early days of pregnancy, as well as consideration of the mechanism of action of norgestrel-containing "morning after" pills.

Animals↗
PubMed2000

Comparison of norgestrel- versus cyproterone acetate-containing hormone replacement therapy on lipid-lipoprotein metabolism.

To compare the effects on the lipid profile of estradiol valerate with norgestrel to a regimen of estradiol valerate with cyproterone acetate. Sixty-four healthy women in their perimenopause or early postmenopause, aged between 40-55 years, were randomized to one of the two 21-day sequential regimens: estradiol valerate 2 mg/day for 21 days and combined with either norgestrel 0.5 mg/day or cyproterone acetate 1 mg/day from day 12 to 21, with 7 days of drug-free interval, for 12 cycles. Lipid profiles were followed at baseline, 6 and 12 cycles. Sixty-one subjects completed the study, 30 in the norgestrel group and 31 in the cyproterone group. During 12 cycles of study, serum HDL cholesterol levels decreased significantly in the norgestrel group (p < 0.01) and were unchanged in the cyproterone group. The levels were significantly lower in the norgestrel group than in the cyproterone group (p < 0.05). No differences were found between groups as regards LDL cholesterol and total cholesterol levels. Triglyceride levels decreased significantly in the norgestrel group (p < 0.01), remained unchanged in the cyproterone group and the levels were significantly different between groups (p < 0.01). In conclusion, the study demonstrated that sequential regimen of estradiol valerate with norgestrel produced less favorable HDL cholesterol but more favorable triglyceride levels than the regimen of estradiol valerate with cyproterone acetate.

Adult↗