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PubMed1992

Interrelationship of serum levonorgestrel and sex hormone-binding globulin levels following vaginal and oral administration of combined steroid contraceptive tablets.

Ten women were treated daily with a standard dose contraceptive tablet containing 0.25 mg levonorgestrel (LNG) in combination with 0.05 mg ethinylestradiol. Five women used the tablet vaginally, while the other five used it orally. Blood samples were taken at frequent intervals on the first day of treatment and after 1 and 2 hours on treatment days 7 and 14. Serum LNG levels were measured by radioimmunoassay, and sex hormone-binding globulin (SHBG) was quantitated by charcoal assay. On day 1, peak concentrations of LNG (5.1 ng/ml) occurred within 2 hours in the oral group, whereas in the vaginal group a peak of 2.2 ng/ml was reached after 4 hours. After 24 hours, mean serum concentrations of LNG were 1.1 and 0.69 ng/ml in the oral and vaginal groups, respectively. In both groups, mean LNG concentrations increased dramatically on days 7 and 14 compared to day 1. There was no significant difference between the two groups in LNG concentrations, except after 2 hours on day 1. SHBG levels were increased after one day of treatment. By day 14 of treatment, there was a 3.5- to 4.5-fold rise in SHBG levels from pretreatment values in both groups. However, there was no significant difference in SHBG levels between the two groups throughout the study. A high correlation was found between serum levels of SHBG and LNG in both the vaginal and oral groups. The results suggest that the increase in serum LNG levels in women receiving combined contraceptive tablets either vaginally or orally is due to increased levels of SHBG. Also, the measured concentrations of LNG in the vaginal group are consistent with the previously reported clinical contraceptive efficacy of combined contraceptive tablets administered vaginally.

Contraceptives, Oral, Hormonal↗
PubMed1995

Influence of high doses of vitamin C on the bioavailability and the serum protein binding of levonorgestrel in women using a combination oral contraceptive.

The absence of an effect of high oral doses of vitamin C on the systemic availability of ethinylestradiol in women using a levonorgestrel-containing combination oral contraceptive (0.15 mg levonorgestrel and 0.03 mg ethinylestradiol) was demonstrated in a recent study. However, it is conceivable that the oral administration of gram quantities of vitamin C could also interfere with the sulfation of levonorgestrel (LNG) metabolites during phase II biotransformation, because sulfates represent a major part of the conjugated metabolites of LNG in the serum. This possible interaction was investigated in the aforementioned study, comparing Cmax and AUC(0-12h) values of LNG on the first and 15th day of two successive treatment cycles with and without co-medication of vitamin C. In addition, the serum protein binding of LNG and the concentration of the binding proteins SHBG and CBG were compared between both treatments. Corresponding parameters obtained during treatment with the oral contraceptive alone and during co-administration of vitamin C were evaluated statistically for possible differences. No effect of vitamin C was observed for any of the parameters investigated. Thus, the repeated oral administration of gram quantities of vitamin C does not impair the sulfation of hydroxylated metabolites of LNG. There was also no observable effect on the serum protein binding of LNG and the concentrations of SHBG and CBG in the serum. The results obtained in this study population (American women) for LNG are in good agreement with those obtained from a previous study in European women, who had taken a combination oral contraceptive containing the same doses of LNG and ethinylestradiol.

Ascorbic Acid↗
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↗
PubMed1983

Long-acting contraceptive agents: analysis and purification of steroid esters.

More than 200 samples of esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) and levonorgestrel (13 beta-ethyl-17 alpha-ethynyl-17 beta-hydroxygon-4-en-3 -one) have been analysed by a combination of techniques, including high performance liquid chromatography (HPLC). Compounds having a purity below the required limit (99.5%) were purified, mainly by preparative HPLC, prior to formulation and biological evaluation as long-acting progestogens.

Chromatography, High Pressure Liquid↗
PubMed1983

Long-acting contraceptive agents: structure activity relationships in a series of norethisterone and levonorgestrel esters.

