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.

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.

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.

Morphometric study of the human endometrium following continuous exposure to levonorgestrel released from vaginal rings during 90 days

The effects of vaginal devices releasing levonorgestrel (LNG) at a constant rate of approximately 20 micrograms/24 hrs on the human endometrium were studied in a group of 69 normally menstruating women during a period of 90 days of continuous use. Peripheral blood samples were withdrawn three times weekly starting at day 10 of a pretreatment (control) cycle and then three times weekly from day 60 to 90 of the treatment period. The levels of LNG, estradiol, progesterone and sex hormone binding globulin (SHBG) were analyzed by radioimmunoassay techniques. Endometrial biopsies were obtained in the luteal phase of the pretreatment cycle and on day 84-87 of the treatment period. Increased bleeding occurred in most subjects exposed to the LNG-releasing device; the mean number of bleeding and spotting days was 26.4 +/- 8.9 S.D. which exceeded that found in their control cycle. Morphometric analyses of the endometrial biopsies using 9 quantitative indices, revealed highly significant changes in glands and stroma following the use of the LNG-releasing vaginal device. Irrespective of the circulating steroid levels, the administration of LNG significantly diminished the glandular diameter (p less than 0.001), reduced the volume density of the glands (p less than 0.001) and of the glandular epithelium (p less than 0.001). and modified the ratio glandular epithelium: glands (p less than 0.001). It is concluded that levonorgestrel released at a rate of 20 micrograms/24 hrs, induces characteristic changes in the histologic structure of the human endometrium. Although no simple correlation has been found between any of the endometrial indices and the numbers of bleeding/spotting days or bleeding days, the changes as such may represent biochemical alterations which could be predisposing factors for intermenstrual bleeding and spotting. To prove a causal relationship between morphological and biochemical changes and changes in bleeding patterns, further in-depth studies may be required.

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.

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.

Ovarian function during use of a levonorgestrel-releasing IUD

Ovarian function was studied for two complete menstrual cycles in 9 regularly menstruating women and for 8 weeks in three amenorrhoeic women who had used levonorgestrel-releasing IUDs (LNG-IUD) for more than four years. Nine patients using copper IUDs (Nova-T) were studied for two complete menstrual cycles as controls. According to progesterone levels, 15/17 cycles in women using LNG-IUDs were ovulatory, whereas only 8/17 cycles showed normal follicular growth and rupture as judged by ultrasound. In ovulatory cycles, the peak progesterone levels were lower than in the controls. The preovulatory estradiol and LH peak levels were also lower than in control subjects. SHBG levels were lower in LNG-IUD users than in copper IUD users. It is concluded that, although the dose of levonorgestrel released from the IUD is very low, it probably exerts an effect on the gonadotrophin secretion, which disturbs follicular development in many of the women studied, which in addition to the local effect on the endometrium, contributes to its high contraceptive efficacy.

Clearance of levonorgestrel from the circulation following removal of NORPLANT subdermal implants

The disappearance of levonorgestrel from plasma after the removal of NORPLANT subdermal implants was studied in 12 women who had been treated from 5.5 to 78 months. The existence of one or two half-lives for the rate of disappearance was assessed. The influence of body weight, body fat and length of treatment upon levonorgestrel clearance was studied through stepwise regression analysis. It was found that the levonorgestrel decay rate after implant removal can be entirely accounted assuming one half-life of 42 +/- 16 h (mean +/- SD; range 13 to 62 h). Stepwise regression analysis showed that levonorgestrel half-life is positively correlated with body weight and not significantly correlated with the length of treatment or body fat. It is concluded that, after long-term administration of levonorgestrel via subdermal implants, the major part of the steroid is cleared from plasma within 96 h and that only trace amounts are detected in the following days.

Estradiol plasma levels during long-term treatment with Norplant subdermal implants

Estradiol-(E2) plasma levels were assessed in forty-seven women treated for one through seven years with the same set of Norplant implants. Each woman was subjected to one (n = 34), two (n = 11) or three (n = 2) sampling runs. At each sampling run, blood samples were drawn every third or fourth day during 5 or 6 consecutive weeks. Sampling runs were classified as ovulatory (n = 11), anovulatory (n = 49) or uncertain (n = 1) according to progesterone levels. Controls were Copper T users (n = 8), all classified as ovulatory. No significant differences were found for the mean E2 levels between Norplant users and Copper T users and between ovulatory and anovulatory cases. The mean of the peak E2 value found in each sampling run was significantly higher in anovulatory Norplant subjects than in the control group. The mean of the minimum E2 level observed was significantly lower in Norplant cases than in Copper T users. A single woman from the Norplant group and none from the Copper T group had all E2 values below 370 pmol/l. The inhibition of the reproductive function induced by Norplant implants is associated with a wider range of E2 circulating levels. None of the values observed at the extremes should cause serious concerns. High peaks are transitory and opposed by the antiestrogenic effect of levonorgestrel. Persistent low levels which could be associated with a hypoestrogenic state were observed in a single case.

