Relation between sex hormone binding globulin and D-norgestrel levels in plasma

Emerging evidence on oral contraceptives and arterial disease

A number of case-control studies published in recent years have shown an apparent increase in the risk of venous thromboembolism (VTE) associated with the use of third-generation oral contraceptives (OCs) compared with second-generation OCs. However, it is thought that these studies were subject to a number of biases that would have increased the risk estimates for third-generation OCs while lowering those for second-generation preparations. Data on the risk of ischemic stroke and myocardial infarction (MI) show no such difference between generations of OCs, with a statistically significant reduction in the risk of acute MI from first- to third-generation in one major study. Available results indicate that there is no significant increase in the risk of ischemic stroke or acute MI associated with the use of low-dose estrogen OCs in young women who are properly screened before use, and who have no pre-existing cardiovascular risk factors, such as smoking and hypertension, for these conditions. These findings should be taken into account when interpreting the results of studies on the risk of VTE in women taking combined OCs.

Myocardial infarction and stroke in young women: what is the impact of oral contraceptives?

Recent discussions have centered on the small apparent risk increase for venous thromboembolism found with newer oral contraceptives (third-generation oral contraceptives containing the progestins desogestrel and gestodene) compared with older oral contraceptives (second-generation). This article reviews the studies addressing the association between oral contraceptive use and thromboembolic conditions affecting the arterial system, ischemic stroke, and myocardial infarction. Differences are found between a US database study, which showed no risk of ischemic stroke or myocardial infarction associated with low-dose oral contraceptive use, and the European studies, which showed oral contraceptive use in general to be associated with increased risks of ischemic stroke and myocardial infarction. The European studies showed no difference between oral contraceptive generations with respect to the occurrence of ischemic stroke; however, the risk of myocardial infarction associated with oral contraceptive use was consistently lower for third- than for second-generation oral contraceptives. Although there seems to be no differential risk of ischemic stroke associated with oral contraceptive generations, third-generation oral contraceptives appear to be consistently associated with no excess risk of myocardial infarction. In all instances, however, cardiovascular risk factors other than oral contraceptive use play the predominant role in the occurrence of ischemic stroke and myocardial infarction.

The use of oral contraceptives and the occurrence of acute myocardial infarction in young women. Results from the Transnational Study on Oral Contraceptives and the Health of Young Women

The objective of this study was to assess the risk of myocardial infarction (MI) associated with the use of new and old combination oral contraceptives (OC). A matched case-control study in 16 centers in Germany, the United Kingdom, France, Austria, and Switzerland explored the association of current use of combination OC with the occurrence of MI. Our subjects were 182 women aged 16-44 years with MI; the controls were 635 women without MI (at least one hospital control and one community control per case) matched for 5-year age group and region. The main outcome measures were odds ratios comparing current use of a specific group of OC against current use of other groups or against no current use. The adjusted overall odds ratio (OR; 95% confidence intervals) for MI for second generation OC versus no current use was 2.35 (1.42 to 3.89) and 0.82 (0.29 to 2.31) for third generation OC (low dose ethinyl estradiol, gestodene, and desogestrel). A direct comparison of third generation users with second generation users yielded an OR of 0.28 (0.09 to 0.86). In subgroup analyses, the odds ratio for the UK alone was 1.25 (0.36 to 4.29), while for continental Europe it was 0.10 (0.02 to 0.48). For hospital controls, the risk estimated was 0.98 (0.22 to 4.44), and 0.18 (0.04 to 0.65) for community controls. The independent risk of MI among current smokers adjusted for OC use was 7.21 (4.58 to 11.36). Among users of third generation OC, the OR for current smokers was 3.75 (0.65 to 21.74) and among users of second generation it was 9.50 (2.93 to 30.96). A comparison of OC use in the UK for the time before and after regulatory action was taken in October 1995 shows that the likelihood of a control (last control accrued June 1996) being treated with second generation OC is seven times higher after 1 November 1995 than it was before. Third generation OC are the first to be associated with no excess risk of MI. A significantly lower risk of MI is found when comparing use of third generation OC with use of second generation OC. There seems to be an impressive amelioration of risk among smokers using newer OC. An impact of regulatory action in the UK was found in the OC use spectrum of controls.