A large number of esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) and levonorgestrel (D-(-)-13 beta-ethyl-17 alpha-ethynyl-17 beta-hydroxygon-4-en-3-one) were synthesized and tested for biological activity. The test employed in these studies was the duration of estrus suppression in cycling mature rats. In the norethisterone series several esters exhibited duration of activity comparable to that of norethisterone enanthate. In the levonorgestrel series the butanoic, cyclobutylcarboxylic and cyclopropylcarboxylic esters were longer acting than medroxyprogesterone acetate (17 alpha-acetoxy-6 alpha-methylpregn-4-ene-3,20-dione) when prepared as aqueous microcrystalline suspensions.

Animals↗
PubMed1982

Effect of duration of low-dose oral contraceptive administration on carbohydrate metabolism.

Two hundred and ten healthy young women volunteered to take a combined oral contraceptive (OC) and to have glucose tolerance in insulin secretion measured in a projected 3-year study with roughly annual investigations. Although the dropout rate was high, glucose tolerance was noted to deteriorate progressively and insulin secretion to rise initially, but thereafter they remained constant. Eventually, insulin levels were lower than would have been expected from the prevailing glucose values. This combination of steroids produced marked insulin resistance to which the pancreas could respond by further insulin secretion. It is suggested that levonorgestrel is too strong a progestin for routine use in the combined OC, and it is recommended that its dose be reduced further or that weaker progestins such as norethindrone be used.

Adult↗
PubMed1983

Pharmacodynamic effects of ethinyl estradiol in women using vaginal devices releasing small doses of levonorgestrel at a constant rate.

Eight normally menstruating women were provided with vaginal devices releasing levonorgestrel (NOG)4) at a constant rate of 20 micrograms/24 h. On day 71 or 72 following the insertion of the device, oral doses of 50 micrograms of ethinyl estradiol (EE) were administered daily for one week. Peripheral blood samples were drawn three times weekly during a pretreatment (control) cycle and from day 29 of the treatment period. The levels of progesterone (P), estradiol (E2) and NOG were measured by radioimmunoassay, sex hormone binding globulin (SHBG) by a steady state polyacrylamide gel electrophoresis and the percentage of binding of NOG, testosterone (T) and E2 by equilibrium dialysis of diluted plasma. An endometrial smear and a biopsy were taken from each subject on 3 occasions, viz. during the control cycle (cycle day 20-22), during the period with the NOG-releasing device in situ (44-50 days after the insertion of the device), and on the 7th day of concomitant EE administration.

Adult↗
PubMed1984

Changes in serum apo-lipoprotein AI and sex-hormone-binding globulin levels after treatment with two different progestins administered alone and in combination with ethinyl estradiol.

Twenty women, oophorectomized as part of the surgical treatment for cervical carcinoma in either clinical stage IB or IIA but otherwise healthy, participated in the study. After a period of six weeks without hormonal treatment, ten of them were given 150 micrograms desogestrel (DG) daily for three weeks followed by 150 micrograms DG + 30 micrograms ethinyl estradiol (EE) for six weeks and, finally, 30 micrograms EE alone for three weeks. The remaining ten women were given 150 micrograms levonorgestrel (NORG) and EE in a similar regimen. Before treatment and after each period of treatment, apo-lipoprotein AI and sex-hormone-binding globulin (SHBG) were assayed in serum. Both progestins decreased apo-AI and SHBG when given alone, thereby indicating an "androgenic" influence. In combination with EE, however, DG seems to be less "anti-oestrogenic" than NORG, as judged from the higher apo-AI and SHBG values after the combination DG + EE compared to those after NORG + EE.

Adult↗
PubMed1985

Measurement of ethynylestradiol and levonorgestrel incorporated into sustained release contraceptive formulations.

High performance liquid chromatography was used to measure the concentrations of ethynylestradiol (EE) and levonorgestrel (LNG) released from contraceptive devices into aqueous medium containing the cationic detergent, benzalkonium chloride. Most of the detergent was removed after solvent extraction of the steroid, although small amounts of it remained in the steroid phase. Over the course of many injections into octasilyl (C8) or octadecylsilyl (C18) reversed-phase columns, the chromatographic profile of EE was gradually altered with multiple peaks emerging. The profile of LNG was not changed. EE chromatographed as a double peak on a fully end-capped C18 column. Rechromatography of each peak yielded a mixture of the two. Mass spectral analysis showed that the peaks differed only in the gain or loss of an equivalent of water. Introduction of a cation exchange column before the analytical column removed residual benzalkonium ions, and by thus preventing deterioration of the column, permitted EE to consistently emerge as a single, symmetrical peak.