Selectivity in progesterone and androgen receptor binding of progestagens used in oral contraceptives

The relative binding affinities (RBAs) of four progestational compounds (norethisterone, levonorgestrel, 3-keto-desogestrel and gestodene) for the human progesterone and androgen receptors were measured in MCF-7 cytosol and intact MCF-7 cells. For the binding to the progesterone receptor, both Org 2058 and Org 3236 (or 3-keto-desogestrel) were used as labelled ligands. The following ranking (low to high) for the RBA of the nuclear (intact cells) progesterone receptor irrespective of the ligand used is found: norethisterone much less than levonorgestrel less than 3-keto-destogestrel less than gestodene. The difference between the various progestagens is significant with the exception of that between 3-keto-desogestrel and gestodene, when Org 2058 is used as ligand. For the cytosolic progesterone receptor, the same order is found with the exception that similar RBAs are found for gestodene and 3-keto-desogestrel. The four progestagens clearly differ with respect to binding to the androgen receptor using dihydrotestosterone as labelled ligand in intact cells; the ranking (low to high) is: norethisterone less than 3 keto-desogestrel less than levonorgestrel and gestodene. The difference between 3-keto-desogestrel and levonorgestrel or gestodene is significant. The selectivity indices (ratio of the mean RBA for the progesterone receptor to that of androgen receptor) in intact cells are significantly higher for 3-keto-desogestrel and gestodene than for levonorgestrel and norethisterone. From these results we conclude that the introduction of the 18-methyl in norethisterone (levonorgestel) increases both the binding to the progesterone and androgen receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetic study of levonorgestrel used as a postcoital agent

The pharmacokinetics and pharmacodynamics of levonorgestrel (LNG) were studied in six women given 0.75 mg LNG orally for seven days during the periovulatory phase of the menstrual cycle. Steady-state concentrations of LNG were reached within three days and serum LNG concentrations at various times on day 7 were generally lower than on day 1, presumably due to a reduced serum level of SHBG. On day 7 the volume of distribution was significantly increased and Co significantly decreased and both the clearance and elimination half-life were higher on day 7 than on day 1. Half-lives varied from 5.6 to 25.1 hours. The day-to-day intra-subject variations in serum LNG concentrations ranged from 23% to 80%. Serum concentrations of pituitary and ovarian hormones suggested that ovulation was not inhibited in four of the six subjects and was delayed in the remaining two. No significant changes in serum prolactin levels were observed.

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.

Pharmacokinetics of oral contraceptive steroids in Egyptian women: studies with Ovral, Nordette and Norminest

Plasma concentration profiles and pharmacokinetic parameters have been obtained following single dose administration of three commonly used oral contraceptive steroid preparations, Ovral, Nordette and Norminest to Egyptian women. The constituents of the preparations are as follows: Ovral (50 micrograms ethinyloestradiol, EE2 and 500 micrograms levonorgestrel, LNG); Nordette (30 micrograms EE2 and 150 micrograms LNG); and Norminest (35 micrograms EE2 and 500 micrograms norethisterone, NOR). Peak plasma concentrations of EE2 ranged between 116-160 pg ml-1 for Ovral, 55-78 pg ml-1 for Norminest and 30-70 pg ml-1 for Nordette. There was no significant difference in half-life (t1/2), oral clearance (CL) or apparent volume of distribution (Vd). The relative values of the area under the plasma concentration-time curve (AUC) reflected well the different amounts of oestrogen in each preparation. There was no significant difference in t1/2, CL or Vd for LNG in the 2 preparations containing this progestogen. The mean AUC following Nordette (150 micrograms LNG) was 40% of that following Ovral (500 micrograms LNG; p less than 0.001). Comparing pharmacokinetic parameters for the same dose of LNG (Ovral) and NOR (Norminest) showed the AUC to be decreased and CL and Vd increased in the latter group. The study indicates that the kinetic profile of the OCS in healthy Egyptian women are similar to other ethnic populations.