Androgen levels in women using a single implant of nomegestrol acetate

This study was undertaken to evaluate the effects of a single implant containing nomegestrol acetate (Uniplant) on plasma levels of sex hormone-binding globulin (SHBG), testosterone, free testosterone, androstenedione and on blood pressure, body weight, and the development of acne vulgaris. Plasma levels of sex hormone-binding globulin, testosterone, free testosterone and androstenedione were measured. Blood pressure and body weight were determined. The development of acne vulgaris was evaluated. Total testosterone and androstenedione decreased significantly during two years of Uniplant use but all levels were within the normal range. There were no significant differences in sex hormone-binding globulin and free testosterone during 24 months of Uniplant use. All changes observed in this study were within normal range. SHBG was not affected by Uniplant use. No significant increase in androgen levels and in the development of acne vulgaris was observed in these women using nomegestrol acetate implant during two years. Based on these results, it is possible to conclude that Uniplant had no androgenic effect in women during this study.

Preclinical evaluation of norgestimate, a progestin with minimal androgenic activity

Norgestimate is a novel progestin with highly selective progestational activity and minimal androgenicity. In rabbits, norgestimate binds to uterine progestin receptors, stimulates the endometrium, and inhibits ovulation. Norgestimate acts directly on target organs, stimulating rabbit endometrium when injected into the uterine cavity and inhibiting luteinizing hormone-releasing hormone-stimulated luteinizing hormone release in dispersed rat pituitary cells in culture. Norgestimate has no estrogenic activity, and like other progestins, it suppresses the action of estrogen. Unlike some other progestins, it is relatively free of androgenic activity. Norgestimate and its 17-deacetylated metabolite demonstrate very poor affinity for androgen receptors compared with levonorgestrel and gestodene and do not exhibit androgenic activity when measured as the stimulation of prostatic growth in immature rats. Norgestimate's lack of affinity for human sex hormone-binding globulin is further evidence of its minimal androgenicity.

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.

Pharmacologic and pharmacokinetic characteristics of norgestimate and its metabolites

Biotransformation, pharmacologic, and pharmacokinetic studies of norgestimate and its metabolites indicate that 17-deacetyl norgestimate, along with the parent drug, contributes to the biologic response. The postulated metabolic pathway, which is based on the identification of urinary products had indicated that three metabolites of norgestimate, 17-deacetyl norgestimate, 3-keto norgestimate, and levonorgestrel, might participate in the response. The pharmacologic evaluation of these metabolites demonstrates that only 17-deacetyl norgestimate has a pharmacologic profile consistent with that of norgestimate, and significant concentrations of this metabolite have been measured in the serum of women after the administration of norgestimate. These studies indicate that 17-deacetyl norgestimate contributes to the pharmacologic response to norgestimate.

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.

Pharmacokinetics and pharmacodynamics of oral contraceptive steroids: factors influencing steroid metabolism

The time-dependent alterations in the serum concentrations of ethinyl estradiol, gestodene, and 3-keto-desogestrel during treatment with 30 micrograms of ethinyl estradiol + 75 micrograms of gestodene or 30 micrograms of ethinyl estradiol + 150 micrograms of desogestrel were investigated during 12 months. The levels of gestodene and 3-keto-desogestrel increased between days 1 and 21 of each cycle, reaching maximal levels during the third and sixth cycles. The serum concentrations of gestodene were fourfold to fivefold higher than those of 3-keto-desogestrel. The ethinyl estradiol levels increased significantly between days 1 and 10 during each cycle and were significantly higher by 70% during intake of ethinyl estradiol/gestodene compared with ethinyl estradiol/desogestrel, although the dose was identical. Intake of gestodene, in addition to 35 micrograms of ethinyl estradiol + 2 mg of cyproterone acetate, caused a rise in ethinyl estradiol levels. During treatment with ethinyl estradiol/gestodene and an additional 150 micrograms of levonorgestrel, there was a continuous increase in gestodene levels, although sex hormone-binding globulin level did not change. During treatment with 30 or 35 micrograms of ethinyl estradiol and 75 micrograms of gestodene, 150 micrograms of desogestrel, or 2 mg of cyproterone acetate, there were large intraindividual and interindividual variations in the steroid levels and ratios of estrogen: progestogen levels. There was no correlation with the occurrence of intermenstrual bleedings. It is concluded that ethinyl estradiol and nortestosterone derivatives may inhibit steroid-metabolizing enzymes in the liver, which results in a rise in the serum levels of contraceptive steroids. The cause of the large intraindividual variations is as yet unknown, but it is probably from changes in steroid metabolism.