Chromatography, High Pressure Liquid↗
PubMed1985

A clinical pharmacological study of a new type of vaginal delivery system for levonorgestrel.

The pharmacokinetic and pharmacodynamic effects of a new type of levonorgestrel-releasing vaginal device (with an in vitro release rate of 25 micrograms/24 h) were studied in a group of 18 normally menstruating women during a period of 90 days of continuous use. Peripheral blood samples were drawn three times weekly (Mondays, Wednesdays, Fridays) during a pretreatment (control) cycle and during the 90 days (3 segments) of exposure to levonorgestrel and the levels of levonorgestrel, progesterone and estradiol were analyzed. Blood samples were also drawn at frequent intervals during the first day and daily during the first week with the devices in situ. In addition, endometrial biopsy specimens were obtained during days 20-22 of the control cycle and then 6 and 10 weeks following the insertion of the devices for morphometric analysis and for the assay of progesterone and estradiol levels. Following insertion of the devices, plasma levels rapidly rose to 1 nmol/l in 12 hours; a plateau of approximately 1.6 nmol/l was reached in 3-4 days, after which the plasma levels declined in a linear fashion with a daily average rate of 7.4 pmol/l to 60% of the initial level in 90 days' time. Of the 54 treatment segments of 30 days, 68% were anovulatory and 24% showed normal, ovulatory-like estradiol and progesterone levels. A complete set of three biopsies were obtained from 15 of the 18 subjects. Of the biopsies obtained during exposure to levonorgestrel only one exhibited signs of atrophy, 80% showed suppressed or arrested proliferation, and 10% had a normal cyclic appearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Trials as Topic↗
PubMed1986

Pharmacokinetic studies with a vaginal delivery system releasing levonorgestrel at a near zero order rate for one year.

Vaginal rings releasing approximately 20 micrograms levonorgestrel per 24 hours were used continuously by ten women for a period of one year. Circulating plasma levels of levonorgestrel (L-NOG) were measured every second week. Steroid hormone binding globulin (SHBG) levels were measured in the first and last four blood samples drawn. A linear relationship between the logarithms of L-NOG concentrations and duration of use was found, indicating an exponential character of decrease in L-NOG levels during the study year. An average of 72% of the mean initial levels of L-NOG was found in the circulation after 6 months' and 52% after one year's use. The L-NOG levels decreased daily by 1.1 pmol/l (0.13%) on the average. The SHBG levels were not influenced by the long-term exposure to L-NOG. The initial SHBG levels were significantly correlated (r = 0.88; P less than 0.001) to the initial L-NOG levels. The rings were well tolerated. Only in two of the ten subjects did the average number of bleeding days per month increase from a pretreatment value of 4.5 days per month to 8.3 and 9.5 days per month, respectively.

Administration, Intravaginal↗
PubMed1992

Pharmacokinetics of ethinylestradiol and levonorgestrel after administration of two oral contraceptive preparations.

Serum concentration profiles and pharmacokinetic parameters (cmax, tmax, AUC24, AUC0-00, MRT) of ethinylestradiol (EE2) and levonorgestrel (LNG) were obtained following administration of two combined oral contraceptives. The constituents of the preparations were as follows: Gravistat (0.05 mg EE2, 0.125 mg LNG); Minisiston (0.03 mg EE2, 0.125 mg LNG). In 20 of the volunteers blood samples were taken before and up to 36 hours following the intake of a single table. In 11 women the investigation was carried out at day 21 of a treatment cycle (steady-state condition). In spite of pronounced interindividual variations of the pharmacokinetic data, a clear dependency of EE2 concentration curves on the estrogen dose of the respective preparation could be demonstrated. Under the condition of steady-state (21st day of administration) there was a slight but significant rise of the EE2 peak serum concentrations and a pronounced increase of the LNG levels, closely reflected by elevation of the AUC values. SHBG serum concentration was significantly increased by the 10th day of treatment in all subjects receiving Gravistat, whereas the mean value in the Minisiston-group did not remarkably change. Although LNG is known to be bound to SHBG with high affinity, the missing parallelism between LNG- and SHBG-concentrations suggests other (additional?) mechanisms for the elevated LNG-binding capacity in women taking combined EE2-LNG preparations.