Enhanced metabolism of levonorgestrel during phenytoin treatment in a woman with Norplant implants

A 26-year-old woman, treated with phenytoin for 10 years because of epilepsy, had Norplant subdermal implants inserted after a legal abortion. She became pregnant again after nine months of Norplant use. Her plasma levonorgestrel (LNG) levels were followed during one month during phenytoin treatment and then later during one month after discontinuation of phenytoin. During phenytoin treatment, plasma LNG levels were markedly below the levels found in healthy women with Norplant. There was a pronounced, statistically significant increase in plasma LNG levels after discontinuation of phenytoin. The plasma levels of sex hormone binding globulin were markedly above those found in normal healthy women during treatment with phenytoin and decreased significantly after cessation of phenytoin. The effects on the pharmacokinetics of LNG were reflected by effects on the menstrual cycle. During phenytoin treatment, the woman had regular ovulatory menstrual cycles. After cessation of phenytoin, her cycles became irregular and during the study period of one month, no signs of ovulation were found. It is concluded that treatment with phenytoin during use of Norplant subdermal implants enhances the metabolism of LNG to an extent where the contraceptive efficacy is endangered.

The bioavailability of ethinyloestradiol and levonorgestrel in patients with an ileostomy

The bioavailability of ethinyloestradiol and levonorgestrel has been studied in 5 young women with an ileostomy following surgery for ulcerative colitis and compared to that in 5 control subjects. Single i.v. and oral doses of both drugs were administered and the bioavailability calculated from the ratio of the two areas under the plasma concentration versus time curve for the two drugs. The mean bioavailability of ethinyloestradiol in the patients with an ileostomy was 55.4 +/- 10.9% (+/- S.D.) compared to a control value of 45.0 +/- 6.1% (p greater than or equal to 0.1). The mean bioavailability of levonorgestrel in the ileostomy patients was 85.2 +/- 13.1% compared to 104.6 +/- 22.3% in the controls (p greater than or equal to 0.1). Women who have an ileostomy following lower bowel surgery can rely on their oral contraceptive preparations being absorbed in the normal way.

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.

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)

The interaction between sex hormone binding globulin and levonorgestrel released from vaginal rings in women

The levels of levonorgestrel (L-NOG), progesterone and estradiol were measured in plasma samples of 17 normally menstruating women during a control cycle and during a subsequent period (90 days) with a L-NOG-releasing vaginal ring. During days 38-66 after the insertion of the vaginal ring the concentrations of sex hormone binding globulin binding sites (hereafter: SHBG levels) were also assayed. Significant correlations were found not only between the corresponding levels of SHBG and L-NOG during exposure to the latter compound (r = 0.44; P less than 0.05), but also between the levels of SHBG in the control cycle and the levels of L-NOG measured during exposure (r = 0.60; P less than 0.01). Furthermore, the decrease in SHBG levels during the vaginal administration of L-NOG was directly proportional to the levels of SHBG in the pretreatment cycle (r = 0.64; P less than 0.01). A significant relationship was found between the levels of L-NOG (and, hence - indirectly - the levels of SHBG) and the degree of suppression of ovarian function. Thus the levels of L-NOG were lower (P less than 0.01) in the subjects (n = 8) with an apparently normal or partially suppressed ovulatory-like pattern of progesterone than in those subjects (n = 9) in whom progesterone levels were completely suppressed.

Hormonal consequences of missing the pill during the first two days of three consecutive artificial cycles

The hormonal effects of the deliberate omission of a low-dose combined oral contraceptive pill (30 micrograms ethinyl estradiol + 150 micrograms levonorgestrel) during the first two days of three consecutive artificial cycles were studied in 10 women. The plasma levels of estradiol, progesterone, levonorgestrel and--whenever justified--of LH were measured three times weekly (Mondays, Wednesdays and Fridays) throughout a 90-day period, and the ovarian reaction to the prolongation of the pill-free period from 7 to 9 days was assessed. One subject (with a premature LH surge) showed a marked follicular and an inadequate luteal activity in 2 of 3 cycles. The remaining cycles were characterized by a varying degree of follicular activity associated with the absence of any luteal function. None of the subjects exhibited peripheral steroid levels indicating a normal ovulatory cycle. The results are interpreted as suggesting that repeated prolongation of the pill-free period from 7 to 9 days might result in a gradual increase in ovarian activity.