Pharmacokinetics of oestrogens and progestogens

There are large inter- and intra-individual variations in the serum concentrations of natural and synthetic sex steroids irrespective of the route of administration. Oral ingestion of steroids has a stronger effect on hepatic metabolism than parenteral administration, as the local concentration in liver sinusoids are 4-5 times higher during the first liver passage. Oestradiol and oestrone are interconvertible, dependent on the local concentrations in liver and target organs, and oestrone sulphate serves as a large reservoir. The oestrone/oestradiol ratio has no physiological significance, as oestrone is only a weak oestrogen. Oestrone is both a precursor and a metabolite of oestradiol. Oestriol is extensively conjugated after oral administration. Therefore, the oestriol serum levels are similar after oral intake of 10 mg and after vaginal application of 0.5 mg oestriol resulting in similar systemic effectiveness. Conjugated oestrogens can easily enter the hepatocytes but are hormonally active only after hydrolyzation into the parent steroids. Ethinylestradiol which exerts strong effects on hepatic metabolism and inhibits metabolizing enzymes, should not be used for hormone replacement therapy. Among the progestogens, the progesterone derivatives have less effects on liver metabolism than the norethisterone derivatives (13-methyl-gonanes and 13-ethyl-gonanes). The highly potent 13-ethyl-gonanes are effective at very low doses, because of a slow inactivation and elimination rate due to the ethinyl group.

Plasma levonorgestrel levels and ovarian function during the use of a levonorgestrel-releasing intracervical contraceptive device

Levonorgestrel, estradiol and progesterone plasma concentrations were measured over four years of use of a 20 micrograms/day levonorgestrel-releasing intracervical device (LNG-ICD). The mean levonorgestrel concentration showed a slight decline, being 142 + 46 (SD) pg/ml in the third month and 81 +/- 22 pg/ml in the 48th month of LNG-ICD use. However, considerable interindividual variation in levonorgestrel plasma levels between study subjects was observed. In 77% of the monitored cycles, ovulation or a luteinized follicle was observed when judged by a plasma progesterone elevation of over 5 ng/ml. Some follicular function was also noted in anovulatory cycles. Inhibition of ovulatory ovarian function is not the mode of contraceptive action of the LNG-ICD.

Serum levels of 3-keto-desogestrel and SHBG during 12 cycles of treatment with 30 micrograms ethinylestradiol and 150 micrograms desogestrel

The serum concentrations of 3-keto-desogestrel (KDG) have been determined radioimmunologically in 11 female volunteers on Day 1, 10, and 21 of the 1st, 3rd, 6th, and 12th cycle of treatment with 30 micrograms ethinylestradiol and 150 micrograms desogestrel during the first 4 hours and 24 hours after intake. On the first day of each cycle the KDG levels were low, but increased thereafter until Day 21. Highest serum concentrations were measured on Day 21 of the 3rd and 6th cycle with peak levels between 1.5 and 6.2 ng/ml. Contrary to this, the KDG levels were significantly reduced during the 12th treatment cycle. The serum concentrations of SHBG rose significantly between Day 1 and Day 21 of each cycle reaching values which were 3-fold of those at the beginning of treatment. During the pill-free intervals, SHBG levels decreased but remained elevated as compared to controls. There was a significant correlation between the SHBG levels and the area under the KDG-concentration-versus-time curves (AUC) indicating a pronounced influence of the serum steroid-binding protein upon the pharmacokinetics of KDG. There were great interindividual differences in the KDG levels. The serum levels of the individual woman remain, however, in a relatively constant range throughout the treatment period of 12 months, possibly due to genetic factors.