Administration, Oral↗
PubMed1982

The effects of ampicillin on oral contraceptive steroids in women.

1 Thirteen women taking long term oral contraceptive steroids were studied while taking ampicillin (500 mg three times daily) and compared to a control cycle while not taking ampicillin. 2 There were no significant changes in the plasma concentrations of ethinyloestradiol, levonorgestrel, follicle stimulating hormone or progesterone, although lower concentrations of ethinyloestradiol were noted in two women. 3 We conclude that most patients taking oral contraceptive steroids do not need to take alternative contraceptive precautions while taking ampicillin.

Adult↗
PubMed1982

Tissue concentrations of levonorgestrel in women using a levonorgestrel-releasing IUD.

Thirteen women who were scheduled for hysterectomy volunteered for the study. Nine women had a levonorgestrel-releasing intrauterine contraceptive device inserted between 36 and 49 days prior to surgery and four women were on oral levonorgestrel treatment for 7 days prior to surgery. After the surgical removal of the uterus, samples of endometrial, myometrial, fallopian tube and fat tissue were obtained. Methods for measuring tissue concentrations of levonorgestrel were developed and the uptake of levonorgestrel by fat tissue in vitro was studied. The concentrations of levonorgestrel in myometrial, fallopian tube and fat tissue were all of the same order, of between 1 and 5 ng/g of wet weight of tissue, in both the intrauterine device group and the orally treated group. In the endometrium the levonorgestrel concentrations were many-fold higher in the intrauterine device group. The in vitro experiments showed a rapid uptake of levonorgestrel and an unsaturability of the fat tissue by the steroid at the concentrations used. The fat tissue concentrations of levonorgestrel correlated with the plasma concentrations.

Adipose Tissue↗
PubMed1991

Pharmacokinetics of levonorgestrel in 18 women after 1 month of treatment with a triphasic oral contraceptive.

A triphasic levonorgestrel (LNG)- and ethinylestradiol-containing oral contraceptive was administered to 18 women. Plasma samples were obtained throughout a treatment cycle just before drug administration and on the last treatment day (day 21), several plasma samples were collected from each individual up to 48 h postadministration. LNG was determined by radioimmunoassay in all plasma samples. In addition, the concentration of sex-hormone-binding globulin (SHBG) was determined in plasma samples collected from the same subjects during treatment, as well as during a pre- and a posttreatment cycle. During the treatment cycle, plasma levels of LNG determined just before drug administration increased and reached steady state at about day 16. This increase was due to an increased dose of LNG according to the triphasic dose regimen, a concomitantly ethinylestradiol-induced increase in SHBG and due to pharmacokinetic accumulation, since LNG had a terminal half-life of approximately 28.5 h and the dosing interval was 24 h. Steady-state levels and pharmacokinetic parameters of LNG determined on the last day of treatment were in good accordance with previously published results.

Adolescent↗
PubMed1982

Plasma progesterone levels during long-term treatment with levonorgestrel silastic implants.

Plasma progesterone levels were measured in 113 women using a subdermal implant containing 200 mg levonorgestrel (NORPLANT) in an attempt to assess the roles of anovulation and inadequate luteal function in the contraceptive action of this method. Twenty-two women using an IUD (Copper T 200) served as a control group. Blood samples were taken twice a week for 6 consecutive weeks. This was done one to four times in each subject during the first 7 years after insertion of NORPLANT. Plasma progesterone was measured by a specific RIA and criteria based upon normal values in this laboratory were used to define each set of samples as ovulatory, uncertain or anovulatory. The rate of anovulation varied between 25 and 80% throughout the 7 years. The highest rate was observed during the first year of treatment of treatment. The rate of anovulation was significantly correlated with the plasma levels of levonorgestrel. Varying degrees of inadequate corpus luteum function were detected among NORPLANT users. All sets of samples in the control group were ovulatory and compatible with normal luteal function. These results clearly show that continuous administration of levonorgestrel by means of NORPLANT interferes with ovulation and/or luteal function in a significant proportion of cycles throughout the first 7 years of use.

Adult↗