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.

Ovarian function in amenorrheic and menstruating users of a levonorgestrel-releasing intrauterine device

The ovarian function of 20 healthy users of a levonorgestrel-releasing intrauterine device was studied by measurements of plasma estradiol, progesterone, and levonorgestrel concentrations. Eight subjects were amenorrheic, and 12 had regular menstrual bleeding. Seventy-five percent of the subjects in both groups had ovulatory cycles. There was no difference between the mean levonorgestrel concentrations in the amenorrheic and regularly menstruating subjects. Estradiol function was undisturbed in the amenorrheic subjects with ovulatory cycles. The effect of levonorgestrel as a cause of amenorrhea is thought to be mainly of local nature. The intrauterine administration of levonorgestrel had only an occasional and weak effect on ovarian function.

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.

Release rates of levonorgestrel from Silastic capsules, homogeneous rods and covered rods in humans

Three forms of subdermal implants containing levonorgestrel are described. These are: capsules, in which the powdered drug is sealed inside of lengths of Medical Grade Silastic tubing; homogeneous rods, in which the drug is uniformly dispersed in Silastic 382 Medical Grade Elastomer; and covered rods, in which a core rod of drug and filler-free polydimethylsiloxane polymer (50:50, Wt:Wt) are sealed inside thin-walled Silastic tubing. Long-term in vivo release rates from human subjects are presented; 6.5 years for capsules, 3.6 years for homogeneous rods and 4 years for covered rods. Sets of six capsules release a decreasing amount of drug through the first few hundred days in situ and after 500 days a fairly constant rate of about 35 micrograms per day is released (2 micrograms/cm). Homogeneous rods deliver a continuously declining amount of drug during the entire time studied. In the first 100 days the release averages 136 micrograms per day from a set of three 3-cm rods (15 micrograms/cm), gradually declining to 30 micrograms per day (3.3 micrograms/cm) from day 800 to day 1300. The covered rods deliver at a constant rate of 17.5 micrograms per day for a 3-cm rod (5.83 micrograms/cm) through 4 years.

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.

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.

Pharmacokinetics of levonorgestrel in Indian women

A low dose combination pill containing levonorgestrel 150 micrograms and ethynylestradiol 50 micrograms was administered orally to 13 women. Based on their anthropometric index they were classed as well-nourished (Group A) or undernourished (Group B). Plasma levels of levonorgestrel at various intervals after dosing were analysed by a specific radioimmunoassay and its pharmacokinetic parameters were computed. Peak plasma levels in both groups occurred within 2 h and the absorption half-lives were also similar. The decline in plasma levonorgestrel showed a tri-exponential decline in all Group A women, whereas it was biphasic in most of Group B. The pi t1/2 was lower in Group A women and the alpha-phase was found to be negligible in Group B. A significant positive correlation between elimination half-life (beta t1/2) and some of the anthropometric indices suggests a possible role of nutritional status in the metabolic handling of levonorgestrel.

Pharmacokinetic and pharmacodynamic investigations with vaginal devices releasing levonorgestrel at a constant, near zero order rate

The pharmacokinetic and pharmacodynamic effects of vaginal devices releasing levonorgestrel (L-NOG) at a constant rate (in vitro release: approximately 20 micrograms/day) were studied in a group of 20 normally menstruating women during a period of 90 days of continuous use. Peripheral blood samples were withdrawn two or three times (in the great majority of subjects, on Mondays, Wednesdays and Fridays) during a pretreatment (control) cycle, during 90 days of exposure and during the first week following the removal of the device, and the levels of L-NOG, estradiol and progesterone were analyzed by radioimmunoassay techniques. In 8 of these subjects, endometrial biopsies were also taken during days 23 to 25 of the control cycle, and then 6 and 10 weeks following the insertion of the devices. In addition, the initial absorption rate and removal half-life of L-NOG were assessed in 7 subjects using the devices for a period of 8 days only. Following insertion of the devices, the levels of L-NOG rose very rapidly, and reached the final "plateau" in some 30 minutes' time. This was followed by a limited period of "burst" with doubling the levels for a few hours, after which the levels remained stable and diminished very slowly in a linear fashion with an average decline of 23-26% during 90 days, corresponding to a daily decrease of 0.2 to 0.3 per cent. The removal half-life (first compartment) after 90 days of exposure in 19 subjects was 16.1 (13.7-18.6) hours. Sixty-nine treatment segments of 30 days were studied with frequent hormone assays; of these, 20 (or 29%) were anovulatory, 13 (19%) exhibited inadequate luteal function, and 32 (52%) had normal ovulatory-like cycles. All endometrial biopsies obtained during the pretreatment cycle were normal secretory; of the 16 biopsies obtained during treatment, 4 were suppressed, 2 proliferative, 6 secretory, and 4 could not be dated because of bleeding. An assessment of the bleeding profiles during exposure to L-NOG revealed almost a doubling of the number of days with bleeding and spotting (35% compared to 18% during the pretreatment cycle). However, significantly more frequent bleeding was found in the 20 anovulatory segments (37.3%) than in the 36 normal ovulatory-like ones (27.7%). It is concluded that differences in the frequency of bleeding and spotting with low-dose progestogens may reflect differences in the frequency of ovulation inhibition just as much as differences in the hormonal profiles of the compounds administered.