Plasma levels of levonorgestrel and free levonorgestrel index in women using NORPLANT implants or two covered rods (NORPLANT-2)

Plasma levels of levonorgestrel, sex hormone binding globulin (SHBG) and estradiol were studied during four years in 283 healthy women using either NORPLANT implants or two covered rods (NORPLANT-2). The women were randomized to use either type of implant. Both implant systems have previously been shown to have similar release rates of levonorgestrel. In both groups plasma levels of levonorgestrel decreased throughout the study, and there were no statistically significant differences between the two groups in mean plasma levels of levonorgestrel. During the study 8 women became pregnant. All pregnancies but one occurred after 35 months of implant use and only in women using the covered rods. No significant differences were seen between the women who became pregnant and the rest of the group using two covered rods with respect to plasma levels of levonorgestrel. SHBG capacity tended to be somewhat higher in women using the two covered rods. As levonorgestrel is to a great extent bound to SHBG, and in that form not biologically active, a "free levonorgestrel index" was calculated as a ratio between levonorgestrel and SHBG. This index was significantly lower in users of two covered rods than in users of NORPLANT implants at 1, 12 and 48 months of use. Women who became pregnant had significantly lower "free levonorgestrel index" than had the rest of the group. It is postulated that the difference in "free levonorgestrel index" between users of the two implant systems reflect differences in release rate, the covered rods having a lower release rate of levonorgestrel than NORPLANT throughout the observation period. It is concluded that "free levonorgestrel index" is a better parameter than levonorgestrel plasma levels to describe implant function, and to discriminate women who are at risk of pregnancy.

The relative bioavailability of levonorgestrel and ethinyl estradiol administered as a low-dose combination oral contraceptive

The relative bioavailability of levonorgestrel (LNG) and ethinyl estradiol (EE) administered concomitantly both as an oral tablet and as a solution was assessed in a randomized two-period crossover study in 24 healthy women. Serum concentrations were monitored for 96 h after each administration. The relative bioavailability (Fr) of LNG in the tablet with respect to the solution was 107%; thus the two formulations were bioequivalent with respect to LNG. The relative bioavailability of EE, however, was significantly lower for the tablet (Fr 83%) compared to the solution. This difference may have been due to either decreased absorption or enhanced presystemic elimination of EE from the tablet formulation.

Androgen levels in women using Norplant implants

Plasma concentrations of sex hormone binding globulin (SHBG), testosterone, free testosterone, androstenedione (A4) and levonorgestrel were studied in 17 women before and during use of two levonorgestrel covered rods resulting in identical plasma concentrations of levonorgestrel as Norplant implants. There was a highly significant decrease in SHBG during treatment. Total testosterone and A4 also decreased significantly. Free testosterone remained unchanged. Diurnal variations were found to occur for A4, total and free testosterone, but not for SHBG or levonorgestrel. Moreover, plasma concentrations of testosterone, free testosterone, levonorgestrel and SHBG were measured in a second group of 88 women participating in a clinical study on Norplant implants, who at the one year follow-up visit either denied or claimed to have developed increased facial acne during treatment. There was no difference regarding SHBG, total testosterone, free testosterone or levonorgestrel between the groups of women with and without facial acne. However, the women in the group noticing increased acne during treatment, reported significantly more often to have had acne before treatment compared to the women who did not notice increased acne during treatment. It is concluded that treatment with Norplant implants does not result in increasing plasma levels of androgens.

Free plasma testosterone levels during the normal menstrual cycle

This report describes the free or unbound testosterone levels in ten normal females during the menstrual cycle, using a simplified technique of equilibrium dialysis of undiluted plasma. Total testosterone concentration fell progressively during the menstrual cycle, whereas the percent free testosterone increased from the follicular to the luteal phase. Free testosterone levels also fell but only significantly at the late luteal phase. For comparison two patients with anovulatory cycles were evaluated. Progesterone displacement of endogenous testosterone from its binding protein(s) was suggested by in vitro studies.

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.