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.

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.

The effect of ethinyl estradiol 20 mcg and levonorgestrel 250 mcg on the pituitary-ovarian function during normal tablet-taking and when tablets are missed

A new combined pill containing 20 micrograms of ethinyl estradiol and 250 micrograms of levonorgestrel has been developed. The safety margin of this type of low-dose preparation needed to be assessed and this was done by evaluating daily levels of LH, FSH, estradiol, progesterone, 1-NG and EE2 as well as cervical mucus characteristics in six patients when one and then two consecutive pills were deliberately omitted mid-way through the cycle. Results demonstrated that there was no evidence of breakthrough ovulation, although there was some continued ovarian steroidogenesis, a feature consistent with previous studies using combined preparations. Existing instructions to patients regarding missed pills should continue in order to ensure maximal contraceptive safety.

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.

The effect of levonorgestrel and estrone rods on male reproductive function

The effect on spermatogenesis of the implantation of six rods containing levonorgestrel and three estrone rods was studied in seven volunteers aged 32-40, with normal pre-treatment spermiogram. None of the subjects achieved azoospermia. The lowest sperm count was below 1 million/ml in three subjects and below 12 million/ml in the other four. Plasma FSH and testosterone were severely depressed during the study, but LH was only transiently depressed for the first two months. Four subjects recovered pre-treatment sperm counts in spite of the FSH levels below 1.5 mIU/ml and testosterone levels below 1 ng/ml, which is contradictory to the current concept on hormonal regulation of spermatogenesis.

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.

Sex hormone levels and intestinal absorption of estradiol and D-norgestrel in women following bypass surgery for morbid obesity

A report of reduced serum levels of progestins, following oral administration after jejunoileal bypass, promoted the present investigation of the absorption of D-norgestrel and estradiol following different types of intestinal bypass surgery for morbid obesity. A group of non-operated obese patients served as control. Apart from significantly higher gonadotrophin levels, which could be attributed to periovulatory sampling in the non-operated group, there was no significant differences in basal levels of estradiol, estrone, conjugated estrone, androstendione, testosterone, and progesterone. The operation did not influence the pattern of the menstrual cycle. Following a single oral dose of 4 mg micronized estradiol and 125 microgram D-norgestrel, serum levels of estradiol and estrone were equal in the three groups. serum D-norgestrel was equal in the two operated groups, but was significantly higher in the bypass group with 1:3 jejunoileal ratio, compared with the non-operated group. Further, a significant negative correlation between peak levels and weight was found. It is suggested that one year following bypass surgery, obesity - but not intestinal bypass - might be associated with reduced serum levels of exogenous sex steroids following oral administration.

Comparison of the metabolic effects of two hormonal contraceptive methods: an oral formulation and a vaginal ring. II. Serum lipoproteins and apolipoproteins

In a long-term, prospective study the effects on lipoprotein lipids and apolipoproteins (apo) of a combined oral contraceptive (OC) (30 micro gram ethinylestradiol and 150 micro gram levonorgestrel) and a contraceptive vaginal ring (CVR) releasing estradiol (about 180 micro gram per day) and levonorgestrel (about 290 micro gram per day) were compared. The two treatments induced significantly different effects. In the OC group the lipoprotein-lipid concentrations showed only minor changes, but apolipoproteins (apo) B and A-I increased by about 15%. In contrast, during treatment with the CVR there was a 25% decrement of cholesterol in high density lipoprotein (HDL) and at most 10% in low density lipoprotein (LDL) cholesterol, with only minor effects on apo B and A-I. The ratio of LDL and HDL cholesterol increased in the CVR group but not in the OC group. The results also indicate a change in the composition of the LDL and HDL particles, with an altered lipid/protein ratio, during both contraceptive treatments. Despite the impressive relative increase in LDL:HDL ratio in the contraceptive ring group, the average absolute value of this ratio did not reach the mena for healthy men.