Pharmacokinetic observations on ST-1435 administered subcutaneously and intravaginally

Plasma levels of ST-1435 were determined by radioimmunoassay in 36 women and three men during treatment with subdermal capsules releasing ST-1435. The total lengths of the capsules used were 180 mm, 90 mm, 30 mm, 15 mm and 7.5 mm. A linear correlation between the mean plasma concentrations of ST-1435 and capsule length was found during the treatment period studied. However, great interindividual variation in plasma levels of ST-1435 between study subjects having similar capsules was observed. In comparison with the mean plasma concentrations in the initial months, only less than half of these plasma concentrations of ST-1435 were measured after six months of treatment, which indicates a short lifetime for this contraceptive system. In two women the disappearance of ST-1435 from the circulation was studied by measuring ST-1435 concentrations in the plasma after removal of a contraceptive vaginal ring (CVR) releasing ST-1435. Triphasic disappearance curves of ST-1435 were found, with half-lives 0.7-1.0 h, 3.1-4.0 h, and 10.7.3-11.8 h.

Pituitary and ovarian function and clinical performance during the use of a levonorgestrel-releasing intracervical contraceptive device

A levonorgestrel-releasing intracervical device (ICD) was inserted postmenstrually to twenty-one voluntary women. Eight subjects gave blood samples twice a week during the initial three months of use of the ICD and during the seventh and twelfth months of use. Clinical performance was studied; plasma concentrations of levonorgestrel were measured by radioimmunoassay and the effects of the treatment on pituitary and ovarian function were determined by assaying plasma concentrations of LH, FSH, estradiol and progesterone. The results of the first year are presented. Dysmenorrhea, menstrual flow and the number of days of bleeding decreased during the first treatment year. Three spontaneous expulsions occurred; two at the very beginning of the treatment and one after six months of use. Side-effects were few. The plasma level of levonorgestrel remained fairly constant during the observation time of 12 months. Thirty-one of the 36 cycles were ovulatory as judged by plasma progesterone elevations. No pregnancies occurred during the study period of one year.

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.

Changes in unbound sex steroids and sex hormone binding globulin--binding capacity during oral and vaginal progestogen administration

Four groups of five cycling women each received either a contraceptive vaginal ring containing a combination of either levonorgestrel or norethindrone with estradiol or oral contraceptives containing a combination of either dl-norgestrel or norethindrone with ethinyl estradiol. Pretreatment as well as 2- and 7-week treatment serum samples were assayed for sex hormone binding globulin-binding capacity (SHBG-BC), estradiol, non-SHBG-bound estradiol, testosterone, and non-SHBG-bound testosterone, d-norgestrel, non-SHBG-bound d-norgestrel, and norethindrone. SHBG-BC was significantly increased in the norethindrone oral contraceptive group, unchanged in the norgestrel oral contraceptive group, and significantly reduced in both contraceptive vaginal ring groups. These findings indicate that the positive effect of oral ethinyl estradiol on SHBG-BC offsets the suppressive effects of d-norgestrel on SHBG-BC, while the estradiol in the d-norgestrel or norethindrone contraceptive vaginal rings is insufficient to alter the suppressive effect of d-norgestrel or norethindrone on SHBG-BC. In contrast, the ethinyl estradiol in the norethindrone oral contraceptive overcame the suppressive effect of norethindrone on SHBG-BC, resulting in a significantly increased SHBG-BC level. Although total circulating estradiol was significantly decreased in the contraceptive vaginal ring groups, the percentage of unbound serum estradiol was significantly increased in both contraceptive vaginal ring groups and significantly reduced in the norethindrone oral contraceptive group. Although total circulating testosterone was significantly reduced only in the norgestrel oral contraceptive group, the percentage and mass of unbound testosterone were significantly decreased in the norethindrone oral contraceptive group, while the percentage of unbound testosterone was significantly reduced in the norgestrel oral contraceptive group and significantly increased in the norethindrone contraceptive vaginal ring group. As levels of unbound (biologically active) steroid differ markedly from levels of total steroid, it is essential to measure levels of non-SHBG-bound estradiol and testosterone in order to determine effects of steroidal contraceptives on physiologically active circulating endogenous steroids.

Effects on sex hormone binding globulin of different oral contraceptives containing norethisterone and lynestrenol

Six combined oral contraceptive drugs containing ethinyloestradiol or mestranol and norethisterone or lynestrenol were studied throughout six 21-day cycles in healthy female volunteers. There was always one menstrual cycle without treatment between every treatment cycle. Plasma levels of norethisterone were determined throughout treatment by use of a specific radioimmunoassay. Sex hormone binding globulin (SHBG) was measured by an ammonium sulphate precipitation method at the beginning and at the end of each treatment cycle. The results indicated an accumulation of norethisterone in plasma when 1 to 3 mg of norethisterone or lynestrenol was given. There was no obvious accumulation during treatment with 0.5 mg norethisterone. SHBG increased during treatment with all combinations studied. However, this increase was most pronounced with the 50 microgram ethinyloestradiol/l mg lynestrenol, 50 microgram mestranol/l mg norethisterone and 35 microgram ethinyloestradiol/0.5 mg norethisterone combinations. There was no statistically significant increase in SHBG with 50 microgram ethinyloestradiol/2.5 mg lynestrenol or 50 microgram ethinyloestradiol/3 mg norethisterone acetate combinations. The results indicated that the induction of SHBG by the synthetic oestrogens was antagonized by the progestogens in a dose-dependent manner. The effect on SHBG by a combind preparation could be one assessment of the oestrogenicity or androgenicity of the preparation.

Effects of progestin-estrogen combination and progestational contraceptives on pituitary gonadotropins, gonadal steroids and sex hormone-binding globulin

The effects of three kinds of hormonal contraceptives on the levels of follicle-stimulating (FSH), luteinizing hormone (LH), estradiol, progesterone, testosterone, and sex hormone-binding globulins (SHBG) in three groups of normally menstruating women were analyzed. During the administration of a very low-dose combination of 150 micrograms of D-norgestrel and 30 micrograms of ethinylestradiol, a progressive suppression of LH, FSH, estradiol, and (to a lesser extent) testosterone levels was observed while progesterone stayed at levels found during the early follicular phase. SHBG levels in these subjects were within the normal range for women. Oral treatment with 0.5 mg of lynestrenol and the intramuscular administration of 200 mg of norethindrone enanthate produced a suppression of LH but not FSH in all cases. Estradiol levels showed peaks in the three women treated with lynestrenol and in half of those treated with norethindrone enanthate, suggesting follicular activity caused by the unsuppressed FSH stimulus; the subsequent elevation of progesterone in two subjects suggested some luteinization, although there was no evidence of an ovulatory surge of gonadotropins. The SHBG in four subjects treated with norethindrone enanthate fell within our normal range for men, and the mean serum testosterone levels fell 40% below the normal basal levels in these cases.

Serum concentrations of estrone, androstenedione, testosterone and sex-hormone-binding globulin in postmenopausal women with breast cancer and in age-matched controls

The concentrations of estrone (E1), androstenedione (A), testosterone (T) and sex-hormone-binding globulin (SHBG) in the serum were determined in 122 postmenopausal women, unselected with respect to age and stage of disease and with a newly diagnosed breast cancer. The results were compared with those in 122 age-matched women without breast cancer, selected from the population register. The patients were found to have a significantly higher mean level than the controls of E1 (132 and 108 pmol/l), A (2.5 and 1.6 nmol/l) and T (1.54 and 1.38 nmol/l) and a lower level of SHBG (40.2 and 47.3 nmol/l) in the serum. A multiple regression analysis revealed in the control group that the serum level of E1 was significantly correlated to A (r = 0.48, p less than 0.001) and T (r = 0.45, p less than 0.001). In the patient group E1 was only slightly correlated to T (r = 0.25, p less than 0.01) and not to A (r = 0.10, p greater than 0.05). A significant negative correlation was found between SHBG and weight in both groups. Otherwise no significant correlations were found between any of the hormone levels and age, stage of disease of weight. It was concluded that an increased availability of A and T, leading to an increased androgenic stimulation--and therefore decreased SHBG--and an increased E1 level, is the most reasonable explanation for the findings. The lack of correlation between E1 and A in the patient group is however difficult to explain and the results do not seem to fit into a definite hypothesis.