Clinical and endocrinologic study of continuous levonorgestrel administration from subcutaneous solid polydimethylsiloxane rods

Three solid polydimethylsiloxane (Silastic) rods containing levonorgestrel were inserted into the subcutaneous tissue of the volar aspect of the forearm of 8 women. Serum samples were drawn three times a week for 2 months and weekly thereafter for 2 years in 3 of the subjects. The other subjects had serum drawn during the twelfth and last treatment months. Levonorgestrel, estradiol and progesterone were measured in all samples. The subject kept a bleeding record. In comparison to an earlier clinical trial in which 6 hollow capsules of Silastic filled with levonorgestrel were used, the 3 solid levonorgestrel-containing rods provided higher serum levels of levonorgestrel, fewer serum estradiol peaks, only a single episode of ovulation and better bleeding performance.

Levonorgestrel plasma concentrations and hormone profiles after insertion and after one year of treatment with a levonorgestrel-IUD

Plasma concentrations of levonorgestrel, progesterone, estradiol, FSH and LH were measured in seven volunteers who had a levonorgestrel-releasing IUD inserted postmenstrually. Blood samples were collected twice weekly during a mean of 93 days immediately postmenstrually and during a mean of 41 days over the twelfth to fifteenth month of treatment. Patterns of bleeding were studied during the first year of treatment. The IUDs used were designed to release 25 micrograms/day of levonorgestrel. The mean +/- SD plasma concentration of levonorgestrel for all subjects during the first three months was 260 +/- 68 pg/ml, and 129 +/- 28 pg/ml after one year of treatment. During the initial period of blood sampling only two of the subjects ovulated, while only two did not ovulate after one year of treatment. Intermenstrual spotting occurred during the first sixty days of treatment. Three subjects developed amenorrhea at the end of the first year. All the subjects continued the use of the IUD and no pregnancies occurred.

Release of 19-nor-testosterone type of contraceptive steroids through different drug delivery systems into serum and breast milk of lactating women

The release of contraceptive steroids through different drug delivery systems into serum and breast milk was investigated in a group of lactating women. Four women in each group were taking either a low dosage progestogen compound like norethisterone (NET) 350 micrograms or d-norgestrel (d-Ng) 50 micrograms alone or low dosage combination pills containing NET 1 mg or d-Ng 150 micrograms with 30 micrograms ethinyl estradiol (EE2) or a biodegradable implant containing 25 mg NET or d-Ng. Peak levels in plasma and milk were seen in oral contraceptive users around 2 hours. Of the two low dosage progestogen compounds, d-Ng was below the detection limit in milk within 4 hours whereas NET was still detectable at the 24-hour interval. In contrast to this, because of the larger quantity of steroids in the combination pills, the NET/d-Ng levels in serum as well as in milk were high throughout the 24-hour period. With the subdermal route because of the sustained low release of the drug from the biodegradable implants, the levels in milk were below the detection limit within a day with d-Ng and within a week with NET.

First year clinical experience with six levonorgestrel rods as subdermal contraception

Previous clinical experience with six levonorgestrel subdermal capsules showed a very good contraceptive effectiveness and continuation rate, but with a high proportion of bleeding disturbances, particularly of increased bleeding. It was hypothesized that bleeding could be reduced by higher plasma levels of the steroid, using subdermal rods instead of capsules, as rods have been shown to have a release rate 3 or 4 times that of the capsules. Fifty volunteers were enrolled in a study of the clinical performance of 6 subdermal levonorgestrel rods. Results were compared with a previous experience with 100 volunteers who wore 6 levonorgestrel capsules for a year in the same clinic. Requirement for volunteers to enter the study were the same for capsules and rods. The proportion of women wearing 6 subdermal rods who had increased bleeding was about one half as for the women using 6 levonorgestrel capsules. On the other hand, women using rods had about twice the incidence of amenhorrea, and about four times more hypomenorrhea (4 days or less of bleeding in a 90-day period). There were no pregnancies among the rod users and the discontinuation rate for medical reasons was not higher than for capsule users in the same clinic.